WFITN2022_Abstract_SY_Oral_ePoster (2025)

S03-1

Rupture sites in multilobed cerebral aneurysm are associated withrelative flow stagnation and elevated local viscosity

Tamer Hassan¹, khalidSaqr², Dalia Ibrahim³, AmrAbdelkerim³

¹Department of Neurosurgery, Alexandria University School ofMedicine, Azarita Medical Campus, Alexandria 21514, Egypt

²College of Engineering and Technology, Arab Academy for Science,Technology and Maritime Transport, El-Alamein Campus, Alexandria 1029,Egypt

³Department of Radiodiagnosis, Alexandria University School ofMedicine, Azarita Medical Campus, Alexandria 21514, Egypt

Background and purpose: Guided and validated by intraoperativephotography, we propose novel hemodynamic parameters that can explain thevisible pathology of ruptured multilobed cerebral aneurysm and identify therupture site.

Materials and methods: A cohort of 15 multilobed cerebralaneurysm (ML-CA) cases, all ruptured and surgically clipped, were subjectedto DSA-based computational fluid dynamics (CFD) simulations withnon-Newtonian blood viscosity to identify the complex hemodynamicsunderlying ML-CA bleb rupture. Flow stagnation factor (FSF) and shearinduced platelet aggregation index (SIPA-I) are proposed and validated asdimensionless markers of rupture site. FSF is a measure of flowinstantaneity in one bleb relatively to the mean flow instantaneity in theentire aneurysm. SIPA-I is a measure of blood viscosity in one blebrelatively to mean blood viscosity in the entire aneurysm. Qualitative andquantitative analyses of 15 ruptured blebs and 22 unruptured blebs wereconducted and presented.

Results: Our CFD results have successfully identified theruptured blebs without any reliance on Wall Shear Stress (WSS). Rupturedblebs were significantly correlated with lower values of FSF and highervalues of SIPA-I compared to unruptured blebs. ROC analytics showed cutoffvalues of FSF and SIPA-I at 0.871 and 1.08 with sensitivity of 73.3% and100%, respectively.

Conclusion: We proposed and validated two new parameters thatcan bridge the gap between DSA-based CFD and aneurysm pathology to achieveclinically viable rupture risk assessment. The study takes DSA-based CFD toa next generation of markers that are independent from WSS and itsderivatives.

S03-2

Angiographic and Clinical Outcomes From 302 Aneurysms Treated with thePipeline Flex Embolization Device With Shield Technology: SubgroupAnalysis and Follow-Up to PEDESTRIAN

Ivan Lylyk, Esteban Scrivano, Javier Lundquist,Carlos Bleise, Nicolas Perez, Pedro Nicolas Lylyk, Rodolfo Nella Castro,Pedro Lylyk

Interventional Neuroradiology, Instituto Medico ENERI-Clinica La SagradaFamilia, Bs As, Argentina

Background: The PEDESTRIAN registry demonstrated high rates ofcomplete long-term occlusion and good clinical outcomes among patients withintracranial aneurysms treated with the Pipeline Embolization Device. ThePipeline Flex Embolization Device with Shield Technology (PED-Shield) wasintroduced to minimize thromboembolic complications. In this study, weinvestigated the safety and effectiveness of PED-Shield among all patientstreated for intracranial aneurysms at our center.

Methods: This was a single-arm retrospective study ofprospectively collected data of patients treated with PED-Shield at ourhigh-volume center between January 2018–January 2021. The primary efficacyendpoint was complete occlusion as measured by a class 1 Raymond-Roy scoreat 1-year and 2-year follow-up. The primary safety endpoint was majormorbidity and neurological mortality up to 1 year following operation.

Results: A total of 238 patients (mean age 55.4 ± 14.7 years;81.1% female), 80 of whom were previously included in PEDESTRIAN, with 302aneurysms, were analyzed. A total of 268 devices were deployed, with 94.7%(286/302) of aneurysms requiring only one device. Follow-up angiography wasavailable for 82.8% (250/283) of the procedures after a mean time of 12.7months. Complete occlusion was demonstrated for 75.1% (171/226) of aneurysmsat 12 months and 92.5% (62/67) at 24 months. The overall rates of majormorbidity and neurological mortality after 2 years were 1.7% (4/238) and0.4% (1/238), respectively.

Conclusion: Our results demonstrate high rates of completelong-term occlusion among patients treated with PED-Shield. We also observedlow rates of mortality and morbidity consistent with fewer thromboemboliccomplications with PED-Shield.

S03-3

Aneurysm treatment with WEB in the combined population of twoprospective, multicenter series: 5-year follow-up

Laurent Pierot, Istvan Szikora, Xavier Barreu,Markus Holtmannspeotter, Laurent Spelle, Joachim Klisch, DenisHerbreteau, Vincent Costalat, Jens Fiehler, Anne-Christine Januel,Thomas Liebig, Luc Stockx, Werner Weber, Joachim Berkefeld, JcquesMoret, Andy Molyneux, James V Byrne

Department of Neuroradiology, CHU Reims, University Reims Champagne Ardenne,Reims, France

Purpose: Evaluating a new endovascular treatment forintracranial aneurysms must not only demonstrate short-term safety andefficacy, but also evaluate longer term outcomes (e.g., delayedcomplications, anatomical results, retreatment). The current analysisreports the 5-year clinical and anatomical results of WEB treatment in twoEuropean combined trial populations (WEBCAST[WEB Clinical Assessment ofIntrasaccular Aneurysm Therapy]and WEBCAST-2).

Material and Methods: Patients’data are collected in 106patients, from baseline to 5-years post-treatment with evaluation visits atdischarge, 1, 6, 12-months and yearly thereafter 5 years post-treatment. Alladverse events occurring during the procedure and between the procedure and5-year follow-up were independently evaluated by an expert. Aneurysmocclusion was evaluated by an independent core lab using a 3-grade scale:complete occlusion, neck remnant, and aneurysm remnant.

Results: Both trials combined population initially included 106patients aged 27 to 77 years. The 5-year follow-up visits were performedbetween 49 and 72 months after initial procedure. The safety and efficacypopulations comprised 100 patients and 95 aneurysms, respectively. Noadverse event related to the device occurred during the procedure and afterthe procedure during the 5-year follow-up period. Mortality at 5 years was7.0% (7/100 patients) including mortality related the procedure (1/100,1.0%) and other conditions (mostly cancer) (6/100, 6.0%). No mortality wasrelated to the WEB. At 5 years, complete aneurysm occlusion and adequateocclusion were observed in 49/95 (51.6%) and 74/95 (77.9%) aneurysms,respectively

Conclusions: This analysis conducted in a population of patientswith complex-to-treat aneurysms (wide neck bifurcation aneurysms) confirmsWEB's great safety profile and long-term stability of aneurysmocclusion.

S03-4

CLEVER: CLinicalEValuation of WEB 0.017device in Intracranial AneuRysms

Safety results for ruptured and unruptured aneurysm at 30 days

Laurent Spelle¹, ChristopheCognard², Istvan Szikora³, VincentCostalat⁴, Fritz Wodarg⁵, DenisHerbreteau⁶, Sebastian Fischer⁷, MarkusMöhlenbruch⁸, Chrysanthi Papagiannaki⁹,Joachim Klisch¹⁰, Riitta Rautio¹¹, JussiNumminen¹², Ansgar Berlis¹³, JonathanDowner¹⁴, Laurent Pierot¹⁵

¹NEURI The Brain Vascular Center, Bicetre Hospital, Paris-SaclayUniversity, Paris, France

²Department of Neuroradiology, CHU Toulouse, Toulouse, France

³Department of Neuroradiology, National Institute of ClinicalNeurosciences, Budapest, Hungary

⁴Department of Neuroradiology, CHU Montpellier, Montpellier,France

⁵Department of Radiology and Neuroradiology, UniversitätsklinikumSchleswig-Holstein, Kiel, Germany

⁶Department of Neuroradiology, CHU Tours, Tours, France

⁷Department of Neuroradiology, UniversitätsklinikumKnappschaftskrankenhaus Bochum GmbH, Bochum, Germany

⁸Department of Neuroradiology, Heidelberg University Hospital,Heidelberg, Germany

⁹Department of Neuroradiology, CHU Rouen, Rouen, France

¹⁰Department of Neuroradiology, Helios General Hospital, Erfurt,Germany

¹¹Department of Radiology, Turku University Hospital, Turku,Finland

¹²Department of Neuroradiology, Helsinki University Hospital,Helsinki, Finland

¹³Department of Neuroradiology, University of Augsburg, Augsburg,Germany

¹⁴Department of Clinical Neurosciences, University HospitalsDivision, Edinburgh, United Kingdom

¹⁵Department of Neuroradiology, Hôpital Maison-Blanche, UniversitéReims-Champagne-Ardenne, Reims, France

Purpose: Intrasaccular flow disruption is an endovascularapproach for treatment of wide-neck. The WEB device has demonstrated itsefficacy and safety for both unruptured and ruptured aneurysms. The CLEVERobjective has been set up to provide safety and efficacy data on the WEB 17device in treatment of bifurcation aneurysms. These results reportdescription of the full population and safety results within 30 days postprocedure.

Material/Methods: CLEVER study is an observational, prospectiveand multicenter study conducted in 17 European sites (France, Germany,Hungary, Finland, United Kingdom) using the WEB 0.017 device, the lastdeveloped model of WEB with a lower profile. The data collected are 100%monitored and the primary endpoints independently evaluated. Patients’dataare collected from baseline to 12-month post-treatment with evaluationvisits at discharge, 1, 6 and 12-months post-treatment. Occlusion resultsare assessed independently by a Corelab and adverse events are adjudicatedby a Clinical Events Committee. Study design allows to analyze the studyresults for the full population as well as separately for ruptured andunruptured aneurysm. An intention treat analysis is performed for the safetypopulation, and sample size calculation is based on objective performanceapproach for safety and efficacy rates.

Results: From March 2019 to February 2021, 163 patients with 103unruptured aneurysms and 60 ruptured aneurysms were enrolled. The aneurysmslocations were on the ACom (37.4%), the MCA bifurcation (30.1%), the PCom(10.4%), the BA (8.6%), the ICAt (3.7%), the pericallosal artery (3.7%), theACA (0.6%) and other locations (5.5%). The aneurysms treated were rangingfrom 2 to 9.2 mm (mean maximum sac width = 5.0 mm). The WEB procedure wascompleted with success in 163 patients (100%). 147/163 (90.2%) of aneurysmwere treated only with WEB implant and adjunctive implant devices were usedin 16/163 (9.8%) of cases. For this report covering analysis of data up to30 days, the primary safety endpoint was the proportion of patients withdeath of any nonaccidental cause or any major stroke (defined as ischemic orhemorrhagic stroke resulting in an increase of 4 points or more on theNIHSS) within the first 30 days after treatment. Two major strokes on 2/163patients (1.2%) met the primary safety endpoint. The mortality rate at 30days was 0%. A detailed description of events reported from per procedure upto 30 days will be provided with a specific attention to the aneurysminitial presentation (ruptured vs unruptured). The 12 months data are notyet available so will not be presented.

Conclusion: These results show good safety profile at 1 month,with low rate of neurological or neurovascular event with permanent deficitand no mortality at 30 days. These data confirm the safety of WEB use inintracranial aneurysm treatment, unruptured as well as ruptured, and areconsistent with the results published up to date.

S03-5

CLinical Assessment of WEB® device in Ruptured aneurYSms (CLARYS):12-month results of a Multicenter Study

Laurent Spelle¹, denisHerbreteau², Jildaz Caroff¹, XavierBarreau³, Jean-Christophe Ferre⁴, JensFiehler⁵, Anne-Christine Januel⁶, VincentCostalat⁷, Thomas Liebig⁸, RomainBourcier⁹, Markus Mohlenbruch¹⁰, Joachimberkefeldv¹, Werner Weber¹², CristianMihalea¹, Leon Ikka¹, AugustinOzanne¹, Christophe Cognard⁶, Ana PaulaNarata², Richard Bibi², Jean-YvesGauvrit⁴, Hélène Raoult⁴, StephaneVelasco¹³, Jan-Hendrik Buhk⁵, VanessaChalumeau¹, Maxim Bester⁵, HubertDesal⁹, Richard du Mesnil de Rochemont¹¹,Georg Bohner¹⁴, Sebastian Fischer¹², SophieGallas¹, Laurent Pierot¹⁵

¹NEURI The Brain Vascular Center, Bicetre Hospital, Paris-SaclayUniversity

²Neuroradiology Department, CHRU, Tours, France

³Neuroradiology Department, Pellegrin Hospital, Bordeaux,France

⁴Neuroradiology Department, Pontchaillou Hospital, Rennes,France

⁵Neuroradiology Department, University Medical CenterHamburg-Eppendorf, Hamburg, Germany

⁶Interventional Neuroradiology Department, Pierre-Paul RiquetHospital, Toulouse, France

⁷Interventional Neuroradiology Department, Gui de ChauliacHospital, Montpellier, France

⁸Institut of Neuroradiology, Ludwig-Maximilian UniversityHospital, Munich, Germany

⁹Interventional Neuroradiology Department, CHU, Nantes, France

¹⁰Department of Neuroradiology, Universitäts Klinikum, Heidelberg,Germany

¹¹Institut für Neuroradiologie, Klinikum der Johann WolfgangGoethe-Universität, Frankfurt, Germany

¹²Department of Neuroradiology, Ruhr-Universitat, Bochum,Germany

¹³Neuroradiology, CHU, Poitiers, France

¹⁴Neuroradiology, Charité Universitätsmedizin, Berlin, Germany

¹⁵Department of Neuroradiology, Maison-Blanche Hospital,Reims-Champagne-Ardenne University, Reims, France

Background: CLARYS has shown that the endovascular treatment ofruptured bifurcation aneurysms with the WEB is safe and effective andprovides effective protection against rebleeding at 1 month and 1 year. The12-month angiographic follow-up is an important endpoint of the study thatis presented in this paper.

Methods: The CLARYS study is a prospective, multicenter studyconducted in 13 European centers. The study enrolled 60 patients with 60ruptured aneurysms of the anterior and posterior circulations. The study wasconducted with an independent assessment of safety outcomes and imaging.

Results: Sixty patients with 60 ruptured bifurcation aneurysmsto be treated with the WEB were included. 53 aneurysms (88.3%) had a broadbase with a dome-to neck ratio <2 (mean DNR of 1.6). Of these, 46patients were evaluated by an independent core-lab with follow-up imagingperformed at 12 months or before their eventual retreatment. At 1-year, 19of 46 aneurysms (41.3%) were completely occluded (Raymond I), 21/46 (45.7%)had a residual neck and 6/46 (13.0%) had residual aneurysm filling. Adequateocclusion was reported in 40/46 (87%) aneurysms. Six patients underwenttarget aneurysm re-treatment.

Conclusions: CLARYS has previously demonstrated that the use ofthe WEB in the endovascular treatment of ruptured bifurcation aneurysmsprovides effective protection against rebleeding with a good safety profile.Described herein CLARYS study angiographic occlusion rates at 1 year arecomparable to those already demonstrated in previous multi-center studieswhich primarily included unruptured aneurysms.

S05-1

Transvenous embolization for brain AVM using ONYX in Japan

Tomoaki Terada

Department of Neurosurgery, Neurovascular Center, Showa University NorthernYokohama Hospital

Purpose: The total number of endovascular treatment for brainAVMs is decreasing in Japan due to the ARUBA and prevalence of gamma knifecenters. However, ruptured deeply seated small AVMs are good indication fortransvenous embolization(TVE) using ONYX. Our method, strategy, and outcomeare presented in this paper.

Material and Method: Six cases of deeply seated brain AVMs weretreated with TVE. M/F ratio is 1/1 and patients’ age varied from 40–71years. The location of AVMs are brain stem; 4 cases, intraventricle; 1 case,corona radiata; 1 case. The size of all AVMs is less than 2 cm in maximumdiameter. Five cases were ruptured and one case was symptomatic (trigeminalneuralgia). Two cases were treated after transarterial embolizaion but other4 cases were treated with only TVE. Transjugular venous approach was chosedin all cases and double microcatheters were navigated into the junctionbetween drainer and nidus. Microcoils were deployed just proximal of thedrainer to make the ONYX plug easy. ONYX was injected under hypotension aswell as feeder occlusion if possible. The microcatheter was left in the veinif retrieval resistance is high.

Results: All cases were successfully treated with TVE and Norecurrence of AVM was found. In two cases perforation of the draining veinwas encountered but perforation point was obliterated with ONYX. One casecaused venous infarction due to the obliteration of normal draining vein andresulted in 1 score aggravation in mRS.

Conclusion: TVE using ONYX is the most effective and safetreatment for ruptured deeply seated small sized brain AVMs.

S05-2

Use of new embolic agents in embolization of cerebral arteriovenousmalformation

George Wong

Neurosurgery, The Chinese University of Hong Kong

Purpose: PHIL (Precipitating hydrophobic injectable liquid;Microvention, USA) and Squid (Emboflu, Switzerland) are two newer liquidembolic agents used in endovascular embolization of cerebral arteriovenousmalformation (AVM). This study aims to investigate and compare theeffectiveness and safety profile of the two newer liquid embolic agents inembolization of cerebral AVM.

Materials and Methods: This is a retrospective study on allpatients diagnosed with cerebral AVM undergoing endovascular embolizationwith liquid embolic agents PHIL and SQUID admitted to the Division ofNeurosurgery, Department of Surgery in Prince of Wales Hospital. Functionaloutcomes, morbidity and mortality were assessed after embolization. Patientdemographics, imaging and embolization records were reviewed. Statisticalanalysis was performed with SPSS™ Version 28.0 (IBM Corp., Armonk, NewYork).

Results: Twenty three patients with cerebral AVM were treatedwith 34 sessions of endovascular embolization with liquid embolic agents ofeither PHIL or SQUID (17 sessions each) with male to female ratio of 2.3:1(male 16; female 7) and mean age of 44.6 (range from 12 to 67). Mean totalnidus obliteration rate per session was 57% (range from 5% to 100%). 21patients (91.3%) received further embolization, stereotactic radiosurgery orsurgical excision after initial endovascular embolization. No mortality wasrecorded. All patients had static or improvement in modified Rankin Scale at3 to 6 months upon discharge.

Conclusion: PHIL and SQUID are effective and safe liquid embolicagents for endovascular embolization of cerebral AVM, achieving satisfactorynidal obliteration rate and functional outcomes. This is the first localexperience comparing two newer liquid embolic agents.

S05-3

Evolution Of Transvenous Embolization In Vein Of Galen Malformation: ASingle Center Case Series

Tomoyoshi Shigematsu, Maximilian J Bazil,Stavros Matsoukas, Johanna T Fifi, Alejandro Berenstein

Cerebrovascular Center, Department of Neurosurgery, Mount Sinai HealthSystem, New York, USA

Introduction: Vein of Galen Malformations (VOGM), in infants,presents with congestive heart failure, macrocephaly, or neurologicalimpairment. Transarterial embolization (TAE) has markedly improved since theinception of endovascular therapy. In our practice, we obtain totalobliteration in close to 80% of all cases with TAE. The remaining 20% of ourcases typically have small arterial contributors that are uncatheterizable.Transvenous embolization (TVE) then becomes an attractive option. Here, wereport our experience with various TVE techniques we have employed overtime.

Methods: A retrospective review of our clinical database forpatients with the diagnosis of VOGM treated between January of 2004 andAugust of 2021 was performed. Patients who underwent TVE were selected fordetailed analysis and further chart/imaging review.

Results: Prior to 2004, three patients were treated by one ofthe authors (AB) with TT technique. The patients’ heart failure resolved,but the treatment led to poor clinical outcome and delay. Our cohort of TVEin VOGM has 14 patients with mostly choroidal VOGMs (13/14; 92.9%) and onemural VOGM (1/14; 7.1%). The age at TVE ranged between 1 and 20-years oldwith a median of 5.5-years. Total prior TAE treatments ranged between 2–14with a median of 6 treatments. TVE with coiling was used in the earlieryears of this case series (10/14; 71.4%) while PCT was employed in the mostrecent four treatments (4/14; 28.6%). Most patients achieved a favorable,immediate angiographic outcome of 7/14 (50%) complete obliteration, 5/14(35.7%) with near-complete obliteration, and 2/14 (14.3%) with incompleteobliteration. The long-term follow-up angiogram median time from TVE was 16months with a range of 6 months to 57 months. Long-term angiographic outcomefor patients who obtained long-term follow-up showed complete obliteration(11/11). We report mostly favorable clinical outcomes, though a significantsubset of our sample (3/14; 21.4%) experienced post-operative bleeding. Oneof these bleeds we considered “major,” and resulted in mortality (TVEcoiling alone). A “minor” post-operative bleed occurred due after TVEcoiling, but fortunately the patient made a full recovery. The final bleedwe considered to be minor (PCT) with full recovery. We report 13/14favorable long-term outcomes and one mortality. Two patients treated withcoils had a small residual; this was treated with post-operativestereotactic radiosurgery (SRS) which led to cure of the malformation.

Conclusion: We find that venous occlusion without prior TAEcarries high risk and may lead to post-procedural hemorrhage. TT TVE itselfcarries a high degree of risk and is the endovascular treatment most highlyassociated with poor outcomes. We believe that transfemoral/transjugular TVEapproaches are safe and effective. We strongly advocate for the PCTtechnique for its security in avoiding reflux and its practicality as afinal treatment after multiple rounds of TAE.

S05-4

Endovascular modalities for the treatment of TraumaticCarotid-Cavernous fistulas

Tamer Hassan, Tamer Ibrahim, AhmedSultan

Neurosurgery, University of Alexandria

Background: cavernous sinus fistulas are rare vascularmalformations, they are usually classified according to etiology intotraumatic and dural, traumatic CCFs are direct high flow fistulas. Symptomsof CCFs include a triad of Proptosis, ecchymosis and orbital bruit.

Methods: This study involved 34 patients of traumatic cavernousfistula; all patients had severe ocular symptoms. TCCF patients wereevaluated by CT, MRI, DS angiography. Treatment options includedTrans-arterial and transvenous routes using Coils alone, Coils with Onyx,Onyx alone, covered stent and ICA sacrifice.

Results: All patients showed full recovery of their symptoms onfollow-up, with no new cranial nerve palsies observed. One patient hadresidual fistula after coiling attempt, which led to progression of symptomsto his opposite eye on follow-up, so he was managed by covered stent to curehis symptoms.

Conclusion: Excellent outcome regardless of the duration ofsymptoms, can be reached by careful pre-operative planning for the treatmentstrategy; good choice of the approach and the materials to be used forendovascular occlusion of the fistula. None of our patients had complainedcranial nerve palsy when onyx was injected intravenously or even through atrans arterial route. Onyx is very valuable in traumatic CCF, with excellentresults and low morbidity and can overcome the economic burden of coilingalone and the disadvantages of detachable balloons or covered stents.

S05-5

The Association Between Dural Arteriovenous Fistulas And CerebralVenous Thrombosis

René van den Berg¹, LeonieKuiper², Mayte Sanchez van Kammen², BertCoert³, Bart Emmer¹, JonathanCoutinho²

¹Department of Radiology and Nuclear Medicine, AmsterdamUniversity Medical Centers (location AMC)

²Department of Neurology, Amsterdam University Medical Centers(location AMC)

³Department of Neurosurgery, Amsterdam University Medical Centers(location AMC)

Purpose: Anecdotal reports suggest a relation between duralarteriovenous fistulas (dAVF) and cerebral venous thrombosis (CVT). We aimedto investigate the temporal and anatomical relation between the twoconditions.

Materials and Methods: Consecutive cohort of adult patients withdAVF seen at Amsterdam University Medical Centers (2007–2020). Anexperienced neuroradiologist reevaluated the presence and imagingcharacteristics of dAVF and CVT on all available imaging. Among patients whohad both dAVF and CVT, we assessed the temporal (previous / concurrent /subsequent) and anatomical (same / adjacent / unrelated venous sinus orvein) relation between the two conditions.

Results: Among 178 patients with dAVF, median age was 59 years(interquartile range 49–67), 85 (48%) were female, and 55 (31%) werediagnosed with CVT. Four patients (7%) were diagnosed with CVT prior to thedevelopment of dAVF, 33 (60%) at dAVF diagnosis (concurrent), and 18 (33%)developed CVT during follow up after (conservative) treatment The incidencerate of CVT after dAVF was 79 per 1000 person-years (95% confidence interval50–124). In 45 (82%) patients with dAVF and CVT, thrombosis was located inthe same venous sinus as the dAVF, whereas in 8 (15%) patients thrombosisoccurred in a venous sinus adjacent to the dAVF.

Conclusions: One-third of patients with a dAVF in this studywere diagnosed with CVT. In almost two-third of patients, CVT was diagnosedprior or concurrent with the dAVF. In 97% of patients there was ananatomical relation between dAVF and CVT. These data support the hypothesisof a bidirectional relationship between the two diseases.

S05-6

Efficiency of Endovascular Therapy for Bilateral Cavernous Sinus DuralArteriovenous Fistula

Anchalee Churojana¹, IttichaiSakarunchai², Thaweesak Aurboonyawat³, EkawutChankaew³, Pattarawit Withayasuk¹, BoonrerkSangpetngam¹

¹Department of Radiology, Siriraj Hospital, Mahidol University,Bangkok, Thailand

²Department of Neurosurgery, Prince of Songkhla University,Songkhla, Thailand

³Department of Neurosurgery, Siriraj Hospital, Mahidol University,Bangkok, Thailand

Purpose: The principles of endovascular treatment of bilateralcavernous sinus dural arteriovenous fistulas (CS-dAVF) are not wellestablished because of the complexity in the number of fistula tracts andtheir behavior, which seem to be more aggressive. We aimed to determine anefficient technique for endovascular treatment of bilateral CS-dAVF and theassociated factors to achieve good clinical and angiographic outcomes.

Materials and Methods: The data were retrospectively analyzedfrom 165 consecutive patients diagnosed with CS-dAVF from January 2005 toSeptember 2018. The data collection included patients’characteristic,approaching route, embolization times, embolization material, sequence ofembolization, number of embolization sessions, and angiographic and clinicaloutcomes. Interrater agreement of bilateral CS-dAVF diagnosis was performedusing the k coefficient. The factors associated with treatment outcome wereanalyzed using a Pearson c2 test

Result: Bilateral CS-dAVF was detected in 43 patients (26%).Angiographic presentations that showed evidence of sinus thrombosis,dangerous venous drainage, and higher Satomi classification were morecommonly found in bilateral CS-dAVF than in unilateral CS-dAVF. Goodclinical outcome and cure from angiography were obtained in 90% and 74%,respectively. Transvenous catheterization via Ipsilateral inferior petrosalsinus to intercavernous sinus and contralateral cavernous sinus was themajor approach route of treatment. The factors associated with improvedclinical outcome were transvenous approach, shunt closure, coilembolization, and sequencing the embolization (P < 0.001).

Conclusion: Dangerous venous drainage tends to increase inbilateral CS-dAVF. Retrograde ipsilateral inferior petrosal sinuscatheterization using coil embolization and sequencing the embolization arethe major concerns for treatment.

S10-1

Current practices in mechanical thrombectomy: per pass operatortechniques in the EXCELLENT registry

Tommy Andersson², Adnan HSiddiqui¹, Albert J Yoo³, Ricardo AHanel⁴, Osama O Zaidat⁵, WernerHacke⁶, Tudor Joven⁷, JensFiehler⁸, Simon F De Meyer⁹, DiogoHaussen¹⁰, Violiza Inoa¹¹, WilliamHumphries¹², Keith B Woodward¹³, EXCELLENTRegistry Investigators¹⁴

¹SUNY Buffalo, Neurosurgery and Radiology, Buffalo, NY

²Neuroradiology, Karolinska University Hospital, Solna, Sweden

³Texas Stroke Institute, Neurointervention, Plano, TX

⁴Baptist Neurological Institute, Lyerly Neurosurgery,Jacksonville, FL

⁵Mercy Health St Vincent Medical Center, Neurology, Toledo, OH

⁶University Hospital Heidelberg Neurology, Heidelberg, Germany

⁷University of Pittsburgh Medical Center, Neurology, Pittsburgh,PA

⁸University Medical Centre Hamburg, Neurosurgery, Hamburg,Germany

⁹KU Leuven, Laboratory for Thrombosis Research, Kortrijk,Belgium

¹⁰Emory University, Neurology and Interventional Neurology,Atlanta, GA

¹¹University of Tennessee Health Science Semmes Murphey Clinic,Memphis, TN

¹²Wellstar Health System, Kennestone Hospital, Neurosurgery,Marietta, GA

¹³Fort Sanders Regional Medical Center, Radiology, Knoxville,TN

¹⁴EXCELLENT Registry Investigators

Purpose: Current real-world mechanical thrombectomy (MT)practices captured in the recently completed EXCELLENT Registry(NCT03685578; Cerenovus) are reported on a per pass basis.

Materials and Methods: From September 2018 through March 2021,1000 “all-comer” subjects treated with EmboTrap as first line MT device wereprospectively enrolled across 36 international centers (28US, 6EU, 1UK, 1Israel) by 129 treating physicians. Except for EmboTrap use in first pass,all techniques and devices were based on routine practices at each centerand operator preference.

Results: Technique choices included conscious sedation in 51.9%cases, followed by 35.0% general and 13.1% local anesthesia and access via93.4% femoral, 6.4% radial and 0.2% carotid puncture. First pass (FP)resulted in 71.3% rate of full or partial clot retrieval and involved aballoon guide (BG) in 52.1% and intermediate catheter (IC) in 76.4%, withco-aspiration employed in 94.3% BG and 99.1% IC cases. When second pass wasrequired, the initial technique was modified 19.1%, and 43.6% of time when athird pass was performed, with persistent clot and vessel size being themost common reasons for change (63.8 and 76.8%, and 19.1 and 11.2%,respectively). 15.7% of passes 2 and higher utilized direct aspiration.Overall, 52.0% and 77.3% passes with clot retrieved used a BG and IC,respectively, with the retrieved thrombus material found on the stentretriever (vs. aspirate, etc.) in 73.9% cases. Additional interventions(e.g., stenting, angioplasty) were performed pre-and post-procedure in 4.4and 5.6% cases, respectively.

Conclusion: This analysis of the large real-world EXCELLENTregistry shows current MT practices. These data can help inform everydayclinical decisions as well as aid in the design of studies to improve MToutcomes. Detailed per pass clot retrieval strategies will be presented atthe time of the conference.

S10-2

Clot composition and outcomes in the EXCELLENT registry

Tommy Andersson¹, Raul GNogueira², Adnan H Siddiqui³, Albert JYoo⁴, Ricardo A Hanel⁵, Osama OZaidat⁶, Werner Hacke⁷, TudorJovin⁸, Jens Fiehler⁹, Simon F DeMeyer¹⁰, Diogo Haussen¹¹, ViolizaInoa¹², William Humphries¹³, Keith BWoodward¹⁴, EXCELLETN RegistryInvestigators¹⁵

¹Neuroradiology, Karolinska University Hospital

²University of Pittsburgh Medical Center, Stroke Institute,Pittsburgh, PA

³SUNY Buffalo, Neurosurgery and Radiology, Buffalo, NY

⁴Texas Stroke Institute, Neurointervention, Plano, TX

⁵Baptist Neurological Institute, Lyerly Neurosurgery,Jacksonville, FL

⁶Mercy Health St. Vincent Medical Center, Neurology, Toledo,OH

⁷University Hospital Heidelberg Neurology, Heidelberg, Germany

⁸University of Pittsburgh Medical Center, Neurology, Pittsburgh,PA

⁹University Medical CeHamburg, Neurosurgery, Hamburg, Germany

¹⁰KU Leuven, Laboratory for Thrombosis Research, Kortrijk,Belgium

¹¹Emory University, Neurology and Interventional Neurology,Atlanta, GA

¹²University of Tennessee Health Science Semmes Murphey Clinic,Memphis, TN

¹³Wellstar Health System, Kennestone Hospital, Neurosurgery,Marietta, GA

¹⁴Fort Sanders Regional Medical Center, Radiology, Knoxville,TN

¹⁵EXCELLENT Registry Investigators

Introduction: EXCELLENT (NCT03685578; Cerenovus) is a large,prospective, global registry of EmboTrap as first line mechanicalthrombectomy (MT) device in routine clinical practice. The study involvedthe collection and analysis of retrieved clot material, providing anopportunity to explore potential associations between clot composition andstudy outcomes.

Methods: Per pass clot was collected from 543 of 1000 subjectsat 26 of 36 study sites and analyzed under standard protocol by central labsblinded to clinical data. The study also used an imaging core lab and ablind 90-day mRS evaluation. In this analysis, site mTICI values were usedin 161 clot and 131 non-clot subjects in combination with available core labreads. Clots were considered RBC-rich (>45%RBC) or RBC-poor, with the 2groups further subdivided based on median platelet content (30.7%) andmedian platelet:fibrin ratio (1.52), respectively.

Results: First pass mTICI 2c-3 = 40.5% showed no significantdifference among clot types (p = .53), with final 2b-3 = 94.5% with2.1 ± 1.45 mean passes (median = 1). However, 90-day outcomes, mRS≤2 or≤pre-stroke 45.6% and all-cause mortality 17.7%, were both significantlydifferent across clot types (p < .001 and p = .006, respectively), withRBC-rich/platelet-poor clots achieving the best (61.2% mRS≤2/≤pre-stroke,9.2% mortality) and RBC-poor clots the worst (34.9% mRS≤2/≤pre-stroke, 23.1%mortality) outcomes. When analyzed individually, high red blood cell and lowplatelet content were significant predictors of good mRS outcome(p < 0.001 and 0.018) and negative predictors of 90-day mortality(p < 0.001 and 0.011, respectively). Fibrin was not found to be asignificant predictor of either outcome (p = 0.235 and 0.119,respectively).

Conclusion: While RBC and fibrin content are considered knownmodifiers of clot properties, the role of platelets in MT has not beenstudied to the same extent. The EXCELLENT Registry dataset provides anopportunity to explore the potential role of platelets, especially inRBC-rich clots.

S10-3

Late-window aspiration thrombectomy for anterior acute ischemic strokepatients: subset analysis for COMPLETE Study

Ameer E Hassan¹, Johanna T Fifi², Osama O Zaidat³

¹Department of Neuroscience, University of Texas Rio GrandeValley

²Icahn School of Medicine at Mount Sinai

³Mercy Health St Vincent Medical Center

Purpose: The purpose of this analysis was to evaluate the safetyand performance of aspiration thrombectomy in patients with late-onset totreatment (> 6 h) acute ischemic stroke (AIS) in a real-worldsetting.

Materials and Methods: This is a subset analysis of a globalprospective multicenter registry (COMPLETE) that enrolled adults with largevessel occlusion AIS and a pre-stroke mRS of 0–1 who underwent aspirationthrombectomy with the Penumbra System. Data are presented for all patientswith late-window treatment (> 6 h onset to puncture) and ASPECTS ≥ 6.Primary endpoints for COMPLETE were successful revascularization (mTICIscore 2b-3) post-procedure, good functional outcome at 90 days (mRS 0–2),and all-cause mortality at 90 days. Imaging findings were core lab evaluatedand independent medical reviewers adjudicated clinical events related tosafety endpoints.

Results: Of 650 patients enrolled across 42 centers (29 in theUnited States and 13 in Europe), 167 patients were included in thisanalysis. Mean age was 68.4 years and 56.3% were female. Median ASPECT andNIHSS score at baseline were 8[IQR 7,9] and 12[IQR 7,17], respectively.Frontline treatment in 59.9% of patients was direct aspiration only. Strokeswere witnessed, wakeup, or unwitnessed in 52.0%, 10.5%, and 37.5% of cases,respectively. Median time from the stroke onset to puncture was 10.5[IQR7.6, 14.8] hours. Late window patients in COMPLETE achieved a successfulrevascularization rate of 49.1% at first pass and 83.2% (139/167)post-procedure, and 90-day good functional outcome rate of 55.4% (87/157).The 90-day all-cause mortality rate was 14.4% (24/167). Symptomatic ICHoccurred in 4.2% (7/167) of patients and procedure-related SAEs occurred in5.4% (9/167) of patients. No device-related SAE were observed. For the DAWNand DEFUSE-3 medical management arms (control), the 90-day good functionaloutcome rates were 13% (13/99) and 17% (15/90), respectively, and the 90-dayall-cause mortality rates were 18% (18/99) and 26% (23/90),respectively.

Conclusion: Late-window aspiration thrombectomy with PenumbraSystem is safe and effective treatment for patients with anteriorcirculation stroke. Our study reports rates of good functional outcome thatcompare favorably to the DAWN and DEFUSE-3 medical management arms.

S10-4

Initial experience with Penumbra RED reperfusion catheters for AcuteStroke intervention: subset analysis from the prospective, multicenterINSIGHT Registry

Donald Francis Frei¹, Christopher P Kellner², Alan R Dabney³, Selva Baltan⁴, Farida Sohrabji⁵, Keith R Pennypacker⁶, Ashish Nanda⁷, Keith Woodward⁸, Dennis Rivet⁹, Justin F Fraser¹⁰

¹Neurointerventional Surgery, Radiology Imaging Associates

²Department of Neurosurgery, Mount Sinai Health System

³Department of Statistics, Texas A&M University

⁴Departement of Anesthesiology & PerioperativeMedicine/Research

⁵Department of Neuroscience and Experimental Therapeutics

⁶Department of Neurology, University of Kentucky

⁷Department of Stroke and Interventional Neurology, SSMNeuroscience Institute

⁸Tennessee Neurovascular Institute

⁹Department of Neurosurgery, Virginia Commonwealth University

¹⁰Department of Neurological Surgery, University of KentuckyCollege of Medicine

Introduction: The INSIGHT Registry is a multicenter ‘multi-omic’analysis of thrombi associated with acute hemorrhagic or ischemic stroke. Tounderstand variances of specimen collection and efficacy based on devicechoice, we performed an interim analysis to evaluate the initial performanceof Penumbra RED catheters used during aspiration thrombectomy in acuteischemic stroke (AIS) patients.

Materials and Methods: This is a subset analysis of dataextracted from a prospective multicenter registry (INSIGHT) aiming tocollect and analyze specimens from ischemic stroke adult patients. All casesin which Penumbra RED catheters (RED 62, 68, or 72) were utilized as afrontline treatment were included in the analysis. Procedural data collectedincluded modified Treatment in Cerebral Ischemia (mTICI) score after thefirst pass and at the conclusion of the procedure and key time metrics. Clotfragments retrieved during the procedure were classified based on theirgross appearance as firm-red, soft-red, firm-white, and soft-white.

Results: Of 284 patients enrolled across 25 US centers, 66patients underwent thrombectomy with Penumbra RED catheters over a 12-monthperiod (Feb 2021 through Feb 2022) and were included in this interimanalysis. Mean age was 69.8 years and 53.8% were female. Median NIHSS scoreat baseline was 14.5[IQR 9–18]. MCA was the most common occlusion site(80.0%; 52/65). IV t-PA was administered before the procedure in 12.1% ofpatients. Median time from stroke onset / last known well to mTICI≥2b was6.5 h[IQR 4–14], and median time from puncture to mTICI≥2b was 23.5 min[IQR16–31.5]. Overall, 62.5% (40/64) of patients had successful first-passrevascularization (mTICI≥2b), and 97.0% (64/66) had successfulrevascularization after final angiogram. Firm-red clots represented 53.3%(32/60) while soft-red clots were found in 33.3% (20/60) of retrieved clots.Firm-white and soft-white clots were relatively uncommon (seen in 6.7%(4/60) of cases each). mTICI scores after the final angiogram were similarbetween catheter sizes and clot types. Final mTICI≥2b scores were reportedin 96.9% (31/32) of patients with firm-red clots and in 100.0% of patientswith other clot types. In turn, rates of the first-pass success mTICI≥2bwere 51.6% (16/31), 70.0% (14/20), 75% (3/4), and 100% (4/4) for firm-red,soft-red, firm-white, and soft-white, respectively.

Conclusion: Aspiration thrombectomy with Penumbra RED cathetersresulted in good revascularization rates for all clot types.

S10-5

Aspiration Thrombectomy of Acute Ischemic Stroke Patients withAnterior Circulation Tandem Lesion

Osama 0 Zaidat¹, Johanna T Fifi², Ameer E Hassan³

¹Neurology, Mercy St Vincent

²Icahn School of Medicine at Mount Sinai

³University of Texas Rio Grande Valley, Valley Baptist MedicalCenter

Introduction: The purpose of this study was to evaluate thesafety and efficacy of aspiration thrombectomy in acute ischemic stroke(AIS) patients with anterior circulation tandem lesion.

Methods: Patients with anterior circulation tandem lesion wereextracted from a global. prospective multicenter registry (COMPLETE) thatenrolled 650 adults with large vessel occlusion AIS and a pre-strokemodified Rankin Scale score (mRS) of 0–1 who underwent aspirationthrombectomy with the Penumbra System. The primary efficacy endpoints weresuccessful post-procedure angiographic revascularization (modifiedthrombolysis in cerebral infarction[mTICI] score of 2b-3) and good 90-dayfunctional outcome (mRS of 0–2). The primary safety endpoint was 90-dayall-cause mortality. Revascularization rates were evaluated by core lab andsafety data were adjudicated by independent medical reviewers. Outcomes ofpatients with and without stenting were also compared.

Results: COMPLETE study enrolled 55 patients with anteriorcirculation tandem lesions with stenosis greater than 50%; of those 20received a stent and 35 did not. Mean age was 67.8 years and 36.4% werefemale. Median ASPECTS and NIHSS score at baseline were 7[IQR 6–9] and15[IQR 9–20], respectively. IV t-PA was administered before the procedure in61.8% of patients. Median time from stroke onset to hospital admission was2.7 h[IQR 1.6–5.9] and median time from arterial puncture to mTICI 2b-3 atfinal angiogram was 33.5[IQR 22–67] mins. First line management of proximal(tandem) lesion involved angioplasty, aspiration and stenting in 34.5%,25.5% and 21.8% of patients, respectively, with additional balloonangioplasty and stenting at the end of procedure (14.5% of patients each).First line treatment for the intracranial occlusion was direct aspirationand aspiration with 3D Revascularization device in 67.3% and 32.7% ofpatients. Successful revascularization mTICI 2b-3 was achieved in 89.1% ofpatients and 90-day mRS 0–2 was achieved in 63.5% of patients. The 90-dayall-cause mortality rate was 7.3%. The symptomatic intracranial hemorrhage(ICH) rate was 7.3% and device-related SAEs rate was 1.8% (at 24 h for bothsubgroups). Vessel perforation and dissection occurred in 1.8% and 5.5% ofpatients, respectively. Embolization in New Territories (ENT) occurred in5.5% of patients. 90-day mRS 0–2 was achieved in 72.2% of patients with astent and in 58.8% of patients without a stent (P = .34).The mortality rate at 90 days was 10.0% with a stent and 5.7% without astent (P = .56). The symptomatic ICH rate at 24 h was 5.0%with a stent and 8.6% without a stent (P = .62).

Conclusion: Aspiration thrombectomy was effective in restoringblood flow and resulting in good 90-day functional outcome in AIS patientswith anterior circulation tandem lesion, and the 90-day mortality rate inthese patients was low. Clinical outcomes were similar between patients withand without stent.

S11-1

Implementation of neuro-interventionist credentialing system in HongKong

George Wong

Neurosurgery, The Chinese University of Hong Kong

We here report the development and implementation of neuro-interventionistcredentialing system in Hong Kong for radiologists, neurosurgeons, andneurologists. We review the underlying framework and consideration andformulation of a work-based training system applicable to our localhealthcare system. The system has the potential be applicable to othercountries and cities in Southeast Asia.

S11-2

Radiation dose reduction by using low frame rate fluoroscopy protocolduring cerebral angiography in the evaluation of intracranialaneurysm

Bum-soo Kim¹, Woo Chul Cho², Jung Koo Lee², Jai-Ho Choi², Yong Sam Shin²

¹Department of Radiology, Seoul StMary's Hospital, The CatholicUniversity of Korea

²Department of Neurosurgery, Seoul StMary's Hospital, The CatholicUniversity of Korea

BACKGROUND AND PURPOSE: The purpose of this study was toevaluate radiation dose reduction and feasibility of low frame rate (5 fps)fluoroscopy during cerebral angiography in the evaluation of intracranialaneurysm.

MATERIALS AND METHODS: A prospective cohort (March, 2022)including 35 patients undergoing cerebral angiography under low frame ratefluoroscopy protocol (LFRF group) was compared with a retrospective cohort(December, 2021) of 35 patients (Pre-LFRF group). Transfemoral cerebralangiography was done for the evaluation of intracranial aneurysm in all thepatients. Navigation of guidewire and diagnostic catheter was done underfluoroscopy of 10 fps in pre-LFRF group and 5fps in LFRF group,respectively. For the evaluation of radiation dose, dose-area product (DAP)and air kerma (AK) were analyzed. Statistical comparison of DAP and AKbetween the two groups was done with independent sample t-test

Results: With implementation of low frame rate fluoroscopy, all35 cerebral angiographic procedures were successfully performed withoutunanticipated adverse event or complication. Fluoroscopic time was notsignificantly different in pre-LFRF group (9.4 ± 3.9 min) and LFRF group(10.6 ± 3.2 min, p = 0.181). LFRF group showed 39.7% reduction influoroscopic DAP (14.6 ± 9.1 Gy-cm2 vs 8.8 ± 5.0 Gy-cm2, p = 0.002) and34.3% reduction in fluoroscopic AK (111.2 ± 69.9 mGy vs 74.0 ± 44.5 mGy,p = 0.002) compared to pre-LFRF group. In LFRF group, the proportion offluoroscopic DAP in total procedural DAP was 26.1% (vs 37.1% in pre-LFRFgroup), and proportion of fluoroscopic AK in total procedural AK was 29.9%(vs 39.9% in pre-LFRF group).

Conclusions: The low frame rate fluoroscopy protocol (5 fps) isfeasible, and significantly reduces the fluoroscopic radiation dose duringcerebral angiography without any compromise on procedural outcome.

S11-3

Changes in subarachnoid haemorrhage distribution on consecutivenon-contrast CT in non-aneurysmal subarachnoid haemorrhage

René van den Berg^1,2, Wouter Dronkers^2,3, Olvert Berkhemer^1,2, Arian Karbe⁴, Bert Coert^2,3, Menno Germans^5,6, Peter Vandertop^2,3, Dagmar Verbaan^2,3, Charles Majoie^1,2, Bart Emmer^1,2

¹Department of Radiology and Nuclear Medicine, AmsterdamUniversity Medical Centers (location AMC)

²Amsterdam Neuroscience, Neurovascular Disorders, Amsterdam, theNetherlands

³Amsterdam UMC location University of Amsterdam, department ofNeurosurgery, Amsterdam the Netherlands

⁴University Hospital Hamburg, department of Neurosurgery, Hamburg,Germany

⁵University Hospital Zurich, University of Zurich, department ofNeurosurgery, Zurich, Switzerland

⁶University Hospital Zurich, University of Zurich, ClinicalNeuroscience Centre, Zurich, Switzerland

Purpose: Non-aneurysmal subarachnoid haemorrhage (nSAH) isstratified into perimesencephalic- (PMSAH) and non-perimesencephalicsubarachnoid haemorrhage (NPSAH). Early redistribution of blood in PMSAHcould incorrectly result in a diagnosis of NPSAH and alter the diagnosticwork-up. We retrospectively studied consecutive non-contrast CT scans (NCCT)to determine whether the distribution of subarachnoid haemorrhage (SAH)changed over time.

Materials and methods: Of 362 nSAH patients admitted from 2009until 2020 at the Amsterdam University Medical Centre and UniversityHospital Zurich, patients were included if at least two NCCT were performedwithin the first 72 h after onset of complaints. Presence of blood wasassessed for all cisterns. Next, changes in distribution of SAH wereassessed based on the presence of blood on consecutive scans, compared tothe initial scans and was performed by two neuro-radiologist independentlyusing a standardized form.

Results: In 114 patients (61 NPSAH and 53 PMSAH), a second NCCTwithin the 72-h window was available. The median (interquartile range[IQR])interval between the first and second scan was 3 h (range, 0–11 h) and; 2 h(range, 0–5 h) for NPSAH and PMSAH, respectively. No change of SAHdistribution was reported in 77 (68%) patients (40[66%] NPSAH and 37[70%]PMSAH). A reduction of SAH distribution was reported in 30 (26%) patients(17[28%] NPSAH and 13[25%] PMSAH). In seven (6%) patients increase in theSAH distribution was reported. None of the NPSAH changed into a PMSAHdistribution or vice versa.

Conclusions: The SAH distribution changed in one third of nSAHpatients. This did not change the diagnosis from NPSAH to PMSAH and viceversa within the first 72 h. The present data confirms the existing 72-hwindow for the diagnosis of PMSAH.

S11-4

Structural Cardiovascular Anomalies in a Large Consecutive Cohort ofInfants with Vein of Galen Malformation

Darren B. Orbach¹, Ari D. Kappel^1,2, Paulina Piwowarczyk², Kristopher Kahle³, Alfred P. See^1,2

¹Neurointerventional Radiology, Boston Children's Hospital

²Department of Neurosurgery, Boston Children's Hospital

³Department of Neurosurgery, Massachusetts General Hospital

Purpose: While high output heart failure is common in newbornswith Vein of Galen Aneurysmal Malformation (VGAM), the association betweencongenital structural cardiovascular anomalies and VGAM hasnot been systematically studied in a large consecutive cohort. Theco-occurrence of anatomic cardiovascular and cerebrovascular anomalies inaffected infants can present an especially severe clinical challenge. Wepresent our review of echocardiographic findings in a consecutive cohort of54 infants with VGAM at our institution.

Materials and Methods: We identified all cases of VGAM seen atour tertiary pediatric hospital in a 15-year window beginning in July 2007.All available echocardiography reports were reviewed for anatomic/structuralfindings involving the four chambers, the atrial septum, ventricular septum,aortic arch, pulmonary veins, superior and inferior vena cava, and theductus arteriosus. Expected findings, such as patent ductus arteriosus atbirth, were excluded.

Results: 54 cases of VGAM were identified. 46 patients (85.2%)had transthoracic echocardiograms available for review and were included. 15patients (32.6%) had atrial septal defects (ASDs), including 6 (13.0%) withsinus venosus atrial septal defect (SVASD) and 9 (19.6%) with other ASDs. 19patients (33.3%) had patent foramen ovale (PFO). 19 patients (33.3%) had apatent ductus arteriosus after expected closure, and one patient (2.2%) hada large aneurysm of the ductus arteriosus. Seven patients (15.2%) hadpartially anomalous pulmonary venous return (PAPVR), including all 6patients with SVASD, and one (2.2%) with a septum secundum ASD with PAPVRand persistent left SVC with an unroofed coronary sinus. Two patients (4.4%)had coarctation of the aorta (CoAo), one of whom also had an SVASD. Thepresence of cardiovascular anatomic anomalies did not track uniformly withsevere neonatal pulmonary hypertension and ventricular failure, as would beexpected if high flow, rather than a genetic embryological mechanism, werethe underlying etiology.

Conclusion: Prior literature, based on case reports or smallseries, has reported the occurrence of SVASD, ASD, CoAo, and a singleprevious case of possible PAPVR in VGAM patients. Our systematic review of aconsecutive cohort of 54 infants with VGAM revealed structural anomalies inover 1/3. All previously described anomalies were found in our cohort, butwith unexpected distributions, such as PAPVR occurring far more frequentlythan CoAo. We describe how severe neonatal cardiopulmonary pathophysiologyunfolds with VGAM alone, and then how the anatomic cardiac anomaliesaggravate this situation. The non-coincidence between the anatomiccardiovascular anomalies and those newborns with clinical andechocardiographic evidence of the highest flow states, suggests that, ratherthan in utero high flow, there may instead be a unifyinggenetic/embryological etiology, warranting further investigation.

S11-5

The role of secondary fluid motion in sidewall aneurysminitiation

Szikora I¹, Csippa B², Gyurki D², Kondor M¹, Czencz M¹, Vadasz A¹, Paal Gy²

¹National Institute of Mental Heath, Neurology and Neurosurgery,Budapest, Hungary

²Budapest University of Technolog and Economics, Budapest,Hungary

Purpose: Aneurysm initiation is an ongoing subject of scientific debate.Understanding the underlying cascade of events involving hemodynamic andbiochemical processes is challenging. Various hemodynamic quantities havebeen associated with aneurysm formation, primarily including the wall shearstress (WSS) distribution on the vessel wall. Results of such studies,however, are often not reproducible. A potential source of error is theoften subjective geometry creation for numerical studies, as demonstrated ina recent international research challenge. The hemodynamic flow field (asthe driving force behind WSS) is much less susceptible to errors of geometrycreation as WSS itself. In this research, we attempted to analise thecrossectional flow fields including secondary flows across aneurysm bearinglocations.

Materials and Methods: Computed Fluid Dynamics (CFD) models of 30 supraclinoid ICAaneurysms were analysed in the numerical study. The aneurysms were virtuallyremoved with an objective technique to reconstruct the pre-aneurysmal state.Scaled boundary conditions were used for each patient for the pulsatilesimulations. An evaluation method was developed to inspect the flow field incross-sections along the arterial centerline. The velocity vectors at thesecross-sections were decomposed into primary axial and secondary components,such as circumferential and radial flows. Averaging the cross-sectionalvelocity values gives a function along the centerline. Hence, the methodallows a direct comparison between the topological markers of the centerline(cross-sectional diameter, curvature, torsion) and the flow field.Furthermore, the time-varying nature of flows can be evaluated by inspectingdifferent time instances of the cardiac cycle.

Results: The median distance between the aneurysms and the ICA bifurcationwere 12,34 mm, with an interquartile range (IQR) of 5,03 mm. Atcross-sections of the aneurysmal site, circumferential flows were moreprominent compared to radial components in 93% of the cases. Seventysix % ofthese aneurysms (within the IQR) were located on he parophthalmic bend ofthe ICA. Another six aneurysms were located more distally on the ICA,outside the IQR and closer to the ICA bifurcation. These cases presented thesame preferentially circumferential pulsatile flows as the previous ones atthe aneurysmal location. However, in these cases a dominant radial flowpattern was observed at the parophthalmic bend proximal to he aneurysmallocations, typically demonstrating large deflections (large curvature andfast diameter decrease due to vessel folding).

Conclusions: Our results demonstrated more robust circumferential secondary flowsat cross-sections in characteristic aneurysmal locations which may serve asthe source of uneven WSS distribution over the vessel wall. The presentedevaluation gives a more profound understanding of the hemodynamics involvedin the formation of aneurysms.

Supported by Program No. 2017-1.2.1-NKP-2017-00002

S11-6

hemodynamic changes real post flow diversion for brainaneurysms

Ali Alaraj

University of Illinois at Chicago, USA

Purpose: The impact of cerebral aneurysm size on distalintracranial hemodynamics such as, blood velocity, arterial pressure andPulsatility Index is not completely understood, either before or after flowdiversion. The aim of the study is to assess the impact of flow diversion ondistal hemodynamics.

Methods: Patients with unruptured cerebral aneurysms in thecavernous to communicating segments of the internal carotid artery, whichwere treated with single flow diversion were included. Prospectivemeasurement of middle cerebral artery pressure (microcatheter transduced)and Pulsatility Index was performed in consecutive patients at theM1-segment ipsilateral to the cerebral aneurysm at baseline and post flowdiversion. Ratio of middle cerebral artery to radial arterial pressure(pressure ratio) was calculated to control for variations in systemic bloodpressure. Correlations between aneurysm size and pressure ratio andPulsatility Index were assessed before and after treatment. Bilateral MCAflow velocities (by TCD), ratio of ipsilateral to contralateral MCA flowvelocity, and bilateral MCA pulsatility index before and after PEDdeployment were assessed.

Results: A total of 28 aneurysms were treated. The mean aneurysmsize was 7.2 mm. Aneurysm size correlated linearly with systolic pressureratio (1% pressure ratio increase per mm aneurysm size increase, P = 0.002,r2 = 0.33), mean pressure ratio (0.6% per mm, P = 0.03, r2 = 0.17) andPulsatility Index (5% Pulsatility Index increase per mm, P = 0.003,r2 = 0.43). After flow diversion, aneurysm size preserved a linearcorrelation with the systolic pressure ratio (1% per mm, P = 0.004,r2 = 0.28), but not with the mean pressure ratio (0.4% per mm, P = 0.15, r2< 0.1) or Pulsatility Index (0.3% per mm, P = 0.78, r2 < 0.1). Amongthe entire cohort, the ratio of MCA to systemic systolic and mean bloodpressure were significantly higher after treatment (respectively 0.76 vs.0.69, p = 0.01, and 0.94 vs. 0.89, p = 0.03), and the ratio of MCA tosystemic diastolic pressures showed an increasing trend (1.08 vs. 1.03,p = 0.09). The percentage of ratio increase was independent of aneurysm size(r = –0.24, p = 0.42 for systolic ratio; r = –0.09, p = 0.74 for diastolicratio; r = –0.09; p = 0.76 for mean ratio, respectively). Two patients had ahigher increase in ipsilateral MCA mean flow velocity after treatmentcompared with patients without DIPH (39.5% vs 5.5%).

Conclusion: Aneurysm size affects distal hemodynamics, also flowdiversion induce changes in the distal hemodynamics including changes inpressure, velocity and pulsatility index.

S11-7

A Novel Internet Platform for Stroke Research Collaboration andFunding

Mayank Goyal^1,3, Arnuv Mayank², Johanna Maria Ospel⁶, Michael Hill³, Joachim Fladt^3,4, Jeffrey Lawrence Saver⁷, Aravind Ganesh³, Manon Kappelhof⁵, Rosalie Victoria McDonough¹

¹Department of Radiology, University of Calgary, Calgary,Canada

²Haskayne School of Business, University of Calgary, Calgary,Canada

³Department of Clinical Neurosciences, University of Calgary,Calgary, Canada

⁴Department of Neurology, University Hospital Basel, Basel,Switzerland

⁵Department of Radiology and Nuclear Medicine, University ofAmsterdam, Amsterdam, Netherlands

⁶Department of Neuroradiology, University Hospital Basel, Basel,Switzerland

⁷Department of Neurology, David Geffen School of Medicine, UCLA,Los Angeles, USA

Background and aims: The current stroke research fundingenvironment is highly competitive, stifling collaboration and hinderingprogress. Further, specific groups of researchers/research topics aredisproportionately affected, resulting in inequity in the funding process.These include early-career researchers, women, and researchers fromlow-middle income countries. Certain conditions, e.g., rare, stroke-relateddiseases are due to their low prevalence not suitable for clinical trialsand therefore even less likely to receive funding. Currently, there is noeasy way for people working on such topics to come together and collaborate.To address this problem, a novel internet-based platform, Collavidence(www.collavidence.com), was designed. The idea is to complement currentsystems of stroke research collaboration and funding for more inclusive,efficient, and impactful research results. The aim of this study is topresent the initial performance of the platform in achieving this goal.

Methods: Analytics on pre-defined user-, project-, andinteraction-based metrics will be performed to describe the level ofplatform engagement in its initial months following launch (March 30th,2022). These include the number of users and projects posted, the amount offunding accumulated, the proportion of successfully funded projects, anditerative improvement of the proposals. Further, the relative engagement ofearly-career, female researchers, and researchers from low-middle-incomecountries will be assessed.

Results: Qualitative assessment of the value of the overallplatform, the process of iterative review, and possibilities forcollaboration will be presented. Further, trends in platform engagementduring the initial 5 months, including the relative distribution of specificuser demographics to assess the platform's success in encouraging equity,diversity, and inclusion, will be presented.

Conclusions: This study will assess the feasibility and initialsuccess of Collavidence as a unique platform of stroke researchcollaboration and funding.

S11-8

Initial experience of using a large-bore (0.096″ inner diameter)access catheter in neurovascular interventions

Donald Francis Frei¹, Isaac J Abecassis², Charles C Matouk³, Ameer E Hassan⁴, Adnan H Siddiqui⁵, R Dana Tomalty⁶, Robert M Starke⁷

¹Neurointerventional Surgery, Radiology Imaging Associates,Englewood, CO, USA

²Department of Neurosurgery, University of Louisville, Louisville,KY, USA

³Department of Neurosurgery and Department of Radiology &Biomedical Imaging, Yale New Haven Hospital, New Haven, CT, USA

⁴Department of Neurology and Radiology, University of Texas RioGrande Valley at Valley Baptist Medical Center, Harlingen, TX, USA

⁵Department of Neurosurgery, University at Buffalo Neurosurgery,Inc., Buffalo, NY, USA

⁶Radiology of Huntsville, Huntsville, AL, USA

⁷Department of Neurological Surgery, University of Miami, Miami,FL, USA

Purpose: Larger-bore access catheters can improve endovasculartherapy by facilitating delivery of interventional devices, enhancingvisualization, and reducing the number of exchange maneuvers needed.Advances in technology have allowed for the manufacture of larger-boreaccess catheters that maintain necessary performance characteristics, suchas a stiffer proximal segment for stability and a flexible distal segmentfor vessel catheterization. The purpose of this study was to report ourinitial experience of using a large-bore (0.096″ inner diameter) accesscatheter in neurovascular interventions.

Materials and Methods: Data were prospectively collected from 7sites in the US for neurovascular procedures performed using an 8Flarge-bore (0.096″ inner diameter) access catheter from January 15, 2020, toApril 21, 2021. The effectiveness outcome was technical success, defined asthe access catheter's successfully reaching its target vessel, withoutconversion to a smaller guide catheter system or to a direct carotidpuncture, and successfully completing the intended neurointervention. Safetyoutcomes were access-related and device-related periproceduralcomplications.

Results: One hundred and thirteen procedures performed in 112patients were included in this study. The mean age of the patients was 67.5years (SD 16.2), and about half (55, 49.1%) were female. The most commontreatment conditions were stroke, 63 (55.8%); aneurysm, 24 (21.2%); carotidatherosclerosis, 19 (16.8%); and intracranial atherosclerosis, 3 (2.7%). Themost common treatments were mechanical thrombectomy, 51 (45.1%); stenting,25 (22.1%); Pipeline/flow diversion, 10 (8.8%); and stent-assisted coiling,8 (7.1%). The most common primary approaches were via the femoral artery(73, 64.6%) and the radial artery (37, 32.7%). Anatomic variations includedsevere vessel tortuosity (26/81, 32.1%), type 2 aortic arch (17/88, 19.3%),type 3 aortic arch (14/88, 15.9%), bovine arch (16/104, 15.4%), severe angle(<30°) between the subclavian and target vessel (11/74, 14.9%), andsubclavian loop (7/79, 8.9%). The median access time to branch was 18 min(IQR 11–28, N = 75).

Technical success was achieved in 107 procedures (94.7%), including 3 accessconversions (radial to femoral or femoral to radial) with the samelarge-bore catheter. Access site complications occurred in 2 patients(1.8%), who had access site hematoma after the procedure. Two complications(1.8%), 1 flow-limiting dissection and 1 non–flow-limiting dissection, wererelated to the large-bore access catheter.

Conclusion: A large-bore (0.096″ inner diameter) access cathetercould be used with both femoral and radial arterial approaches, had a hightechnical success rate, and had a low rate of periproceduralcomplications.

S13-1

Ophthalmic Artery Angioplasty For Age Related MacularDegeneration

Ivan Lylyk, Esteban Scrivano, Javier Lundquist,Carlos Bleise, Nicolas Perez, Pedro Nicolas Lylyk, Rodolfo Nella Castro,Pedro Lylyk

Interventional Neuroradiology, Instituto Medico ENERI-Clinica La SagradaFamilia

Background: Age-related macular degeneration (AMD) is theleading cause of irreversible blindness among the elderly in the developedworld, for which there is currently no available treatment. Compromisedocular microcirculation due to aging and vascular disease contribute toretinal dysfunction and vision loss; decreased choroidal perfusion isevident in eyes with dry AMD. In an effort to evaluate whether or not thethe ophthalmic artery (OA) is a contributor to decreased retinal perfusionin eyes with AMD, a study was conducted utilizing a 7 T MRI and a custombuilt 32 channel head receive array coil with a birdcage transmit coil tonon-invasively capture hemodynamic data of both arteries The studydemonstrated a statistically significant decrease in both lumen diameter(p = 0.006) and volumetric flow rates (p = 0.041), and an increase inresistive index (p < 0.001), which measures dynamic flow properties, inthe OA of AMD patients as compared to age matched controls without AMD.These findings indicate the changes in or around the OA, may be contributingto decreased retinal perfusion in AMD patients, and present a potentialtreatment target in a patient population without therapeutic options.

Methods: Five patients who presented late-stage AMD as evidencedby the presence of geographic atrophy or stabilized history of choroidalneovascularization, best corrected visual acuity (BCVA) of 20/400 or worse,in combination with processed intraarterial cone beam–volume CT imagesregarding the precise OA origin and the relationship with an atheroma plaquenearby or in the artery were selected. The eye with the worst visual acuitywas chosen for treatment.

Results: After a difficult canulation of the OA due to itsnarrowing, balloon angioplasty was successfully performed in all of the fivecases. Subjective patient reports indicated all patients perceived a benefitfollowing the procedure; however, improved postoperative visual acuity didnot confirm that perceived benefit for one of the patients. Meanpreoperative BCVA was 20/710 and improved to 20/383 at 1 week postoperative,representing a mean gain of nearly 3 lines, remaining stable through monthsix.

Conclusion: Our preliminary experience in a small cohort ofpatients suggest that OA angioplasty may be performed safely and there issubjective evidence of efficacy. The OA is a viable target to increase bloodflow to the eye, restore retinal perfusion, and perhaps disrupt the diseaseprocess of AMD. To proceed with a randomized controlled trial, devicesspecific to this application should be developed.

S13-2

First-in-human endovascular treatment ofhydrocephalus with a miniaturebiomimetictransdural shunt

Ivan Lylyk¹, Esteban Scrivano¹, Javier Lundquist¹, Carlos Bleise¹, Nicolas Perez¹, Pedro Nicolas Lylyk¹, Rodolfo Nella Castro¹, Carl B Heilman², Adel Malek², Pedro Lylyk¹

¹Interventional Neuroradiology, Instituto Medico ENERI-Clinica LaSagrada Familia

²Department of Neurosurgery,Tufts Medical Center,Boston,Massachusetts, USA

Surgical ventriculoperitoneal shunting remains standard treatment forcommunicating hydrocephalus, despite significant infection and revisionrates. A new minimally-invasive endovascular cerebrospinal fluid shunt hasbeen developed (CereVasc eShunt™) to mimic arachnoid granulation function.This implant is intended to be deployed via femoral transvenous approachacross the inferior petrosal sinus dura mater into the cerebellopontineangle cistern. We hereby present the first patient to be treated using thisapproach. An 84-year-old woman with intractable hydrocephalus followingsubarachnoid hemorrhage underwent an external ventricular drain clampingwhich was not tolerated owing to intracranial pressure (ICP) reaching44cmH­₂O. On the following day, her drain was clamped eighthours prior to undergoing successful endovascular deployment of the eShuntdevice with post-implant CT head showing no hemorrhage. Within 90 min ofeShunt insertion, the patient's ICP decreased from 38 to <20cmH₂O to followed by subsequent resolution ofventriculomegaly. This is the first patient treated for communicatinghydrocephalus using a novel endovascular CSF shunt without the need for aburr hole, brain penetration or multiple skin incisions. This novel andunique percutaneous transluminal access to the central nervous system ushersa new pathway for non-invasive treatment of hydrocephalus and potential forpercutaneous access to the central nervous system for intervention againstneurological disorders.

S13-3

Identifying acute ischemic stroke thrombus composition usingex vivo electrochemical impedancespectroscopy

Waleed Brinjikji, Jean Darcourt, OlivierFrancois, Smita Patil, Senna Staessens, Jorge Pagola, Jesus Juega, MarcRibo, Hirotoshi Imamura, Nobuyuki Sakai, IVan Vukasinovic, PedragStanarcevic, Ramanathan Kadirvel, Mahmoud Mohammaden, Leonardo Pisani,Gabriel Rodrigues, Duaa Jabrah, Cansu Sahin, Vitor Pereira, NicoleCancelliere, Alice Giraud, Franz Bozsak, Pierluca Messina, Simon DeMeyer, David Kallmes, Karen Doyle, Christophe Cognard, RaulNogueira

Radiology, Mayo Clinic

Background and aim: Despite significant advances, roughly 75% ofEVT procedures require two or more retrieval attempts and 20% of EVTprocedures fail to achieve TICI 2b/3.^1,2 While the precisereasons remain poorly understood, there is mounting evidence that thrombuscomposition is a key factor influencing revascularizationrates.^2–4 Recent clinical and in vitrodatasuggest that fibrin/platelet-rich thrombi are more difficult to extract,resulting in poorer revascularization rates,^23,5 while red bloodcell- (RBC-) rich thrombi are associated with a reduced number ofrecanalization maneuvers and higher revascularization rates.^6,7We investigated the capacity of electrochemical impedance spectroscopy (EIS)to determine thrombus composition ex vivo with the ultimateaim of developing a neurovascular wire which could characterize acuteischemic stroke thrombi in vivo.

Methods: To date, two independent multicentric internationalstudies, called Clotbase Pilot and Clotbase International, collected theimpedance spectra, composition and related clinical procedural EVT data of179 and 99 AIS thrombi, respectively. A custom EIS platform was used tocollect the impedance spectra ex vivo and Martius ScarlettBlue staining was applied to determine the histological thrombus composition(RBC, white blood cells, fibrin, platelets and “other”). Thrombi from thePilot study were then used to train a machine learning model to predict theRBC content of AIS thrombi, and the second database was used as a validationset to demonstrate the generalizability of the model. Linear regression wasused to evaluate the correlation between histological analysis andimpedance-based prediction of RBC content for the two datasets.

Results: The linear regression for the Pilot dataset showed verygood correlation between the impedance-based prediction and the histologydetermination of RBC content with a slope of 0.78 and a Pearson coefficientof 0.72. The linear regression of the validation set showed similar resultswith a slope of 0.82 and a Pearson coefficient of 0.68.

Conclusions: The very strong correlation results across twoindependent datasets demonstrates that EIS can be used as a reliable tool todetermine the RBC content in AIS thrombi. The currently ongoing research ofthese studies aims to demonstrate the capability of EIS to also determineplatelet and fibrin content of AIS thrombi and correlate thrombuscomposition and EIS data with the collected clinical data. These findingsraise the possibility of developing a neurovascular guidewire integrating animpedance-based sensor to characterize AIS thrombi in situ. The informationcould help physicians identify optimal EVT strategies to improve outcome forstroke patients.

S13-4

new and exciting material on an active coating for flowdiversion

Matthew Gounis

S13-5

Characterizing wall responses to complex flow stresses in cerebralaneurysms

Naoki Kaneko

S13-6

COATING study: A RCT evaluating the coated flow diverterP64-MW-HPC

Laurent Pierot, Saleh Lamin, Laurent Spelle,Christophe Cognard

Department of Neuroradiology, CHU Reims, University Reims Champagne Ardenne,Reims, France

Purpose: Flow Diversion is increasingly used for the treatmentof intracranial aneurysms due to its high efficacy. However its use is stillrestricted to unruptured and recanalized aneurysms due to the need of a dualantiplatelet therapy to prevent thromboembolic complications. P64-MW-HPC(phenox, Bochum, Germany) is a coated flow diverter. Hydrophilic PolymerCoating (HPC) is a glycocalyx-like glycan based polymer covalently bonded tothe surface of the p64 flow diverter, which is supposed to reduce plateletaggregation. COATING is a randomized controlled trial (RCT) dedicated to thecomparative evaluation of this coated flow diverter.

Materials and Methods: COATING (Coating to Optimize AneurysmTreatment in the New Flow Diverter Generation)is a RCT comparing the rate ofthromboembolic complications in patients treated with bare p64-MW under dualantiplatelet treatment and patients treated with coated p64-MW-HPC undersingle anti platelet treatment. The primary safety endpoint is the number ofDiffusion-weighted Imaging lesions depicted within 48 h ( + /- 24 h) of theindex procedure by 3T-MRI. COATING study is conducted in 14 InterventionalNeuroradiology centers in 6 countries (France, Germany, Italy, UnitedKingdom, Switzerland, Israel). The population of the study will be maximum200 patients (100 per arm. An interim analysis will be conducted afterinclusion of 50% of the population.

Results: The protocol of COATING study as well as the status ofinclusions at the time of presentation will be presented.

Conclusions: COATING study is the first comparative study toproperly evaluate a coated flow diverter. The results of this study willpotentially change the indications of flow diversion of the endovasculartreatment of intracranial aneurysms.

O2-1-1

A Treatment Outcome of Large Cavernous Carotid Artery Aneurysms: anexperience in Siriraj Hospital, Thailand

Jirapong Vongsfak^1,2, Pattawawit Withayasuk¹, Boonrerk Sangpetngam¹, Thaweesak Aurboonyawat^1,3, Ekawut Chankaew^1,3, Anchalee Churojana¹

¹Department of radiology, Siriraj hospital, University of Mahidol,Bangkok, Thailand

²Division of Neurosurgery, department of surgery, Chiang MaiUniversity, Chiang Mai, Thailand

³Division of Neurosurgery, department of surgery, Sirirajhospital, University of Mahidol, Bangkok, Thailand

Purpose: Cavernous carotid aneurysms (CCA) are considered benignlesion with low risk for life-threatening conditions. However, for a largeaneurysm (size>10 mm) usually become symptomatic which requiresmanagement. The purpose of this study is to evaluate the outcome of ourtreatment for large cavernous carotid aneurysms in different modalities.

Material and methods: A retrospectively review of all patientswho were treated for large CCA during 2010–2022 at Siriraj Hospital,Bangkok, Thailand was performed. Data collection included patientcharacteristics, clinical presentations, radiographic findings, modality oftreatment and outcomes. The treatment was categorized into four groups, 1Parent vessel sacrifice (PVS), 2 Parent vessel sacrifice with high-flowbypass (PVS & bypass), 3 Stent assisted coiling (SAC) and 4 Flowdiverting stent (FDS). Patient outcomes were defined as angiographic andclinical outcome at 6-month follow up period. The complications weredetermined immediately after each treatment.

Results: There were 22 patients (19 females, 3 males) with meanage at 57.5 years. Cavernous sinus syndrome was presented in 83%. Themodalities of treatment were PVS in 5, PVS & bypass in 9, SAC in 2 andFDS in 6. All patients passed balloon occlusion test, except one whoreceived FDS. The aneurysms had angiographically disappeared in all of thePVS and PVS & bypass groups, 1/2 patients of SAC group and 4/6 patientsof FD group. Good clinical outcomes (symptomatic improvement) weredemonstrated in all 5 cases with PVS, 7/9 cases with PVS & bypass, 1/2cases with SAC and all 6 cases with FDS. Major complications occurred in 2cases. Both were PVS & bypass group, one had iatrogenic injury of middlecerebral artery and the other had remote intracerebral hemorrhage.

Conclusion: Endovascular sacrifice of internal carotid artery inpatients with large CCA who had passed balloon occlusion test brought aboutgood result in both angiographic and clinical outcome. PVS & bypassshould be considered when distal flow preservation is in concern, however,major complications may occur as a result of open surgery. FDS is the safealternative method for patent artery preservation, with an inferiority ofdelayed response of aneurysmal occlusion.

O2-1-2

Endovascular treatment for the middle cerebral artery hilltopaneurysm

Sang Kyu Park¹, Woo Sung Lee², Jun Ho Jung¹, Hyun Jin Han³, Keun Young Park³

¹Department of Neurosurgery, Gangnam Severance Hospital, YonseiUniversity

²Department of Neurosurgery, Ewha Seoul Hospital, Ewha Women'sUniversity

³Department of Neurosurgery, Severance Hospital, YonseiUniversity

Background: M1 segment of middle cerebral artery (MCA) aneurysmis a relatively rare clinical condition. However, due to its complexgeometry and deep location, microsurgical treatment is challenging. With thedevelopment of devices and techniques, the range of aneurysms that can betreated with endovascular treatment (EVT) continues to expand. We performedthis study to define a specific form of M1 aneurysm that can be safely andeffectively treated through EVT as M1 hilltop aneurysm, and to report ourtreatment results.

Methods: Of 757 MCA aneurysm between December 2017 and October2021, 54 M1 segment aneurysms were treated with EVT, and these aneurysmswere designated M1 hilltop aneurysms. Clinical and radiographic data,including aneurysm characteristics, endovascular techniques, angiographicoutcome, procedure-related complications and clinical outcomes at the timeof the last follow-up, were collected and reviewed retrospectively.

Results: Treatments were successful in all 54 cases, 21 caseswere treated with coiling and 33 cases with stent-assist coiling (SAC). Themean height of the aneurysm was 4.35 ± 1.9 mm, the mean width was4.59 ± 1.9 mm, and the mean neck size was 3.63 ± 1.4 mm. Of the 54 cases, 50(92.6%) cases were identified as wide-neck aneurysms. The neck of aneurysmincorporating branch vessel was found in 49 (90.7%) cases. Immediatepost-procedural angiogram showed favorable occlusion in 32 (59.3%),incomplete occlusion in 22 (40.7%). There were 4 (7.4%) procedures-relatedcomplications including thromboembolism and internal carotid arterydissection, but there were no cases of permanent neurological impairment.The mean follow-up duration was 18.2 months. During the follow-up period,there was no neurological deterioration or aneurysmal rupture in any of thepatients. On 50 available follow-up angiographic studies, minor recurrencewas found in 6 (12%) cases and major recurrence was found in 1 (2%) case.Recurrence was significantly related to aneurysm neck (OR 3.9, 95% CI 1.2 to12.9, p = 0.025).

Conclusions: EVT for M1 hilltop aneurysms appears to be safe andefficacious, with low mid-term recurrence rate. However, long-term and largecohort study will be needed.

O2-1-3

Endovascular Treatment of 1253 Middle Cerebral Artery Aneurysms

HYUN-SEUNG KANG

Neurosurgery, Seoul National University College of Medicine, Seoul NationalUniversity Hospital

The middle cerebral artery (MCA) is one of principal sites of intracranialaneurysms, where open surgical treatment and endovascular treatment areavailable. We aimed to study on the outcomes of endovascular treatment inpatients with MCA aneurysms, including both ruptured and unruptured, in asingle tertiary referral hospital.

During the period from December 1997 to June 2021, 1253 MCA aneurysms weretreated with endovascular means, including 134 ruptured (10.7%) and 1119unruptured aneurysms (89.3%). 450 aneurysms (35.9%) were treated in thesetting of multiple aneurysms which were treated in the same treatmentsession. Among the patients with ruptured MCA aneurysms, Hunt and Hessgrades were Grade I in 7, Grade II in 68, Grade III in 38, Grade IV in 19,and Grade V in 2.

Various technical treatment methods were used including double microcathetertechnique and microcatheter protection technique. Stent assistance wererequired in 337 aneurysms (26.9%) and sole stenting was used in 5 amongthem. Balloon remodeling was used in 12. Trapping or segmental occlusion wasused in 14 with or without bypass.

Procedure-related events occurred 29.3% (annual range, 0 to 66.7%) inruptured aneurysms and 6.0% (annual range, 0 to 16.0%) in unrupturedaneurysms (P < 0.00001). Among patients with ruptured MCA aneurysms, goodrecovery was achieved in 100% in Grade I patients, 93% in Grade II, 71% inGrade III, 53% in Grade IV, and 0% in Grade V. Among patients withunruptured aneurysms, excellent clinical outcome could be achieved in 99% ofpatients. One patient with giant MCA aneurysms died after stent-assistedcoiling. Among cases where adequate follow-up imaging was available 6 monthsor more after treatment (n = 1015), stable aneurysm occlusion was maintainedin 89.0% and major recurrence and/or retreatment occurred in 5.1%.

With proper case selection, endovascular treatment could achieve excellentclinical outcome with an acceptable retreatment rate for patients withunruptured MCA aneurysms. Stricter case selection is required in patientswith ruptured MCA aneurysms.

O2-1-4

Basilar artery trunk aneurysm: clinical and angiographic outcomes ofendovascular treatment

Joonho Chung

Department of Neurosurgery, Gangnam Severance Hospital, Yonsei UniversityCollege of Medicine

Background and Purpose: Basilar artery (BA) trunk aneurysms arerare, and the clinical characteristics and outcomes of endovasculartreatment (EVT) remain unclear. The purpose of this study was to reportclinical and angiographic outcomes of BA trunk aneurysm treated with EVT andto analyze risk factors for unfavorable outcomes.

Methods: From October 2004 to December 2020, a total of 40patients with BA trunk aneurysms underwent EVT. Clinical characteristics andoutcomes were evaluated retrospectively from a prospectively collecteddatabase. Of the 40 enrolled patients, nine were treated by coiling withoutstents, 17 were treated by stent-assisted coiling, six by stent only, fiveby flow diverters, and three by vertebral artery occlusion.

Results: In total, 27 (67.5%) patients had subarachnoidhemorrhage as an initial presentation, and 20 (50.0%) had large/giantaneurysms. Procedure-related complications occurred in five patients(12.5%); favorable clinical outcome was achieved in 27 patients (67.5%); andsix patients (15.0%) died. Favorable angiographic outcome was achieved in 26(83.9%) of 31 patients who underwent follow-up angiography. Poor initialHunt-and-Hess grade (OR 7.67, 95% CI 1.55 to 37.80; p = 0.018) was the onlyindependent risk factor for unfavorable clinical outcome. Large/giantaneurysm (OR 8.14, 95% CI 1.88 to 27.46; p = 0.047) and long lesion (OR14.25, 95% CI 1.48 to 69.80; p = 0.013) were independent risk factors forunfavorable angiographic outcomes during follow-up.

Conclusions: EVT might be a feasible option for this raredisease entity. Unfavorable angiographic outcome might be expected in alarge/giant aneurysm or a long lesion. It can be difficult to treat BA trunkaneurysms by EVT, needing multiple procedures or various techniques due todiverse clinical and angiographic features.

O2-1-5

Endovascular treatment for aneurysms at the basilar arteryfenestration

Yuma Miki, Yuki Sato, Yasunobu Mitura, HirotakeFujishima, Hiroo Yamaga, Tomoaki Terada

Department of Neurosurgery, Showa University Northern Yokohama Hospital

Background: Aneurysms located at the fenestrated basilararteries are rare, and treatment strategies are still controversial. Wereviewed basilar artery fenestration (BAF) aneurysm cases treated in ourhospital and related institutions, with review of literatures.

Materials and Methods: A total of 13 BAF aneurysms in 12patients were treated by endovascularly therapy. The patients’ mean age was55.8 years, the ratio of male to female is 7 to 5. There were 6 rupturedaneurysms and 7 unruptured ones. All aneurysms were located in the lowerbasilar trunk. Simple coiling, balloon assist, or stent assist technique wasused for coil embolization.

Results: Six patients were treated by stent-assisted coilembolization (SAC), and one patient was treated by balloon-assisted coilembolization. In one case SAC, H stents were used for coiling. All aneurysmswere successfully occluded. Procedure-related complications were seen in onepatient treated with H stent. The complication was brainstem infarctionbecause of occlusion of perforating branches. One patient was ruptured 20years after initial embolization, which was treated by SAC.

Discussion: In our study, the technical success rate was 100%and the procedure-related complications rate was 7.7%. Our ischemiccomplication case was supposed to be related with H stents. KORKMAZ et al.reviewed endovascular-treated 113 BAF aneurysms in 46 studies between 1993and 2019 and reported the technical success rate was 97–100% and theprocedure-related complications rate was 7.6–8.8%. Since 2010, they reportedthat the proportion of SAC has become as high as 62%, and the same tendencyas 75% was seen in our study. In BAF aneurysms, four branches communicatewith the aneurysm, and the stent is necessary for safe embolization, whilethe use of the stent increases the risk of thrombotic complications.

Conclusion: Endovasculat therapy should be the first linetreatment for the BAF aneurysms considering from our results.

O2-1-6

Aneurysmal coiling is the optimal option for the first treatment formedium-sized intracranial aneurysm

Sangnyon Kim, Nobuhiro Mikuni

Department of Neurosurgery, Sapporo Medical University

The basic procedure of the aneurysmal coil embolization is single cathetertechnique(SCT) treated with one microcatheter (MC). Double cathetertechnique (DCT) has an advantage not to leave an any device for in cerebralvessel although it is not chosen among concern of the complexity of theprocedure and further aneurysmal recanalization positively widely. Althoughflow diverter treatment, many new devices fit it and were increased, it isthe current situation in Japan that a practiced hand becomes limited tofacilities. For 101 ruptured cerebral aneurysms (R group) after 2013,unruptured cerebral aneurysm (U group) 112, 77 of R group (76%), 69 of Ugroup (62%) were treated only with MC. DCT was chosen in 44 of R group, 49of U group, and stent was used in 2 of R group and 21 of U group, andballoon was applied in 8 of R group, 16 of U group, respectively. There wasno case of intraprocedural aneurysmal rupture, and only a case of R groupthat grew sylvian hematoma postoperatively left aftereffects. For fiveischemic complications (2.3%, four of R group), they passed without anysymptoms, and mean greatest dimensions of those 5 cases were 10.7 mm. There-treatment was performed in eight of R group (9%), and the mean diameterof those cases at the time of the first operation was 10.1 mm. In theseretreatment cases, the perforator diverged from the aneurysmal body was seenin all cases.

Appropriate MC forming, safety insertion of the tip of MC into the aneurysm,placement and stability of MC lead to avoid hemorhagic complications. Thebeing well informed to treatment only with MC is the treatment that anyneurointerventionalists can give in the current situation, and it is thoughtthat we can secure security on the embolization for less than medium sizedaneurysm. We present the results of the treatment with policy that assumeSCT and DCT as a basic strategy of the embolization.

O2-2-1

Mechanical Thrombectomy in Nonagenarians

Xiao Zhang^1,2, Xuesong Bai^1,2, Hongyan Zhang³, Wuyang Yang⁴, Tao Wang^1,2, Yao Feng^1,2, Yan Wang⁵, Kun Yang⁶, Xue Wang⁷, Yan Ma^1,2, Liqun Jiao^1,2,8

¹Department of Neurosurgery, Xuanwu Hospital, Capital MedicalUniversity

²China International Neuroscience Institute (China-INI), Beijing,China

³Medical Administration Division, Xuanwu Hospital, Capital MedicalUniversity, Beijing, China

⁴Department of Neurosurgery, Johns Hopkins University School ofMedicine, Baltimore, USA

⁵China Medical University, No.77 Puhe Road, Shenyang North NewArea, Shenyang, Liaoning Province, China

⁶Department of Evidence-Based Medicine, Xuanwu Hospital, CapitalMedical University, No. 45 Changchun Street, Beijing, China

⁷Medical Library, Xuanwu Hospital, Capital Medical University, No.45 Changchun Street, Beijing, China

⁸Department of Interventional Neuroradiology, Xuanwu Hospital,Capital Medical University, Beijing, China

Purpose: This study aimed to summarize the current literature onmechanical thrombectomy (MT) in nonagenarians and to provide updatedclinical evidence of its feasibility, effectiveness, and safety innonagenarians.

Methods: PubMed, EMBASE, the Cochrane Library, and Web ofScience were searched for relevant randomized controlled trials andobservational studies that reported the clinical outcomes of nonagenarianswith acute ischemic stroke after undergoing mechanical thrombectomy. Risk ofbias was assessed using different scales. I² statistic was usedto evaluate the heterogeneity of the results, while meta-regression andsensitivity analyses were performed to investigate the source ofheterogeneity.

Results: Thirteen studies and 657 patients were included. Theestimated rate of successful revascularization was 80.82% (95% confidenceinterval[CI]: 77.48% - 83.97%), and the rate of favorable outcome (modifiedRankin score[mRS] 0 - 2) was 21.60% (95% CI: 13.81% - 30.41%). The rate ofgood outcome (mRS score 0 - 3) was 23.08% (95% CI: 18.88% - 27.55%). Theestimated risk of death during hospitalization was 20.55% (95% CI: 15.93% -25.55%), while the mortality rate at 3 months was 44.38% (95% CI: 33.66% -55.36%). The rate of intracranial hemorrhage (ICH) occurrence was 12.84%(95% CI: 5.27% - 22.68%), while the rate of symptomatic intracranialhemorrhage (sICH) was 3.52% (95% CI: 1.67% - 5.85%). The rate ofhospital-related complications was 26.93% (95% CI: 10.53% - 47.03%).

Conclusions: MT in nonagenarians demonstrated a high rate ofsuccessful revascularization. Conversely, the rate of futilerevascularization is high with a low functional independence proportion.Therefore, MT should not be indiscriminately advocated in nonagenarians.Satisfactory results require careful selection of patients. Furtherhigh-quality studies are needed to clarify the selection algorithm.

O2-2-2

Direct aspiration thrombectomy as a first-pass approach for veryelderly patients with ischemic stroke

Jae Jon Sheen, Eunhye Lee

Department of Neurosurgery, Uijeongbu St Mary's Hospital, College ofMedicine, The Catholic University of Korea

Objective: This study aimed to determine whether an age of ≥ 80years would affect the radiological and clinical outcomes of the directaspiration first pass strategy for large vessel occlusion.

Methods: This study analyzed single-center data of patients withstroke who were treated with mechanical thrombectomy between May 2018 andOctober 2020. Baseline characteristics, as well as radiological and clinicaloutcomes of patients were recorded, analyzed, and compared between the veryelderly (≥ 80 years) and elderly patients (< 80 years).

Results: Sixty patients underwent mechanical thrombectomy usingthe Sofia aspiration catheter for mainstem occlusion of the middle cerebralartery. The direct aspiration first pass strategy was effective in 56.3%(n = 9) and 54.4% (n = 24) in the very elderly and elderly groups,respectively (p = 0.907). The final successful recanalization rates(thrombolysis in cerebral infarction ≥ 2b) were 75.0% (n = 12) and 70.5%(n = 31) in the very elderly group and elderly groups, respectively(p = 0.999). There was no significant between-group dif- ference in the good90-day clinical outcome (modified Rankin Scale ≤ 2) (50.0% and 56.8% in thevery elderly and elderly groups, respectively, p = 0.639). Further, therewere no significant between-group differences in complication rates.

Conclusion: There was no difference in the recanalization ratesand clinical outcomes of the direct aspiration first- pass strategy forpatients aged ≥ 80 and < 80 years with occlusive lesions in largevessels.

O2-2-3

Outcomes and prognostic factors of Mechanical Thrombectomy for veryelderly patients over 90 years old with acute ischemic stroke.

Yushiro Take^1,2, Mai Okawara¹, Manabu Osakabe¹, Hiroyuki Yamaguchi¹, Mikiya Ueda¹, Takahiro Maeda¹, Hiroki Kurita²

¹Department of Neurosurgery, Ohkawara Neurosurgical Hospital,Muroran, Japan

²Department of Cerebrovascular surgery, Saitama InternationalMedical center, Hidaka, Japan

Background: It is unclear whether the efficacy and safety ofMechanical Thrombectomy for over 90 years old patients. In this study, weinvestigated the outcomes and prognostic factors of mechanical thrombectomyin those patients.

Methods: Retrospectively, we reviewed twelve patients over 90years old with acute ischemic stroke, who performed mechanical thrombectomyin our hospital between 2018 and 2021. We analyzed baseline characteristics,procedural and functional outcomes using Thrombolysis in Cerebral Infarctionscale (TICI) and modified Ranking Scale(mRS), respectively. Additionally,morbidity (symptomatic intracranial hemorrhage, serious adverse events) andmortality rate were analyzed. We defined a good functional outcome as mRS≤3at 90 days or discharge.

Results: Good functional outcome was observed in 41.6%(5/12).Morbidity and mortality rates were 8.3% (1/12) and 16.6% (2/12),respectively. No patients were observed with symptomatic intracranialhemorrhage. The rate of successful recanalization (TICI≥2b) was 75% (9/12).In comparison between the two patients’ groups mRS≤3 and mRS≥4 at 90 days ordischarge, The National Institute of Health Stroke Scale(NIHSS)(p = 0.046), occludedvessels(p = 0.027), and the rate of TICI≥2b in a firstprocedure(p = 0.027) were statistically significant.Logistic regression analysis suggested Alberta Stroke Program Early CT Score(ASPECT) (adjusted odds ratio, 1.90; 95% CI, 1.071–4.949;p = 0.025) as predictors of mRS≤3. Additionally, it wassuggested that successful recanalization, MCA occlusion, and first proceduresuccessful recanalization increased the proportion of the mRS≤3 group anddecreased the proportion of the mRS≥4 groups and mortality rate at 90 daysor discharge.

Conclusions: This study suggested the efficacy and safety ofmechanical thrombectomy for over 90 years old patients. However, it washigher mortality and less favorable outcome than younger patients, sotreatment decisions for mechanical thrombectomy in over 90 years oldpatients may be considered to NIHSS, ASPECTs, and embolic vessels.

O2-2-4

Relationship between the elderly population and the number ofmechanical thrombectomies.

Yushiro Take^1,2, Mai Okawara¹, Manabu Osakabe¹, Hiroyuki Yamaguchi¹, Mikiya Ueda¹, Takahiro Maeda¹, Hiroki Kurita²

¹Department of Neurosurgery, Ohkawara Neurosurgical Hospital,Muroran, Japan

²Department of Cerebrovascular Surgery, Saitama InternationalMedical Center, Hidaka, Japan

Background: The elderly population is increasing in developedcountries, however, it has not been reported how the number of mechanicalthrombectomies will change in the future. We retrospectively examined therelationship between the elderly population and the number of mechanicalthrombectomies.

Methods: We investigated the area with a high elderly populationrate and located in the south-central parts of Hokkaido, north of Japan, intwo periods (2014–2015 and 2016–2019). The area has five regions, Murorancity, Noboribetsu city, Date city, Toya lake town, Sobetsu/Toyoura town.

Results: The average population over 65 years old is 31.84% inthat area. The number of cases in the whole area increased from 15.1cases/100,000 people in the first period to 19.5 cases/100,000 people in thesecond period. However, the numbering of mechanical thrombectomies decreasedfrom 15.33 to 7.58 and 14.03 to 10.30 in the two regions (Lake Toya, Sobetsu/ Toyoura). The whole population decline rate of the area was 6.5%, and theincrease rate of the elderly aged 65 and over was 6.86% on average.Especially, the population remarkably declined in 2 regions (Lake Toya,Sobetsu / Toyoura) compared to others. The population decline rate was high(9.6%, 8.7%) in those regions. Additionally, the rate of increase in theelderly aged 65 and over was low (2.3%, 1.3%).

Conclusion: Our study suggests that the number of mechanicalthrombectomies may increase in areas where the elderly population increase,while it may decrease in areas where the whole population remarkablydeclines and low increase rate of the elderly population.

O2-2-5

A Prognostic Scoring System of Mechanical Thrombectomy for ElderlyAcute Ischemic Stroke Patients

Koichi Arimura¹, Kenji Miki¹, Ryu Matsuo², So Tokunaga³, Keisuke Ido⁴, Shinya Yamaguchi⁵, Hidenori Yoshida⁶, Katsuharu Kameda⁷, Koji Iihara⁸, Osamu Ito⁹, Kenta Hara³, Ryota Kurogi⁶, Yuya Koyanagi¹, Tomohiro Okuda¹, Katsuma Iwaki¹, Soh Takagishi¹, Ataru Nishimura¹, Akira Nakamizo¹, Koji Yoshimoto¹

¹Department of Neurosurgery, Graduate School of Medical Sciences,Kyushu University

²Department of Health Care Administration and Management, GraduateSchool of Medical Sciences, Kyushu University, Fukuoka, Japan

³Department of Neuroendovascular Therapy, Clinical ResearchInstitute, National Hospital Organization Kyushu Medical Center, Fukuoka,Japan

⁴Department of Neurosurgery, Saga-ken Medical Center Koseikan,Saga, Japan

⁵Department of Neurosurgery, Stroke Center, Steel Memorial YawataHospital, Fukuoka, Japan

⁶Department of Neurosurgery, Fukuoka Tokushukai Hospital, Fukuoka,Japan

⁷Department of Neurosurgery, Shin Koga Hospital, Fukuoka,Japan

⁸Department of Neurosurgery, National Cerebral and CardiovascularCenter, Osaka, Japan

⁹Department of Neurosurgery, Fukuoka Kieikai Hospital, Fukuoka,Japan

Background and Purpose: Japan has a rapidly aging population andthe application of mechanical thrombectomy (MT) for acute ischemic stroke(AIS) among elderly patients has increased, but feasibility and safety of MTfor elderly patients are still debated. Therefore, this study aimed toelucidate feasibility and safety of MT for elderly patients by analyzing theretrospective multicenter database.

Methods: A total of 763 consecutive patients who underwent MTfor AIS between January 2013 and January 2020 at seven comprehensive strokecenters were enrolled in this study. We analyzed elderly AIS patientsdefined as those aged ≥ 75 years with IC/M1/M2 occlusion. Good outcome wasdefined mRS 0–2 at 90 days after onset, and we investigated the factorsassociated with good outcome.

Results: Overall, data from 251 elderly patients and 220non-elderly patients were analyzed retrospectively. Functional outcomes werepoor in the elderly group. In elderly patients, female sex (odds ratio (OR):0.45, 95% confidence interval (CI): 0.23–0.86), anticoagulant drug use (OR:0.37, 95%CI: 0.17–0.81), the National Institutes of Health Stroke Scale(NIHSS) score (OR: 0.91, 95%CI: 0.88–0.96), the Alberta Stroke Program EarlyComputed Tomography Score (ASPECTS) (OR: 1.3, 95%CI: 1.07–1.49), and themodified Thrombolysis in Cerebral Infarction (mTICI) score (≥2b) (OR: 4.5,95%CI: 1.46–13.8) were independent factors for functional outcomes. Wedeveloped a scoring system consisting of six factors, including age, femalesex, a pre-modified Rankin Scale (mRS) score of 2, anticoagulant drug use,the NIHSS score, and the ASPECTS. A score ≤ 5 predicted an mRS score of 0–2at 90 days with a sensitivity of 74% and a specificity of 65%. In thevalidation study, a score ≤ 5 predicted an mRS score of 0–2 at 90 days witha sensitivity of 70% and a specificity of 60%. In addition, 50% of thepatients with a score ≤ 3 achieved good clinical outcomes, whereas only 5%of those with a score ≥ 9 achieved good functional outcomes. Our scoringsystem's accuracy was validated in the prospective study.

Conclusion: eAIS-PSS was useful to predict good outcome in MTfor elderly AIS patients.

O2-2-6

Comorbidity Burden and Clinical Outcomes after Mechanical Thrombectomyfor Large Vessel Occlusion

Satoru Fujiwara¹, Yoshinori Matsuoka², Masamune Kimura¹, Kota Maekawa¹, Junji Takasugi¹, Tadashi Sunohara³, Ryu Fukumitsu³, Nobuyuki Ohara¹, Masanori Goto³, Masaomi Koyanagi³, Michi Kawamoto¹, Hirotoshi Imamura³, Tsuyoshi Ota³, Nobuyuki Sakai³

¹Department of Neurology, Kobe City Medical Center GeneralHospital

²Department of Emergency medicine, Kobe City Medical CenterGeneral Hospital

³Department of Neurosurgery, Kobe City Medical Center GeneralHospital

Purpose: The effectiveness of mechanical thrombectomy (MT) forlarge vessel occlusion (LVO) has demonstrated in elderly or patients withpre-stroke disability, however, the impact of pre-existing comorbidities hasnot been well studied. We therefore examined the association betweencomorbidity burden before LVO onset and clinical outcomes after MT.

Methods: In this single-center retrospective study from April2016 to December 2021, we enrolled consecutive patients with community-onsetLVO treated with MT. To quantity each patient's comorbidity burden, wecalculated Charlson Comorbidity Index (CCI), a scoring method using numberand severity of 19 pre-defined comorbid conditions, by reviewing medicalrecords or interview sheets, then classified the patients into Low CCI(<3) and High CCI (≥3) groups. The primary outcome was good neurologicaloutcome at 90 days; the incidence of hemorrhagic complication after MT andall-cause mortality within 90 days were also evaluated.

Results: Of 358 patients who met the eligibility criteria, 270(75.2%) patients were classified into the Low CCI group, and 88 (24.8%)patients were in the High CCI group. The High CCI group patients were olderand less likely to have premorbid modified Rankin Scale (mRS) ≤ 1 thanpatients in the Low-CCI group. The proportion of good neurological outcomeat 90 days was 124 (45.9%) in the Low CCI group and 20 (22.7%) in the HighCCI group, and the adjusted odds ratio (OR) (95% confidence interval (CI))was 2.35 (1.19 to 4.66). Compared to patients with mRS 0-1 and CCI < 3,the adjusted OR for neurological good outcome were 0.62 (0.28–1.40) inpatients with mRS 0-1 and CCI ≥ 3, 0.40 (0.18 to 0.91) in mRS ≥ 2 and CCI< 3, and 0.28 (0.10 to 0.80) in mRS ≥ 2 and CCI ≥ 3 (p for trend <0.0001). All-cause mortality within 90 days was significantly higher in theHigh CCI group (11.1% vs 26.1%, p = 0.0006). The High CCI group were morelikely to have symptomatic intracranial hemorrhage within 72 h of admissionthan the Low CCI group (4.9% vs 10.3%, p = 0.06).

Conclusion: High CCI was associated with poorer clinicaloutcomes after MT and the effect was greater with addition of pre-strokedisability. General assessment of comorbidity burden using CCI should beconsidered to determine an indication for MT, especially in patients withpre-stroke disability.

O2-3-1

Dural feeders from the posterior cerebral artery and superiorcerebellar artery in the medial tentorial dural AVFs

Meshari Ali AlAli¹, Deok Hee Lee²

¹Radiology, AlMajmaah University, Radiology department, Saudi

²Asan medical center, Seoul, Korea

AlAli, AlAhideb, Kwon, Song, Park JC, Lee DH

BACKGROUND: Tentorial dural AVFs tend to show isolated corticalvenous reflux. Furthermore, the lesions in the medial side of the tent,medial tentorial DAVFs (MTDAVFs), show deep venous drainage notinfrequently, calling us active treatment for them. Endovascular treatmentbecomes more manageable with the advent of liquid embolic material; however,the common presence of fine feeders from the PCA and SCA could be a sourceof incomplete embolization.

PURPOSE: In this retrospective review of our single-centerexperience with the MTDAVFs, we focused on those dural feeders from the PCAand SCA (posterior circulation) for the treatment planning and embolizationoutcome.

MATERIALS AND METHODS: A retrospective study was carried out atAsan Medical Center reviewing cases from 2011 To 2022 with isolated MTDAVFs,including the lesions having the fistula at the medial tentorial free margin(free margin group), at the anterior falcotentorial junction (FTJ) near thevein of Galen (anterior FTJ group), at the mid-FTJ surrounding the straightsinus (mid-FTJ group), or at the posterior FTJ surrounding the torcula(posterior FTJ group). Patients who have additional fistula other than theMTDAVFs were excluded. After identifying the fistula hole, arterial feeders,draining veins, embolization route, and method, embolization results wereanalyzed, focusing on the presence of the dural feeders from the PCA and SCAand their influence on the embolization outcome.

RESULTS: There were 16 males (80%) and four females (20%). Agebetween 35 to 80 years. Most of the patients presented with headaches, and 2patients presented after intracranial hemorrhage. On angiographic analysis,there were two patients (10%) in the free margin group, 9 (45%) in theanterior FTJ group, 6 (30%) in the middle FTJ group, and 3 (15%) in theposterior FTJ group. Posterior circulation feeders were seen in 1 patient(5%) in the free margin group, 6 (30%) in the anterior FTJ group, 3 (15%) inthe middle FTJ group, and 1 (5%) in the posterior FTJ group. 15 patients outof 20 have been treated endovascularly; 11 (73%) of them had a residualshunt, including the 7 patients with additional feeders from the posteriorcirculation contribution.

Conclusion: We could see the expected contribution of the duralfeeders from the posterior circulation for the MTDAVFs. Since the presenceof these feeders may hamper the embolization outcome performed bytransarterial embolization via other dural feeders, additional controlangiography would be helpful in the determination of embolization resultsduring the procedure before removing the embolization microcatheter.

O2-3-2

Parasagittal dural arterio-venous fistula as a new entity of non-sinustype dural arterio-venous fistula: Cadaveric and clinicalevaluation

shigeta miyake^1,2, Yasunobu Nakai¹, Jun Suenaga², Kengo Funakoshi³, Tetsuya Yamamoto²

¹Department of Neurosurgery, Yokohama Brain and Spine Center,Yokohama, Japan

²Department of Neurosurgery, Yokohama City University, Yokohama,Japan

³Department of neuroanatomy, Yokohama City University, Yokohama,Japan

Background: In parasagittal dural arteriovenous fistula (DAVF),the shunt point is on the falx cerebri and drains directly into the corticalvein. The anatomy of the venous structure of the falx cerebri is not wellunderstood. We focused on the anatomy of the cortical vein directly flowinginto the falx cerebri, the venous route in the falx cerebri, and theclinical characteristics of parasagittal DAVF.

Methods: In seven cadaver heads, we exposed the entire length ofthe falx cerebri and the cortical veins flowing into it were recorded. Thefalx cerebri was divided down the midline into the dura propria to examinethe venous pattern. Additionally, six patients with parasagittal DAVFs wereobserved between April 2009 and March 2019.

Results: Seven (50.0%) venous structures directly flowed intothe falx cerebri and were located in para-sinus portion below the lambdoidsuture in five (35.7%) cadavers. The veins directly flowing into the falxran through the intradural space on each side. Clinically, all six caseswere classified as parasagittal DAVF. Intracerebral hemorrhage occurred intwo patients (33.3%). In all six cases, only the cortical vein was thedraining vein ipsilateral to the shunt point. One patient (16.7%) underwenttransarterial embolization (TAE), two (33.3%) underwent direct surgery, andtwo (33.3%) underwent combined TAE with direct surgery.

Conclusions: This is the first study to describe parasagittalDAVF as a non-sinus-type DAVF using cadaver analysis and clinical expertise.Parasagittal DAVF should be treated with TAE or direct interruption of thedraining vein.

O2-3-3

Utility of three-dimensional-rotational angiography and heavily T2volumetric magnetic resonance fusion imaging for the diagnosis of spinalvascular malformations

Bikei Ryu^1,2, Kazuki Kushi², Tatsuki Mochizuki², Tomomi Ishikawa², Shogo Shima², Shinsuke Sato^1,2, Tatsuya Inoue², Yoshikazu Okada², Yasunari Niimi¹

¹Department of Neuroendovascular Therapy, Saint Luke'sInternational Hospital, Tokyo, Japan

²Department of Neurosurgery, Saint Luke's International Hospital,Tokyo, Japan

Purpose: Recent advances in imaging technology have made itpossible to visualize the microvasculature of spinal arteriovenous shunts(SAVS) and elucidate their pathophysiology in detail. 3D-volume data can beused to create fusion images (FI) with different image modalities, allowingmore anatomical information to be depicted simultaneously. This studyinvestigated whether 3D rotational angiography (3D-RA) and 3D-volumetric T2MRI (3D-MRI) FI could improve the diagnostic accuracy of SAVS.

Materials and Methods: Forty-two SAVS images were reviewedretrospectively. Finally, the FI of 3D-RA and 3D-RA + 3D-MRI in 12 cases wasrated at 2 levels by 7 blinded reviewers. The SAVS type and shunt point ofeach case were first evaluated with 3D-RA alone and then again with the FI.The results of the 2-stage evaluation were compared with the final diagnosis(overall diagnosis of 2 endovascular advisors) and the interobserveragreement with the final diagnosis was calculated (kappa statistic: 3D-RA vsFI). The quality of each 3D-RA and FI image was rated on a 4-point scale foreach case.

Results: Interobserver agreement for SAVS diagnosis was markedlyhigher with the FI than with 3D-RA (κ = 0.35 vs. 0.70). The FI could be ableto simultaneously depict dura mater, nerves, and spinal cord in addition tovascular architecture. Image quality was significantly higher with the FIthan with 3D-RA (p < 0.0001). In particular, the FI improvedinterobserver agreement for SDAVF and SEAVF subtype diagnosis (κ = 0.14 vs0.63, κ = 0.30 vs 0.80).

Conclusion: Conventional 3D-RA alone might fail to delineatesoft tissues such as dura mater and spinal cord, sometimes leading toincorrect SAVS subtype diagnosis. The FI enabled simultaneous delineation ofsurrounding soft tissues at high resolution. Detailed anatomicalinformations obtained from FI contribute to the accurate diagnosis ofSAVS.

O2-3-4

Treatment strategies and outcomes for Intracranial dural AVF with pialartery supply

Shinsuke Sato^1,2, Yasunari Niimi², Mituki Itou¹, Makiko Sakaguchi¹, Tatuki Mochizuki¹, Tomomi Ishikawa¹, Shougo Shima^1,2, Bikei Ryu^1,2, Tatuya Inoue^1,2, Yoshikazu Okada¹

¹Department of Neurosurgery, St Luke's International Hospital

²Department of Neuroendovascular therapy, St Luke's InternationalHospital

Introduction: Dural arteriovenous fistula with pial arterysupply is reported to be more frequent in the order of tentorium and SSS.Pial artery supply is classified into a true pial artery and dilated duralbranch of a pial artery. However, the treatment risk of each branch is stillarguable. Whether a true pial artery should be pre-treated with a pialfeeder? If so, to what extent? In dilated dural branches of pial arteries,liquid materials from the dural branch into the pial feeder is a problem inthe cases of high-flow dural arteriovenous fistula. Treatment strategies andoutcomes are examined from a retrospective viewpoint.[Subject/Method] 16cases of dural AVF with pial artery supply from December 2013 to December2021 were examined. 9 male patients. The mean age was 61 years old. Theinvolved sites were (1) tentorium in 6 cases, (2) transverse sinus in 6cases, (3) SSS in 2 cases, and (4) SMCV in 2 cases. Borden types were (1)type 2: 1 case, type 3: 5 cases, (2) type 2: 4 cases, type 3: 2 cases, (3)type 3: 2 cases, and (4) type 3: 1 case.[Result] The treatment methods andresults were as follows. In case of 1), 3 cases of TAE(onyx) (CO), 1 case ofTAE(NBCA/Onyx) (CO), 1 case of TAE(Onyx/Coil/NBCA)(PO), and 1 case ofTAE(NBCA/Onyx)(PO). In 2), 2 cases of TVE(coil)(CO), 2 cases ofTAE(Onyx)(PO, CO)(PO: with pial feeder, no sinus packing, GKRS was added tothe residual shunt at a later date, and the patient showed a tendency toregress), 2 cases of TAE(Onyx/NBCA)(PO, CO). In 3), 1 case of TVE(coil)(PO), 1 case of TAE(Onyx/coil) (CO), and 2 cases of TAE(Onyx) (CO).Complications were as follows. In 1), 1 case of postoperative temporaryfacial nerve palsy due to Onyx 18 injection from PCB. In high flow shuntcases, 1 case of Onyx18 infusion from MMA led to stray into distal ACA (viaa dilatated dural branch of pial feeder). 1 case of cerebellar infarctiondue to NBCA embolization from SCA pure pial artery.[Conclusion] Preoperativeimaging evaluation and understanding of the aberrant pattern to the pialfeeder were essential to reduce the risk of perioperative complicationsduring the treatment of liquid materials.

O2-3-5

Characteristics and treatment for dural arteriovenous fistulas withosseous shunt

Shunji Matsubara, Hiroki Takai, YoshihiroSunada, Yoshifumi Tao, Eiji Shikata, Maoki Matsubara, Yukari Minami,Satoshi Hirai, Kenji Yagi, Masaaki Uno

Department of Neurosurgery, Kawasaki Medical School, Kurashiki, Japan

Dural AVF (dAVF) is thought to occur in and near the sinus, dura mater, tent,and falx cerebri, but several literatures have recently described somefistulas existing in the skull (Osseous AVF: OsAVF).

Patients and methods: Of the 66 intracranial and spinal dAVFpatients experienced at our institution between April 2009 and December2021, 15 patients (22.7%) were retrospectively diagnosed with OsAVF based onmaximum intensity projection (MIP)of rotational angiography, CTA, MRA, andintraoperative findings. The average age was 67.4 years and the male/femaleratio was 7: 8.

Results: Intraosseous shunts were observed at anterior cranialfossa (ACF) in 4/4 patients (100%), cavernous sinus in 4/14 patients(28.6%), middle cranial fossa (MCF) in 2/2 patients (100%), transversesigmoid in 2/18 cases (11.1%) and anterior condylar confluence (ACC) in 3/3cases (100%), respectively. However, it could not be found in other lesionsincluding tent, convexity, craniocervical junction, spine. In those OsAVFs,the ascending pharyngeal artery was the most involved as the feeding artery,while the ascending frontal vein in ACF, the anterior condyle vein in ACC,and the diploic vein in CS, TS, MCB were the most involved as the drainingveins. Preoperative images showed small bone erosion in the fistula in 9patients (ACF: crista galli, MCF: posterolateral aspect of foramen rotundum,ACC: hypoglossal canal). As a symptom, only one patient of ACF developedwith intracranial hemorrhage, and the other 14 patients had pulsatiletinnitus, ocular symptoms, or no symptoms. They were treated by surgicaldrainer ligation in 4 patients and transvenous embolization (TVE) in 11patients, all of which were cured. Transient hypoglossal nerve paralysisoccurred in 1 patient (6.7%), but the outcome was mRS 0/1 in allpatients.

Conclusion: OsAVF was present in about 20% of the patients thatseemed to be dAVF at first diagnosis. If the fistula was present in theskull, TVE or surgical drainer ligation was considered effective and safefor treatment.

O2-3-6

Anatomical considerations of intraosseous arteriovenous fistula

Yu Iida¹, Nobuyuki Shimizu¹, Takeshi Hongo¹, Ryosuke Suzuki², Yohei Miyake¹, Yutaro Takayama¹, Masaki Sonoda¹, Naoki Ikegaya¹, Satoshi Hori¹, Mitsuru Sato¹, Kensuke Tateishi¹, Jun Suenaga¹, Tetsuya Yamamoto¹

¹Department of Neurosurgery, Yokohama City University

²Department of Neurosurgery, Odawara Municipal Hospital

Purpose: Dural arteriovenous fistulas (DAVFs) are diseases inwhich abnormal shunts form in arteries and veins or venous sinuses on thedura mater. However, there have been rare AVFs with shunts in theintraosseous rather than in the dura mater. Current imaging modalities havemade it possible to accurately diagnose intraosseous AVFs, which areidentified in some cases conventionally diagnosed as DAVFs. In this study,we analyzed our cases of intraosseous AVFs and discussed their embryologicaland anatomical characteristics.

Materials and Methods: Sixteen patients underwent endovasculartreatment for cerebral DAVFs in our institution between January 2019 andApril 2022. They were analyzed retrospectively using 3-dimensionalrotational angiography and cone-beam computed tomography to identify theshunt point.

Results: Intraosseous AVFs were identified in 4 cases with fiveintraosseous shunt points. Intraosseous shunts were placed in the condyle,jugular tubercle, clivus, posterior clinoid, and lesser sphenoid wing. Allpatients were treated by transvenous embolization. Three patients were curedwithout complication, and one is currently undergoing treatment.

Conclusions: Accurate evaluation of intraosseous shunt pointsand targeted embolization can prevent postoperative cranial nerve palsy andpreserve the venous drainage route. This study revealed that intraosseousAVFs were located in the condyle, jugular tubercle, clivus, posteriorclinoid, and lesser sphenoid wing. This distribution was consistent with theskull formed from the endochondral bones. This suggests that differences inthe formation of the skull may influence shunt formation.

O2-4-1

Withdraw

O2-4-2

Drug-coated balloons for the treatment of in-stent restenosis in theneurovascular setting

Philipp v. Gottberg¹, Victoria Hellstern¹, Alexandru Cimpoca¹, Ali Khanafer¹, Hansjörg Bäzner³, Hans Henkes^1,2

¹Klinik für Neuroradiologie, Klinikum Stuttgart, Stuttgart,Germany

²Medizinische Fakultät, Universität Duisburg-Essen, Essen,Germany

³Klinik für Neurologie, Klinikum Stuttgart, Stuttgart, Germany

PURPOSE: Neurointerventional treatment of cervical andintracranial atherosclerotic stenosis has not seen the breakthrough yet asin other fields of neurointerventional therapy. Several major trials couldso far not show a clear superiority of minimal invasive endovascularcervical artery stenosis treatment and for intracranial stenosis, especiallySAMMPRIS, VISSIT and the WEAVE trial highlighted the problem of in-stentrestenosis (ISRS) following endovascular treatment.

We therefore investigated the role of drug-coated balloons (DCB) for thetreatment of cervical and intracranial ISRS to address a common problemfollowing endovascular treatment of atherosclerotic stenosis in theneurovascular field.

MATERIAL AND METHODS: Data from 100 patients with ISRS ofcervical (n = 50) or intracranial (n = 50) artery segments who underwenttranscutaneous re-angioplasty with DCB at our institution between 2008 and2021 were retrospectively analyzed. Follow-up was by regular digitalsubtraction angiography and clinical examinations. The mean follow-up timewas 4 years (2-129 months). Endpoints were ISRS of >50% followingDCB-treatment, any TIA and major stroke related to the treated vessel.

RESULTS: All procedures of re-angioplasty were successfullyperformed. There were no periprocedural complications, no in-hospital deathor major stroke. Following DCB treatment, the mean interval of freedom fromsymptoms and/or stenosis was 3.5 years (2-122 mo). Forty percent of thepopulation reached the endpoint of ISRS (n = 33), TIA (n = 6) or majorstroke (n = 1). No intracranial treated vessel segment was identified to beat higher risk for ISRS.

CONCLUSION: In our study, DCB was an uncomplex way to treatcervical and intracranial ISRS. The low rate of periprocedural complicationsand the median time of freedom from symptoms and/or restenosis suggest thatDCB angioplasty for ISRS is a viable treatment.

O2-4-3

Bilateral limb-shaking transient ischemic attacks treated withunilateral carotid artery stent placement

Toshihiko Shimizu¹, Keiko Haro², Masahiko Tagawa³, Masaaki Hirata⁴, Sachiko Iwano⁴, Hiroshi Kosaka¹, Yuji Yamamoto¹

¹Department of Neurosurgery, Matsuyama Shimin Hospital, Matsuyamacity, Ehime, Japan

²Department of Neurology, Matsuyama Shimin Hospital,Matsuyamacity, Ehime, Japan

³Department of Neurosurgery, Ehime University Hospital, Tōon city,Ehime, Japan

⁴Department of Radiology, Matsuyama Shimin Hospital, Matsuyamacity, Ehime, Japan

Purpose: Limb-shaking transient ischemic attack (LS-TIA) is arare clinical disease involving carotid artery stenosis and is characterizedby tremor-like involuntary movements of the arms and legs. LS-TIA resultsfrom inadequate blood flow to the basal ganglia and usually occursunilaterally, with bilateral LS-TIA being even rarer and poorly understood.To date, unilateral carotid artery stenting (CAS) in cases with bilateralballism due to carotid artery stenosis has not been reported. Here, wepresent a case of bilateral LS-TIA in which unilateral CAS wasperformed.

Summary of case: A male in his 80s presented with continuousbilateral ballism in the arms and legs, along with dyskinesia of the tongue.Magnetic resonance (MR) imaging showed no ischemic lesions, while MRangiography revealed right internal carotid artery (ICA) occlusion and 80%stenosis of the left ICA. ^99mTc-ethyl cysteinate dimersingle-photon emission computed tomography (ECD-SPECT) demonstratedhypoperfusion in the right cerebral hemisphere.Consequently, he was treatedwith dopamine receptor blockers (tiapride and haloperidol) and dualantiplatelet therapy (DAPT). Although the dopamine receptor blockerseffectively controlled the ballism, cognitive function was decreased(Hasegawa's Dementia Scale-Revised[HDS-R] score: 3/30) at day 25. Left ICAstenting was performed, and the involuntary shaking of the limbs improved.Hypoperfusion in the right hemispheric brain was improved by cross flow fromthe left side. Postoperatively, quantitative CBF-SPECT at rest showed theblood flow of the right cortical area and right basal ganglia were greaterthan those in the left area. Dopamine receptor blockers were graduallydecreased and eventually discontinued on postoperative day 45. Involuntarymovements disappeared over a six-month follow-up period, and cognitivefunction recovered (HDS-R score: 21/30)

Conclusion: Misdiagnosis of ballism-like limb-shaking oftenleads to inappropriate treatment. Carotid artery stenting is an effectivetreatment for this type of involuntary movement.

O2-4-4

The efficacy of carotid artery stenting with only pre-stenting balloondilatation for patients with unstable plaques.

Atsushi Ogata, Takashi Furukawa, YurikoShojima, Jun Masuoka, Tatsuya Abe

Department of Neurosurgery, Saga University, Saga, Japan

Purpose: Unstable plaque is one of the risk factors for embolismduring carotid artery stenting (CAS). It has been reported that debrisgeneration is more common during post-stenting dilation. We use a techniquein which sufficient dilatation is achieved in the pre-stenting balloondilatation and post-stenting balloon dilatation is omitted. The purpose ofthis study was to investigate the efficacy of this technique for patientswith unstable plaques.

Materials and Methods: CAS with pre-stenting balloon dilationonly was performed using a 4-5 mm balloon for pre-dilation and stenting(pre-SB). Of the 116 patients who underwent CAS from 2013 to 2021, 90 casesof pre-SB were included in the study. The patients were divided into twogroups according to the presence or absence of unstable plaque. The twogroups were compared in terms of patient background, stroke within 30 daysafter CAS, and ipsilateral high intensity signal (HIS) on MRI-diffusionweighted image (DWI) the day after CAS. Unstable plaque was defined as HISon magnetization prepared rapid acquisition with gradient echo (MPRAGE)(plaque muscle ratio (PMR) >1.5) or HIS on time of flight (TOF)-MRangiogram (MRA) (PMR >1.5), respectively.

Results: Patients with pre-SB had two TIA (2.2%) and nominor/major stroke. We compared 64 patients with MPRAGE HIS and 36 withoutthose. Symptomatic patients were significantly high (75vs46%, P = 0.01) andPatients with CAS using filter protection were significantly low (30vs65%,P = 0.002) in MPRAGE HIS group. There was no difference in TIA between thetwo groups (1.6vs3.9%, P = 0.51). There was no difference in ipsilateralMRI-DWI HIS after CAS (25vs27%, P = 1.0). Next, we compared 35 patients withHIS on TOF-MRA and 55 patients without those and found no significantdifferences in patient background except for more dyslipidemia with TOF-MRAHIS. there was no difference in TIA between the two groups (0vs3.6%,P = 0.52). There was no difference in ipsilateral MRI-DWI HIS after CAS(23vs27%, P = 0.80).

Conclusions: CAS with adequate pre-dilation and no post-dilationmight be a reasonable first choice for unstable plaques.

O2-4-5

Predictive factors of ischemic stroke caused by mild stenosis ofcervical internal carotid artery

～Importance of evaluation of plaque characteristics by MRI imaging～

Fukuta Shinya, Mitsuhiro Iwasaki, HidekazuYamazaki, Masahiro Maeda, Yasufumi Inaka, Hiroaki Sato, Masaki Kou,Masafumi Morimoto

Neurosurgery, Yokohamashintoshi Neurosurgical Hospital

Background: While a favorable natural history of mild internalcarotid artery stenosis (mild ICS) has been reported, however, such lesionsmight cause ischemic stroke. The purpose of this study is to identify thevalidity of MRI plaque imaging for the predictive factor of ischemic strokeby mild ICS.

Method: Between April 2018 and February 2022, 52 consecutivecases of mild ICS with less than 50% NASCET on digital subtractionangiography (DSA) were included in the study. All of them underwent both MRIplaque imaging and carotid ultrasound examination for the evaluation ofcarotid plaque characteristics. They were divided into two groups bypresence or not of ischemic stroke, and the plaque characteristics of themin each group was respectively investigated.

Result: Of the total 52 cases, 25/27 were symptomatic /asymptomatic cases, respectively. Median age was 75/74, 21(84%)/24(89%) weremale, and NASCET was 40/41(%). 10 (40%)/6 (22%) were with ulceration, andthere were no significant differences between the two groups for the abovefactors. On the other hand, the plaque sternocleidomastoid signal intensityratio (SIR) measured by MRI T1 black blood was significantly higher in thesymptomatic group (1.6 compared to 1.2 in the asymptomatic group)(p < 0.001). The ROC curve was plotted with SIR and a cutoff value of1.38 for SIR resulted in a sensitivity and specificity of 96% and 80%,respectively for the development of ischemic events (AUC 0.84).

Conclusion: High SIR might be the valuable predictor for onsetof ischemic stroke caused by mild ICS. It is important to evaluate not onlythe degree of stenosis, but the plaque characteristics by MRI imaging. Suchresults might suggest aggressive medical treatment and determine theindication of revascularization for mild ICS.

O2-4-6

Clinical Outcomes of Radiation-induced Carotid Stenosis

Xiao Zhang^1,2, Yanying Yu³, Kun Yang⁴, Xuesong Bai^1,2, Tao Wang^1,2, Yao Feng^1,2, Ran Xu^1,2, Bin Yang^1,2, Liqun Jiao^1,2,5, Yan Ma^1,2

¹Department of Neurosurgery, Xuanwu Hospital, Capital MedicalUniversity

²China International Neuroscience Institute (China-INI), Beijing,China

³Department of Clinical Medicine, Peking Union Medical College

⁴Department of Evidence-Based Medicine, Xuanwu Hospital, CapitalMedical University

⁵Department of Interventional Neuroradiology, Xuanwu Hospital,Capital Medical University, Beijing, China

Background: Clinical outcomes of radiation-induced carotidstenosis are still unclear. Therefore, this study is aimed to evaluate theshort-term and long-term outcomes after surgery for radiation-inducedcarotid stenosis.

Methods and analysis: PubMed, EMBASE, the Cochrane Library andWeb of Science were searched for relevant RCTs and observational studieswhich reported short- and long- term outcomes after carotid endarterectomy(CEA) and carotid angioplasty and stenting (CAS) for carotid stenosisinduced by radiation, and examination of grey literature were also conductedby independent reviewers. Only studies conducted from 1 January 2000 to 1January 2022 and published in English were included. Risk of bias wereassessed through different scales according to study design. I²statistic were used to evaluate the heterogeneity, and meta-regression andsub-group analysis were performed to investigate the source ofheterogeneity. Visual inspection of funnel plots and the Egger's test wereused to judge publication bias.

Results: A total of 26 studies with 1002 patients were included.CEA was performed in 364 patients and CAS in 638 patients. The estimatedrate of short-term stroke was 0.19% (95% CI = 0–0.90%), and the rate oflong-term stroke was 2.68% (95% CI = 1.19–4.57%). The rate of CNI in CEAgroup was significantly higher than that in CAS group[risk ratio(RR) = 6.03, 95% CI = 1.63–22.22, P = 0.007)], however,there was a tendence of decreasing year after year. The univariatemeta-regression analysis showed that the risk of stroke in CAS group weresignificantly higher than CEA group in both short-and long term[incidencerate ratio (IRR) = 3.62, 95% CI = 1.21–10.85, P = 0.22;IRR = 2.95, 95% CI = 1.02–8.59, P = 0.046),respectively].

Conclusion: This study provided the worldwide profile of outcomeof treatment for radiation-induced carotid stenosis, and also found that CEAcan yield better results for these patients than CAS. Nonetheless, aslarge-scale studies have not yet been conducted, and there is a definiteneed for further research studies in the future.

O2-5-1

Topical Nitropaste in radial artery access for cerebralangiography

Matthew B Potts¹, Khizar Nandoliya¹, Ramez Abdalla², Amr Alwakeal¹, Rushmin Khazanchi¹, Emily Winterhalter¹, Jon Klein¹, Sameer Ansari², Donald Cantrell², Ali Shaibani², Babak Jahromi¹

¹Neurological Surgery, Northwestern University Feinberg School ofMedicine

²Radiology, Northwestern University Feinberg School ofMedicine

Purpose: Transradial access in cerebral angiography is gainingpopularity. Intra-arterial administration of nitroglycerin, verapamil, andheparin is commonly performed to facilitate catheterization of the radialartery. Topical nitropaste has also been shown to improve radial arterycaliber prior to access. We have incorporated the use of topical nitropastein our transradial artery cerebral angiography practice and sought toanalyze of experience with it.

Materials and Methods: We retrospectively reviewed our series ofconsecutive cerebral angiograms performed with transradial artery access.All patients receive topical nitropaste applied to the right wrist andforearm. After access, patients are administered intra-arterialnitroglycerin, verapamil, and heparin. A subgroup of patients underwentultrasonography of the right radial artery to measure the radial arterycross-sectional diameter before topical nitropaste application as well as atthe time of arterial access. A contemporaneous cohort of transfemoral arterycerebral angiograms was evaluated for comparison.

Results: One hundred seventy attempted transradial arterydiagnostic cerebral angiograms were identified. Pre- and post-nitropasteultrasonography was performed in 47 cases. The mean vertical and horizontalcross-sectional diameters of the radial artery were 0.19cm and 0.23cm,respectively. These increased to 0.22cm and 0.26cm, respectively, after thetopical application of nitropaste (p < 0.001 and p < 0.01,respectively). There were 143 cases with final radial artery controlangiograms. Among these cases, 53.1% showed no radiographic vasospasm, 33.6%showed mild spasm, 13.3% showed moderate spasm. There were no cases ofsevere spasm. Procedural vital signs were evaluated in 143 radial patientsand compared to 333 transfemoral patients. Comparing these groups, therewere no differences in conscious sedation medications (fentanyl and versed)administered. The mean systolic blood pressures were 123.7 ± 1.5 and131.3 ± 1.0 mmHg for patients in the radial and femoral groups, respectively(p < 0.001). Twenty percent of patients undergoing radial accessdeveloped intraprocedural hypotension (defined as systolic < 90 mmHg ordiastolic < 60 mmHg) compared to 8% undergoing femoral access (p <0.001). Multivariate logistic regression modeling with midazolam dose,fentanyl dose, history of anti-hypertensive medications, and access routedemonstrated radial patients were significantly more likely to experienceintraprocedural hypotension (adjusted odds ratio = 2.78, 95% CI: 1.57–4.91,p < 0.001).

Conclusion: The use of topical nitropaste in addition to thestandard radial artery “cocktail” of intraarterial nitroglycerin, verapamil,and heparin during transradial cerebral angiography is safe and increasesthe caliber of the radial artery prior to access. However, intraproceduralhypotension is more likely to occur compared to transfemoral cases wherethese medications are not used.

O2-5-2

Restrospective survey about patients’ preference for transradialaccess versus transfemoral access in catheter-based cerebralangiography.

Yuk Yiu NG, Yee Ming Chong, Yin Lun Edward Chu,Raymand Lee

Department of Radiology, Queen Mary Hospital, Hong Kong

Introduction: Catheter-based cerebral angiography is animportant invasive procedure to examine cerebral vasculature.Traditionally,the procedure was performed via femoral access. In recent times, there is ashift from transfemoral to transradial approach for this procedure in theinternational neurointerventional community. This transition was fueled bystrong evidence of lower complication rates, earlier ambulation and reducedhospital costs. We describe our findings from a retrospective survey ofpatients’ preferences for transradial (TRA) and transfemoral(TRA) access incatheter based cerebral angiography.

Objectives: To determine patients’ preference for transradialaccess (TRA) versus transfemoral access (TFA) after they underwentcatheter-based cerebral angiography via both routes.

Methodology: This is a single center, consecutive survey for allpatients who had undergone successful catheter cerebral angiography via bothtransfemoral and transradial approaches. Our center has adopted a‘radial-first’ approach for cerebral angiography since September 2020. Weretrospectively analyzed our institutional database of cerebralangiographies performed via trans-radial route between September 2020 andDecember 2021. Past medical and procedural records were reviewed viaelectronic patient record (EPR). A total of 26 patients were found to haveundergone both TRA and TFA cerebral angiography and so met the inclusioncriteria. Survey were conducted via phone interview to gain a betterunderstanding of the patients’ viewpoints and experiences with these twoapproaches.

Result & Outcome: The survey was completed by 20 patientswho had radial access cerebral angiography following a previous femoralaccess cerebral angiography (20/26, 77%).

No major complications including wound infection and symptomatic occlusion orinjury of the access vessels were encountered in any cases.Because TRA didnot necessitate groin exposure, 16 of the 20 patients in this survey (80%)felt less embarrassed with it. 9 patients (45%) reported the overallperceived pain during the procedure was less in TRA compared to TFA, whilst3 patients (15%) reported less pain with TFA.

The radial compression band haemostasis is more satisfactory to 14 patients(70%).In postprocedural care, 15 (75%) regarded TRA to be superior to RFA.16patients (80%) stated that they preferred TRA over TFA and that if theyneeded another operation in the future, they would choose TRA.

In our single-center retrospective survey, patients showed a substantialpreference for radial artery access (TRA)over femoral artery (TFA) access incatheter-based cerebral angiography. With TRA, patients generallyexperienced less procedural pain and earlier ambulation after procedure. Inthis age of patient-centered care, a ‘radial-first’ approach for cathetercerebralangiography should be considered.

O2-5-3

The safety and efficacy of catheter 3.0 system in diagnostic cerebralangiography: a randomized controlled trial

Boseong Kwon¹, Ki Baek Lee², Jong-Tae Yoon³, Joon Ho Choi³, Jeong Soo¹, Yun Hyeok Choi¹, Deok Hee Lee¹, Yunsun Song¹

¹Department of Radiology, Research Institute of Radiology,University of Ulsan College of Medicine, Asan Medical Center, Seoul, SouthKorea

²Biomedical Engineering Research Center, Asan Institute for LifeSciences, Asan Medical Center, Seoul, South Korea

³Department of Radiologic Technology, University of Ulsan Collegeof Medicine, Asan Medical Center, Seoul, South Korea

Purpose: A conventional catheterization method of a cathetercerebral angiography had several limitations due to an innate necessity forflushing and weak catheter support. Therefore, it is required to advance acerebral angiographic system to cope with potential embolism and vasculartortuosity. Our neurointervention suite introduced a new angiographic systemnamed catheter 3.0 system. Its feasibility and possible superiority weredemonstrated in the previous phantom and retrospective studies,respectively. We conducted a single-center, randomized, single-blind,controlled trial to compare the safety and efficacy of the system with aconventional angiography system using a 4F diagnostic catheter.

Materials and methods: The new angiography system consisted of afabricated 5F angiography catheter, a 0.032-in fortified guidewire, and acontinuous heparinized flushing system with a hemostatic valve. A contrastmedium was injected while keeping the guidewire through the 5F catheter.From September 2021 to December 2021, patients above 18 years who underwenttransfemoral cerebral angiography for an unruptured intracranial aneurysmwork-up were screened. Patients consenting to participation were randomlyassigned in a 1:1 ratio to one of a 4F or 5F group in permuted blocks withstratification by age and an operator. The primary safety outcome was anycomplications, including vasospasm, dissection, and thromboembolism. Theprimary efficacy endpoint was procedural time. Secondary endpoints includedfluoroscopy time and radiation dose on fluoroscopy.

Results: A total of 100 patients were included in this study. Ofthese, 48 patients were assigned to the 4F group, and 52 patients wereassigned to the 5F group. The mean age was 58 ± 9.56 years in the 4F groupand 59.3 ± 9.16 years in the 5F group. Senior operators performed 20 exams(41.7%) in the 4F group and 23 (44.2%) in the 5F group. The number ofdigital subtraction angiography acquisitions was 7.2 ± 0.45 in the 4F groupand 7.62 ± 0.59 in the 5F group. The number of three-dimensional rotationalangiography acquisitions was 2.33 ± 1.03 in the 4F group and 2.23 ± 1.01 inthe 5F group. None of the primary safety outcomes occurred in both groups.The primary efficacy endpoint—procedural time—was 20.1 ± 4.55 min in the 4Fgroup and 15.07 ± 4.07 min in the 5F group. The fluoroscopy time was7.79 ± 2.80 min in the 4F group and 6.37 ± 3.28 min in the 5F group. Lastly,the radiation dose on fluoroscopy was 542.55 ± 245.13 µGym2 in the 4F groupand 406.44 ± 216.53 µGym2 in the 5F group. All test results of the outcomeand endpoints were statistically significant.

Conclusion: The new angiographic system—catheter 3.0system—significantly demonstrates good safety and efficacy compared with theconventional 4F angiography system.

O2-5-4

Introduction of Distal Radial Artery Approach in CerebralAngiography

Motoyuki Umekawa, Satoshi Koizumi, SatoshiKiyofuji, Nobuhito Saito

Department of Neurosurgery, The University of Tokyo, Tokyo, Japan

Purpose: Cerebral angiography is an essential examination ininterventional neuroradiology. In addition to the trans-femoral approach,the trans-radial artery approach has become an option to reduce patients’complaints and complications. Recently, the distal radial artery (DRA)approach, puncturing the radial artery running through the anatomicalsnuffbox, has been expected as an even less invasive method in cardiology.DRA approach is considered a safe and applicable technique toneurointervention; however, efficacy, degree of difficulty, andcomplications remain unknown. Since 2021, we have actively performed DRAapproach in patients who do not require the distal branch selection to makecerebral angiography and endovascular treatment less invasive. To evaluatethe utility of DRA approach in cerebral angiography, we investigate thedegree of difficulty and complications of the puncture and procedure.

Materials and Methods: We retrospectively selected 30consecutive cases in which DRA approach was attempted in cerebralangiography performed at our institution between June 2021 and February2022. Vascular ultrasound was used in all cases at the time of puncture andthe diameters of both DRA and conventional radial artery (RA) were measured.The correlation between successful puncture/complications as outcomes andpatients’ backgrounds were investigated.

Results: Among the 30 patients, 21 (70%) were males, and themedian age was 67 years (range: 25–87 years). The number of diagnoses forthe examination was eight (27%) for cerebral arteriovenous malformations,eight (27%) for internal carotid artery stenosis, seven (23%) for unrupturedaneurysms, and seven (21%) for other diseases. The mean DRA and RA diameterwere 2.31 (standard deviation[SD], 0.38) mm and 2.75 (SD, 0.42) mm, and thedifferences between sex were not observed in both mean lengths (DRA,p = 0.741; RA, p = 0.056). Bodyweightwas correlated with DRA diameter (p = 0.049). DRA puncturewas successful in 23 patients, and a success rate was 77%. There was nosignificant correlation between successful puncture and any patient factors,including DRA diameter. The success rate increased significantly from 57% inthe 14 patients in the former three months of the study period to 93% in the15 patients in the latter five months (p = 0.035). In allcases, the scheduled examinations were completed via DRA or conventional RA.No examination-related complications were observed.

Conclusion: The arterial diameter was not a limiting factor inperforming cerebral angiography via DRA. The puncture success rate increasedwith proficiency in the echo-based puncture technique. Our results suggestedthat DRA approach is useful in interventional neuroradiology to reduceexamination burden and might be safely introduced for endovascular treatmentfor selected cases.

O2-5-5

Usefulness of distal radial approach for neuroendovasculartreatment.

Eisuke Tsukagoshi^1,2, Hiroki Sato², Satoshi Iihoshi², Shinya Kohyama²

¹Stroke Center, Medical Corporation Bishinkai Kurosawa Hospital,Gunma, Japan

²Department of Endovascular Neurosurgery, Saitama MedicalUniversity International Medical Center, Saitama, Japan

Purpose: We analyzed cases treated with a distal radialapproach(dRA) at our hospital.

Methods: The 11 patients who underwent endovascular treatment bydRA between December 2021 and April 2022 at our hospital were included inthe study. A retrospective analysis of the outcomes of endovasculartreatment with the dRA was performed to evaluate efficacy and safety.

Result: There was one case in which the treatment was switchedfrom a distal radial approach to a femoral approach during the same period.The mean age was 58 years (31–78 years), 8 female cases. All were treatedwith a right dRA, the first puncture. All sheaths implanted were guidingsheaths, 4 Fr or 6 Fr. Sheaths were placed in 2 cases for right vertebralartery(VA), 3 cases for right internal carotid artery(ICA), 2 case for rightcommon carotid artery(CCA), 2 cases for left ICA, 2 cases for left CCA, 1case for left external carotid artery, and no left VA. Treatment includedarteriovenous malformation embolization in 1 case, unruptured cerebralaneurysm in 1 case, ruptured aneurysm in 3 cases, carotid artery stenting in2 cases, tumor embolization in 1 case, and flow diverter implantation in 2cases. There were no cases of puncture site complications.

Conclusion: The dRA was considered to be less invasive withfewer complications. Future accumulation of cases and statistical analysisof efficacy were considered necessary.

O2-5-6

Usefulness of 3Fr guiding sheath in trans-radial neuroendovasculartherapy

Taisuke Kawasaki, Junichi Ayabe, HiroyukiMishima, Mutsumi Takadera, Yusuke Tsuchiya, Masayuki Okano, RaisaFunatsuya, Yoshihide Tanaka

Department of neurosurgery, Yokosuka Kyosai Hospital, Kanagawa, Japan

Purpose: In this study, the usefulness of the new 3Fr guidingsheath for trans-radial neuroendovascular therapy is investigated. Intrans-radial interventions, 4Fr–6Fr guiding sheaths are typically used. Thesheath diameter is an important factor affecting the invasiveness of theprocedure. Smaller sheaths may result in difficulties in manipulating thecatheter. Initial cases in which the 3Fr guiding sheath was used fortrans-radial neurointerventions are reported in this study.

Material and Methods: The new 3Fr guiding sheath, Axcelguide 3Fr(Medikit, Japan), was used for preoperative tumor embolization in twopatients: a 73-year-old man with petrosal meningioma supplied by the middlemeningeal artery and ascending pharyngeal artery and a 49-year-old womanwith parasagittal meningioma supplied by the occipital artery.

Results: Tumor embolization was successful under localanesthesia for both patients. In the patient with petrosal meningioma, thetip of the 3Fr guiding sheath was inserted to the origin of the middlemeningeal artery, allowing for easy microcatheter manipulation. In thepatient with parasagittal meningioma, a distal access catheter was insertedvia the 3Fr guiding sheath, resulting in an effective microcatheter approachto the feeding artery.

Conclusion: The new 3Fr guiding sheath is safe and effective fortrans-radial neuroendovascular therapy and may be less invasive. This sheathmay also be effective for other treatments such as coil embolization.

O2-6-1

Unilateral Delayed Post-hypoxic Leukoencephalopathy (DPHL) aftercarotid artery dissection

Johannes A.R. Pfaff¹, Eugen Trinka^2,3,4,5, Johannes Sebastian Mutzenbach²

¹Department of Neuroradiology, University Hospital Salzburg,Christian Doppler Klinik, Paracelsus Medical University, Salzburg,Austria

²Department of Neurology, University Hospital Salzburg, ChristianDoppler Klinik, Paracelsus Medical University, Centre for CognitiveNeuroscience Salzburg, Austria

³Neuroscience Institute, University Hospital Salzburg, ChristianDoppler Klinik, Paracelsus Medical University, Centre for CognitiveNeuroscience Salzburg, Austria

⁴Karl Landsteiner Institute for Neurorehabilitation and SpaceNeurology, Salzburg, Austria

⁵Spinal Cord Injury and Tissue Regeneration Centre, Salzburg,Austria

Purpose: Delayed posthypoxic leukoencephalopathy (DPHL) is arare entity clinically characterized by neurologic deterioration following aperiod of clinical stability or improvement after an episode of acutehypoxic-ischemic injury. In DPHL extensive hyperintense subcortical whitematter changes on T2-weighted and FLAIR images can be identified, usuallyconfluent, homogeneous, and most importantly bilateral.

Case Summary: We report a case of an 81-year-old male patient,who presented with a partial anterior circulation syndrome due to adissection-related occlusion of the left carotid artery (NIHSS: 17, mRS: 5),showed clinical improvement immediately after endovascular stroke therapy(NIHSS: 5, mRS: 3), followed by a clinical and especially significantcognitive deterioration in the following days (NIHSS: 7, mRS: 5) and aclinical recovery after several weeks (mRS: 2). The clinical course of thepatient was accompanied by morphological changes on MRI characteristic forDPHL - strictly limited and localized unilaterally to the left anteriorcirculation (Figure1).

Conclusion: This case demonstrates that clinical symptoms andmorphological changes on MRI compatible with DPHL do not necessarily onlyoccur with global hypoxia but can also occur in patients with a large vesselocclusion in the corresponding vascular territories.

O2-6-2

Prevalence and functional outcome of symptomatic intracranialhemorrhage following endovascular thrombectomy in acute ischemic strokepatients at Siriraj hospital: 10 years results

Sarun Jotikasthira, Ekawut Chankaew, ThaweesakAurboonyawat, Boonrerk Sangpetngam, Pattarawit Withayasuk, SaowaneeHomsud, Rungnapa Buasuwan, Anchalee Churojana

Siriraj Center of Interventional Radiology, Department of Radiology, MahidolUniversity, Bangkok, Thailand

Purpose: One of the most serious complications followingendovascular thrombectomy (EVT) is symptomatic intracranial hemorrhage(sICH). Prevalence of sICH has been reported about 0–7.7% from differentstudies. This study aims to define prevalence of sICH in 10 years periods(Jan 2010 to Nov 2020) after Siriraj Hospital established EVT, factorsrelate to hemorrhagic complication, and ninety days mRS in sICH patients asa functional outcome.

Materials and Methods: Retrospective study, all acute ischemicstroke (AIS) patients caused by LVO who had age ≥ 18 years were included.Baseline characteristic and details of the procedure had been reviewed andcollected for statistical analysis. Ninety days mRS in sICH patients werecollected as a functional outcome.

Results: Among 423 AIS patients who were treated by EVT. 323patients had no hemorrhagic complication. Prevalence of sICH following EVTaccounted for 7.32%. No differences in baseline characteristic and detailsof procedure between hemorrhagic complication and non-hemorrhagiccomplication groups. Significant factor associated with hemorrhagiccomplication was pre – thrombectomy intravenous rTPA (OR, 3.88[95% CI,1.768- 8.529]; P = 0.001). First pass recanalization seemed tobe a protective factor (OR, 0.422[95% CI, 0.184–0.967]; p – value 0.041).All sICH resulted in dependent ninety days mRS (mRS 3–6).

Conclusion: Prevalence of sICH for 10 years period from Jan 2010to Nov 2020 at Siriraj Hospital, was 7.32%. Pre - thrombectomy IV rTPAsignificantly associated with ICH following EVT. First pass recanalizationappeared to be a protective factor. All sICH resulted in functionaldependent at ninety days.

O2-6-3

Iatrogenic air embolisms during endovascular interventions: the impactof the point of origin and the number of air bubbles on cerebralinfarctions in an experimental in vivo model

Dominik F. Vollherbst¹, Tabea Schaefer¹, Svenja Greive¹, Sabine Heiland¹, Martin Kramer², Stine Mencl³, Christoph Kleinschnitz³, Martin Bendszus¹

¹Department of Neuroradiology, Heidelberg University Hospital

²Clinic for small animals, Justus-Liebig-University Gießen,Gießen, Germany

³Department of Neurology, University Hospital Essen, Essen,Germany

Purpose: Iatrogenic air embolisms (AE) causing cerebralinfarction can occur during any endovascular intervention at the ascendingaorta, including the aortic valve, the aortic arch and the vessels whichsupply the brain. The aim of this study was to investigate the impact of thepoint of origin and the number of air bubbles on cerebral infarctions in anexperimental in vivo model.

Materials and Methods: In 20 rats, 1200 or 2000highly-calibrated micro air bubbles (MAB; size: 85 µm) were injected at thelevel of the aortic valve (Group Ao, sub-groups Ao-1200 and Ao-2000), intothe left common carotid artery (Groups CA, sub-groups: CA-1200 and CA-2000)or into the right atrium (Group RA) using a microcatheter via a transfemoralaccess, resembling endovascular interventions in humans. In 4 animals,saline was injected into the aorta or carotid artery, serving as controlgroups. MRI using a 9.4 T system was performed 1 h after MAB injection.Animals were finalized afterwards and histopathological examinations of thebrain tissue was performed.

Results: MABs injected into the aorta caused bilateralinfarctions, whereas MABs injected into the CCA caused exclusivelyipsilateral infarctions. The number of infarctions was similar between GroupAo and Group CA (5.5 vs. 5.5 (medians); p = 0.769), while the total volumeof infarctions was higher for Group CA (5.2 mm³ vs. 1.5mm³; p = 0.003). The number of infarctions was significantlyhigher comparing 2000 vs. 1200 injected MABs (6 vs. 4.5; p < 0.001). InGroup RA and in the control groups, no infarctions were detected.Histopathological analyses showed early signs of ischemic stroke.

Conclusion: The point of origin of AEs and the number of MABshave a major impact on the number and size of ischemic cerebralinfarctions.

O2-6-4

Evaluation of intracranial hemorrhage with dual-energy CT afterendovascular mechanical thrombectomy

Nanto Masataka, Shogo Ogita, Daisuke Maruyama,Naoya Hashimoto

Department of Neurosurgery, Kyoto Prefectural University of Medicine

Purpose: Recently, the efficacy of dual energy CT (DECT)immediately after mechanical thrombectomy (MT) for acute large vesselocclusion (LVO) has been reported. We review our experiences treatingpatients with acute LVO who underwent DECT immediately after MT, and reportthe utility of DECT.

Materials and Methods: We examined characteristics of hyperattenuation on DECT, postoperative management based on the results of DECT,and intracranial hemorrhage (ICH) complications after MT.

Results: DECT was performed in 23 patients (16 men, seven women)treated at our institution for acute LVO. The mean age of these patients was74.0 years, and the median National Institutes of Health Stroke Scale was16. Intravenous tissue plasminogen activator was administrated before MT inthree cases. The recanalization of modified Thrombolysis in CerebralInfarction score 2b-3 was achieved in 22 cases, and 0 was achieved in onecase. Hyper attenuation on the original image of DECT (ORG) was observed in14 cases. Of these 14 cases, hyper attenuation was diagnosed as intracranialhemorrhage in seven cases (59%) on the virtual non-contrast image of DECT(VNC). On the ORG, hyper attenuation was observed in the cortex in sixcases, subcortex in 10 cases, subarachnoid space in eight cases, and basalganglia in three cases. Five of six cases of cortex lesion (83.3%) and allthree cases of basal ganglia lesion (100%) were considered to beextravasation of contrast material. The mean CT number of hyper attenuationon ORG was 60.5 Hounsfield Units (HUs) in ICH lesions and 58.7 HUs innon-ICH lesions. Among the seven cases diagnosed as ICH on VNC, theanticoagulation effect was reversed in three cases (42.9%) immediately afterDECT, and no expansion of ICH was observed in any of these three cases. Inanother four cases (57.1%), the anticoagulation effect was not reversed, andexpansion of ICH was observed in all four cases.

Conclusion: Hyper attenuation of cortex or basal ganglia maytend to be associated with extravasation of contrast material. DECTimmediately after MT is useful for preventing ICH complications onpostoperative management due to this technique's accuracy of ICHdetection.

O2-6-5

Hemorrhagic complications of mechanical thrombectomy for acutestroke

Fumitaka Yamane¹, Tatsuya Tanaka¹, Yuhei Michiwaki¹, Ren Fujiwara¹, Yu Hirokawa¹, Ryuhei Sashida¹, Eiichi Suehiro¹, Akira Matsuno¹, Ichiro Nakasato², Takeshi Suma², Kenichi Oyama², Yuta Oyama³, Takeshi Uno³

¹Department of Neurosurgery, International University of Healthand Welfare Narita Hospital

²Department of Neurosurgery, International University of Healthand Welfare Mita Hospital

³Department of Neurosurgery, Teikyo University School ofMedicine

Purpose: Mechanical thrombectomy (MT) for large vesselsocclusion (LVO) of acute stroke is an effective treatment. Two aspects of MTare to perform early reperfusion as soon as possible and to preventpostoperative reperfusion injury. In this study, we investigated thehemorrhagic complications associated with both aspects of MT.

Materials and Methods: Ninety-sixth patients underwent MT foracute stroke experienced at our hospital and affiliated facilities fromApril 2017 to April 2022. There were 57 male patients and 39 female, averageage was 73.4 years. The cases included 77 cardiogenic, 14 atherothrombotic,2 dissection cases, and 2 other cases. Of these, only angiography wasperformed without MT in 3 cases. The site of LVO was internal carotid artery(ICA) in 27 cases (28%), proximal M1 in 17 cases (18%), distal M1 in 17cases (18%), M2 in 14 cases (15%) and basilar artery (BA) in 10 cases (11%).The pre- and postoperative factors including NIHSS, ASPECT, recanalizationtime, and other related data were investigated based on the surgicalrecords. Methods of MT was based on CT and CTA, and MRI and A were addedwhen necessary. The procedure was basically a combination of stent retriever(SR) and aspiration catheter (ARTS and ASAP)．

Results: There were 14 (14.5%) complications, all of which werecardiogenic embolic stroke, and the mean age of the patients was 81.1 years,older than that of the uncomplicated group :72.1 years. Hemorrhagiccomplications occurred in 12 cases (12.5%), and 9 cases were considered tobe related to intraoperative procedures. The number of complications by MTwas 4 (14.8%) for ICA, 5 (29.4%) for proximal M1, 2 (11.8%) for distal M1, 1(7.1%) for M2, and 1 (10%) for BA. The frequency of proximal M1 was slightlyhigher. Intraoperative procedures were considered to be caused by devicemanipulation, but the details of the reasons could not always be identifiedin all cases. Two of these cases (22%) resulted in a worse prognosis. Theremaining three patients had postoperative hemorrhagic complications, one ofwhich was due to the underlying disease, and two patients died of fatalsubarachnoid hemorrhage. There were 2 ischemic complications, 1 case ofrecurrent postoperative cerebral infarction, and 1 case of cerebral edemathat worsened and led to external decompressive craniotomy.

Conclusion: Of the 12 cases of hemorrhagic complications, 9 wereprocedure-related with a prognostic influence of 22%, and 2 cases ofpostoperative hemorrhagic complications, serious subarachnoid hemorrhage,and the patients died. The risk of hemorrhagic complications from thistechnique exists both intraoperatively and postoperatively, andpostoperative complications may worsen the prognosis, making strict bloodpressure control essential during and after the procedure. It was alsosuggested that the technique of MT and the devices should be standardizedamong institutions, which may reduce complications.

O2-6-6

Withdraw

O2-7-1

The Incidence of Medium Vessel Occlusions: A Population-BasedStudy

Michael D Liu¹, Deena Nasr¹, Waleed Brinjikji^2,3

¹Neurology, Mayo Clinic

²Radiology, Mayo Clinic

³Neurosurgery, Mayo Clinic

Purpose: The incidence of cerebral infarction attributed tonon-large vessel occlusion is not well known. We aim to examine theincidence of medium vessel occlusions in a population-based study.

Materials and Methods: Consecutive patients who resided inOlmsted County, Minnesota, USA who presented for acute ischemic stroke seenat Mayo Clinic Hospital (Rochester, Minnesota) from 1/1/2018–12/31/2019whose imaging revealed a medium vessel occlusion were included in thisstudy. Medium vessel occlusion was defined as occlusion at or beyond thelevel of the following vasculature: middle cerebral artery M2 segment,anterior cerebral artery A2 segment, posterior cerebral artery P1 segment,and branching vessels off the internal carotid artery, vertebral artery, andthe basilar artery. Census data for Olmsted county was obtained from theUnited States Census Bureau from the year 2020. Statistical analysis wasperformed using the assistance of SPSS software (IBM, Version 27).

Results: Of 1192 patients presenting for acute stroke, 50patients (4%) presented with confirmed medium vessel occlusions during the2-year study time period. The population of Olmsted County was estimated tobe 162,847. The incidence rate for medium vessel occlusions is 15 (95% CI 11to 20) per 100,000 people per year. Of the medium vessel occlusions, 36(72%) presented with an anterior circulation medium vessel occlusion with anincidence rate of 11 (95% CI 7 to15) per 100,000 people per year. 14 (28%)presented with posterior circulation medium vessel occlusion with anincidence rate of 4 (95% CI 2 to 7) per 100,000 people per year. Based onestimates of the US population in 2020 of 331,449,281 and our data, weestimate there are 50,884 (95% CI 44,096 to 57,672) new medium vesselocclusions per year.

Conclusion: As the only comprehensive stroke center in Olmstedcounty and the immediate surrounding area, we have been able to estimate theincidence of ischemic stroke due to medium vessel occlusions. The incidenceof medium vessel occlusions is less than large vessel occlusions, but stillplays a large role in acute ischemic stroke and identifies a population thatwould benefit from further studies in acute intervention.

O2-7-2

Recanalization of the proximal site accompanying perforators to basalganglia might be effective in PCA occlusion

Mitsuhiro Iwasaki¹, Masahiro Maeda¹, Masaki Koh¹, Yasufumi Inaka¹, Hidekazu Yamazaki², Shinya Fukuta¹, Hiroaki Sato¹, Masafumi Morimoto¹

¹Neurosurgery, Yokohama Shintoshi Neurosurgical Hospital,Kanagawa, Japan

²Neurology, Yokohama Shintoshi Neurosurgical Hospital, Kanagawa,Japan

Purpose: In recent years, mechanical thrombectomy forMevo(medium vessel occlusion) has become more frequent and has been shown tobe effective for the middle cerebral artery, however, indication oreffectiveness of the treatment for PCA occlusion was not clear. We report aretrospective analysis of the cases of the treatment for PCA occlusion inour hospital.

Materials and Methods: Between January 2017 to December 2021, weperformed mechanical thrombectomy for 14 patients with PCA occlusion. Theindication of such interventions was DWI-FLAIR mismatch within 24 h of onsetand NIHSS score ≧5.

Results: The median (interquartile range[IQR]) age was 78(70–85.5) years and 10 (71.4%) were male individuals. The median (IQR)National Institutes of Health Stroke Scale (NIHSS) scores were 10(8.25–13.25). 3 patients (21.4%) in P1 segment (including posteriorcommunicating artery), 8 patients (57.1%) in P2 segment and 1patient (7.1%)in P3 segment were located. The average time from puncture to recanalizationis 48.5 min. The average number of passes is 1.64. The number of patients ofthrombolysis in cerebral infarction (TICI) grade 2b/3 was 10 (71.4%) andasymptomatic intracranial hemorrhage was 1 (7.1%). The number of patientswith a modified Rankin Scale (mRS) score≦2 at 3 months of onset was 9(64.3%). In 3 of 4 cases with TICI grade≦2a, symptom was improved causedjust by recanalization in the P1 and P2 segment. In most of the cases ofhigh NIHSS scores, the occlusive location was P1-P2 proximal segmentincluding paramedian thalamic artery or thalamo-geniculate artery supplyingblood to posterolateral thalamus and posterior limb of internal capsule.

Conclusion: Posterior cerebral artery occlusion causing severesymptoms might be associated with ischemia of the perforating arteries ofPCA. That's why recanalization of just proximal PCA including perforators tobasal ganglia might make the symptom better.

O2-7-3

Efficacy and safety outcomes of mechanical thrombectomy for mediumvessel occlusion

Takeshi Yoshimoto¹, Kanta Tanaka², Junpei Koge³, Masayuki Shiozawa³, Naruhiko Kamogawa³, Tsuyoshi Ohta⁴, Tetsu Satow⁴, Manabu Inoue^2,3, Hiroharu Kataoka⁴, Masatoshi Koga³, Kazunori Toyoda³, Masafumi Ihara¹

¹Department of Neurology, National Cerebral and CardiovascularCenter

²Division of Stroke Care Unit, National Cerebral andCardiovascular Center, Suita, Japan

³Department of Cerebrovascular Medicine, National Cerebral andCardiovascular Center, Suita, Japan

⁴Department of Neurosurgery, National Cerebral and CardiovascularCenter, Suita, Japan

Purpose:We aim to investigate the efficacy and safety ofmechanical thrombectomy (MT) for medium vessel occlusion (MeVO).

Methods: Of the consecutive acute ischemic stroke (AIS) patientswith prestroke modified Rankin Scale (mRS) score of 0–2 admitted to ourinstitute from 2010 to 2021, AIS patients due to MeVO (middle cerebralartery[MCA] M2, M3, anterior cerebral artery A1, A2/A3, or posteriorcerebral artery P2/P3 occlusion) within 24 h of onset were enrolled.Outcomes including the favorable outcome (3-month mRS score of 0–2),mortality at 3-month, any intracerebral hemorrhage (ICH) within 36 h fromonset, and symptomatic ICH (SICH) were assessed between patients receivingMT and standard medical treatment (SMT).

Results: Of 428 patients (167 women; median age, 77 years;median NIH Stroke Scale score[NIHSS] 9), 374 (84%) patients had MCA M2occlusion. Patients who received MT (n = 119) have a higher median NIHSSscore (14 vs. 8, P < 0.01), and more intravenousthrombolysis (55.5% vs. 36.5%, P < 0.01) than thosereceived SMT (n = 321). There were no significant differences in thefavorable outcome (57.1% vs. 54.8%, P = 0.67), mortality at3-month (5.9% vs. 3.4%, P = 0.28), SICH (1.7% vs. 2.6%,P = 0.73) between both groups, but any ICH within 36 hfrom onset were more frequent in patients received MT than those receivedSMT (41.9% vs. 27.5%, P < 0.01). In patients with NIHSSscore ≥10, favorable outcome was more frequent in patients received MT thanthose received SMT (adjusted odds ratio[aOR] 2.04, 95% confidenceinterval[CI] 1.17–3.57), but not in those with NIHSS score <10 (aOR 0.93,95% CI 0.44–1.98; P for interaction thinsp;= 0.10).

Conclusions: MT may be more effective than SMT for a part ofMeVO.

O2-7-4

Mechanical thrombectomy for acute ischemic stroke in posteriorcirculation

Tomohiro Okuda¹, Koichi Arimura¹, Keisuke Ido², So Tokunaga³, Shinya Yamaguchi⁴, Hidenori Yoshida⁵, Katsuharu Kameda⁶, So Takagishi¹, Katsuma Iwaki¹, Yuya Koyanagi¹, Akira Nakamizo¹, Koji Yoshimoto¹

¹Department of Neurosurgery, Kyushu University

²Department of Neurosurgery, Saga-ken Medical Center Koseikan

³Department of Neuroendovascular Therapy, Clinical ResearchInstitute, National Hospital Organization Kyushu Medical Center

⁴Department of Neurosurgery, Stroke Center, Steel Memorial YawataHospital

⁵Department of Neurosurgery, Fukuoka Tokushukai Hospital

⁶Department of Neurosurgery, Shin Koga Hospital

Background and purpose: The efficacy of mechanical thrombectomy(MT) for posterior circulation large vessel occlusions has not been fullyelucidated, because there is no evidence from randomized trials. Weinvestigated the efficacy and safety of MT for posterior circulation stroke(PCS) compared anterior circulation stroke (ACS).

Methods: We analyzed 885 consecutive patients who underwent MTfor acute ischemic stroke between January 2013 and December 2020 at sixcomprehensive stroke centers. The patients were divided into two groups; thePCS and ACS group. The procedural and clinical outcomes were comparedbetween the groups.

Results: A total of 794 patients (PCS group, 83; ACS group,701), were analyzed.

PCS patients were significantly younger (75 vs. 79 years, P = 0.01) and had ahigher NIHSS score at baseline (23 vs 19 p = 0.01) and longer door topuncture time (97 vs 73 min, p = 0.01). The rate of Male (67.4 vs 47.5%p < 0.01) and atherosclerotic brain infarction (22.8 vs 8.9% p < 0.01)were higher, comorbid atrial fibrillation (50.6 vs 62.9% p = 0.03) was fewerin the PCA group. The rate of mTICI 2c-3 recanalization at the first pass(40.9 vs 28.2% p = 0.01) was significantly higher in the PCS group. However,the rates of final mTICI ≥ 2b recanalization (86.6 vs 73.3% p = 0.48)andsymptomatic hemorrhagic complications (6 vs 4.1% p = 0.42) and goodclinical outcome at 90 days (34.3 vs 33% p = 0.82), mortality (22.3 vs 16%p = 0.18) were similar in the groups. In the PCS group, the single use of astent retriever for the first pass was associated with higher mortality rate(36 vs 14.6% p = 0.04) compared with use of ADAPT or combined technique.

Conclusions: MT for PCS seemed to be beneficial, having similarcomplication, recanalization rate, and clinical outcomes with ACS.

O2-7-5

Endovascular treatment of Acute Basilar Artery Occlusion: TREATstudy

Junya Kaneko¹, Takahiro Ota², Keigo Shigeta³, Tatsuo Amano⁴, Masato Inoue⁵, Yuki Kamiya⁶, Yuji Matsumaru⁷, Yoshiaki Shiokawa⁸, Teruyuki Hirano⁴

¹Department of Emergency and Critical Care Medicine, NipponMedical School Tama Nagayama Hospital, Tokyo, Japan

²Department of Neurosurgery, Tokyo Metropolitan Tama MedicalCenter, Tokyo, Japan

³Department of Neurosurgery, National Hospital OrganizationDisaster Medical Center, Tokyo, Japan

⁴Department of Stroke and Cerebrovascular Medicine, KyorinUniversity, Tokyo, Japan

⁵Department of Neurosurgery, Center Hospital of the NationalCenter for Global Health and Medicine, Tokyo, Japan

⁶Department of Neurology, Showa University Koto Toyosu Hospital,Tokyo, Japan

⁷Division of Stroke Prevention and Treatment, Department ofNeurosurgery, University of Tsukuba, Ibaraki, Japan

⁸Department of Neurosurgery, Kyorin University, Tokyo, Japan

Objective: The effectiveness of mechanical thrombectomy (MT) foracute basilar artery occlusion (ABAO) remains unknown even though tworandomized control trials (RCT) were published. We retrospectively evaluatedthe feasibility, safety, and efficacy of endovascular treatment forABAO.

Methods: We investigated patients with ABAO who underwent MTusing modern stent retrievers and an aspiration device between January 2015and December 2020 at 20 comprehensive stroke centers in Tokyo. Functionaloutcomes and 90-day mortality rates were analyzed as primary outcomes.Factors influencing outcomes were analyzed as secondary outcomes.Relationships between outcome and affected area of infarction on arrivalwere also analyzed.

Results: One hundred-twenty-four patients were included. Goodand moderate outcomes (modified Rankin Scale score 0–2, 0–3) were achievedin 45/124 (36.3%) and 58/124 (46.8%) respectively and the all-cause 90-daymortality rate was 21.8% (27/124). Successful recanalization (modifiedThrombolysis In Cerebral Infarction (mTICI) grade 2b and 3) was achieved in113/124 patients (91.1%). In univariate analyses, age, gender, NationalInstitutes of Health Stroke Scale (NIHSS) score, posterior circulationAlberta Stroke Program Early CT Score (pc-ASPECTS), mTICI grade, hemorrhagiccomplication, and onset to recanalization time differed significantlybetween good and poor functional outcome groups. Age, NIHSS, and pc-ASPECTSwere significantly associated with functional outcomes in the logisticregression model. Positive findings for the thalamus on diffusion-weightedimaging on pc-ASPECTS were significantly associated with poor outcomes.

Conclusion: MT with modern devices for ABAO resulted in highlysuccessful recanalization and good outcomes. A positive finding for thethalamus on initial imaging might predict poor outcomes. After two RCTs werepublished, it should be necessary to discuss about the superiority of MTover the best medial treatment. According to our results, cut off pointsabout age, severity of the patients and affected area might be one of theanswers for the indication of MT.

O2-7-6

Brain Tissue Perfusion Status of FLAIR Vascular Hyperintensity in DWINegative Areas Differ Between Acute Large and Medium VesselOcclusion

Daisuke Maruyama, Hiroyuki Yamamoto, ShogoOgita, Masataka Nanto, Naoya Hashimoto

Department of Neurosurgery, Kyoto Prefectural University of Medicine, Kyoto,Japan

Purpose: In acute ischemic stroke due to large vessel occlusion,FLAIR vascular hyperintensity (FVH) with diffusion-weighted imaging (DWI)hyperintensity stratifies regional collateral status and tissue fate aftersuccessful recanalization by mechanical thrombectomy (MT). However, therelationship of tissue perfusion hemodynamics with the occlusion siteremains unknown. This study elucidated the relationship between cortical MRIfindings of FVH with DWI and tissue parameters of CT perfusion (CTP) priorto MT.

Methods: Patients with acute ischemic stroke due to internalcarotid artery (ICA) or middle cerebral artery (M1 or M2 segment) occlusionwho underwent both MRI and CTP before MT between May 2018 and January 2021were enrolled. Template regions of interest of cortical areas were appliedto co-registered MRI and CTP images to distinguish cortical Alberta strokeprogram early CT score (ASPECTS) areas. ASPECTS of M1–M6 was categorized asgroup A (DWI-, FVH-), B (DWI-, FVH + ), C (DWI + , FVH + ), or D (DWI + ,FVH-). Quantitative regional perfusion parameters, such as cerebral bloodflow (CBF), cerebral blood volume (CBV), and time-to-maximum (Tmax), wereevaluated in each categorized group, and also compared between large (ICA orM1 segment) and medium (M2 segment) vessel occlusions to examine regionaldifferences. The relative values of CBF, CBV, and Tmax were alsoexamined.

Results: Seventeen hemispheres of 16 patients were included inthis study. Twelve patients were male (75%), and the median age and initialNIHSS score were 76[interquartile range (IQR) 70–79] and 14[9–23],respectively. A total of 99 cortical regions were analyzed; of these, 30(30.3%) were categorized into group A; 49 (49.5%), group B; 12 (12.1%),group C; and 8 (8.1%), group D. Tmax values significantly increased by theorder of groups A to D, and the values were significantly different fromgroup A and the others. In group B, both the mean Tmax and the rate of Tmax>6 s was significantly higher in territories of large vessel occlusionthan those of medium vessel occlusion (9.8 ± 3.5 vs. 5.1 ± 2.2 s,P < 0.01; 87.9% vs. 25%, P < 0.01, respectively). The same tendencywas observed in the Tmax relative value analysis.

Conclusion: The combined evaluation of FVH and DWI stratifiesregional perfusion status in acute arterial occlusion indicating MT. Thepresence of FVH could differentiate regional pathophysiology, especially inTmax values among cortical areas, although its significance in DWI negativeareas may differ depending on large or medium vessel occlusion.

O2-8-1

Transumbilical Access For Vein Of Galen Malformation And Dural / PialArteriovenous Fistula Embolization: A Review Of Literature

Maximilian Jeremy Bazil, Johanna T Fifi,Alejandro Berenstein, Tomoyoshi Shigematsu

Neurosurgery, Icahn School of Medicine at Mount Sinai

Introduction: Vein of Galen Malformations (VOGM), in infants,presents with congestive heart failure, macrocephaly, failure to thrive,developmental delays, or other serious neurological impairment. In theneonatal period, the traditional transfemoral access may be complicated bythe endovascular sheath size (typically 4F) needed to perform embolizationtherapy, especially if retreatment is required. Our practice, betweenJanuary of 2014 and September of 2021 has utilized the trans-arterial,trans-umbilical embolization approach for VOGM, dural AVF, and pial AVF, buta lack of reporting in the literature demonstrates a need for a review.

Methods: We performed a literature review by parameterizing asearch on PubMed with the terms, “umbilical” and either “Vein of Galen,”“pial AVF,” or “dural AVF.” The five articles chosen for detailed reviewdescribed the use of trans-umbilical, cerebral angiography or endovascularembolization of VOGM, dural AVF, or pial AVF.

Results: The initial results of the PubMed query provided 12articles with no duplicates, seven of which were removed due to focus ondiagnosis rather than intervention. The five articles selected for detailedreview range widely over the span of 19 years (1997–2016). Berenstein et al.originally presented the trans-umbilical technique in 1997 as a means toameliorate high output cardiac failure, preserve the femoral arteries forfuture treatments, and effectively de-vascularize the VOGM with no reportedcomplications. Two years later, Komiyama et al. reported a similar use ofthe trans-umbilical technique to treat a dural AVF at the torcula of aneonate which, while distinct from VOGM, mimicked the pathology bydemonstrating a choroidal-type, arterio-arterial maze in the blood supply ofthe pial fistula. Notably, this procedure was performed through theumbilical vein and treatment was repeated through the same trans-umbilicalcatheter up to 17 days post-placement with no complication. Komiyama furtherreported, in 2004, a VOGM case treated with four rounds of coil embolizationtrans-umbilically with a combination of umbilical artery/vein access who wasleft with a slight developmental delay. Köroğlu et al., in 2006, reportedanother case of VOGM, trans-umbilical embolization via the umbilical arterywhich allowed for complete obliteration of the lesion, but by 20 monthsshowed a neurological deficit. Finally, in 2016, Komiyama et al. reportedone additional case of trans-umbilical embolization for a pial AVF, thoughdue to a combination of underlying, pre-interventional, brain damage and anintraoperative bleed the outcome resulted in a vegetative state.

Conclusion: Trans-umbilical access for pial AVF, dural AVF, andVOGM is largely safe and effective throughout the literature, but thisliterature is limited. The benefits of trans-umbilical access are sparing ofthe femoral arteries for future treatments and potential applicability toother high-flow fistulas of the brain.

O2-8-2

Transumbilical Access For Vein Of Galen Malformation And Dural / PialArteriovenous Fistula Embolization: A Case Series.

Maximilian Jeremy Bazil, Johanna T Fifi,Alejandro Berenstein, Tomoyoshi Shigematsu

Neurosurgery, Icahn School of Medicine at Mount Sinai

Introduction: Vein of Galen Malformation (VOGM), in infants,presents with congestive heart failure, developmental delay, or otherserious neurological impairment. Pial arteriovenous-fistulas (pAVF) aredistinct from VOGM, but present similarly. In the neonatal period,transfemoral access may be complicated by sheath size needed forembolization, especially if retreatment is required. Here, we report 15cases of trans-umbilical access for VOGM/pAVF embolization between January2014 and September 2021.

Methods: A retrospective review of our clinical database forpatients with pAVF/VOGM treated between January 2014 and September 2021 wasperformed. Prior to 2014, some data was inaccessible following record lossafter administrative changes in the hospital system. Out of 15 casesselected for detailed analysis, five continued treatments beyond this recordloss and are reported to the fullest extent available.

Results: Out of 15 trans-umbilically accessed VOGM/pAVFembolizations, 10 (66.6%) were female. 13/15 demonstrated choroidal VOGMangioarchitecture (86.7%) with one mural VOGM and one pial dAVF. The mediantreatments performed trans-umbilically was two (Range:1–4). The median ageat first treatment was 3 days (Range:1–13). Of the 15, seven (46.7%) werediagnosed antenatally. 14 presented with heart failure. In four cases, thisheart failure was accompanied by either seizure, mass-effect/respiratoryfailure, pulmonary hypertension, or hydrocephalus. Line placement in theumbilical artery (UAC) was successful (1UA in 8, both in 7). A 4F-sheath wasplaced intra-procedurally in all cases. In cases where the sheath wasmaintained post-procedurally, the median time of use was 4-days with a(Range:1–7), monitored daily. No patients displayed thrombosis orinflammation. Intraprocedural complications included a case of pulmonaryhemorrhage, which resolved, a case of left PCA micro-guidewire perforationwhich led to a spontaneously resolved bleed, and a subarachnoid hemorrhage.Three (20%) members of our cohort passed away due to the severity of theirillness. Five (33.3%) have achieved complete obliteration, six (40%) remainin treatment, and one patient was lost to follow-up. Of the 12 who remain inour care or were cured, 4 (33.3%) experience a mild developmental delay and8 (66.6%) are neurologically intact/developing normally.

Conclusion: We report that trans-umbilical access forendovascular embolization of VOGM and a similar high-flow malformation was asafe and effective therapy for 15 cases which demanded immediateintervention in the neonatal period. The benefits of trans-umbilical accessare sparing of the femoral arteries for future treatments and potentialapplicability to other high-flow fistulas of the brain. It should be notedthat this procedure may be the difference between life and death, and assuch we stress the importance of effective UA and UV catheterization in theNICU.

O2-8-3

4D Flow MRI for non-invasive monitoring of high flow vascularmalformations in neonates and infants: initial experience and lessonslearned

Jonathan Massachi, Kazim Narsinh, ChristopherYoo, Steven Hetts

Department of Radiology, University of California, San Francisco

Purpose: High-flow intracranial vascular malformations canresult in hemorrhage or high-output heart failure. DSA is currently used toassess lesion angioarchitecture, evaluate risks to the patient, and guideintervention if needed, however, repeated imaging subjects patients to bothionizing radiation and procedural risks. Phase contrast MRA with “4D flow”sequences may be a non-invasive alternative to DSA and provides insight intoadditional hemodynamic parameters that may further inform management.

Materials and Methods: For this study, two pediatric patientswere selected from our institution's database, one with vein of Galenmalformation (VoGM) and one with nongalenic pial arteriovenous fistula(NGPAVF). Each patient was imaged both before and after endovascularembolization procedures using a 4D flow MRI sequence on a GE SIGNA architectMRI scanner. Embolization was performed with a combination of detachableplatinum embolic coils (Balt Optimax, Stryker Target) and n-butylcyanoacrylate (n-BCA) liquid adhesive (Cerenovus Trufill).

4D Flow images were then imported into Arterys software v27.9 (Arterys Inc.)for post-processing. Two independent readers (JM and CY) were trained in theuse of the software and measured the flow through the designated vessels foreach patient. Inter-rater reliability was assessed by calculating anintra-class correlation coefficient.

Results: Patient 1 was diagnosed with VoGM and underwent a thirdembolization treatment on day 152 of life. 4D flow images were captured ondays 152 and 153 of life, before and after the embolization. Patient 2 wasdiagnosed with NGPAVF and underwent embolization on day 1 of life. 4D flowimages were captured on days 0, 14, and 141 of life. Limited by the qualityof images captured on day 14 of life, this point was excluded from theanalysis and images from day 141 were used to assess the hemodynamicspost-embolization.

Overall, quantitative changes in flow rates measured by 4D flow MRIcorrelated well with independent qualitative assessment by two experiencedinterventional neuroradiologists (KN and SH). An intra-class correlationcoefficient was calculated across all of the flow values measured by theindependent readers and was found to have a high degree of agreementICC = 0.946. Additional hemodynamic quantities such as pulsatility index,peak speed, and wall shear stress were also explored.

In our experience, a key aspect of generating high quality images is carefulselection of the velocity encoding parameter (Venc) to eliminate aliasing ofhigher velocities while also balancing for scan length (and by extensionanesthesia time) and spatial resolution.

Conclusion: Our initial investigation demonstrates that 4D flowcan reproducibly quantify the flow rate in intracranial vessels associatedwith both VoGM and NGPAVF. Further investigation is needed and initialfindings from our single-center experience may help guide protocols forfuture studies.

O2-8-4

Pediatric intracranial pial arteriovenous fistula

Jingwei Li^1,2,3, Zhenlong Ji^1,2,3, Xinglong Zhi^1,2,3, Guilin Li^1,2,3, Hongqi Zhang^1,2,3

¹Department of Neurosurgery, Xuanwu Hospital, Capital MedicalUniversity

²China International Neuroscience Institute

³National Center for Neurological Disorders

Objective: As a type of cerebrovascular abnormality, pialarteriovenous fistulas (PAVFs) are mostly seen in children. However, theoverall angioarchitecture and clinical features, treatments and long-termprognosis for pediatric patients are still unclear.

Methods: Clinical data of 42 pediatric PAVFs treated withendovascular techniques were documented and analyzed. According to thedifferences of age distribution and clinical features, they were dividedinto a younger group (≤3-year-old; 20 cases) and an older group(3∼14-year-old; 22 cases).

Results: The mean age was 4.9 ± 3.9 years, and the meanpreoperative mRS score was 1.64 ± 1.57. Fourteen patients (33.3%) wereasymptomatic, followed by epilepsy (21.4%), cerebral hemorrhage (16.7%),hydrocephalus (9.5%), developmental delay (7.1%), intermittent headache(7.1%) and congestive heart failure (4.8%). The annual bleeding rate andrebleeding rate before treatment reached 3.86% and 3.17%. Eleven cases(26.2%) with additional cerebralspinal vascular lesions. Dynamic sinusobstruction and sinus occlusion (poor venous drainage) were found in 21cases and 17 cases respectively. After treatment, 33 cases were cured(78.57%), and 4 cases faced surgery-related complications (9.52%). During24–140 months’ follow-up, the mean mRS score reduced to 0.57 ± 0.40, andonly 22 cases (52.38%) recovered to absolute normal. Compared with oldergroup, younger group showed more chronic symptoms, more secondarypathological changes, poorer venous drainage, poorer cure rate and prognosis(P＜0.05). Poor venous drainage was the risk factor for patients’ incompleterecovery.

Conclusions: Pediatric PAVF has different angioarchitectures andclinical features in different age groups. Poor venous drainage is a majorfactor leading to poor prognosis.

O2-8-5

Inherited central nervous system pial arteriovenous fistula in CM-AVMfamily with pathogenic RASA1 germline sequence variation

Jingwei Li^1,2,3, Zhenlong Ji^1,2,3, Jiaxing Yu^1,2,3, Guilin Li^1,2,3, Hongqi Zhang^1,2,3

¹Department of Neurosurgery, Xuanwu Hospital, Capital MedicalUniversity

²China International Neuroscience Institute

³National Center for Neurological Disorders

CM-AVM is an autosomal dominant disorder first recognised in 2003, eventhough the incidence is unknown, but could be as high as 1/10 000. Thephenotype is characterised by cutaneous CM or port-wine stain, which is themost common vascular malformation, occurring in 0.3% of newborns. Assumingcutaneous CMs have been present since birth and asymptomatic, cliniciansalways pay little attention to these carries. However, almost one-thirdpatients are associated with fast-flow AVMs/AVFs, which can causelife-threatening complications such as congestive heart failure,intracranial hemorrhage and neurologic sequelae.

In this study, we provide a unique and important case of inherited high-flowcentral nervous system arteriovenous malformation (CNS-AVM), of which aperamedullary arteriovenous fistula was found in a 3-year-old girl and anintracranial pial arteriovenous fistula was found in her father. Multiplecutaneous red maculae were seen in the girl, her father and grandfather,indicating they were a capillary malformation-arteriovenous malformation(CM-AVM) family. Whole-exome sequencing of genomic DNA confirmed thissymptomological diagnosis, and detected a new mutation site of RASA1gene.

Our findings alert clinicians to further investigate for the presence ofAVMs/AVFs in CM-AVM family members, in case to avoid the high risk ofdisability or death caused by the concomitant lesions. To our knowledge,this is the first case of inherited central nervous system pialarteriovenous fistula and the mutation site found in this study is also anewly discovered mutation site of RASA1 gene. This case shows thatCNS-AVM/AVF may have a hereditary tendency (especially in CM-AVM families)for the first time. At the same time, combined with our previous studies onthe pathogenetic mechanism of CNS-AVM, a possible mechanism for thecombination of CM-AVM with CNS-AVM/AVF is proposed, hoping to provide someevidence and reference for the study of this mechanism.

O2-8-6

Manifestation and endovascular treatment of CM-AVM relatedarteriovenous shunting

Yasunari Niimi, Tatsuya Inoue, Shinsuke Sato,Ryu Bikei, Shogo Shima, Tatsuki Mochizuki

Department of Neuroendovascular Therapy, St Luke's International Hospital

Purpose: Retrospective analysis of manifestation andendovascular treatment of CM-AVM syndrome related arteriovenous shunting(AVS).

Materials and methods: In the last 9 years, we experienced 7cases of CM-AVM syndrome. Clinical presentation, imaging characteristics,and endovascular treatment of these cases were retrospectively analyzed.

Results: There were 4 males and 3 females. The age of diagnosisfor the AVS ranged from newborn to 8 years old. There were 4 geneticallyproven RASA1 mutations, one negative for both RASA1 and EPHB4, one pendingfor the genetic analysis, and one case without genetic test One presentedwith hydrocephalus, one with asymptomatic hemorrhage, one with progressivefrontal bone protrusion, and one with headache. The other 3 wereasymptomatic.

Six cases had typical CMs. Six cases had family history of typical CMs. Fivecases had pure pial AVF of the brain or the spinal cord. One case hadcombination of nidus AVM and pial AVF of the brain. The nidus AVM of thiscase was relatively slow flow and diffuse with slightly dilated multipledraining veins. One case had cranial AVM in the frontal bone. All pial AVFsunderwent embolization with NBCA and / or coils, and all but 1 case werecompletely occluded. One case had small residual after embolization. Onecase developed a nidus type AVM after embolization of the pial AVF, whichwas nearby the embolized pial AVF and completely obliterated by additionalembolization with NBCA. One case with combined pial AVF and nidus AVM hadparenchymal hemorrhage 2 months after embolization of the AVM followingembolization of the pial AVF. One pial AVF developed dural AVS afterembolization.

Conclusion: CM-AVM associated AVSs are mostly pial AVF of thebrain or the spinal cord. CM has a high penetration rate and should bealways searched for among the patient and family members to make an accuratediagnosis of CM-AVM syndrome. Nidus type AVM may co-exist or appear aftertreatment of pial AVF. Nidus AVM of this syndrome is different from thesolitary AVM in its angiographic appearance. Those AVSs associated withCM-AVM syndrome tend to be more dynamic than solitary cases. Therefore,close follow up is necessary even after complete occlusion of the existingAVS.

O2-9-1

Effectiveness of Proximal Balloon Occlusion versus Distal Filter forEmbolic Protection during Carotid Artery Stenting

Seung young Chung¹, Moonsun Park¹, Jae guk Kim²

¹Department of Neurosurgery, Daejeon Eulji Medical Center, EuljiUniversity, Daejeon, South Korea

²Department of Neurology, Daejeon Eulji Medical Center, EuljiUniversity, Daejeon, South Korea

Purpose: Carotid artery stenting (CAS) is rapidly becoming apopular alternative to CEA for treating carotid stenosis, and even moreeffective for high risk CEA cases. The main concern during transfemoral CASis preventing cerebral embolus dislodgement and so preventative embolicprotection devices (EPDs) have significantly improved neurologicalprognosis. We compared clinical outcomes and intraprocedural embolizationrates of CAS using a distal filter protection device or proximal balloonocclusion device.

Materials and Methods: This retrospective, single center studyincluded symptomatic and asymptomatic carotid stenosis patients treated withCAS with either of 2 EPDs: a proximal balloon occlusion device (PBO) or adistal filter protection (DFP). A series of 106 patients with symptomatic orasymptomatic ICA stenosis ≥70% were treated with CAS with embolic protectiondevice in single center. All patients underwent pre- and post DWI to detectnew ischemic lesions. We compared clinical outcomes and postproceduralembolization rates.

Results: CAS was performed in all 111 patients. DFP success ratewas 98.4% (63/64), whose mean age was 70.9 years, and mean stenosis was 81%.After CAS, subsequent DW-MRI revealed 249 new ischemic lesions in 81%(51/63) patients. In contrast, PBO success rate was 91.4% (43/47), whosemean age was 68.8 years and mean stenosis was 86%. Postprocedural DWIrevealed 71 new ischemic lesions in 58% (25/43) patients. No significantdifferences were observed in success rate with Fisher's exact test(p = 0.16). Compared with DFP, PBO resulted in lower incidence of newischemic lesions (p = 0.031, Chi squared test). PBO also showed fewer numberof total new ischemic lesions (p = 0.002) and new ischemic lesions perpatient (p = 0.027). And in ≥3 new DWI positive group, the number ofpatients was significantly lower in PBO (p = 0.002). In each group as thesubtype of stent, there is no significant interaction effect between stentand EPDs (p = 0.36, Two-way analysis of variance) and type of stent also didnot affect the number of new ischemic lesions (p = 0.056). Only 4 neurologiccomplications occurred but all improved in the successfully treated patients(1 for DFP, 3 for PBO).

Conclusion: The incidence of postprocedural ischemic lesions waslower in PBO than DFP. And the total number and new ischemic lesions perpatient on DWI were also lower in patients treated with CAS using PBD. So,as compared with DFP, PBO might be more effective in reducing cerebralembolism during CAS.

O2-9-2

Transcarotid revascularization in Chinese inpatients

Renjie Yang, Tao Wang, Xuesong Bai, Yan Ma, BinYang, Yabing Wang, Jie Wang, liqun Jiao

neurosurgery, Xuanwu Hospital of Capital Medical University

Objective: Transcarotid artery revascularization (TCAR) hasemerged as an alternative to transfemoral carotid artery stenting (tfCAS).Existing research shows that 72% carotid arteries were eligible for TCAR onthe basis of the instructions for use criteria, 69% in the arteries thatwere considered to be at high risk for tfCAS. However, there are differencesbetween Asian populations and European and American populations in neckanatomical features such as the height of carotid bifurcation, and there isno large sample study on the neck anatomical features of Asian populations.We investigated the proportion of carotid arteries undergoingrevascularization procedures that would be eligible for TCAR based onanatomic criteria and how many arteries at high anatomic risk for tfCASwould be amenable to TCAR.

Methods: We performed a retrospective review of consecutivepatients who underwent carotid endarterectomy or carotid stenting between2019 and 2021. We assessed TCAR eligibility on the basis of the instructionsfor use of the ENROUTE Transcarotid Neuroprotection System (Silk RoadMedical, Sunnyvale, Calif) and high anatomic risk for tfCAS on the basis ofanatomic factors known to make carotid cannulation more difficult orhazardous.

Results: Of the 500 patients and 1000 carotid arteriesidentified, 75 carotid arteries were excluded for presence of an occludedinternal carotid artery (ICA) or poor image quality. Of the remaining 925carotid arteries, 63% were eligible for TCAR. 72% of carotid arteries wereconsidered to be at high risk for tfCAS for the presence of a type IIIaortic arch (29%), severe aortic calcification (17%), aortic arch variation(12%), moderate to severe stenosis or calcification at the carotid ostium(293%), and tortuous distal CCA (29%). Of the arteries that were consideredto be at high risk for tfCAS, 63% were eligible for TCAR.

Conclusion: The anatomical characteristics of the carotid arteryin the Asian population are quite different from those in the European andAmerican populations, and a more reasonable choice should be made among thethree cervical revascularization procedures, tfCAS, TCAR, and CEA.

O2-9-3

Clinical outcomes of carotid artery stenting using MoMaUltra as anemboli protection device.

Yasuhiro Kawabata^1,2, Osamu Kawakami¹, Norio Nakajima², Koichi Fujimoto¹, Motohiro Kajiwara¹, Hidenori Miyake²

¹Department of Neurosurgery, Kishiwada City Hospital

²Department of Neurosurgery, Kyoto Katsura Hospital

Purpose: we retrospectively analyzed the clinical outcomes ofcarotid artery stenting (CAS) using MoMaUltra as an emboli-protectiondevice.

Materials and methods: The clinical characteristics of 32patients (25 men, seven women; median age, 75 years) who underwent carotidartery stenting using MoMaUltra (8 asymptomatic lesions and 24 symptomaticlesions) and the combined 30-day complication rates were analyzed.

RESULTS: Carotid plaque imaging was performed in 30 patients, 27of whom had high intensity plaques on T1WI of MRI. Proximal endovascularblood flowblockage was performed during the procedure using a MoMa Ultra(Medtronic) combined with a filter-type device in 30 procedures and combinedwith a Guardwire (Medtronic) in a procedure. In only one procedure,MoMaUltra was used by itself to reverse the carotid flow. Carotid Wall(Boston Scientific), Protégé (Medtronic), CASPER(Terumo), and Precise(Cordis) stents were used in 20, 5, 4, and 3 cases, respectively. Technicalsuccess rate was 100%. One patient (3.1%) experienced a transientneurological worsening within 30 days of the procedure. There were noperioperative disabling strokes or deaths.

CONCLUSIONS: Our data suggest that carotid artery stenting usingMoMaUltra can be performed safely even in patients with vulnerableplaques.

O2-9-4

The impact of device choice between CASPER Rx and WALL STENT RP forcarotid artery stenosis.

Hiroki Sato, Satoshi Iihoshi, Hiroya Shiwaku,Keita Tamada, Yukihiro Imaoka, Syouhei Iijima, Shinya Kohyama

Department of Neurosurgery, Saitama Medical University International MedicalCenter

Purpose: There are two types of stents used in carotid arterystenting (CAS): open-cell and closed-cell. CASPER Rx is a hybrid stent withboth properties and is expected to be the next-generation stent. Weretrospectively evaluated the outcomes of CAS using CASPER Rx and WALL STENTRP at our hospital based on medical and surgical records.

Materials and Methods: For comparison, 32 CAS cases were treatedwith CASPER Rx at our hospital from October 2020 to May 2021, while 25 CAScases were treated with WALL STENT RP from May 2019 to September 2020.Preoperative modified Rankin Scale (mRS), mRS at three months after surgery,the degree of restenosis based on ultrasound velocities (PSV>210cm/sec)or occlusion within six months, and other factors were examined.

Results: Among 32 patients in the CASPER Rx group (25 males andseven females), seven patients (22%) developed restenosis or occlusionwithin six months. Two patients (6%) had worsened mRS at three monthscompared to preoperatively. In the WALL STENT RP group, among 25 patients(24 males and one female), no patient developed restenosis within sixmonths, and no patient had worsened mRS at three months. There was asignificant difference in restenosis or occlusion within six months betweenCASPER Rx and WALL STENT RP group (p < 0.05).

Conclusion: We report the results of CAS using CASPER Rx at ourhospital. Although there was more restenosis with CASPER Rx than with WALLSTENT RP we think the results are good from the viewpoint of preventingrecurrent strokes. Further case studies are needed.

O2-9-5

Incidence of plaque protrusion during carotid artery stenting usingmicromesh stent

Katsutoshi Takayama, Kaoru Myouchinn, TakeshiWada

Interventional Neuroradiology / Radiology, Kouseikai Takai Hospital

Purpose: It has been reported that plaque protrusion (PP) duringcarotid artery stenting (CAS) using conventional stent was stronglyassociated with ischemic complication. On the other hand, recently micromeshstent has been developed. Micromesh stent (Casper stent) is double layerstent whose cell size has smaller than conventional stent. Therefore,micromesh stent has been expected to reduce ischemic complication and PPduring CAS.

Purpose: We investigated the initial treatment result andincidence of PP during CAS using Casper stent.

Material and Methods: We prospectively analyzed 42 patients with48 carotid artery stenoses (31 men; age 54–94 years[mean 76.8 years];symptomatic stenosis, 16 lesions; unstable plaque, 20 lesions; mean stenosisrate, 84.1%) who underwent CAS using Casper stent from October 2020 to April2022. Technical success rate, Incidence of plaque protrusion evaluated byintravascular ultrasound (IVUS), incidence of ischemic lesions within 48 hafter CAS and major adverse event (stroke, MI, death) within 30 days wereassessed using diffusion weighted images. All CAS was performed by astandard procedure using embolic protection devices.

Result: Technical success rate was 100%. PP occurred in onepatient (2.1%). In this case, the additional micromesh stent was placed andpatient did not suffer from stroke. New ischemic lesions were found in ninepatients (18.8%). No MAEs were observed in any patients.

Conclusion: Micromesh stent seemed to reduce ischemiccomplication by preventing PP during CAS.

O2-9-6

Carotid artery stenting with flow reversal system using the Mo.MaUltra, a proximal embolic protection device.

Hirofumi Matsubara, Yukiko Enomoto, TakamasaKinoshita, Yusuke Egashira, Toru Iwama

Department of Neurosurgery, Gifu University Graduate School of Medicine

Purpose: The most common complication in endovascular carotidrevascularization is distal embolism. In order to reduce the incidence,numerous cerebral protection devices have been proposed. Here, we reviewedthe treatment outcome of endovascular carotid revascularization with flowreversal system using the Mo.Ma Ultra in our institution.

Material & Methods: A total of 105 patients (male: 89 cases,age: 74.2 ± 7.6 years), 123 procedures (CAS: 104 procedures, PTA: 19procedures) who underwent carotid revascularization with this method at GifuUniversity Hospital from February 2014 to April 2022 were included in thestudy. The incidence of periprocedural both ischemic and hemorrhagiccomplication were retrospectively investigated.

Results: There were 69/105 (65.7%) symptomatic internal carotidartery stenosis, and the mean preoperative stenosis rate was NASCET84.3 ± 10%. Vulnerable plaque sign on MRI-TOF image was observed in 25% ofpatients. Ischemic complications including asymptomatic infarction onMRI-DWI was detected in 55/123 procedures (44.7%). Among them, symptomaticischemic complications were observed in only 1/123 procedures (0.8%).Hemorrhagic complications were in four cases (intracranial hemorrhage:1.Puncture site complication; 3). Post-operative-anemia requiring bloodtransfusion was observed in one case, however, the average Hb change betweenpre- and post-procedure was −1.04 ± 1.0 g/dl.

Conclusion: Proximal protection has been reported fewer distalembolisms compared with distal protection device. Our method “MoMa. Ultrawith flow reversal” is considered to be an effective protection system thatprovide complete reverse flow with or without superior thyroid artery, andreduce intraoperative blood loss.

O2-10-1

New Generation Fusion Technique for Enhanced Understanding ofNeurovascular Pathology

Tomas Dobrocky¹, Eike Immo Piechowiak¹, David Bernini², Pasquale Mordasini¹, Jan Gralla¹

¹Institute of Diagnostic and Interventional Neuroradiology,University of Bern

²Department of Neurosurgery, University of Bern, Inselspital, BernUniversity Hospital, and University of Bern, Switzerland

Purpose: Digital subtraction angiography provides excellentspatial and temporal resolution, however lacks the capability to depict thevessel wall or adjacent brain parenchyma or spinal cord.

Material & Methods: A review of the institutional databasewas performed to identify patients in whom a new integrated fusion work-flowof cross-sectional imaging and 3D rotational angiography (3DRA) providedimportant diagnostic information and assisted in the treatment planning.

Results: In 6 presented cases, including two acutely rupturedbrain arteriovenous malformation (AVM), small superficial brainstem AVMafter radiosurgery, thalamic micro-aneurysm, spine AVM, fusion was crucialfor diagnosis and influenced further therapy.

Conclusion: Fusion of 3DRA and cross-sectional imaging mayprovide a deeper understanding of neurovascular disease. This seems crucialfor planning, providing and most importantly minimizing complication ratesof our therapy. Integrating image fusion in the neurointerventionalwork-flow is likely to have a major impact on the neurovascular field in thefuture.

O2-10-2

Volume reduction effect of skull base tumor embolization revealed byanalysis of our 93 cases

Hiroki Sakamoto, Takao Hashimoto, Yusuke Arai,Muneaki Kikuno, Kengo Takahashi, Michihiro Kohno

Department of Neurosurgery, Tokyo Medical University, Tokyo, Japan

Purpose: In this study, we analyzed the effects of tumorembolization on tumor volume reduction and skull base surgery based on ourcases.

Materials and Methods: The subjects were 93 consecutive cases ofcerebellopontine angle tumors including 61 meningiomas, 31 schwannomas, and1 hemangioblastoma who underwent embolization and surgery at our hospitalfrom September 2013 to March 2021. It is classified into 4 groups of none(0%), slight (<5%), partial (<50%), and significant (> 50%) groupaccording to the degree of contrast-enhanced defect of the tumor in enhancedmagnetic resonance imaging after embolization compared to beforeembolization. We compared the volume reduction rate, operation time, removalrate, and amount of bleeding per tumor volume.

Results: Tumor volume of all cases were reduced by an average of12.4% after embolization (p < 0.001). Embolization reduced the volume ofmeningiomas by an average of 10.5% and the volume of schwannomas by anaverage of 15.4% (p = 0.80). The volume reduction rates of 4 groups were3.0%, 10.7%, 15.2%, and 15.1% for none, slight, partial, and significantgroup (none vs partial : p = 0.005, none vs significant : p = 0.003),respectively. The operation time of 4 groups were 409 min, 372 min, 370 min,and 340 min for none, slight, partial, and significant group, respectively.The removal rates of 4 groups were 89.3%, 87.0%, 92.7%, and 92.9% for none,slight, partial, and significant group, respectively. The blood loss pertumor volume of 4 groups were 54.7 ml/cm³,26.7 ml/cm³, 27.4 ml/cm³, and 21.0 ml/cm³for none, slight, partial, and significant group, respectively. A comparisonof the removal rates of the (none + slight) group and(partial + significant) group was 88.4% and 92.9% (p < 0.05),respectively. A comparison of the amount of blood loss per tumor volume inthe significant group and the other group were 21.0 ml/cm³ and36.3 ml/cm³ (p = 0.013), respectively.

Conclusion: In addition to shortening the operation time,improving the removal rate, and reducing the amount of intraoperativebleeding, the volume reduction effect of embolization was observed. Althoughno significant difference was observed, embolization tended to reduce thevolume of schwannoma more than that of meningioma.

O2-10-3

Cone-Beam Computed Tomography Fusion Imaging for Vascular Assessmentof Brain Tumors

Keisuke Yoshida¹, Takenori Akiyama², Satoshi Takahashi², Tomoru Miwa², Takashi Horiguchi², Hikaru Sasaki², Kazunori Akaji¹, Masahiro Toda²

¹Department of Neurosurgery, Mihara Memorial Hospital

²Department of Neurosurgery, Keio University School ofMedicine

Purpose: Cone-beam computed tomography (CBCT) imagesreconstructed from three-dimensional rotational angiography (3DRA) forintracranial tumors provide detailed vascular information. Hypervasculartumors are often supplied by multiple arterial systems. Information aboutthe contributions from each arterial system and distribution of tumorvascular compartments would be helpful in assessing the risk and benefit ofpreoperative embolization and planning surgical resection strategy. Wereport the use of CBCT fusion imaging for vascular assessment of braintumors.

Methods: Seventeen patients with intracranial tumors supplied bymultiple arterial systems were preoperatively evaluated using CBCT fusionimaging. Fusion images were reconstructed from 3DRA with contrast injectionsfrom the internal carotid artery (ICA) and external carotid artery (ECA) in12 cases, vertebral artery (VA) and ECA in 4 cases, and ICA and VA in 1case. Neurointerventionists and neurosurgeons could observe thethree-dimensional fusioned volume images using multiplanar reconstruction.The slab thickness of the maximum intensity projection could be alteredarbitrarily so that the 2 datasets changed simultaneously.

Results: The feeding pedicles and tumor stains from 2 arterialsystems were differentiated by separate colors, which helped predictingdevascularization effect of tumor embolization from each system. The coursesand territories of the ICA dural feeders or ICA/VA pial feeders were easilydistinguished from the ECA dural feeders. Anastomoses between thin feedersfrom different arterial systems could be detected. Mixed stain (stain withboth colors) was observed in some tumor compartments, suggesting dual supplyfrom 2 arterial systems and the presence of peritumoral anastomoses.

Conclusions: CBCT fusion images clearly visualized the feedersfrom each arterial system, the vascular compartments within the tumor, andpossible peritumoral anastomoses. This technique provides a substantialcontribution to both preoperative embolization and surgical resection ofintracranial tumors, especially skull base meningiomas.

O2-10-4

Effectiveness and Safety of Particle Embolization through AscendingPharyngeal Arteries Prior to Skull Base Tumor Resection

Daiichiro Ishigami, Satoshi Koizumi, HirotakaHasegawa, Yuki Shinya, Nobuhito Saito

Department of Neurosurgery, The University of Tokyo

Purpose: The ascending pharyngeal artery (APhA) feeds a varietyof cranial nerves and has anastomoses with the internal carotid artery andthe vertebral artery. As for preoperative tumor embolization, the procedureoccasionally ends with feeder occlusion using coils. On the other hand, theAPhA is one of the most common feeding arteries of skull base tumors and ischallenging to cauterize during surgical approaches. Our department has beenperforming preoperative tumor embolization, especially for hypervascularskull base tumors. We report our experience of embolization of skull basetumors involving APhAs herein.

Materials and Methods: Of the preoperative tumor embolizationsperformed in our institution from 2017 to 2021, we reviewed cases in whichAPhAs were embolized with particle agents. In each case, embolized branchesof the APhA, complications, and postoperative neurological deficits wereretrospectively reviewed.

Results: Eleven patients (median age: 56 years; eight women)were eventually included in the study: six patients with meningioma, threewith chordoma, one with chondrosarcoma, and one with spindle cell neoplasmin the clivus. Ten patients underwent transnasal endoscopic surgery. Themedian tumor volume was 25.82 cm³ (range: 5.12–124.19). Allpatients underwent preoperative embolization with Embosphere® 300–500 μm andcoils under local anesthesia and conscious sedation, and Embosphere wasdiluted 2–6 times. Six cases were embolized from the APhA pharyngeal trunk,one from the transosseous ramus of the superior pharyngeal branch, one fromthe jugular branch, and one from the hypoglossal branch. The intervalbetween the embolization and resection surgery varied from 1 to 6 days.Reduction of tumoral gadolinium enhancement was observed in 8 of 11patients, and particle-associated intratumoral hyperdense areas in thepost-embolization CT were confirmed in 3 cases. No patient showed newpostoperative neurological deficits, both after endovascular embolizationand after tumor resection.

Conclusions: In the preoperative embolization of skull basetumors, particle injection through APhA can be safely performed andfacilitate the tumor resection. In addition, preoperative identification ofthe entire vasculature by 3D rotational angiography and confirmation ofdangerous anastomoses by forced injection from the targeted vesselcontribute to safer embolization.

O2-10-5

Navigation and embolization of inferolateral and meningohypophysealfeeders in skull base tumors

Masaaki Shojima¹, Yudai Hirano¹, Takeshi Uno¹, Yuuta Oyama¹, Satoshi Koizumi², Masahiro Indo³, Akira Saito³, Masahiro Shin¹

¹Neurosurgery, Teikyo University

²Neurosurgery, Tokyo University

³Neurosurgery, Saitama Medical University General Hospital

Introduction: Some skull base tumors have side-branch feedersarising from the internal carotid artery (ICA), such as the inferior lateralartery or the meningeal hypophyseal artery. Despite the need forpreoperative embolization of these arteries to control bleeding duringresection, access is not easy due to the steep divergence from the ICA.Microcatheters would bent into the distal ICA, even though the tip of theguidewire was engaged into these tiny feeders.In 2013, we started a newtechnique to access the tiny sidebranches from ICA, where the tip of aspecial intermediate catheter, FUBUKI 043 (Asahi Intech, Aichi, Japan), hasbeen shaped and used to orient and support the microcatheter and guidewire.Here, we did a retrospective study to investigate the utility of thistechnique.

Subjects and method: A total of 41 preoperative tumorembolizations were performed between 2013 and 2022. For each case, theinvolvement of the ICA side branch feeder, embolization attempts,embolization success rate, and complications were recorded.

Results and discussion: ICA side-branch feeders were involved in15 skull base tumors. Of these, feeders were so fine that embolization wasnot planned in 6 cases. In the other 9 cases, embolization of the sidebranch feeder from ICA was attempted and was successful in 8 cases.In onecase, a wire perforation that occurred in the distal part of inferiorlateral artery caused a mild arteriovenous fistula. After embolizing withhistoacrylic glue, it disappeared with the tumor feeder. Postoperative CTshowed no intracranial hematoma.FUBUKI 043 has a smooth hydrophilic coatingon the surface of the catheter for excellent distal mobility. However, thetip is stiffer than a normal intermediate catheter, can be thermoformed, andcan maintain its shape. FUBUKI 043 also has a diameter suitable forstability in ICA. It provided the orientation and support for navigating tothe depth of a small feeder that branches the microcatheter and guidewire ata steep angle.

Conclusion: Assisted by a special intermediate catheter that isformable and has substantial shape retention, microcatheters were able tonavigate into small feeders branching at a steep angle from the largeintarnal carotid artery for embolization.

O2-10-6

Usefulness of syngo Dyna 4D DSA for understanding angioarchitecture ofcerebrospinal arteriovenous fistula

Yuya Koyanagi, Koichi Arimura, Soh Takagishi,Katsuma Iwaki, Tomohiro Okuda, Akira Nakamizo, Koji Yoshimoto

Department of Neurosurgery, Graduate School of Medical Sciences, KyushuUniversity, Fukuoka, Japan

Background and Purpose: An understanding of blood vesselconstruction in the treatment of cerebrospinal arteriovenous fistula isessential, but it is not necessarily easy to understand it for inexperiencedsenior residents. Usually, in addition to 2D DSA, diagnosis is used to makeuse of three-dimensional images such as 3D DSA, but these three-dimensionalimages have weakness that the time resolution is poor. Syngo Dyna 4D DSA (4DDSA) is an application which has the information of time axis, andvascularization of shunt disease may be more easily and visuallyunderstandable. We examined the usefulness of 4D DSA in cerebrospinalarteriovenous fistula.

Methods: From April 2017 to December 2021, we analyzed 9patients (cavernous sinus 4, tentorial sinus 1, transverse-sigmoid sinus 2,craniocervical junction 1, spinal 1) conducted diagnosis and treatment atour hospital. For each case, 4 senior residents evaluated vascularconstruction visibility of feeder, shunting point, and drainer with a 2D /3D / 4D DSA on a scale of 4(4: Very Good, 3: Good, 2: Moderate, 1; Poor),and we evaluated the difference between the three images.

Results: Feeder and shunting point were more accuratelyevaluated in 3D compared to 2D DSA and in 4D compared to 2D / 3D DSA, and 4Dimages were useful for understanding the vascularization. The visibility ofdrainer was more accurately evaluated by 4D DSA compared to 2D/ 3D DSA, butthere was no difference between 2D DSA and 3D DSA. However, it was thoughtthat there were room for improvement of 4D DSA, not enough for micro bloodvessel resolution. No major variation among the evaluators in each item wereobserved.

Conclusion: Syngo Dyna 4D DSA is useful for understanding thevascularization of cerebrospinal arteriovenous fistula in seniorresidents.

O2-11-1

Timing and Outcomes of Intracranial Stenting in the Post-SAMMPRISEra

Tao Wang, Xiao Zhang, Liqun Jiao

Department of Neurosurgery, Xuanwu Hospital, Capital Medical University

Objective: To investigate the impact of timing on the safety andefficacy of stenting for ICAS, we reviewed high-volume randomized controlledtrials or prospective cohort studies of stenting for intracranialatherosclerotic artery stenosis (ICAS) after the SAMMPRIS trial.

Methods: We included randomized controlled trials or prospectivecohort studies since 2011 (the publication of the SAMMPRIS trial),evaluating the outcomes of intracranial stenting for ICAS patients. Theprimary outcomes were perioperative and 1-year stroke or death rate. Theinteraction of timing and outcomes were shown on trend plots. Overallmeta-analysis and subgroup analysis by timing of intracranial stenting wereconducted.

Results: Fourteen studies with a total of 1950 patients wereincluded. The perioperative and post-operative stroke or death ratesdecreased with the time of stenting to the qualifying events. Theperioperative stroke rate was significantly higher in patients treatedwithin 21 days after the qualifying events, compared to those beyond 21 days(IRR = 1.60, 95%CI: 1.10–2.33; p = 0.014), similar relationships wereobtained for both post-procedural (IRR = 1.61, 95%CI: 1.02–2.55; p = 0.042)and 1-year (IRR = 1.51, 95%CI: 1.10–2.08; p = 0.012) stroke or deathrate.

Conclusions: The timing of intracranial stenting may influencethe safety and efficacy outcomes of stenting. Intracranial stenting within21 days from the qualifying events may confer a higher risk of stroke ordeath. More studies are needed to confirm the impact of timing and theproper cut-off value.

O2-11-2

Safety of endovascular therapy for symptomatic intracranial arterystenosis: a national prospective registry

Tao Wang, Yabing Wang, Liqun Jiao

Department of Neurosurgery, Xuanwu Hospital, Capital Medical University

Introduction: The safety outcomes of endovascular therapy forintracranial artery stenosis in a real-world stetting are largely unknown.The Clinical Registration Trial of Intracranial Stenting for Patients withSymptomatic Intracranial Artery Stenosis (CRTICAS) was a prospective,multicentre, real-world registry designed to assess these outcomes and theimpact of centre experience.

Methods: 1140 severe, symptomatic intracranial arterial stenosis(ICAS) patients treated with endovascular therapy were included from 26centres, further divided into three groups according to the annual centrevolume of intracranial angioplasty and stent placement procedures over 2years: (1) high volume for ≥25 cases/year; (2) moderate volume for 10–25cases/year and (3) low volume for <10 cases/year.

Results: The rate of 30-day stroke, transient ischaemic attackor death was 9.7% (111), with 5.4%, 21.1% and 9.7% in high-volume,moderate-volume and low- volume centres, respectively (p < 0.05).Multivariable logistic regression confirmed high-volume centres had asignificantly lower primary endpoint compared with moderate-volume centres(OR = 0.187, 95% CI: 0.056 to 0.627; p ≤ 0.0001), while moderate-volume andlow-volume centres showed no significant difference (p = 0.8456).

Conclusion: Compared with the preceding randomised controlledtrials, this real-world, prospective, multicentre registry shows a lowercomplication rate of endovascular treatment for symptomatic ICAS.Non-uniform utilisationin endovascular technology, institutional experienceand patient selection in different volumes of centres may have an impact onoverall safety of this treatment.

O2-11-3

Endovascular Therapy for Symptomatic Intracranial ArteryStenosis

Xiao Zhang^1,2, Tao Wang^1,2, Kun Yang^3,4, Jichang Luo^1,2, Ran Xu^1,2, Xue Wang⁵, Yutong Yang⁶, Xuesong Bai^1,2, Yan Ma^1,2, Yuxiang Yan^4,7, Liqun Jiao^1,2,8

¹Department of Neurosurgery, Xuanwu Hospital, Capital MedicalUniversity

²China International Neuroscience Institute (China-INI), Beijing,China

³Department of Evidence-Based Medicine, Xuanwu Hospital, CapitalMedical University, Beijing, China

⁴Department of Epidemiology and Biostatistics, School of PublicHealth, Capital Medical University, Beijing, China

⁵Medical Library, Xuanwu Hospital, Capital Medical University,Beijing, China

⁶National Heart & Lung institute, Imperial College London,United Kingdom

⁷Municipal Key Laboratory of Clinical Epidemiology, Beijing,China

⁸Department of Interventional Neuroradiology, Xuanwu Hospital,Capital Medical University, Beijing, China

Background: Intracranial artery atherosclerotic stenosis (ICAS)is one of most common causes of stroke. Endovascular therapy includingballoon angioplasty alone (BA), balloon-mounted stent (BMS), orself-expanding stent (SES) was an important alternative to treat symptomaticICAS refractory to medical treatment, while none of the three subtypes hasbeen established to be the primary option. We conducted a study to determineboth the safety and efficacy and establish a hierarchy of differentendovascular therapies on symptomatic ICAS.

Methods: Major databases including MEDLINE, EMBASE, the CochraneCentral Register of Controlled Trials were searched for studies comparingoutcomes of three different endovascular approaches and other comparablenon-endovascular therapies for symptomatic ICAS patients published from 1January, 2000 to 1 November, 2021. Primary outcomes included short-termmortality or stroke rate (peri-procedural, or mean follow-up ≤ 3 month), andlong-term mortality or stroke rate (mean follow-up ≥ 6 month). Pairwise andnetwork meta-analyses based on the above systematic review wereconducted.

Results: A total of 19 eligible studies involving 3386 patientstreated with 4 different approaches (BA, SES, BMS and medical treatment)were analyzed. For primary outcome, BA had the highest ranking (SUCRA value78), followed by BMS (SUCRA value 21.5) and SES (SUCRA value 13.1). Theshort-term mortality or stroke rate was significantly lower in BA groupcompared to SES (OR = 2.50; 95% CI 1.12 to 5.57; p = 0.026) or BMS(OR = 0.43; 95% CI 0.19 to 0.96; p = 0.038). Other primary and secondaryoutcomes were no different among all three types of endovascular therapy.Overall, the studies were of good methodological quality and the consistencywas acceptable across all network meta-analyses.

Conclusions: BA offers the highest level of safety outcomes interms of short-term mortality or stroke in treating symptomatic patientswith intracranial artery stenosis, compared to SES and BMS, which needs tobe confirmed in future studies. (Trial registration in PROSPERO database:CRD42018084055)

O2-11-4

Computational Fluid dynamics to detect system failure pressure inposterior circulation intracranial atherosclerosis after stenting

George Renchao Wu, Ravi Kaushikkumar Shastri,Goetz Benndorf

Department of Radiology, Baylor College of Medicine, Houston TX USA

Purpose: Intracranial atherosclerosis is challenging in thefield of stroke therapy. Utilizing computational fluid dynamics (CFD), wehope to evaluate regional changes in flow velocity that may be associatedwith severe vascular resistance. These regional changes may help to identifyand predict the likelihood of successful stenting.

Materials and Methods: We retrospectively reviewed 5 patientsbetween 2009–2019 who have undergone intracranial stenting for symptomaticintracranial atherosclerosis in the posterior circulation on dualantiplatelet therapy pre and post procedure. Clinically significant strokepost procedure and patency on follow up exam was recorded. Preoperative CTAand MRA images were used to extract the vessel models. Preoperative werecompared to postoperative models. Segmentation was performed using 3D slicer4.11 (Brigham and Women's Hospital, Harvard Medical School, Boston, MA,USA). Input and output patches for the vertebral arteries and posteriorcerebral arteries were created using blender 2.93.3 (blender.org). Fluiddynamic simulation was carried out using OpenFoam 2112 (The OpenFOAMFoundation: OpenFOAM version 9 (2021)). Using Birds Carreau Model forkinematic viscosity, the mean arterial pressure (MAP) of blood wascalculated through the vessel model. Assumptions were taken for a tubularstructure regarding k-omega turbulence modeling. Mean flow velocity at theinput was given as 80cm/s. After completing the simulation, the distancefrom the area of highest MAP before the stenosis to the area of lowest MAPwithin the stenosis was calculated as well as the pressure difference. Thepressure difference between highest pre stenosis pressure and lowestpressure was recorded as the gradient mean arterial pressure (gMAP).Gradient pressures and distance to area of maximal pressure loss wascalculated to determine the potential failure pressure of the system.

Results: Two of the five patients developed occlusion afterstenting with a fatal outcome with gMAP greater than 100mmHg over a distanceless than 6 mm. In the three patients who survived and had decreasedgradient after one year, the preoperative gMAP was 4–35 mmHg over distanceof 12–28 mm. All surviving patients were compliant with aspirin and Plavixpost procedure for 6 months and had no additional strokes. The two patientswho died were compliant with dual antiplatelet therapy until they died.

Conclusion: Evaluation of this limited subset of patients,occlusion was observed where the pressure gradient of over 100mmHg over adistance less than 6 mm. Findings suggest a relation of distance as well asthe severity of pressure gradient to procedure success. These valuescalculated using CFD analysis may be helpful in evaluating the clinicaloutcome after stenting and may be grounds for further study.

O2-11-5

Use of Neuroform Atlas stent for intracranial atherosclerotic disease:clinical and radiographic outcomes

Yosef Ellenbogen², Everadus Hendricks¹, Ivan Radovanovic², Joanna Schaafsma³, Ronit Agid¹, Timo Krings¹, Patrick Nicholson¹

¹Division of Neuroradiology, Toronto Western Hospital, Universityof Toronto, Toronto, Ontario, Canada

²Division of Neurosurgery, Toronto Western Hospital, University ofToronto, Toronto, Ontario, Canada

³Division of Neurology, Toronto Western Hospital, University ofToronto, Toronto, Ontario, Canada

Purpose: Intracranial atherosclerotic disease (ICAD) is animportant cause of ischemic stroke. Treatment of intracranialatherosclerosis failing medical management may include intracranialstenting, which can happen in both the acute or elective stage. There arespecific devices which are designed for this indication, however less datais available on the off-label use of devices. One possible such device whichcan be used off-label for the treatment of ICAD is the Neuroform Atlasm,which is a self-expanding nitinol laser-cut stent. This retrospective cohortstudy assesses the use of the Neuroform Atlas stent for the treatment ofsymptomatic ICAD.

Materials & Methods: Patients who underwent electiveintracranial stenting for symptomatic intracranial stenosis using theNeuroform Atlas stent between November 2018 and March 2021 were included.Clinical data, technical details and clinical and radiographic outcomes werecollected.

Results: Eighteen patients met the inclusion criteria with amean follow-up duration of 9.6 + 6.8 months. No intra-proceduralcomplications occurred. There were two delayed mortalities (1 symptomaticintracranial hemorrhage and 1 groin site complication with sepsis) within 90days. Fifteen of the patients were alive at the 6-month follow-up. Of these,all had satisfactory stent patency without any new ischemic events.

Conclusion: Intracranial stenting with the Neuroform Atlas stentmay be a safe and effective treatment of symptomatic intracranial stenosisfailing aggressive medical management. This warrants further prospectivestudies with large patient cohorts and longer duration of follow-up.

O2-11-6

Imaging and Clinical Follow-Up Data of Intracranial Stenting forIntracranial Atherosclerotic Disease

Sang-il Suh¹, Jung Hoon Han², Wonki Yoon³, Chi Kyung Kim², Taek Hyun Kwon³

¹Radiology, Korea University Medicine, Guro Hospital, Seoul,Korea

²Neurology, Korea University Medicine Guro Hospital,Seoul,Korea

³Neurosurgery, Korea University Medicine Guro Hospital, Seoul,Korea

PURPOSE: To evaluate the radiological and clinical follow-updata of intracranial stenting for intracranial atherosclerotic stenosis inacute period (less than 7 days symptom onset) and elective cases.

MATERIAL AND METHODS: We collected the imaging and clinical datafrom our intracranial arterial stenting (ICS) registry for intracranialatherosclerotic disease (ICAD) from 2011 to 2021. Among them, we evaluatedthe angiographical and clinical follow-up (FU) data of ICS in acute andelective period. In all cases, we used pre-balloon dilatation andself-expandable intracranial stent. In acute period stenting group, total 20cases (Male: Female 12:8; mean ages 61 yrs old) were collected. In electivegroup, total 21 cases (M:F 14:7/ mean ages 59 yrs old) were included.

RESULTS: In acute period stenting group, imaging FU wereconducted upto110 months: 15 cases showed no in-stent-restenosis (ISR); 2cases, less than 50% ISR; 1 case, 51∼70% ISR; 2 cases, more than 71% ISR.Clinical FU in acute period ICS were evaluated upto 120 months: 1, anystroke < 30 days; 2, any stroke < 1 year; no major stroke, nostroke-related death; difference between 3-month mRS and initial mRS was −3to 0.

In elective stenting group, radiological FU were performed upto 101 months;17 cases showed no in-stent-restenosis (ISR); 3 cases, less than 50% ISR; 1case, more than 71% ISR. Clinical FU in elective period ICS were evaluatedupto 120 months: 0, any stroke < 30 days; 1, any stroke < 1 year; 1major stroke (14 months later), no stroke-related death; difference between3-month mRS and initial mRS was −2 to 1.

CONCLUSIONS: We report the good radiological and clinical FUdata of ICS with self-expandable intracranial stent for management in acuteand elective period of ischemic stroke in patient with intracranialatherosclerotic stenotic lesions.

O2-12-1

Impact of thrombectomy technique on stroke clot pathology

Taichiro Imahori, Mahsa Ghovvati, Lea Guo,Satoshi Tateshima, Naoki Kaneko

Department of Radiological Sciences, David Geffen School of Medicine,University of California Los Angeles, Los Angeles

Purpose: Identification of stroke origin is essential foroptimal secondary stroke prevention strategies. Recently, many studies haveevaluated retrieved clots to assess the stroke origin after mechanicalthrombectomy for large vessel occlusion. However, previous studies focusingon histological evaluation of cellular components have yielded inconsistentresults. We hypothesized that retrieved clots would receive differenthistological modifications from their original state, depending on thethrombectomy technique. To test our hypothesis, we investigated whetherendovascular techniques affect the clot pathology during mechanicalthrombectomy.

Materials and Methods: Two types of clot analogs were createdfrom ovine blood; red blood cell (RBC)-rich and fibrin-rich clots. Withthese clots, the middle cerebral artery M1 segment was occluded in asilicone human vasculature intracranial vessel replica connected to aphysiological flow loop. For each clot, three groups of retrieved clots wereinvestigated: 1) stent retriever use, 2) aspiration alone, and 3) control(direct removal from the model inlet). After histological processing,Martius Scarlet Blue (MSB)-stained sections of the clots were quantitativelyanalyzed with respect to the relative proportions of the major cellularcomponents (RBC and fibrin). The obtained data were compared among the threegroups.

Results: For both clot types, the degree of volume reduction ofretrieved clot compared to the control group was greater in the stent groupthan in the aspiration group. The extent of these volume reductions wasparticularly prominent in the fibrin-rich type. For Fibrin-rich clots, therelative ratio of RBC to fibrin did not differ among the three groups on MSBstaining. In contrast, in the RBC-rich clot, there was a slight decrease inRBC rate in the aspiration group compared to controls, but a marked decreasein RBC rate in the stent group. Accordingly, our results demonstrated thatthe stent use reduced RBC components on retrieved clot pathology.

Conclusion: Histological evaluation of retrieved clots can beaffected by the type of mechanical thrombectomy technique. This implies thatthe physical force on the clot during the thrombectomy procedure would varyfrom different endovascular techniques. The differences in changes in clotpathology by thrombectomy techniques need to be recognized for strokeresearch.

O2-12-2

Combined Aspiration and Stent-retriever Thrombectomy in Patients withAcute Ischemic Stroke and Large Vessel Occlusion: results of asingle-center, prospective trial using computed tomography perfusion forpatient selection

Eduardo Portela de Oliveira¹, Greg Walker², Atyani Almohannad¹, Maria Gladkikh³, Adela Cora⁵, Grant Stotts², Dar Dowlatshahi², Robert Fahed², Richard Aviv¹, Dana Iancu⁶, Howard Lesiuk⁴, Santanu Chakraborty¹, Brian Drake⁴

¹Division of Neuroradiology, Department of Radiology, Universityof Ottawa, The Ottawa Hospital, Ottawa, Ontario, Canada.

²Division of Neurology, Department of Medicine, The OttawaHospital, Ottawa, Ontario, Canada.

³Faculty of Medicine, University of Ottawa.

⁴Division of Neurosurgery, University of Ottawa, The OttawaHospital, Ottawa, Ontario, Canada

⁵Division of Neuroradiology, Department of Radiology, DalhousieUniversity, Halifax, Nova Scotia, Canada.

⁶Department of Radiology, University of Montreal, Canada.

Background: Mechanical thrombectomy (MT) is an effective therapyin patients with acute ischemic stroke (AIS) and large vessel occlusion(LVO). Combined use of stent retriever (SR) and aspiration holds promise asa first-line reperfusion therapy for patients with LVO. However, there islimited data regarding the safety and success of this approach, especiallywith use of computed tomography perfusion (CTP) for patient selection. Thisstudy aimed to report on the safety and efficacy of the combined techniqueas first-line therapy of AIS with LVO imagined with CTP.

Methods: We prospectively enrolled 39 AIS patients selected formechanical thrombectomy who underwent advanced imaging. All patients hadunenhanced CT head, CT angiography and CTP pre-procedure and DWI-MRI within24 h post-procedure. The primary outcome was recanalization rate,peri-procedural complications, and clinical outcome (90-day mRS 0–2).Secondary outcomes were the sensitivity and specificity of CTP in predictinginfarct on 24-h DWI-MRI.

Results: 36 patients (92.3%) had successful recanalization. 32(82%) patients presented <6 h from symptom onset. 25 (64%) receivedintravenous tissue plasminogen activator. 5 patients (12.85%) hadsignificant peri-procedure complications. 90-day functional outcome wasachieved in 69.2% of patients. Using a cut-off of at least 70 ml estimatedcore infarct on CTP to predict final infarct on DWI-MRI, the AUC wascalculated at 0.730, with an accuracy of 74.3%, sensitivity of 52.9% andspecificity of 94.4%.

Conclusion: We prospectively report on the safety and efficacyof MT with combined SR and aspiration technique as first-line therapy forpatients selected by CTP. In our cohort, the patients achieved highrecanalization rate and good 90-day functional outcome with minimalimmediate peri-procedural complications. CTP demonstrated good accuracypredicting infarcts on 24-h MRI. Further investigation is required toclarify the optimal endovascular strategy based on patient and strokecharacteristics.

O2-12-3

Optimal strategy for mechanical thrombectomy based on preoperativeimaging diagnosis of thrombus composition

Hiroyuki Sakata¹, Masayuki Ezura¹, Atsushi Saito¹, Yoshinari Osada¹, Hidenori Endo¹, Teiji Tominaga²

¹Department of Neurosurgery, National Hospital Organization SendaiMedical Center

²Department of Neurosurgery, Tohoku University Graduate School ofMedicine

Purpose: Recanalization is unsuccessful after mechanicalthrombectomy in some patients, possibly due to thrombus characteristics. Weinvestigated whether the most appropriate thrombectomy strategy could bedetermined based on thrombus imaging findings.

Materials and Methods: We retrospectively studied 70 patientswith acute large-vessel ischemic stroke who underwent mechanicalthrombectomy. Thrombus density was measured using non-contrast computedtomography (ΔCT value) and computed tomography angiography (thrombuspermeability). Difficult-to-retrieve thrombi were defined based on themedian ΔCT value and thrombus permeability. The primary analysis aimed toevaluate the predictors of favorable outcome (modified Rankin Scale 0–2) andsuccessful recanalization (Thrombolysis in Cerebral Infarction scale 2b or3). The secondary analysis evaluated the interaction between thrombusimaging diagnosis and thrombectomy strategy (stent retriever (SR) alone vs.combined strategy) on recanalization and functional outcome.

Results: Patients with favorable outcomes and successfulrecanalization had significantly higher ΔCT values (p < 0.001, p <0.001) and thrombus permeability (p < 0.001, p = 0.014). Patients withunsuccessful recanalization had a higher frequency of difficult-to-retrievethrombi than those with successful recanalization (69% vs. 19%, p <0.001). The combined strategy was significantly more effective for achievingsuccessful recanalization with a difficult-to-retrieve thrombus comparedwith SR alone strategy (33.3% vs 87.5%, OR 0.07 (95% CI 0.01 to 0.79),p = 0.028), whereas the normal thrombus showed a similar response with bothstrategies (96.2% vs 87.5%, OR 3.57 (95%CI 0.34 to 36.94), p = 0.34).

Conclusion: Our data suggest that measuring thrombus density,which predicts thrombus characteristics as well as clinical outcomes, is asimple and beneficial approach to enhance the effectiveness of mechanicalthrombectomy by indicating the optimal strategy.

O2-12-4

The validity of Aspiration with Blood dripping Contact: ABC techniqueusing Tron & SOFIA

Keisuke Sato¹, Naoki Yajima¹, Daiju Mitsuhashi¹, Takuya Okada¹, Toyotaka Aiba¹, Hitoshi Hasegawa²

¹Department of Neurosurgery, Niigata prefectural Shibata Hospital,Niigata, Japan

²Department of Neurosurgery, Brain Research Institute, NiigataUniversity, Niigata, Japan

Objective: We show our mechanical thrombectomy technique whichwe call Aspiration with Blood dripping Contact (ABC) technique and reportthe treatment result of ABC technique using Tron & SOFIA.

Methods: We performed ABC technique as follows. For step 1, wetotally deployed Tron at the more distal area than a thrombus and SOFIA wasgradually advanced with blood dripping from the side port of the Yconnecter. For step 2, we concluded the optimal SOFIA contact for a thrombusafter the stop of blood dripping and finished to advance SOFIA. For step 3,after one minute continuous aspiration, we withdrew both Tron and SOFIA froma guiding catheter.

Between April 2021 and January 2022, we performed 13 mechanical thrombectomyprocedures with ABC technique using Tron & SOFIA. We validated theresult of the procedures such as the recanalization rate, the passing numberof times and the related hemorrhagic complication.

Result: In all cases, we succeeded the procedures. The positionsof the thrombus were IC in three cases, M1 in 6, M2 in 1 and BA in 3.Successful recanalization (modified thrombolysis in cerebral infarction(TICI) ≧ 2b) could be achieved in 100% with ABC technique. Therecanalization results were TICI 3 in seven cases, TICI 2c in 1 and TICI 2bin 5. The mean passing number of times was 1.62 ± 0.96. The asymptomaticintracranial hemorrhage was occurred in 1 of 13 (7.7%) and there was nosymptomatic intracranial hemorrhage related the procedures.

Conclusion: ABC technique is effective for the optimal contactfor a thrombus. This study suggested that ABC technique using Tron &SOFIA might advance not only the recanalization rate but also the safety ofthe procedures.

O2-12-5

Mechanical thrombectomy for M1-M2 occlusion: how to select theoccluded M2 trunk at 1^stpass

Shinya Hagiwara¹, Kentaro Hayashi², Haruo Takigawa³, Shinichi Yasuda⁴, Takeshi Uemura⁴, Yohei Shibata¹, Masahiro Uchimura¹, Kazuyuki Mikami^1,2, Mizuki Kambara¹, Tsutomu Yoshikane^1,2, Hidemasa Nagai¹, Yasuhiko Akiyama¹

¹Department of neurosurgery, Shimane University Hospital

²Advanced stroke center, Shimane University Hospital

³Department of neurosurgery, Matsue city hospital

⁴Department of neurosurgery, Sakura-kai hospital

Purpose: M1 occlusion is divided into pure M1 occlusion in whichthrombus exists only in M1 and M1-M2 occlusion that in M1 to M2. M1-M2occlusion can be classified into M1-M2 superior trunk occlusion, M1-M2inferior trunk occlusion, and M1-bilateral M2 occlusion according to thelocation of the distal thrombus. When performing mechanical thrombectomy(MT) using a stent-type device for acute ischemic stroke (AIS), it isimportant to identify the thrombus region and deploy the device beyond thedistal end of thrombus. If distal thrombus cannot be captured by stent, itmay leads to incomplete recanalization and increases the risk of distalmicroembolization due to thrombus fragmentation. However, during MTintervention, vascular anatomy beyond M1 is unknown. Under these limitedcircumstances, is it possible to identify the occluded M2 trunk ?

We extracted cases of M1-M2 occlusion from MT cases at our institutes. Wehypothesized that “thrombus may migrate to the smaller bifurcation angle M2trunk”, and retrospectively examined the location of the thrombus and theM1-M2 bifurcation angle.

Material and methods: We performed MT for 127 cases of AISduring past 3 years and 5 months. The thrombus was located at the M1-2bifurcation in 16 cases and the following data was evaluated.

1. Number of cases, which the M1-M2 superior trunk angle is larger thanthe M1-M2 inferior trunk angle

2. Number of cases, which the M1-M2 inferior trunk angle is larger thanthe M1-M2 superior trunk angle

3. Distal thrombus position (M2superior trunk occlusion, M2 inferiortrunk occlusion, bilateral M2 occlusion)

4. Recanalization rate of MT retrieved from the occluded M2 and nonoccluded M2 respectively

Result: 13 of 16 cases (81.2%), M1-M2 superior trunk angle waslarger than the M1-M2 inferior trunk angle. 3 of 16 cases(18.8%), M1-M2inferior trunk angle was larger than the M1-M2 superior trunk angle. Distalthrombus location was superior trunk occlusion: 4 of 16 (25%), inferiortrunk occlusion: 11 of 16 (69%) and bilateral M2 trunk occlusion: 1 of 16(6%). Except for one case of bilateral M2 trunk occlusion, 11 of 15 cases(73%) had a distal thrombus in M2 with a smaller M1-M2 bifurcationangle.

The recanalization rate of MT retrieved from the occluded M2 was TICI2b-3:93.8%. On the other hand, the rate from non occluded M2 was TICI2b-3: 0%,TICI 1-2a: 30%, and TICI 0: 70% respectively.

Conclusion: Thrombus tends to migrate to the smaller bifurcationangle M2 trunk, dominantly inferior trunk. And the success rate of MT ishigher in case retrieved from occluded M2 trunk. If it failed, we should tryto retrieve from another M2 trunk.

O2-12-6

Timing of Suction Start in the Technique Combining Aspiration Catheterand Stent Retriever in Mechanical Thrombectomy for Acute IschemicStroke

Makoto Dehara, Nao Shimooka, Shiromaru Ishida,Mayuko Kunii, Hanako Sasaki, Takahiro Uno, Mikako Nomoto, YasushiHagihara

Department of Neurosurgery, Rinku General Medical Center, Osaka, Japan

Purpose: In conducting mechanical thrombectomy for the treatmentof acute ischemic stroke, many hospitals employ a technique combining stentretriever and aspiration catheter. When pulling a thrombus into a suctioncatheter with a stent retriever while aspirating with a suction catheter,there may be strong resistance to pulling in the stent retriever. At thattime, excessive traction of blood vessels by the stent retriever occurs. Itis thought that the traction of the occluded vessel due to this excessiveresistance causes the tearing and pulling out of the thin perforating branchemerging from the vessel, causing subarachnoid hemorrhage. We investigatedwhat causes the traction force of blood vessels when collecting a thrombuswith a stent retriever while sucking with an aspiration catheter. Weconsidered measures to prevent the phenomenon.

Materials and Methods: A stent retriever was inserted into avessel model with softness close to that of a real vessel made with PVA.While adding suction force to the distally closed vascular model with asuction machine, stent retriever was pulled to observe the shapes ofvascular model and resistance for pulling that.

Results: With just a half of the suction pressure compared tothe normal therapy, the original shapes of both the vascular model and theinserted stent retriever were collapsed. The vessel wall bite into each cellof the stent retriever, and the stent retriever could not be pulled.

Conclusion: If the tip of the aspiration catheter is wedged intothe vessel and the target thrombus is still distant from the stentretriever, the intravascular space between the aspiration catheter andthrombus is exposed to a strong negative pressure. The blood vessel wallbite into the cells of the stent. That prevents the smooth sliding of thestent on the vessel wall, which results in the strong tugging of the vessel.The study concludes that it is advisable not to start the suction with theaspiration catheter until the thrombus attached to the stent contacts withthe tip of the aspiration catheter.

O2-13-1

Usefulness of Cone Beam CT in Prediction of Stent Expansion afterCarotid Stenting

Jieun Roh¹, Jeong A Yeom¹, Jin Wook Baek², Seung Kug Baik¹

¹Department of Radiology, Pusan National University YangsanHospital

²Department of Radiology, Inje University Busan Paik Hospital

Objectives: The long-term durability of carotid artery stenting(CAS) may be determined by various factors; however, residual stenosis is aknown risk factor for in-stent restenosis. The authors of this articleutilized cone-beam CT (CBCT) in angiosuite to investigate plaque featuresaffecting the character and quality of stent expansion after CAS.

Methods: Forty-two CAS cases with both pre- and post-CAS CBCTevaluations were included in this retrospective analysis. Five featuresderived from pre-CAS images were tested: 1) eccentricity, 2) overballoon, 3)maximum plaque thickness, 4) calcification barrier, and 5) stenotic degree.For post-CAS CBCT, stent configuration was assessed if the stent wasexpanded and oval or round in shape as well as outward or inward inorientation. Variables were tested if they were associated with ovalexpansion, outward expansion, and 20% residual stenosis after CAS.

Results: Oval or outward expansion is directly related toresidual stenosis. Oval expansion was associated with maximum plaquethickness, and outward expansion was associated with the presence of acalcification barrier. Variables related to > 20% residual stenosis werethe maximum plaque thickness, calcification barrier, and pre-CAS stenoticdegree.

Conclusions: CBCT for carotid stenosis may provide valuableinformation about plaque features, especially calcification features thatmay interfere with the angioplasty effect, as well as the characteristicsand quality of stent expansion. Residual stenosis > 20% was associatedwith calcification barrier, maximum plaque thickness, and pre-CAS stenoticdegree.

O2-13-2

Thrombosis may be an etiological factor of intracranial arterystenosis in young adults: novel findings guided by optical coherencetomography

Ran Xu^1,2, Hengxiao Zhao^1,2, Tao Wang^1,2, Yutong Yang³, Yan Ma^1,2, Adam A. Dmytriw^4,5, Ge Yang⁶, Bin Yang^1,2, Liqun Jiao^1,2,7

¹Department of Neurosurgery, Capital Medical University

²China International Neuroscience Institute (China-INI), 45Changchun Street, 100053, Beijing, China

³National Heart & Lung Institute, Faculty of Medicine,Imperial College London, G210 Guy Scadding Building, SW3 6LY, London, UnitedKingdom

⁴Neuroendovascular Program, Massachusetts General Hospital,Boston, MA 02114, USA

⁵Neuroradiology & Neurointervention Service, Brigham andWomen's Hospital and Harvard Medical School, Boston, MA 02215, USA

⁶National Laboratory of Pattern Recognition, Institute ofAutomation, Chinese Academy of Science, Beijing 100190, China

⁷Department of Interventional Neuroradiology, Xuanwu Hospital,Capital Medical University, 45 Changchun Street, 100053, Beijing, China

Purpose: Intracranial arterial stenosis (IAS) is one of theleading cause of ischemic stroke globally. The common cause of IAS includeintracranial atherosclerotic stenosis (ICAS), moyamoya disease, inflammatoryvascular disease et al. However, ischemic stroke occurs among young adultswho harbor no risk factor or pathological features of known causes for IAS.Optical coherence tomography (OCT) provides an ideal approach to investigatethe morphology and structural features of intracranial stenotic lesions.Therefore, we aim to investigate potential pathological basis of ischemicstroke in young adults by application of OCT.

Methods: From May 2020 to November 2021, three symptomatic youngadults with AIS was enrolled in this study. OCT was performed before andpost interventional therapies. Thus, plaque morphology, structure and theefficiency of interventional treatment were evaluated under OCT.

Results: OCT and the following interventional treatment wasperformed among three young adults safely and efficiently. Thrombosis wasobserved under OCT before interventional therapies. In addition, arterialdissection, strut malapposition and other complications were not foundduring peri-operation time. The extent of stenosis and symptoms werereleased in all three patients after stenting.

Conclusions: OCT showed its distinct advantage in evaluating themorphology and structure of IAS lesions, as well as the treatment efficiencyof stenting. Remarkably, by application of OCT, we discovered thatthrombosis may be a fundamental pathological cause of young adults with IAS.Early thrombolytic and anticoagulant therapy may beneficial for IAS whenthrombosis were found under OCT. Therefore, we uncovered novel cause of IASin your adults, which provided novel references for treatment of IAS.

O2-13-3

Impact of magnetic resonance plaque imaging before carotid arterystenting: Initial result of (MR-CAS) study

Kiyofumi Yamada^1,2, Manabu Shirakawa², Yukiko Enomoto³, Takao Kojima⁴, Kazuki Wakabayashi⁵, Daniel S Hippe⁶, Chun Yuan⁶, Thomas S Hatsukami⁷, Shinichi Yoshimura²

¹Department of Neurosurgery, National Cerebral and CardiovascularCenter, Suita, Japan

²Department of Neurosurgery, Hyogo Medical University,Nishinomiya, Japan

³Department of Neurosurgery, Gifu University, Gifu, Japan

⁴Department of Neurosurgery, Fukushima Medical University,Fukushima, Japan

⁵Department of Neurosurgery, Fujioka General Hospital, Fujioka,Japan

⁶Department of Radiology, University of Washington, Seattle,USA

⁷Department of Surgery, University of Washington, Seattle USA

Background: Carotid artery stenting (CAS) has recently emergedas a potential alternative to carotid endarterectomy. One of thedisadvantages of CAS is the high incidence of distal embolism. It has beenreported that there is an association between unstable components such aslipid rich necrotic core (LRNC) and intraplaque hemorrhage (IPH) and anincreased number of emboli after CAS. However, most of these studies hadlimitations such as a retrospective design, single center, and lack ofquantitative measurement of plaque component or plaque burden and thedefinition of high-risk plaque for CAS is unclear. Magnetic ResonanceImaging (MRI) is noninvasive and has excellent soft tissue contrast whichallows for evaluation of the compositional and morphologic features ofcarotid plaque. Numerous studies have validated multicontrast MRI assessmentof IPH, LRNC, and plaque burden against histology in advancedatherosclerotic lesions and shown it to have high sensitivity andspecificity and be capable of volumetric analysis. MR-CAS study was nonrandomized prospective multicenter observational study to compare the plaquecharacteristics evaluated by MRI and ischemic complications after CAS.

Materials and Methods: We enrolled 128 arteries which underwentCAS. Quantitative analysis of carotid plaque was evaluated by multicontrastMRI. Diffusion weighted (DW) MRI of pre- and post- CAS were performed todetect new ischemic lesion of the brain after the procedure. New ischemicsymptoms within 30 days after CAS were also assessed. Comparison betweenquantitative plaque characteristics and ipsilateral new ischemic lesions ofDW-MRI of the brain and new ipsilateral ischemic symptom was evaluated.

Results: Fifty one arteries (40%) had new DW-MRI positivelesions in the ipsilateral carotid territory. Five patients (3.9%) showednew ischemic symptom within 30 days after CAS. There were no significantdifferences in IPH volume and LRNC volume between DW-MRI positive group andnegative group (IPH: 44 mm³ [95%CI: 0–1140] vs. 18 mm³[0–804] p = 0.43, LRNC: 233 mm³ [0–1606] vs. 311 mm³[0–1374] p = 0.75). However, IPH and LRNC volume were significantly largerin the patients with new ischemic symptoms after CAS than the patientswithout ischemic symptoms (IPH: 323 mm³ [95%CI: 18–478] vs. 22mm³ [0–1140] p = 0.009, LRNC: 501 mm³ [392–1185]vs. 261 mm³ [0–1606] p = 0.013).

Conclusions: Quantitative tissue characterization of carotidplaques using MRI was useful to predict ischemic symptoms after CAS. Thesedata suggest that identification of carotid plaque components such as IPHand LRNC by MRI before CAS may improve the clinical outcome of thisprocedure.

O2-13-4

Hemodynamic changes in the internal carotid artery, external carotidartery, and ophthalmic artery before and after carotid arterystenting

Morito Hayashi, Satoshi Fujita, SatoshiIwabuchi, Yu Hiramoto, Norihiko Saito, Nozomi Hirai, Sho Sato, NaokiKushida, Haruo Nakayama, Keisuke Ito

Neurosurgery, Toho University Ohashi Medical Center

Purpose: The ophthalmic artery is one of the main branches ofthe internal carotid artery, but it also has multiple anastomoses with theexternal carotid artery. Therefore, in cases of severe stenosis or occlusionof the internal carotid artery, the ophthalmic artery may supply blood flowfrom the external carotid artery. It has been reported that ocular ischemiasyndrome often occurs when the ophthalmic artery is supplied blood by theexternal carotid artery. In this study, we quantitatively analyzed thehemodynamic changes using the time-density curves of digital subtractionangiography in the internal carotid artery, external carotid artery, andophthalmic artery before and after carotid artery stenting (CAS). Inaddition, the direction of ophthalmic arterial blood flow before CAS andthat after CAS were evaluated to determine the effect of CAS on theophthalmic arteries.

Materials and Methods: A total of 38 patients with carotidartery stenosis who underwent CAS at our hospital from March 2018 to April2022 were analyzed. For the blood flow evaluation, a parametric imagingsystem (Cannon Medical System®, Tochigi, Japan) was used to measure thetime-to-peak (TTP) values from the time-density curves of the cerebralangiography images before CAS and after CAS. The regions of interest werethe petrous portion for the internal carotid artery, the origin of themaxillary artery for the external carotid artery, and the origin of thecentral retinal artery for the ophthalmic artery. ①Changes in the TTP ateach site were measured before and after CAS. ②The correlation between thedirection of the ocular arterial blood flow and the change in the TTP wasexamined.

Results: The TTP of the internal carotid artery weresignificantly shortened before CAS compared with after CAS (p < 0.01) andthat of the ophthalmic artery were also similar (p = 0.02). On the otherhand, the external carotid artery exhibited a prolonged TTP in 22 patients(55.3%), and it exhibited no significant improvement from before CAS toafter CAS. In addition, the direction of the ophthalmic arterial blood flowbefore CAS was antegrade (from the internal carotid artery to the ophthalmicartery) in 63.2% of cases and nonantegrade (from the external carotid arteryto the ophthalmic artery) in 46.8% of cases. However, after CAS, anantegrade ophthalmic arterial blood flow was confirmed in 97.4% of cases.Furthermore, although a correlation between the TTP of the internal carotidartery and the TTP of the ophthalmic artery was observed before CAS(Spearman's rank correlation coefficient[rs] = 0.560, p < 0.01), thecorrelation became stronger after CAS (rs = 0.703, p < 0.01).

Conclusion: This study demonstrated that CAS not only improvesthe internal carotid artery blood flow but also improves the ophthalmicarterial blood flow by normalizing the pathway of the blood flow from theinternal carotid artery to the ophthalmic artery.

O2-13-5

Atherosclerotic Carotid Plaque Characteristics Vary with Time FromIschemic Event: A Multicenter, Prospective Magnetic Resonance VesselWall Imaging Registry Study

Manabu Shirakawa¹, Kiyofumi Yamada², Yukiko Enomoto³, Takao Kojima⁴, Kazuki wakabayashi⁵, Thomas S Hatsukami⁶, Chun Yuan⁶, Shinichi Yoshimura¹

¹Department of Neruosurgery, Hyogo medical university

²Department of Neurosurgery, National Cerebral CardiovascularCenter, Osaka, Japan

³Department of Neurosurgery, Gifu University, Gifu, Japan

⁴Department of Neurosurgery, Fukushima Medical University,Fukushima, Japan

⁵Department of Neurosurgery, Fujioka General Hospital, Fujioka,Japan

⁶Departments of Surgery and Radiology, University of Washington,Seattle, USA

Introduction: Recent studies report that the rate of recurrentstroke is highest in the stages immediately following cerebral infarctionand decreases over time in patients with atherosclerotic carotid stenosis.The purpose of this study was to identify temporal differences in earlystage carotid plaque components from acute cerebrovascular ischemic eventsusing carotid magnetic resonance imaging (MRI).

Methods: Carotid plaque images were obtained on 3 T MRI from 128patients enrolled in the Carotid Artery Stenting study (MRCAS). Among the128 subjects, 53 were symptomatic and 75 asymptomatic. The symptomaticpatients were classified into three groups based on interval from onset ofsymptoms to the date of the carotid MRI (Group <14days; 15–30days; and>30days). The volume of each plaque component was identified andquantified from MR images. The presence of juxtaluminal loosematrix/inflammation (LM/I) was identified as a possible indicator ofinflammation on the luminal side. Plaque components were compared betweengroups using the Kruskal-Wallis or the Chi-square test

Results: Patient characteristics and carotid plaque morphologywere similar among all four groups. The median volume of LM/I in Group>30 days was significantly lower than in other groups (0 mm³vs 12.3 mm³ and 18.1 mm³; p = 0.003). In addition, theprevalence of juxtaluminal LM/I decreased over time(p_trend = 0.002). There were no statistically significantdifferences in other plaque components between the symptomatic groups.

Conclusions: The volume of LM/I was significantly smaller inGroup >30 days and prevalence of juxtaluminal LM/I in the atheroscleroticcarotid plaque was high in the early stages after events. This suggests thatcarotid plaques undergo rapid evolution after an acute cerebrovascularischemic event.

O2-13-6

1-Blood flow quantification of steno-occlusive cerebral disease andresponse to intervention (1 from 284–286)

Ali Alaraj

O2-14-1

In vitro comparison of robotic and manual mechanical thrombectomy foracute ischemic stroke

Naoki Kaneko¹, Taichiro Imahori¹, Ariel Takayanagi^1,2, Hamidreza Saber¹, Satoshi Tateshima¹

¹Department of Radiological Sciences, David Geffen School ofMedicine, University of California, Los Angeles

²Department of Neurological Surgery, Riverside University HealthSystem

Background: Robotic endovascular systems have the potential tonot only reduce radiation exposure to interventional physicians but alsoenable acute intervention for patients in remote areas. The goal of thestudy was to compare robotic and manual interventions for mechanicalthrombectomy to understand the current status and limitations of roboticsystems.

Methods: We used a human vascular simulator with moderatetortuosity intracranial artery, and an elastic ovine clot was placed in theM1 segment of the left middle cerebral artery. We assessed the preparationand procedural time for guiding catheter navigation from the descendingaorta to the carotid artery, microcatheter navigation and thrombectomyprocedures with a robotic (CorPath GRX) and manual technique. We alsoevaluated the success thrombectomy rates and radiation dose duringmechanical thrombectomy procedures. Due to the limited device compatibilityof CorPath GRX, a simple technique with a stent retriever and guidingcatheter without balloon was used in the study.

Results: Endovascular thrombectomy was successfully performed inboth robotic and manual groups. In robotic intervention, the mean total time(preparation and procedural time) was 892[95% CI: 673 - 1111] seconds, whichwas significantly longer than manual intervention than manual procedures(357[95% CI: 314 - 401] seconds, p = 0.0001). The mean radiation exposure tooperating physicians during robotic intervention was 0.02[95% CI: 0.015 -0.025] μSv, which was significantly less than manual intervention (0.215[95%CI: 0.168 - 0.263] μSv, p < 0.0001). The robotic intervention wasassociated with significantly higher radiation exposure to the vascularsimulator than the manual intervention (Air Kerma, robotic: 5.53[95% CI:4.09 - 6.99] mGy vs manual 3.21[95% CI: 2.52 - 3.91] mGy, p = 0.0041). Therewas no significant difference in the success rate (robotic: 28.6% vs manual42.9% mGy, p = 0.577).

Conclusions: The robotic intervention significantly reducedradiation exposure to operating physicians during endovascular treatments,whereas it resulted in longer time and more radiation to the simulator whencompared to manual procedures. Broad device compatibility with thecapability of a tri-coaxial system is needed to achieve effectiveneurovascular interventions.

O2-14-2

Gluing blood into a gel through electrostatic interactions: A new pathof intravascular embolisation

Zhiping Jin¹, Hailong Fan², Toshiya Osanai¹, takayuki Nonoyama³, Takayuki Kurokawa³, hideki Hyodoh⁴, Jianping Gong^2,3, Miki Fujimura¹

¹Department of Neurosurgery, Hokkaido University, Sapporo,Japan

²Institute for Chemical Reaction Design and Discovery(WPI-ICReDD), Hokkaido University, Sapporo, Japan

³Faculty of Advanced Life Science, Hokkaido University, Sapporo,Japan

⁴Department of Forensic Medicine, Faculty of Medicine, HokkaidoUniversity, Sapporo, Japan

Purpose: Development of novel liquid embolic agent with novelembolization mechanism.

Materials and Methods: By mimicking the formation of thrombus,we developed a series of water-soluble polymers, calledpoly(cation-adj-π), consisting of adjacent cationic andaromatic residues that adhere to negatively charged blood substances throughelectrostatic interactions in a physiological environment. In this series ofpolymers, poly(2-(acryloyloxy)ethyl trimethyl ammoniumchloride-adj-2-phenoxyethyl acrylate) (poly(ATAC-adj-PEA))was chosen as a representative, and its aqueous solution was used to conductthe present study. A series of experiments, including the aggregationability test, rheological test, injection force test, and adhesion test,were performed in vitro (n = 3 subjects in each group). Thebiocompatibility test (subcutaneous polymer aqueous solutions implantation),embolic ability test (femoral arterial injection of rats), andpost-operative computed tomography (CT) imaging (polymer aqueous solutionsmixed with tantalum powders) were performed in vivo usingSprague-Dawley rats (n = 3 rats in each group). Hematoxylin and Eosin(H&E) staining and Immunohistochemical staining (IHC, anti-CD3 antibody)were used for histological analyses. A two-tailed unpaired Student's t-testwith unequal standard deviations was used for statistical analysis. Thedifferences in the means of the control and test groups are indicated asfollows: ns, p > 0.05, *p < 0.05, **p < 0.01.

Results:In vitro: Poly(ATAC-adj-PEA) aqueoussolutions showed the ability to rapidly glue whole blood into a gel-likematerial. The blood gel remained stable in saline solution for more than 2months. Furthermore, this polymer aqueous solutions were injected usingclinical catheters by applying a low injection force. Lastly, no adhesionwas observed between the formed blood gel and catheters.

In vivo: Four biochemical parameters representing liver andkidney functions did not increase after polymer aqueous solutionsimplantation. Both H&E and IHC staining of the skin and subcutaneoustissue near the incision did not show significant inflammatory responses.The femoral arterial injection test showed that this polymer aqueoussolutions successfully embolized the artery. Finally, the CT results showedthat post-injection of poly(ATAC-adj-PEA) aqueous solutionscan be confirmed by mixing with tantalum powders. The CT results alsoindicated that the degree of embolisation was related to the amount ofpolymer in the aqueous solutions and the injection speed.

Conclusion: We demonstrated a new conceptual strategy forendovascular embolisation. We found that a water-soluble polymer bearingadjacent cationic-aromatic residues can glue the negatively charged bloodsubstances into a gel-like material through electrostatic interactions in aphysiological environment. The easy delivery, coupled with biocompatibility,made poly(cation-adj-π) aqueous solutions promising liquidembolic agent.

O2-14-3

Remote surgery using a cerebral endovascular treatment support robotequipped with a sensing function -Experimental verification

Shigeru Miyachi, Reo Kawaguchi, TomotakaOhshima, Naoki Matsuo

Neurosurgery, Aichi Medical University

Purpose: Expectations for remote surgery in endovasculartreatment are increasing to reduce radiation exposure to surgeons and avoiddirect contact with corona patients. We conducted the world's first wirelessremote catheter surgery experiment using the endovascular treatment supportrobot that we have developed. Based on the results, we examined issues andcountermeasures for practical use.

Method: The slave robot on the surgeon side is an originalmachine that enables sensing feedback by combining the insertion forcemeasuring device developed from the beginning, and the master side wasoperated with a joystick. We described the pressure stress on the bloodvessel detected by the insertion force measuring device by a scale set sothat the higher the pressure, the higher the sound. The slave robot was putat the foot of the blood vessel model on the procedure table in theangiography room, and the master side was set in a separate room 50m or moreaway. They were connected by HTTP communication using a LAN line. Thesurgeon operated with looking at the PC monitor that shared the screen withthe monitor in the angiography room, and in the angiography room, the slaverobot catheterized and inserted the coil for the aneurysm in the siliconblood vessel model.

Result: Compared to the conventional wired experiment, there wasalmost no delay. It responded to the surgeon's operation promptly and to thejoystick's swift movements pretty accurately. In terms of stress on bloodvessels, the surgeon could control it, like stopping the operation andreinserting the device, since the surgeon could listen to the sound from theinsertion force measuring device in real-time that the microphone in theangiography room picked up. However, there was a time gradient to reach astable advanced speed at the time of initial movement, and there was aslight time lag from braking to complete stop when the surgeon stoppedadvancing.

Conclusion: In the world's first remote experiment using anendovascular treatment robot equipped with our sensing function, it seemedthat the level was sufficiently feasible to perform the surgery safely. Inthe future, it seems to be clinically applicable if we make further effortsfor long-distance experiments, safety, accuracy, sterilization, etc. Thissystem seems extremely promising for preventing radiation exposure to themedical staff and COVID infection and protecting safety. It will also enablemedical professionals to operate in remote areas and create a ubiquitousmedical environment.

O2-14-4

Impact of a multisource video recording system in the skill trainingof neuroendovascular treatment

Satoshi Koizumi¹, Masaaki Shojima^1,2, Osamu Ishikawa^1,3, Motoyuki Umekawa¹, Satoshi Kiyofuji¹, Nobuhito Saito¹

¹Department of Neurosurgery, University of Tokyo, Tokyo, Japan

²Department of Neurosurgery, Teikyo University, Tokyo, Japan

³Department of Neurosurgery, Asama General Hospital, Nagano,Japan

Purpose: The coronavirus disease 2019 pandemic has made directcommunication between surgeons difficult, thus warranting new methods forsurgical skill education. To overcome these difficulties in the field ofneuroendovascular treatment, we invented a novel video recording systemdesigned for skill training.

Materials and Methods: In 2014, we introduced a new videorecording system in our hybrid operating room. The X-ray fluoroscopy imagesand ceiling-mounted camcorder videos were laid out onto a single largescreen and recorded synchronously. The ceiling-mounted camcorder was movedand positioned as appropriate throughout the procedures to record theoperator's hand motion. In addition, wearable video cameras were mounted onthe operator's eyeglasses. These recorded videos were integrated and editedinto short videos of 3 to 5 min to summarize the procedure.

Results: Using this system, 24 neuroendovascular procedures wererecorded between April 2021 and January 2022. The recording from theceiling-mounted camcorder was useful in simultaneously reviewing theoperator's hand motions and the movement of devices on the fluoroscopyimages. The wearable camcorder helped in reviewing the shaping ofmicrocatheters and microguidewires. The integrated video was usefulespecially in reviewing dynamic procedures such as flow-diverter placementand liquid embolizing material injection. Some of those videos will be shownin the presentation.

Conclusion: Our multisource recording system was beneficial inneuroendovascular skill training.

O2-14-5

Bone removal of Cone Beam CT using machine learning

Shuntaro Shimizu¹, Kazuyuki Yamamoto¹, Naofumi Aida¹, Kittipong Srivatanakul²

¹Department of Radiation Technology, University of TokaiHospital

²Department of Neuro Surgery, University of Tokai Hospital

Purpose: CBCT (3D-DSA) is an indispensable technique formeasuring aneurysm and stenosis rate in cerebral aneurysm and carotid arterystenting. 3D-DSA requires mask image and live image, and the imaging time islong, so sometimes body movement occurs during imaging. While 2D-DSA hasfunctions such as pixel shift to reduce misregistration, 3D-DSA has nofunction to reduce misregistration artifacts. In this study, we attempted toreduce misregistration artifacts by using machine learning to extract onlythe contrast agent component from the live image.

Materials and Method: The contrast component was segmented usingU-net, which is one of the Fully Convolution Network (FCN). Reconstructedimages of live and subtraction images of 3D-DSA were used withoutmisregistration artifacts due to body movements such as swallowing. U-nettraining was carried out using live image (with bone) as input image andsubtraction image (boneless) as correct answer image. We trained using 2000pairs of images (2000slices + 2000slices) using input images (2000 slices)and correct answer images (2000 slices) as pairs. In addition, peak Signalto Noise Ratio (PSNR) was used for the evaluation function of training, and1000 epoch learning was made using adam for the loss function, and the modelof U-net was constructed using the coefficient with the highest evaluationfunction. The image was evaluated using Structual Similarity (SSIM) of thepredicted image obtained from the correct answer image and machinelearning.

Results: The PSNR used as the evaluation function of the U-netmodel also showed a high numerical value. In addition, the SSIM of thepredicted image and the correct answer image also showed a highevaluation.

Conclusion: Although there were some areas where bone removalfailed, it was suggested that bone removal images could be created by usingonly live 3D-DSA images. With the establishment of this technology, normal3D Xray exposure is halved compared to DSA. Also, since there is no need toshoot a mask image and a live image, there is no misalignment artifact dueto the misalignment between the mask image and the live image. Also, thenoise is 1 / √2 because there is no need to subtract the mask image and thelive image.

O2-14-6

Reducing Misregistration Artifacts Using Machine Learning

Naofumi Aida¹, Shuntaro Shimizu¹, Kittipong Srivatanakul²

¹Department of Radiological Technology, Tokai University Hospital,Kanagawa, Japan

²Department of Neurosurgery, Tokai University Hospital, kanagawa,Japan

Purpose: In thrombectomy for stroke patients, higher braindysfunction may make it difficult to maintain body movement duringtreatment. If it becomes difficult to obtain good quality images due to bodymovements, it will hinder the treatment. In this study, we investigated thereduction of misregistration artifacts in DSA imaging using machinelearning.

Methods: Using pixel shift, images of the misregistrationartifact and the correct images for those images were prepared. The timephase of the images was the phase in which the internal carotid artery wasdepicted. These images were trained on a CNN with improved WIN5-RB. We alsofocused on structural similarity. The comparison targets are the correctimages and the images of misregistration artifacts, and the correct imagesand the training images.

Results: The effectiveness of the reduction depended on thedegree of misregistration artifacts. When artifacts were large, reductionwas difficult; when artifacts were small, reduction was possible. When theartifact was large, it was recognized as a contrast agent because the signalvalue was close to that of the contrast agent, and the artifact could not bereduced. In addition, SSIM of values were lower the correct andmisregistration artifact images than the correct and training images.

Conclusion: Although the effectiveness of the reduction dependedon the degree of misregistration artifact, we were able to reducemisregistration artifact using machine learning in DSA imaging.

O2-15-1

Ruptured Intracranial Mycotic Aneurysm after Coronary AVF closuretreated with Transarterial embolization: Uncommon cause ofStroke.

Tiplada Boonchai¹, Nongluk Jakkrit², Methinee Damaied²

¹Department of Medicine, Trang hospital

²Nuring department, Trang hospital

Purpose: To demonstrate a case of ruptured mycotic aneyrsm inpatient with infective endocarditis after cardiac intervention.

Materials and methods: Cerebrovascular complications ininfective endocarditis are common and carry a high-morbidity and mortalityrate, especially ruptured intracranial cerebral aneurysm. Endovasculartreatment play important role for ruptured mycotic aneurysm before heartsurgery for endocarditis.

Result: We reported a 29-year-old man with history of coronaryfistula, proximal type LMCA fistula to right atrium with normal LCx andsmall LAD, RCA dominant status 2 devices closure. He developed high gradefever with gram positive septicemia one day after cardiac intervention andceftriaxone 2 gm was given intravenously for 2 weeks. Two months later, hevisited the emergency room with sudden onset left-sided headache and normalon neurological examination. CT brain showed subarachnoid hemorrhage at leftbasal cistern and left sylvian fissure. Cerebral angiogram showed fusiformaneurysm at parieto-occipital branch of left PCA branch which was measuredabout 3.13 mm in height, 3.26 mm width, and 3.36mm*3.13 mm in dimensions,suggestive of septic aneurysm. Then simple coil embolization was performedsuccessfully, however there was intraoperative ruptured due to microcatheterperforation. Post-operative CT scan of brain showed hematoma at leftparieto-occipital lobe and patient clinical was stable. Three weeks later,patient again developed right-sided headache and left homonymous hemianopia.CT brain revealed hypodense lesion at right parieto-temporal lobe withhyperdense in right MCA. His echo cardiogram showed perforated AML withparavalvular abscess, severe aortic valve regurgitation, and moderate mitralvalve regurgitation. He underwent cardiac surgery for aortic and mitralvalve replacement in 4 months after onset of stroke and rusumed normalfunction.

Conclusion: Endovascular treatment for ruptured intracranialmycotic aneurysm was safe and effective.

O2-15-2

Effectiveness of preoperative endovascular embolization of occludedvertebral artery to prevent thromboembolic stroke after repair surgeryfor traumatic cervical fracture

Masahiro Indo¹, Soichi Oya¹, Koichi Inokuchi², Masaaki Shojima³

¹Department of Neurosurgery, Saitama Medical Center, SaitamaMedical University, Saitama, Japan

²Department of Emergency and Critical Care Medicine, SaitamaMedical Center, Saitama Medical University, Saitama, Japan

³Department of Neurosurgery, Teikyo University Hospital, Tokyo,Japan

Purpose: Extracranial vertebral artery (VA) occlusion associatedwith traumatic cervical vertebral fracture or dislocation may causethromboembolic infarction due to the recanalization of vertebral arteryafter repairing of fracture. We previously reviewed our retrospective dataand reported the usefulness of endovascular VA coil embolization beforerepairing operation. The aim of this study is to validate the effectivenessof this strategy based on the analysis of cases after our initialreport.

Materials and Methods: Between March 2019 and April 2022, weevaluated the treatment outcomes of additional new 11 patients of traumaticcervical vertebral fracture with VA occlusion who had required cervicalsurgery in the acute stage. As in the previous study, we focused on theincidence of thromboembolic infarction after repairing operation andevaluated the significance of extracranial VA embolization before repairing.Based on the result of our initial report, we conducted endovascular VAembolization in all cases before repairing operation for cervical vertebralfracture or dislocation to prevent postoperative thromboembolic infarction.No patient in this series received antiplatelet or anticoagulanttherapy.

Results: No patient had thromboembolic stroke after repairingoperation in this study. Although asymptomatic small infarction related toendovascular procedure was found in two cases (18%), no neurologicaldeterioration after repairing operation occurred.

Conclusion: We believe that the risk of thromboembolicinfarction due to the distal migration of thrombus in the occluded VA isunderevaluated when repair surgery for fracture or dislocation is planned.According to our previous report, the rate of symptomatic thromboemboliccerebral infarction after repairing operation without VA embolization was upto 25%. Our additional data have indicated that preoperative embolization ofthe occluded VA significantly reduces the risk of postoperativethromboemnolic infarction.

O2-15-3

Preoperative tumor embolization prolongs time to recurrence ofmeningiomas: a retrospective propensity-matched analysis

Taisuke Akimoto¹, Makoto Ohtake¹, Shigeta Miyake², Ryosuke Suzuki², Yu Iida², Wataru Shimohigoshi¹, Nobuyuki Shimizu², Takashi Kawasaki¹, Katumi Sakata¹, Tetsuya Yamamoto²

¹Department of Neurosurgery, Yokohama City University MedicalCenter

²Department of Neurosurgery, Yokohama City University GraduateSchool of Medicine

Objective: Preoperative embolization of meningiomas is oftenperformed to reduce intraoperative blood loss and facilitate tumorresection. However, negative effects of this procedure have also beenreported, and preoperative embolization is controversial. The subsequenteffects of preoperative embolization on tumors have not been studied indetail. The purpose of this study was to evaluate preoperative embolizationfor meningiomas and its effect on postoperative outcome and recurrence.

Methods: We retrospectively reviewed the medical records of 186patients with meningiomas who underwent surgical treatment at our hospitalbetween January 2010 and December 2020. Propensity score matching was usedto generate cohorts of 42 patients each with WHO grade I meningiomas in theembolization and no embolization groups to examine the effect ofembolization. The controlled variables were age, gender, symptoms, tumorlocation (skull base and infratentorial), tumor diameter, MRI T2 highintensity, calcification, peritumoral edema, cyst formation, and MIB-1index.

Results: Preoperative embolization was performed in 71 patients(38.2%). Patients with MRI T2 high-intensity meningioma, cyst formation, orsymptomatic meningioma were more likely to have undergone preoperativeembolization. In the propensity-matched analysis with 42 pairs, theembolization group showed favorable recurrence-free survival (RFS) (mean,49.4 vs. 24.1 months; Wilcoxon p = 0.049). The embolization group showedsignificantly less intraoperative blood loss (178 ± 203 ml vs. 220 ± 165 ml;p = 0.0093) and shorter operation time (5.6 ± 2.0 h vs. 6.8 ± 2.8 h;p = 0.036). There were no significant differences in Simpson grade IVresection (33.3% vs. 28.6%; p = 0.637), overall perioperative complications(14.3% vs. 11.9%; p = 0.241), or favorable modified Rankin Scale (mRS) score(0–2) at last follow-up (97.6% vs. 90.5%; p = 0.167). In addition, tumorembolization prolonged RFS in a sub analysis of cases that experiencedrecurrence (n = 39) among the overall cases before variable control (meanRFS, 33.2 vs. 16.0 months, log-rank p = 0.0030).

Conclusions: After controlling for several variables,preoperative embolization for meningioma did not improve the Simpson gradeor patient outcomes; however, prolonged RFS without increasingcomplications.

O2-15-4

Preoperative embolization for giant pituitary adenoma

Takeshi Fujimori^1,2, Shunsuke Omodaka^1,4, Tomohiro Kawaguchi³, Hidenori Endo³, Yasushi Matsumoto¹, Teiji Tominaga⁴

¹Department of Neuroendovascular Therapy, Kohnan Hospital,Sendai

²Department of Neurological Surgery, Kagawa University Faculty ofMedicine

³Department of Neurosurgery, Kohnan Hospital, Sendai

⁴Department of Neurosurgery, Tohoku University Graduate School ofMedicine, Sendai

Objective: Giant pituitary adenoma (GPA) is one of the mostdifficult cerebral tumors to treat, even with the improved surgicalequipment and techniques. In our hospital, we have evaluated angiography ofGPA and actively performed preoperative embolization when possible. Weassessed effectiveness of preoperative embolization for GPA.

Methods: GPA was defined as a pituitary adenoma larger than4 cm. We included patients with GPA underwent surgical resections betweenJanuary 2011 and December 2021. We classified GPA patients into threegroups: evolving patients with GPA performed successfully preoperativeembolization before surgical resection (PE-success), those whoseembolization were only trial (PE-trial), and those who were not embolized(non-PE).

Results: we included 41 GPA patients. Preoperative embolizationwas tried in 21 patients and embolization could be performed in 13 patients.Main targeted vessels were meningohypophyseal trunk (69%) and inferolateraltrunk (31%). Defrictor Nano catheter was used more in PE-success than inPE-trial (85% vs. 13%, P < 0.01). Max diameter of tumors of PE-successpatients are larger than PE-trial patients (5.7 ± 1.6 cm vs. 4.6 ± 0.8,P = 0.03). Symptomatic apoplexy tends to be occurred in less patients ofPE-success than non-PE[0 (0%) vs. 5 (23%), P = 0.08].

Conclusion: Preoperative embolization of GPA has the potentialto prevent postoperative pituitary apoplexy. If appropriate cases anddevices are selected, safe and effective preoperative embolization may bepossible.

O2-15-5

Treatment outcome of trans-arterial embolization for intracranialtumor: A comparison with JR-NET 3

Kazuhiko Nishi, Kenji Sugiu, TomohitoHishikawa, Masafumi Hiramatsu, Jun Haruma, Yoko Yamaoka, Yu Sato, YukiEbisudani, Hisanori Edaki, Ryu Kimura, Masato Kawakami, Isao Date

Department of Neurological Surgery, Okayama University Graduate School,Okayama, Japan

OBJECTIVE: Trans-arterial embolization of intracranial tumors iswidely performed as an adjunctive treatment to craniotomy. We comparedbetween Japanese Registry of NeuroEndovascular Therapy 2 and 3(JR-NET2&3) and reported that embolization for feeders other than theexternal carotid artery (ECA) and the use of liquid materials could increasethe complication rate.

METHODS: 108 consecutive patients who underwent preoperativeembolization for intracranial tumors between January 2015 and April 2022 atour institute were included. Based on JR-NET analysis, age, gender, type oftumors, target vessels, embolic materials, and complications resulting fromembolization were investigated.

RESULTS: The patients (69 females and 39 males) had a median agerange of 63 years, with a range of 13–83 years. The tumors included 96(88.9%) meningiomas, 6 (5.6%) hemangioblastomas, and 6 (5.6%) others.Embolization for feeders from the ECA was performed in 96 patients (88.9%)and embolization for feeders other than the ECA in 14 patients (13.0%). Theembolic materials used were particle materials in 84 cases (77.8%), pushablecoils in 52 cases (48.1%), detachable coils in 29 cases (26.9%), and liquidmaterials in 9 cases (8.3%). Asymptomatic procedure related complicationsoccurred in 6 (5.6%) cases. These were all iatrogenic arteriovenous fistulaof the middle meningeal artery. Transient symptomatic complications occurredin 2 (1.9%) cases: including one abducens nerve palsy due to occlusion ofvasa nervorum and one oculomotor nerve palsy due to post-embolization edemaaround the tumor. Permanent complications occurred in one case (0.9%), whichwas hearing loss after embolization of the anterior inferior cerebellarartery for cerebellar hemangioblastoma.

CONCLUSION: There were nine procedure related complications inthe preoperative embolization of intracranial tumors in our department afterJR-NET3 period, including only one permanent complication. Safe andeffective embolization is required, considering the risk factors such asembolization for feeders other than the ECA and the use of liquid materials,which have been reported in previous studies.

O2-15-6

Current status and problems of tumor feeding arterial embolizationbranching from arteries running in the brain

Motoharu Hayakawa¹, Kazuhide Adachi¹, Shigeo Ohba¹, Akiko Hasebe², Sadayoshi Watanabe², Kenichiro Suyama², Akiyo Sadato³, Mitsuhiro Hasegawa¹, Ichiro Nakahara², Yuichi Hirose¹

¹Department of neurosurgery, Fujita health University

²Department of Comprehensive Strokology

³Department of Neurosurgery, Okazaki Medical Center, Fujita HealthUniversity

Purpose: Embolization via the external carotid artery is a safeprocedure during intracranial tumor resection. In this study, we evaluatedonly embolization performed on the tumor-feeding artery and the peripheralophthalmic artery branching from the brain parenchymal arteries.

Materials and Methods: Between January 2010 and April 2022, 125embolization procedures for intracranial tumors were performed. Of these, 96procedures performed via the carotid artery were excluded, and 29 (27 cases)were included. Embolization was performed on the meningohypophyseal trunk(MHT) (n = 15), inferior lateral trunk (ILT) (n = 7), ophthalmic artery(n = 2), anterior cerebral artery (n = 3), posterior cerebral artery(n = 2), meningeal branches of the vertebral artery (n = 1), posteriorinferior cerebellar artery (n = 1), and superior cerebellar artery (n = 2).Tumor resection was performed in 24 patients with meningioma, 2 withhemangioblastoma, and 1 with hemangiopericytoma. Coil embolization orparticle embolization using distal balloon protection (DBP) was performed onthe ILT and MHT. For other arteries, superselective embolization of arteriesrunning only from the cerebral artery to the tumor was performed usingn-butyl-2-cyanoacrylate.

Results: Transient left hemiplegia and decreased visual acuityin the left eye each occurred once. Furthermore, cerebellar infarctionoccurred in one patient who simultaneously underwent embolization via theexternal carotid artery. The proportion of patients who experiencedcomplications following embolization was 6.8%; however, none of the 15patients who underwent embolization during the latter part of the studyperiod experienced complications.

Discussion: Preoperative arterial embolization reduces thetechnical difficulty of surgical resection in cases in whom intraoperativehemostatic control is difficult. Embolization of the main tumor-feedingartery is associated with successful management of intraoperative bloodloss, even in patients without sufficiently decreased tumor stain. Attentionmust be paid to the collateral circulation when performing ILT embolization.In our cohort, one patient experienced decreased visual acuity in the lefteye, presumably due to disrupton of the communication from the ILT to theophthalmic artery. Cerebral infarction may occur after embolization of anartery running only from the cerebral artery to the tumor; thus, attentionshould be paid to the backward blood flow. The incidence of complicationsdecreased in the latter part of the study period, possibly because the ILTand MHT were selected in all patients when performing embolization usingDBP, resulting in a reduction in Embosphere.

Conclusion: Embolization of brain parenchymal arteries iseffective in patients in whom hemostatic control is difficult during tumorresection. Therefore, surgeons should carefully evaluate the indications forthis risky procedure.

O2-16-1

Arteriovenous Fistulas at the Craniocervical Junction Region:ASingle-Center Study of 163 cases

Yongjie Ma^1,2, Hongqi Zhang^1,2, Zihaò Song^1,2

¹Xuanwu Hospital,Capital Medical University

²China International Neuroscience Institute

Background: Arteriovenous fistulas (AVFs) at the craniocervicaljunction (CCJ) region are rare. There are few reports on such diseases.There is still uncertainty about the diagnosis and treatment of CCJ AVFs.This study retrospectively reviewed 163 consecutive cases with CCJ AVFs fromour neurosurgical center, which can enrich the experience of diagnosis andtreatment of such arteriovenous fistulas.

Objective: To further explain the clinical manifestations,angiographic characteristics, and treatment strategies of CCJ AVFs. Sharethe treatment experience of our neurosurgical center.

Methods: A total of 163 patients with CCJ AVFs treated at ourinstitution between January 2002 and December 2020 were enrolled. Afteranalyzing their imaging data patients, 173 CCJ AVFs were included. Clinicalpresentation, angiographic characteristics, intraoperative findings, andtreatment outcomes were analyzed.

Results: The median age was 56 years old (interquartile range47–62 years). 153 patients had 1 fistula and 10 patients had 2 fistulas.Subarachnoid hemorrhage (SAH) occurred in 87 cases (53.4%) and were the mainclinical manifestation. Venous hypertensive myelopathy (VHM), includingsensory and motor dysfunction, occurred in 71 case (43.6%). 122 patients(74.8%) were treated with surgery only, 23 (14.1%) with embolization andsurgery, and 13 (8.0%) with interventional embolization only. A total of 117patients have been followed up to now. The median follow-up time was 58months. 102 patients had favorable outcomes (mRS 0–2).

Conclusion: SAH was the most common presentation of CCJ AVFs.Surgery is the common treatment for CCJ AVF. Different treatment modalitiesshould be selected based on different angioarchitecture.

O2-16-2

Angioarchitecture of the normal lateral spinal artery andcraniocervical junction arteriovenous fistula using contrast-enhancedcone-beam CT

Masafumi Hiramatsu, Kenji Sugiu, TakaoYasuhara, Tomohito Hishikawa, Jun Haruma, Kazuhiko Nishi, Yoko Yamaoka,Yu Sato, Yuki Ebisudani, Isao Date

Department of Neurological Surgery, Okayama University Graduate School ofMedicine

Background and Purpose: The lateral spinal artery (LSA) perfusesthe dorsolateral part of the spinal cord at the craniocervical junction(CCJ). We analyzed the angioarchitecture of the normal LSA and CCJAVF.

Methods: The first study included 26 patients with a cerebralaneurysm of the posterior circulation. Using slab MIP images fromthree-dimensional-rotational angiography (3D-RA) and contrast-enhancedcone-beam CT (CE-CBCT), we analyzed the origin of the LSA, its anastomosiswith the PICA, the point where it reaches the spinal cord, and thevisualized range. In the second study, we analyzed the angioarchitecture andtreatment results of seven CCJAVF lesions treated in our department between2016 and 2021.

Results: We visualized the normal LSA using slab MIP images forall patients. In 23 patients with a normal-origin PICA, all LSAs originatedfrom the C1 or C2 radicular artery, and eight patients had an anastomosiswith the PICA. In three patients with a C1 level origin PICA, all LSAsoriginated from the PICA. All LSAs reached the dorsolateral part of thespinal cord. The mean visualized range of the LSA was 27.4 mm. The LSA wasinvolved in five of seven CCJAVF lesions (71%). There was one lesion with ainfarction of the lateral funiculus after LSA embolization. Other lesionswere treated by direct interruption of the AVF, and the ASA and LSA werepreserved.

Conclusions: We visualized the LSA using slab MIP images from3D-RA and CE-CBCT. Most CCJAVF lesions involved the LSA, and the treatmentstrategy preserving the LSA is needed.

O2-16-3

Challenges of Endovascular Treatment of Anterior Cranial Fossa DuralArteriovenous Fistula

Satoshi Iihoshi, Hiroki Sato, Shinya Kohyama,Hiroki Kurita

Department of Neurosurgery, Saitama Medical University International MedicalCenter

OBJECTIVES: Among intracranial dural arteriovenous fistulas(C-DAVF), anterior cranial fossa lesions are extremely rare (4.3%) and areconsidered to be difficult to treat with endovascular therapy, and surgicalcraniotomy is often the first choice. However, there are many cases that canbe cured by endovascular treatment by fully understanding the vasculararchitecture and developing a treatment strategy. In this study, weretrospectively reviewed 11 cases (12 procedures) of C-DAVF in the anteriorcranial fossa that had been treated endovascularly in the past, anddiscussed the key points and strategies of treatment.

Presentaion case: A 63-year-old male patient underwent cerebralangiography for close examination of an unruptured cerebral aneurysmdiscovered by headache. Cerebral angiography incidentally revealed a duralarteriovenous fistula with a shunt in the cribriform plate of anterior skullbase. Although asymptomatic, the patient was judged to be amenable totreatment for Borden type 3 and Cognard type 4, and endovascular treatmentwas performed under well-informed consent. A microcatheter was inserted intothe anterior falcine artery of the middle meningeal artery just before theshunt, and Onyx 18 was injected. Onyx 18 was injected into the anteriorfalcine artery of the middle meningeal artery, and the shunt was completeobliteration. The patient was discharged from the hospital withoutpostoperative complications.

Conclusion: Transarterial embolization is the mainstay ofendovascular treatment for anterior cranial fossa C-DAVF, but there arescattered case reports of transvenous embolization. If a reliable branchclearance and adequate penetration of liquid embolizing material can beachieved, there is a high possibility of radical cure. However, thedifficulty of access to the ophthalmic artery and the backflow of liquidembolizing material into the central retinal artery make this a challengingprocedure, so the indications and strategies must be carefullyconsidered.

O2-16-4

Treatment outcome of anterior cranial fossa dural arteriovenousfistula: Endovascular therapy as first-line treatment.

Takeshi ASANO^1,2, Kanako Kawanami², Shunsuke Kubota², Hideyuki Tomita², Ken Kado², Shigeo Mitsuhashi², Iwao Yamagami², Yusuke Kageyama², Juro Sakurai³

¹Neuroendovascular therapy, Chiba Medical Centre

²Neurosurgery, Chiba Medical Centre

³Neurosurgery, Asahikawa Red Cross Hospital

Purpose: To retrospectively review the outcome of anteriorcranial fossa (ACF) dural arteriovenous fistula (DAVF) treated byendovascular embolization as the first-line approach.

Material and methods: Six consecutive patients with ACF DAVFstreated with endovascular technique as a first line approach were included.Their clinical presentation, angioarchitecture, strategy, complications,immediate angiographic, and follow-up results were included in theanalysis.

Results: Age ranged from 46 to 80 (mean 65.8years, all male) andall lesions were identified incidentally. 5 patients underwent transarterialembolization with NBCA and 1 patient was treated with transvenous coilembolization. The overall immediate angiographic cure rate afterendovascular treatment was 83.3% (5/6 patients). There was no permanentneurological complication found after the procedures (only temporal headacheor nose pain occurred in 3 cases). 6 months angiographic follow-up wasavailable in 5 out of the 6 patients. In these 5 patients, the DAVF wascompletely cured in 5 (100%). At 6months follow-up, all patients had amodified Rankin scale (mRS) 0.

Conclusion: Our experience suggests that endovascular treatmentfor ACF DAVFs has an safety profile with high rates of complete occlusion,both with transarterial and transvenous approach.

O2-16-5

Anatomy and endovascular treatment of foramen magnum duralarteriovenous fistula-Report of 2 cases

Rie Aoki, Chiaki Shinohara, Azusa Sunaga,Takahiro Osada, Masaaki Imai, Kaori Hoshikawa, Shinri Oda, MasamiShimoda

Neurosurgery, Tokai university Hachioji hospital

Purpose Foramen magnum dural arteriovenous fistula (FM-DAVF)is extremelyrare. Only a little number of series have been reported. FM-DAVF isaggressive lesion which may results in venous hypertension and subarachnoidhemorrhage and requires risk assessment and appropriate treatment. In thepresent study, we report our experiencesregarding angioarchitecture andtreatment of 2 cases ofFM-DAVF with some literature reviews. Materials andMethods From 2018–2022, 2 cases were diagnosed with FM-DAVF and treated byTransarterial embolization (TAE) in our institution. We reviewed clinicalfeatures, anatomic details and treatment outcomes. Results Patient 1 is67-year-old man who is detected incidentally. The shunt was supplied byposterior meningeal artery (PMA), ascending pharyngeal artery (APA), andoccipital artery (OA), and drained to anterior spinal vein (ASV), petrosalvein and superior petrosal sinus. After the jugular branch of OA wasembolized using n-butyl-2-cyanoacrylate (NBCA), the shunt was obliteratedcompletely. Patient 2 is 48-year-old man who suffered from motor and sensorydisturbance of left upper extremity due to myelopathy. The shunt wassupplied by PMA, APA, OA and middle meningeal artery, and drained to ASV,posterior spinal vein, anterior middle pontine vein and basal vein ofRothenthal. After two sessions of embolization of PMA and neuromeningealbranch of APAusing NBCA, he recovered with near-complete occlusion.Noprocedure-related complication occurred in both cases. ConclusionEndovascular treatment of FM-DAVF remains a challenge given their tortuousand complex vascular feeders and the potential for treatment-relatedischemic or hemorrhagic complications. Nevertheless, accurate analysis ofthe angioarchitecture can lead to safety and efficacy TAE forFM-DAVF.

O2-17-1

Flow diverter treatment of intracranial aneurysms-An institutionalexperience from tertiary care center of India

Shailesh Baburao Gaikwad^1,2,3,4, Puneeth KT^1,23,4

¹Neuroimaging and Interventional Neuroradiology, All IndiaInstitute of Medical Sciences

²Ansari Nagar, Aurobindo Marg

³New Delhi-110029

⁴India

Purpose: Flow diverters are increasingly being used for thetreatment of intracranial aneurysms. We report long-term clinical andangiographic outcomes of the treatment of complex intracranial aneurysmswith flow diverter (FD) stents.

Materials and Methods: Patients treated with FD stents fromNovember 2013 through November 2019, were retrospectively analyzed. Theclinical details, technical success, complications, long-term angiographic,and clinical outcomes were recorded.

Results: A total of 46patients with 53 aneurysms were treated.Aneurysm size ranged from 1.7 mm to 43mm. A total of 49 FDs (PED-36,SURPASS-9, FRED-4) were used and all procedures were successful. The ratesof transient, permanent morbidity, and mortality were 9.7%, 2.4%, and 4.8%respectively. None of the mortality was directly device-related. Minorcomplications were seen in 5% of patients without clinical sequelae. Meanclinical (43/46) and angiographic (41/46) follow-up was 40 months and 24months respectively. Long-term angiographic results showed 77% with adequate(complete and small residual neck) occlusion and 23% with small residual&incomplete occlusion. Asymptomatic in-stent stenosis was noted in 14.2%of patients. Symptomatic improvement at long-term follow-up was noted in87.5% of patients.

Conclusion: Endovascular treatment of complex intracranialaneurysms with FD is a feasible, safe, and effective therapeutic option.Posterior circulation aneurysms, especially fusiform aneurysms involving thebasilar artery are challenging to treat with FD. Safety margins are withinexpected limits and device-related complications are infrequent.

O2-17-2

Single-antiplatelet Protocol for Acute Flow Diverter treatment ofRuptured Aneurysms

Jawid Madjidyar¹, Tilman Schubert¹, Patrick Thurner¹, Emanuela Keller², Giovanna Brandi², Luca Regli³, Isabelle Barnaure¹, Daniel Toth¹, Vaia Anagnostakou^1,5, Shakir Husain¹, Roberto Fisch⁴, Zsolt Kulcsar¹

¹Neuroradiology, University Hospital of Zurich

²Intensive Care Unit, University Hospital of Zurich

³Neurosurgery, University Hospital of Zurich

⁴University of Zurich

⁵New England Center for Stroke research, University ofMassachusetts Medical School

Background and Purpose: Flow diversion treatment (FD) of acutelyruptured aneurysms remains challenging due to the need ofantiplatelet-therapy. We report our experience with acute FD stenting undersingle-antiplatelet therapy of acutely ruptured aneurysms.

Material and Methods: We performed a retrospective analysis ofall patients with acutely ruptured blister and dissecting aneurysms, whowere treated in the acute phase with a phosphoryl-bonded FDS (Pipeline FlexEmbolization Device with Shield Technology, Medtronic, USA). The medicationprotocol was based on weight adapted eptifibatid i.v. and 3000 IU heparini.v. periprocedurally. After 6–12 h, eptifibatid was switched to prasugrelp.o. (60 mg loading, 10 mg/d maintenance) alone, without secondaryantiplatelet agent.

Results: Nine patients with acute SAH due to blister-type ordissecting aneurysms were treated, eight within 24 h of symptom onset. Onepatient was treated 13 days after symptom onset, as the initial DSA wasnegative. Two aneurysms were additionally coil-embolized (dissectinganeurysms with saccular component). Seven patients were treated with one FDdevice, one patient received two FDs in the same session, and in one case, asecond FD had to be implanted because of aneurysm growth 14 days afterinitial treatment. There were no thromboembolic events related to the FD.Eight of nine patients survived, one patient suffered a rerupture 8 daysafter the intitial treatment. Six patients showed complete occlusion of theaneurysm (3 month to 2.5 years follow-up). Two patients showed subtotalocclusion of the aneurysm at the last follow-up after 3 month and 6 month,respectively. Favorable clinical outcome was achieved in five patients.

Conclusions: Single-antiplatelet therapy with eptifibatidperiinterventionally followed by prasugrel in the acute stage was sufficientto prevent thromboembolic events using a phosphoryl-bonded FD, demonstratingthat this medication regimen might be a viable option for rupturedblood-blister and dissecting aneurysms in an acute setting.

O2-17-3

First clinical multicenter experience with the new Pipeline Vantageflow diverter

Dominik F. Vollherbst¹, Saruhan H. Cekirge², Isil Saatci², Feyyaz Baltacioglu³, Baran Onal⁴, Osman Koc⁵, Riitta Rautio⁶, Matias Sinisalo⁶, Alejandro Tomasello⁷, Pedro Vega⁸, Mario Martínez-Galdámez⁹, Jeremy Lynch¹⁰, Vitor Mendes Pereira¹¹, Martin Bendszus¹, Markus A. Möhlenbruch¹

¹Department of Neuroradiology, Heidelberg University Hospital

²Interventional Neuroradiology Department, Koru Hospital, Ankara,Turkey

³Department of Radiology, Marmara University School of Medicine,Istanbul, Turkey

⁴Radiology Department, School of Medicine, Gazi University,Ankara, Turkey

⁵Radiology Department, Meram Faculty of Medicine, NecmettinErbakan University, Konya, Turkey

⁶Department of Interventional Radiology, Turku UniversityHospital, Turku, Finland

⁷Interventional Neuroradiology Section, Department of Radiology,Vall d’Hebron University Hospital, Barcelona, Spain

⁸Interventional Neuroradiology, Department of Radiology, HospitalUniversitario Central de Asturias, Oviedo, Spain

⁹Department of Interventional Neuroradiology/EndovascularNeurosurgery, Hospital Clínico Universitario de Valladolid, Valladolid,Spain

¹⁰Neuroradiology, Toronto Western Hospital, Toronto, Canada

¹¹Department of Neurosurgery, St Michael's Hospital, University ofToronto, Toronto, Canada

Purpose: Flow diversion is an innovative, increasingly usedtechnique for the treatment of intracranial ane urysms. New flow diverters(FD) are being introduced to improve the safety and efficacy of thistreatment. The aim of this study was to assess the safety, feasibility andefficacy of the new Pipeline Vantage (PV) FD.

Materials and Methods: Patients with intracranial aneurysmstreated with the PV at 10 international neurovascular centers wereretrospectively analyzed. Patient and aneurysm characteristics, proceduralparameters, complications, and the grade of occlusion were assessed.

Results: Sixty patients with 70 aneurysms (5.0% with acutehemorrhage, 90.0% located in the anterior circulation) were included.Eighty-two PVs were implanted in 61 treatment sessions. The PV could besuccessfully implanted in all treatments. Additional coiling was performedin 18.6%, and in-stent balloon angioplasty (to enhance the vessel wallapposition) in 24.6%. Periprocedural, technical complications occurred in24.6% of the treatments, were predominantly FD deployment problems, and wereall asymptomatic. The overall symptomatic complication rate was 8.2% and theneurological symptomatic complication rate was 3.3%. Only one symptomaticcomplication was device-related (perforator artery infarctions leading tostroke). After a mean follow-up of 7.1 months, the rate of complete aneurysmocclusion was 77.9%. One patient (1.7%) died due to aneurysmal subarachnoidhemorrhage which occurred prior to treatment, unrelated to theprocedure.

Conclusions: The new PV FD is safe and feasible for thetreatment of intracranial aneurysms. The short-term occlusion rates arepromising but need further assessment in prospective long-term follow-upstudies.

O2-17-4

Angiographic and Follow-up Results of Endovascular Treatment of LargeIntracranial Aneurysms Treated with Surpass Evolve Flow Diverter

Hae Woong JEONG¹, Jin Wook Baek¹, Sung Tae Kim², Young Gyun Jeong², Sung-Chul Jin³, Jung Hyun Park⁴, Seung Kug Baik⁵

¹Department of Diagnostic Radiology, Inje University Busan PaikHospital, Busan, Korea

²Department of Neurosurgery, Inje University Busan Paik Hospital,Busan, Korea

³Department of Neurosurgery, Inje University Haeundae PaikHospital, Busan, Korea

⁴Department of Neurosurgery, Kosin University Gospel Hospital,Busan, Korea

⁵Department of Diagnostic Radiology, Pusan National UniversityYangsan Hospital, Yangsan, Korea

Purpose: Surpass Evolve (SE) represents the new generation ofthe Surpass flow diverter. The purpose of this study is to reportangiographic and follow up results of endovascular treatment of largeintracranial aneurysms treated with Surpass Evolve flow diverter.

Materials and Methods: Between November 2019 and March 2022,eighteen consecutive patients (eleven women, average age 57.6 years old),with anterior or posterior circulation aneurysms treated with Surpass Evolveflow diverter in three centers. Treated aneurysm characteristics, technicalsuccess rate, immediate angiographic outcome, procedure relatedcomplications were recorded and analyzed. And we assessed clinical andimaging result during follow up period.

Results: Locations of treated aneurysms were nine in anteriorcirculation and nine in posterior circulation. Technical success (successfuldeployment with contrast stagnation within the aneurysm) was achieved in allcases. Immediate angiographic result was 3B in all cases according to OKMangiographic grading scale. There was no immediate procedure relatedcomplication. No procedure related major morbidity or mortality was foundwithin the 30 days after the procedure.

Imaging follow up was performed in thirteen cases out of eighteen cases.Complete or near complete occlusion was seen in six cases and decreased sizeof the aneurysm was seen in seven cases. And there was no bleeding duringclinical follow up period.

Conclusion: Angiographic and follow up results of endovasculartreatment of large intracranial aneurysms were favorable in our case series.Further clinical and imaging follow up should be needed.

O2-17-5

Flow diversion of the unruptured fusiform aneurysm in vertebralartery: case series

Sung-Tae Kim¹, Jin Wook Baek², Hae Woong Jeong², Young Gyun Jeong¹

¹Department of Neurosurgery, Inje University Busan PaikHospital

²Department of Diagnostic Radiology, Inje University Busan PaikHospital

Purpose: It is unclear not only natural history of fusiformaneurysm in vertebral artery (VA) but also outcome of flow diversion of it.In this study, we evaluated clinical and angiographic outcome of flowdiversion in cases of unruptured symptomatic fusiform aneurysm in VA.

Material & method: Between May 2016 and March 2022, 13unruptured fusiform aneurysm in VA of 13 patients (55.1 year-old; Male,9)underwent flow diversion. 6 patients had uncontrolled occipital headache,another 1 patient had repeated syncope, another 2 patients had brainstemcompression symptom, and the other 4 patients had aneurysm growing infollow-up image. One of them was retreatment after double stenting. Lengthof the VADAs was 14.97 mm (ranged from 7.5 mm to 30 mm), outer diameter was12.49 mm (ranged from 7 mm to 25 mm), and inner diameter was 8.98 mm (rangedfrom 5.6 mm to 15 mm). In 7 patients, partial thrombosis of the aneurysm wasdetected. In 5 patients, branching artery like PICA or AICA was involvedwith the aneurysm. Angiographic outcomes were evaluated usingO’Kelly-Marotta (OKM) grading scale, and evaluated status of branchingartery.

Result: Two flow diverters were deployed in one case. In 6aneurysms, Pipeline (Medtronic) was deployed. (Flex 2, Shield 4) In 7aneurysms, Surpass (Striker) was deployed. (Streamline 3, Evolve 4) In all 5branching artery-involved type, flow diverter stent was laid covering branchorigin. Immediately, 7 patients presented A3 grade, 1 patient presented A2,and other 5 patients showed B3 or B2 grade. There was no periproceduralissue or failure of deployment.

For follow-up study, DSA (mean 19.2 months, 6–40 months) was possible in 6patients, and HRMRI (mean 14 months, 6–19 months) in 3 patients, and CTA in2 patients. 6 patients who underwent DSA follow-up, showed improvement ofOKM grade. In patients who underwent other imaging modality, definitereduction of the aneurysm was detected. Although, the branching artery waswell preserved in all 4 patients, aneurysmal sac remained near branchingartery origin. Interestingly, one of them, who was initially not showed thePICA due to infarction, recanalization occurred after flow diversion.Clinical follow-up was possible about 24 months after procedure, (From 1months to 50 months) Embolic infarction occurred in 1 patient. Most ofpatients had good clinical outcome. (mRS 0 in 5 patients, 1 in 5 patients)The other 2 remained mRS 2, and another one scored mRS 6 because of otherunderlying disease.

Conclusion: In our study, all patients had remarkableimprovement about aneurysm reduction and the PICA preservation after flowdiversion. Flow diversion seems to be one of treatment option for unrupturedfusiform aneurysm having symptom or changing size.

O2-17-6

Clinical results of flow diverter treatments for cerebral aneurysmsunder local anesthesia

Saujanya Rajbhandari, Hidetoshi Matsukawa,Uchida Kazutaka, Manabu Shirakawa, Shinichi Yoshimura

Neurosurgery, Hyogo College of Medicine

Purpose: Flow diverter (FD) has become a mainstay ofendovascular aneurysm treatment over the past decade, especially for largeand giant wide-necked aneurysms. Most FD procedures are performed undergeneral anesthesia. To date, influence of local anesthesia on clinicaloutcome remains unknown in aneurysmal treatment by FD. The aim of this studyis to evaluate the clinical results of FD placement under local anesthesiain patients with intracranial aneurysm.

Materials and Methods: Clinical and radiological characteristicsof patients treated with FD under local anesthesia between August 2016 andJanuary 2022 were analyzed. Good clinical outcome was defined as a modifiedRankin Scale score of 0 to 2. Major stroke, steno-occlusive events of FD,mortality, and satisfactory aneurysm occlusion were evaluated.

Results: Results: One hundred sixty-nine patients with 172cerebral aneurysms undertook 182 treatments, 140 (83%) female, mean age61 ± 11 years, were included in this study. Proportion of pre-mRS 0–2 was165 (98%). Mean aneurysm dome size and neck length were 11.2 ± 6.4 mm and6.8 ± 3.2 mm, respectively. There were 146 (85%) aneurysms with saccular and23 (13%) aneurysms with fusiform morphology, the remaining 3 (1.3%)aneurysms were blister. One hundred fourty-four (84%) aneurysms were locatedat the internal carotid artery being the predominant location. FlowRe-Direction Endoluminal Device and Pipeline Embolization Device (43%) wereused in 95 (55%) and 77 (45%) treatments. Three patients (1.8%) experiencedmajor stroke and steno-occlusive events of FD were observed in 4 patients(2.4%). Good clinical outcome at 90-day was obtained in 163 patients (98%)and mortality was 1.2% (2 of 169 patients). During the median follow-upperiod (366 (IQR 195–509) days), satisfactory aneurysm occlusion wasobserved in 124 of 157 aneurysms (79%).

Conclusion: Our results suggest that FD placement under localanesthesia is a safe and effective treatment for cerebral aneurysms withsatisfactory occlusion and comparably low rates of permanent neurologicalmorbidity and mortality.

O2-18-1

Multicenter US Clinical Experience with The Scepter Mini BalloonCatheter

Mohamed M. Salem¹, Sophie Ostmeier², Alex Hoang³, Gustavo Cortez⁴, Kareem El Naamani⁵, Rawad Abbas⁵, Maxim Mokin⁷, Michael R. Gooch⁵, Pascal Jabbour⁵, Peter Kan⁶, Ricardo Hanel⁴, Omar Tanweer³, Brian T. Jankowitz¹, Jeremy J. Heit², Jan-Karl Burkhardt¹

¹Department of Neurosurgery, University of Pennsylvania,Philadelphia, Pennsylvania, USA.

²Department of Radiology, Neuroadiology and NeurointerventionDivision, Stanford University, California, USA.

³Department of Neurosurgery, Baylor College of Medicine, Houston,Texas, USA

⁴Lyerly Neurosurgery, Baptist Neurological Institute,Jacksonville, Florida, USA

⁵Department of Neurological Surgery, Thomas Jefferson UniversityHospital, Philadelphia, Pennsylvania, USA.

⁶Department of Neurosurgery, University of Texas Medical Branch,Galveston, Texas, USA.

⁷Department of Neurosurgery and Brain Repair, University of SouthFlorida, Tampa, FL, USA

Introduction: Distal catheter navigability and imprecisedelivery of embolic agents remain as the two most important limitationsencountered during endovascular liquid embolization of cerebrospinalvascular malformations. The new dual lumen Scepter-Mini Balloon (SMB)microcatheter was introduced with the aim of overcoming these limitationsencountered with conventional microcatheters with few small single-centerreports suggesting favorable results; however, multicenter data from the USremain lacking.

Methods: Series of consecutive patients undergoing endovascularembolization utilizing SMB were extracted from prospectively maintainedregistries in 7 North American cerebrovascular centers (November 2019-December 2021).

Results: 42 patients undergoing embolization utilizing the SMBwere included (median age 58.5; 55.9% females). Cranial dural arteriovenousfistula (dAVF) embolization was the most common indication (55.8%) followedby cranial arteriovenous malformation (AVM) embolization (20.6%).Staged/pre-operative embolization was done in 23.5% of the cases, with 94.1%of procedures utilizing Onyx-18 as embolic agent. The majority of proceduresutilized transarterial approach (88.3%), while arterial flow arrestutilizing Scepter-Mini concurrently with transvenous embolization wasutilized in 4.7% of procedures. Femoral access and triaxial setups wereutilized in most procedures (85.2% and 59%, respectively). The median vesseldiameter where balloon was inflated of 1.7 mm, with median 1.5cc of injectedembolic material per procedure. Technical failures were encountered in 9.5%of procedures requiring replacement with other microcatheters withoutclinical sequalae in any of the patients, with SMB-related proceduralcomplications of 2.4%. Complete occlusion (100%) or >50% occlusion onlast follow-up were documented in 78.3% of the cases, with unplannedretreatments needed in 2.4% of the cases, over a median of 3.4 months offollow-up.

Conclusion: The Scepter-Mini Balloon microcatheter is a usefulnew adjunctive device for balloon-assisted embolization of cerebrospinalvascular malformations requiring distal access with high technical successrate, favorable outcomes, and reasonable safety profile.

O2-18-2

Direct Sinus Approach Through a Feeding Artery in DAVF: Based onBetter Understanding of Angioarchitecture

Jieun Roh¹, Jeong A Yeom¹, Hae Woong Jeong², Seung Kug Baik¹

¹Department of Radiology, Pusan National University YangsanHospital

²Department of Radiology, Inje University Busan Paik Hospital

Background and Purpose: The study aimed to determine the shapeof the feeding artery and the fistula point in DAVF. These could be used toreach the dural sinus via the artery in endovascular treatment.

Materials and Methods: We conducted a retrospective reviewinvolving 106 DAVF who underwent endovascular treatment. In cases in whichwe reached the treatment target area directly through a feeding artery, weaccessed the feeding artery, including the site where the diameter changed,types according to the classifications, and rotational images.

Results: A total of 106 cases were treated. The arterialapproach was performed in 41 cases. Microcatheters were used to reach thetarget area via the arteries in 12 cases. Using the Cognard's classificationand the Suh's classification, the largest portion was classified as highgrade (type II a + b) and was regarded as late restrictive. The distallyenlarged non-taped appearance of the feeding vessel was observed in all 12cases. The narrowing point was seen in 11 of the 12 cases. The feedingartery's narrowing point was discovered around the dural sinuses (n = 5), invenous lakes in dural sinus wall (n = 3), and around the foramen(n = 4).

Conclusion: Blood vessels that can access the targeted duralsinus via the feeding artery show a distally enlarged appearance with anarrowing point. This is thought to be the shunt point of transition fromthe artery to the vein. In most cases, the shunt point occurs far from thedural sinus.

O2-18-3

Role of surgical intervention for intracranial dural arteriovenousfistulas with cortical venous drainage in an endovascular era: A caseseries

Yosuke Akamatsu^1,2, Santiago Paz Gomez², Justin M Moore², Ajit S Puri³, Christopher S Ogilvy², Kuniaki Ogasawara¹, Ajith J Thomas⁴

¹Department of Neurosurgery, Iwate Medical University

²Neurosurgical Service, Beth Israel Deaconess Medical Center

³Department of Radiology, University of Massachusetts MedicalSchool

⁴Department of Neurological Surgery Cooper University HealthCare

OBJECTIVE: To demonstrate the angioarchitecture which maynecessitate surgical intervention.

METHODS: A retrospective review of the patients withintracranial dAVFs with CVD treated at two academic institutions betweenJanuary 1st 2009 and July 31st 2019 was performed. Patients who requiredsurgical intervention were selected in this study, and angiographic findingswere analyzed.

RESULTS: Eighty-one dAVFs in 80 patients were treated during thestudy period. Endovascular treatments were attempted for 72 (88.9%) dAVFs,resulting in complete obliteration in 55 (76.4%). Surgical interventionswere performed in 18 (22.2%) dAVFs, resulting in complete obliteration inall lesions. Overall, complete obliteration was achieved in 74 (93.7%) of 79dAVFs with follow-up. In the surgically treated dAVFs, curativetransarterial embolization was deterred by the angioarchitecture whichincluded dominant feeding vessels from the ophthalmic artery,meningophypophyseal trunk, posterior meningeal artery, pial artery, orascending pharyngeal artery. Drainage through tortuous cortical vein, deepvenous system or isolated sinus made transvenous approach challenging.

CONCLUSION: Despite continued improvement in endovasculartechnology, surgical approaches to dAVFs are still of great value as initialand salvage treatment of dAVFs with angioarchitecture hampering endovasculartreatment.

O2-18-4

Onyx embolization for isolated type dural arteriovenous fistula bytransarterial intrasinus catheterization using a flow-directed catheterwith temporary Balloon Occlusion: two case reports

Rie Yako, Naotugu Toki, Masamichi Ishi, NaoyukiNakao

Department of neurological surgery, Wakayama medical university

Objective: We report two cases of isolated type duralarteriovenous fistulas (DAVFs) treated by onyx embolization of the affectedsinus and fistula via transarterial intrasinus catheterization using aflow-directed catheter, with a balloon guide catheter (BGC) for flowcontrol.

Case Presentation: A-78-year-old woman was diagnosed withisolated transverse sinus (TS) and superior petrosal sinus (SPS) DAVFs. Aflow-directed catheter was inserted into the isolated TS through the fistulavia middle meningeal artery (MMA), which was the feeding artery of the DAVF.These DAVF were total occluded by onyx embolization of the isolated sinusand multiple fistulas under flow control using a balloon guide catheter(BGC) for flow control. A 66-year-old man was diagnosed with isolated TSDAVF. A flow-directed catheter was inserted into the isolated TS through thefistula via MMA which was the feeding artery of the DAVF. The DAVF wasoccluded by a few coil and onyx embolization of the affected sinus andfistula with a BGC.

Conclusion: These cases suggested that onyx embolization viatransarterial intrasinus catheterization using flow-directed catheter, withtemporary balloon occlusion of the proximal feeding artery to decrease theshunted flow, is one of the effective treatment options for isolated typeDAVF.

O2-18-5

The significance of preserving the anterior condyle vein in themanagement of Anterior Condylar Confluence dural arteriovenous fistulae(ACC-DAVF): A retrospective study

Masahiro Nishihori, Takashi Izumi, KojiroIshikawa, Eiki Imaoka, Hiroki Matsuno, Hayato Yokoyama, Keita Suzuki,Taketo Hanyu, Ryuta Saito

Department of Neurosurgery, Nagoya University Graduate school of Medicine

Purpose: Transvenous embolization (TVE) is the first-linetreatment for Anterior Condylar Confluence Dural Arteriovenous Fistulas(ACC-DAVF). Still, there is concern that the mass effect of the coil mayworsen hypoglossal nerve palsy (HNP) as a complication. We have recentlyattempted to preserve the Anterior Condylar Vein (ACV) by selectiveembolization of an intraosseous shunt around the hypoglossal canal or outletocclusion. The authors will discuss the usefulness through a review of ourown experiences.

Materials and Methods: There were 28 ACC-DAVF patients treatedat our institute from 2001 to 2020. Seven cases were excluded becausedetails of surgical records and images could not be consulted. Aretrospective analysis of 21 shunts in 20 ACC-DAVF cases was finallyperformed. We collected data on symptoms, treatment, and shunt occlusion.The 11 cases that were embolized with preservation of the ACV wereclassified as a group (P), and the 9 cases that were embolized of the ACVand/or ACC were classified as a group (O). One patient who underwent stagedembolization was classified as a group (O), in which the packing of ACV wasfinally performed due to symptoms worsening after initial selectiveembolization.

Results: The study included 19 patients (median age 65 years, 14females and 5 males) with 20 lesions. The mean follow-up was 21 months.Symptoms were tinnitus in 19 cases (91%), HNP in 12 cases (57%), andhyperemia and external ophthalmoplegia in six cases (29%). Almost allpatients underwent transvenous embolization. Pial/perimedullary reflux typewas just one case, in which the treatment was only trans-arterialembolization (TAE). TAE was used in 11 patients in combination, and completeocclusion was observed immediately after treatment in 16 patients (80%) andin other patients during follow-up. There was a trend toward longertreatment times and shorter total lengths of coils used in the P group, butthe differences were insignificant. One procedure-related complicationoccurred in the P group: coil migration. Tinnitus disappeared in 16 patients(n = 18, 94%) and external ophthalmoplegia improved in 5 patients (n = 6,83%). These symptoms changes were not significantly different between thetwo groups. Since two patients in group O had worsening hypoglossal nervepalsy in the chronic phase, there was a significant difference in the finalnumber of patients who achieved improvement in hypoglossal nerve palsy: 7/7patients in group P and 1/5 patients in group O. (P = 0.01)

Conclusion: In performing TVE for ACC-DAVF, preservation of ACVis essential because it does not increase the recurrence rate and minimizesthe subsequent hypoglossal nerve palsy including in the chronic period.

O2-18-6

Transvenous ONYX embolization for tentorial dural arteriovenousfistulae: Report of two cases

Yasunobu Mitsura¹, Tomoaki Terada², Yuma Miki², Yuki Sato², Hiroo Yamaga², Hirotake Fujishima²

¹Department of neurosurgery, Tokyo Rousai Hospital

²Department of neurosurgery, Showa University Northern YokohamaHospital, Japan

Purpose: Tentorial dural AVFs (dAVF) are non-sinus type andtransarterial liquid embolization is sometimes very difficult due totortuosity or embolization risk of accessible arteries. We report two casesof tentorial AVFs embolized mainly from transvenous route using ONYX due tothe difficulty of transarterial access. Our strategy and possiblecomplication are discussed in this paper.

Cases 1: A 40-year-old male was admitted to our hospital due tothe incidentally found a tentorial dAVF at the left medial tentorial edge.Main feeding arteries were lt-middle meningeal artery (petrosal branch) andlt-meningohypophyseal trunk. Both feeding arteries were very tortuous tonavigate the microcatheter into the safety point for ONYX injection.However, transvenous route was seemed to be easy to access. 6Fr sheath wasintroduced into the right jugular vein and 6Fr guiding catheter wasintroduced into the straight sinus.Then, two microcatheters were navigatedinto the just proximal portion of the shunt points through the straightsinus and basal vein of Rosenthal. After positioning the microcoils at theproximal point of the microcatheter for ONYX injection, ONYX 18 was injectedthrough the microcatheter and pushed ONYX to the arterial side beyond theshunt. dAVF was completely disappeared.

Case 2: A 30-year-old male had a history of epilepsy. dAVF wasfound near the left confluence. A tentorial dAVF fed only by left posteriorcerebral artery(PCA) including dural branches of PCA and draining into theinternal parietal vein and tentorial sinus. Transarterial and transvenousembolization were planned. Initially TAE using ONYX or NBCA was performedfrom the accessible PCA feeders. Then, TVE was performed using ONYX 18 fromthe tentorial sinus accessed from the transverse sinus. dAVF was completelydisappeared. However, on the next day of embolization, the patientcomplained of visual field disturbance. A small hemorrhage was identifiedadjacent to ONYX. His visual field disturbance was disappeared in a weekafter embolizaion. Disappearance of dAVF was confirmed on angiography oneweek after embolization.

Discussion: Transvenous ONYX embolization is the curativetreatment for non-sinus type dAVF. However, as the mechanism of hemorrhagein case 2, two possibilities were considered as follows, the remaining pialfeeders from the PCA or venous infarction by obliterating the normaldrainage route due to progressing venous thrombosis.

Conclusion: Transvenous ONYX embolization is the curativetreatment for non-sinus type dAVF, although still a few remaining problemsshould be resolved.

O2-19-1

A novel intracranial exchange guidewire improves navigation and devicedelivery in challenging settings: an in vitro study

Ariel Takayanagi^1,2, Naoki Kaneko¹, Hamidreza Saber¹, Lea Guo¹, Satoshi Tateshima¹

¹Interventional Neuroradiology, University of California LosAngeles

²Department of Neurological Surgery, Riverside University HealthSystem, Morono Valley, California, USA

Purpose: Navigation to the target vessel and stable access arekey to success during endovascular procedures. The Stabilizer is a anexchange length wire (300cm) with a soft 0.014 diameter retrievable stent atthe distal end made for navigation and exchange maneuvers. We conducted astudy to evaluate the efficacy of the Stabilizer in a variety of challenginganatomical settings.

Materials and Methods: Three challenging vascular models wereused to determine the efficacy of the Stabilizer. A giant aneurysm model, asevere tortuosity model, and an M1 stenosis model were used. In each model,the Stabilizer was compared with a conventional wire during navigation ineach model.

Results: The Stabilizer achieved a significantly higher successrate when advancing an intermediate catheter beyond the aneurysm neck in agiant aneurysm model. There was no significant difference in success ratesduring straightening of looped wire in the giant aneurysm model compared tothe conventional wire. When advancing an intermediate catheter through amodel with severe tortuosity, the Stabilizer had significantly greatersuccess compared to the conventional wire. The Stabilizer also hadsignificantly greater success compared to a conventional exchange wire whenperforming an exchange maneuver for intracranial stenting in an M1 stenosismodel.

Conclusion: In our in vitro model, the Stabilizer hadsignificantly improved success rates during navigation and device deliveryin all three challenging situations compared to a conventional wire.

O2-19-2

Preclinical Evaluation of Aqua Embolic System using a swine AVMmodel

Ichiro Yuki¹, Kousaku Ohkawa², Timothy Shimizu¹, Zachary Weizen Hsu¹, Hemdeep Kaur¹, Earl Steward³, Brandon Nguyen¹, Frank P.K. Hsu¹, Shuichi Suzuki¹

¹Department of Neurosurgery, University of California, Irvine

²Institute of Fiber Engineering Shinshu University, Japan

³Department of Surgery, University of California, Irvine

Introduction: Currently available Liquid Embolic Materials(LEMs) have limitations of potential catheter entrapment or the cytotoxicityassociated with the organic solvents used in the material (e.g., DimethylSulfoxide (DMSO)). Aqua Embolic System (AES) is a non-DMSO-based LEM mainlycomposed of multiple polysaccharides. AES, when injected via amicrocatheter, immediately forms a hydrogel cast upon exposure to Ca2 + inthe bloodstream and occludes the target vessel. The performance of AES wasevaluated on an established AVM model utilizing swine rete-mirabile.

Methods: Under general anesthesia, the left ascending pharyngealartery (APA) of Yorkshire swine (40 kg) was catheterized with a balloonmicrocatheter, and AES loaded in a 1cc syringe was manually injected intothe rete-mirabile under fluoroscopy. The following parameters were assessedto evaluate the embolization performance of the AES; 1) the amount of AESrequired for the complete occlusion of the feeding artery, 2) injectionspeed, 3) radiopacity during the deployment, and 4) incidence of catheterentrapment after the injection. The same evaluation was performed on thecontralateral rete-mirabile.

Results: 12 arteries in 4 swine were treated, and all arterieswere completely occluded without technical complications. The injectedmaterials immediately formed AES cast in all vessels, followed by the refluxover the tip of the balloon microcatheter. All catheters were withdrawnwithout any sign of catheter entrapment. The AES showed sufficientradiopacity during the procedure. With an injection speed of 0.02ml/sec, theaverage volume required was 0.85mL. No increased thrombogenicity orvasospasm near the treated lesion was observed during the procedure.

Conclusions: AES, which is a DMSO-free, non-adhesivepolysaccharides-based LEM, may be used as an embolic material for thetreatment of hemorrhagic stroke caused by cerebrovascular diseases, such asbrain AVM.

O2-19-3

Fucoidan-coated coils improve aneurysms healing : a preclinical studyin rabbits

Zoltan Szatmary^1,2, Jérémy Mounier^2,3, Sylvia M Bardet^2,3, Frédéric Chaubet^4,5, Kevin Janot^2,6, Claude Couquet³, Charbel Mounayer^1,2, Aymeric Rouchaud^1,2

¹Dupuytren Hospital, Radiology; Limoges University

²XLIM UMR CNRS no 7252

³Limoges University

⁴Laboratory for Vascular Translational Science, UMRS 1148,INSERM

⁵Université de Paris; Université Sorbonne Paris Nord - Campus deBobigny

⁶Regional University Hospital Centre Tours Radiology Diagnosticand Interventional Neuroradiology;

Purpose: Endovascular treatment is the first-line therapy formost intracranial aneurysms; however, recanalization remains a majorlimitation. In this presentation we give an overview of modified surfacecoil technologies and summarize the state of art regarding their efficacyand limitations based on experimental and clinical results. We also presentpotential perspectives to develop biologically optimized devices. We proposean innovative approach to optimize the healing of aneurysms withfucoidan-coated coils.

Material and method: We have conducted a feasibility study onrabbit elastase-induced aneurysms. Embolization was carried out with bareplatinum coils or coated coils. 1 month later control DSA was performed,aneurysm filling was measured by modified Raymond-Roy scale. Histologicalsamples were collected and aneurysm healing and fibrosis were measured byquantifying mainly collagens with advanced multiphoton microscope. Weincluded in the study 45 rabbits divided into 3 groups treated with bareplatinum coils or coated coils either with fucoidan or with dextran as acontrol.

Results: Angiographic results: We observed a trend towards lessrecanalization in the fucoidan group, however no significant differencecould be found (p = 0.21).

Histological results: A significant difference was found withthe presence of more collagen in the neck region of aneurysms treated withfucoidan-coated coils versus bare platinum coils (p = 0.011).

We established a new histological score combining standard light microscopeand multiphoton images. According to this classification, histological indexwas significantly better in the fucoidan group than the bare coil group atthe aneurysm neck (p = 0.004). Collagen organization index was alsosignificantly better in the fucoidan-coated coils than the bare platinumcoils (p = 0.007).

Conclusion: Our work presents a proof-of-concept study thatdemonstrates the feasibility and biological efficacy of treatment withfucoidan-coated coils to improve aneurysms healing. Using innovativemulti-photon microscopy technology, we have established a new type ofhistologic classification for the evaluation of aneurysm healing. Overall,this animal study demonstrates that fucoidan-coated coils have the potentialto improve healing following endovascular treatment.

O2-19-4

Efficacy of Thermoplastic Polyurethane and Gelatin blendedNanofibers-coated Stent-graft in the Porcine Iliac Artery

Dae Sung Ryu, Dong-Sung Won, Jeon Min Kang,Jung-Hoon Park

Stent Translational Medicine Laboratory, Biomedical Engineering ResearchCenter, Asan Institute for Life Sciences, Asan Medical Center, Seoul, SouthKorea

Purpose: Stent-grafts composed of expandedpolytetrafluoroethylene, polyethylene terephthalate and polyurethane arecharacterized by poor endothelialization, high modulus, and low compliance,leading to thrombosis and intimal hyperplasia. A composite synthetic/naturalmatrix is thought to be a promising alternative to conventional syntheticstent-grafts. The purpose of this study was investigated the efficacy ofthermoplastic polyurethane (TPU) and gelatin (GL) blended nanofibers (NFs)coated stent-graft in the porcine iliac artery.

Materials & Method: The TPU and GL blended NFs membrane wasconstructed using ES techniques on surface of the stent with 6 mm indiameter and 30 mm in length. A total of twelve Yorkshire domestic pigs wererandomly sacrificed 7 days (n = 6) and 28 days (n = 6) after stent-graftplacement in the left iliac artery. The efficacy of the TPU and GL blendedNFs-coated stent-graft was assessed by comparing the results of follow-upangiography, the degree of thrombosis, and histological examinations.

Results: TPU and GL blended NFs-coated stent-grafts weresuccessfully placed in all pigs without procedure-related complications. Themean (± SD) luminal diameters at 28 days follow-up angiography (2.8 ± 0.34mm) were significantly lower than those at 7 days follow-up (4.6 ± 0.39 mm,p < 0.001) and post-procedure (5.1 ± 0.24 mm, p < 0.001)angiographies. The mean (± SD) thrombogenicity score was significantlyincreased at 28 days than at 7 days (2.67 ± 0.51 vs. 1.33 ± 0.51, p <0.001). The mean (± SD) thickness of neointimal hyperplasia, degree ofinflammatory cell infiltration, and degree of collagen deposition were allsignificantly higher at 28 days than at 7 days (847.8 ± 162.6 μm vs.373.7 ± 53.25 μm, 3.66 ± 0.51 vs. 1.83 ± 0.40, 3.50 ± 0.83 vs. 1.33 ± 0.51,respectively; all p < 0.001).

Conclusion: The TPU and GL blended NFs -coated stent-graftssuccessfully maintained the patency for 28 days in the porcine iliac artery.Although thrombosis with neointimal tissue were observed, there were nosubsequent occlusion of the stent- graft until the end of the study. Acomposite synthetic/natural matrix-coated stent-graft may be promising forprolonged stent-graft patency.

O2-19-5

Laser angioscopy: an intravascular eye for InterventionalNeuroradiology

Luis Savastano¹, Sarosh Madhani¹, Jorge Arturo Larco², Pedro N Lylyk², Yang Liu³, Eric Seibel⁴

¹Department of Neurosurgery, University of California SanFrancisco, San Francisco, CA, USA

²Department of Neurosurgery, Mayo Clinic, Rochester, MN, USA

³Department of Radiology, Mayo Clinic, Rochester, MN, USA

⁴Department of Mechanical Engineering, University of Washington,Seattle, WA, USA

Purpose: Interventional Neuroradiology has historically reliedon shadows to diagnose diseases and guide interventions. Fluoroscopy andAngiography have enabled the rise and astonishing growth of our field.However, they offer minimal information pertaining to the lumen/wallinterface, it cannot characterize structural and biological markers that canpredict symptomatology and has limited power to identify key anatomicalfeatures during endovascular procedures. To address these limitations, wedeveloped a new imaging platform that provides high-quality, laser-based,video imaging of the vascular lumens. This novel technology has thepotential to catalyze major advances in our diagnostic and prognosticcapabilities, and to radically transform the way we doneurointerventions.

Material and Methods: A scanning fiber angioscope (SFA), ahigh-definition 1 mm camera that generates videos by spirally scanning laserbeams, was developed and used to analyze the lumen/wall interface, intrinsicfluorescence, and MMP-dependent proteolytic activity using an activatablefluorescent probe of ex vivo human carotid arteries(n = 150), endarterectomized carotid plaques (n = 80) and human brains(n = 10). Then, in vivo multimodal angioscopy was performedin rabbits with normal vasculature (n = 5), vulnerable (n = 7) and disruptedatherosclerotic lesions (n = 7).

Results: Angioscopy images were generated at a frame rate of 30Hz with a spatial resolution of ∼12 μm at typical imaging distances (>1 Mpixels in a screen). Laser Angioscopy revealed the structure and label-freebiochemical make-up of healthy and diseased arteries, and detectedthrombogenic lesions invisible by other modalities, including erosions,fissures, ulcerations and dissections. In addition, angioscopy characterizedthe nature and chronicity of steno-occlusive lesions and provided keydetails to guide intervention such as the ostia of neovascular channels inchronic total occlusions. Angioscopy also detected preferential proteolyticactivity in regions of fibrous cap disruption and symptomatic stentedlesions. Finally, we consistently generated high-quality multimodal laserangioscopy videos in vivo.

Conclusions: Laser angioscopy generates structural andbiological images of large vascular surfaces with unprecedented andunparalleled resolution. These true-color video images are artifact-free,intuitive, and forward looking, enabling the identification ofpathophysiological hallmarks of complicated and vulnerable atheroscleroticlesions and the capacity to guide interventions on real-time. Thistechnology has the potential to revolutionize research, diagnosis,prognosis, and image-guided therapy in Interventional Neuroradiology.

O2-19-6

Primary robotic-assisted endovascular treatment of intracranialaneurysms.

ZELEŇÁK Kamil

Clinic of Radiology, Comenius University in Bratislava, Jessenius Faculty ofmedicine in Martin, University Hospital Martin, Kollárova 2, 03659 Martin,Slovakia

Background: The aim of the study is to evaluate technicalsuccess of primary robotic-assisted endovascular treatment of intracranialaneurysms using the CorPath GRX Robotic System.

Methods: Six patient (two males and four females) with medianage 52.5 years (42–70) underwent primary robotic-assisted endovasculartreatment of intracranial aneurysms between March 30 and April 27, 2022. Onepatient was treated after subarachnoid hemorrhage.

Results: Aneurysms originated form internal carotid artery inthree cases, anterior communicating artery two times and once from themiddle cerebral artery. Non-ruptured aneurysms were treated by flow-diverterimplantation and one ruptured aneurysm was treated by coiling. The technicalsuccess rate of the procedures was 100%.

Conclusions: Robotic-assisted endovascular treatment ofintracranial aneurysms is technically feasible.

O2-20-1

Hospital case volume is associated with mortality in aneurysmalsubarachnoid hemorrhage (aSAH) who underwent endovascular coiling inThailand

Phumtham Limwattananon^1,2, Ekachat Chanthanaphak¹, Chai Kobkitsuksakul¹, Pichayen Duangthonpon²

¹Department of Radiology, Faculty of Medicine, RamathibodiHospital, Mahidol University, Thailand

²Department of Surgery, Faculty of Medicine, Khon Kaen University,Thailand

Purpose: aSAH is a potentially devastating cerebrovasculardisease. Several studies have reported an inverse relationship between deathand the case volume of aSAH. The goal was to find if there was anassociation between in-hospital and 90-day death of patients with aSAH aftercoiling and case volume.

Methods: A dataset of patients with aSAH and treated withendovascular coiling during 2009 to 2020 was analyzed. The study outcomeswere patient death during hospitalization and within 90 days after hospitaldischarge. Treatment context of an individual patient was captured through acombined variable between hospital types and coiling case volume perhospital in each year (<10, 10–29, and >30 patients). Distribution ofthe patient characteristics and hospitalization context was compared acrossthe combined hospital case volume and tested for a statistical significanceat p < 0.05, using chi-square statistics for a categorical variable andone-way analysis of variance (ANOVA) for a continuous variable. Anassociation of the in-hospital or 90-day death with the hospital case volumegroups as the independent variable was estimated by an OR with 95% CI.

Results: 831 patients with aSAH were treated with coiling in 28hospitals. All 15 non-teaching hospitals performed coiling in less than 10patients each year. Anterior circulating aneurysms were more common in theteaching hospitals with high (>30) case volume and in the non-teachinghospitals than in low volume teaching hospitals (p < 0.001). Teachinghospitals tended to treat patients who had more severe comorbidities and whowere transferred by other facilities. Younger (18–49 year) adults had alittle higher mortality than mature (50–59 year) adults, whereas the elderlyover 60 years had an increasing mortality(p = 0.086 for in-hospital deathand p = 0.001 for 90-day death). In-hospital death was less common inpatients with anterior circulating aneurysms (5.3 vs. 10.5%, p = 0.006 forin-hospital death and 12.3 vs. 16.3%, p = 0.105 for 90-day death). Bothin-hospital and 90-day mortalities decreased with respect to the coilingcase volume per hospital High volume teaching hospitals had the lowestproportion of in hospital death (2.5%) and within 90 days (8.1%) whilenon-teaching hospitals had the highest mortalities (19.6 and 29.4% forin-hospital and 90-day death). Patients who had coiling in the low volumeteaching hospitals were 76 and 60% less likely to die during thehospitalization and within 90 days (OR, 0.24 and 0.40). Patients treated inhigh volume teaching hospitals had a decreasing odd of death: in 10–29yearly cases by 69 and 66% (OR, 0.31 and 0.34) for the in-hospital and90-day death, and in >30 yearly cases by 90 and 80% (OR, 0.10 and 0.20)for the in-hospital and 90-day death.

Conclusion: An increase in mortality was observed in hospitalswith low endovascular coiling case volume. We propose that endovascularprocedures be performed at high volume centers.

O2-20-2

Cognitive decline, psychological distress and quality of life afterruptured anterior communicating artery aneurysm EndovascularTreatment

Saima Ahmad, Hira Jamil

Diagnostic and Interventional Neuroradiology Department, Lahore GeneralHospital, Lahore, Pakistan

Background: Neuropsychiatric dysfunction is very commonlyobserved in post-treated cases of ruptured anterior communicating arteryaneurysms. This study aimed to evaluate cognitive function, depression, andquality of life in patients with ruptured anterior communicating arteryaneurysms after coiling.

Methods: In this study, we retrospectively enrolled patientswith ruptured Anterior Communicating Artery aneurysms who were treated atour institution from August 2018 to October 2021. All participants wereasked to complete the Mini-Mental State Examination (MMSE) for cognitivefunction, Center for Epidemiology Studies-Depression (CES-D) questionnaire.Patient charts were retrospectively reviewed for baseline demographics andclinical status, endovascular coiling details, and postoperative course.

Results: In total, 60 patients treated with coiling wereincluded in this study. All of them completed follow-up cognitive and QoLquestionnaires. 38 were males and 22 were female. Time of duration of thepresentation was from 6 months up to 3 years, mostly present within 1 year.27% have post coiling neurological deficits while 73% had no deficits. 21%suffered from mild depression, 20% from moderate depression and 21% fromsevere depressive symptoms whereas 38% have no symptoms.

Conclusions: Our results suggest that about 62 percent ofpatients showed cognitive impairments and depressive symptoms aftertreatment for ruptured AComA aneurysms. These symptoms can be caused by thechallenges unique to AComA-related aneurysms related to damaged anteriorcerebral structures such as the frontal cortex, the ventromedial prefrontal(orbitofrontal) cortex, or the striatum.

Our exploratory study results emphasize the importance of conducting futurestudies that evaluate long-term outcomes with validated daily measures offunctioning in deciding on a management approach for ruptured AcomAaneurysms.

O2-20-3

Pros and cons of endovascular intraarterial injection of verapamil fortreatment of cerebral spasm including patients with Hunt and Hess grade4–5. Single center experience.

Acad. N.N. Burdenko Institute of Neurosurgery of the Russian Academyof Medical Sciences, Russia

ketevan Mikeladze, Konovalov Anton, EvgeniVinogradov, Irina Kurzakova, Georgi Gvazava, Sergey Yakovlev

Department of Endovascular Surgery, N.N. Burdenko Institute ofNeurosurgery

In the period from 2012 to 2022 at the Acad N. Burdenko Institute ofNeurosurgery intraarterial injection of verapamil for treatment of cerebralspasm was performed in 110 patients. More than 300 procedures were preformedafter closing a ruptured aneurysm in the acute stage of SAH. Age from 12 to79 years.

15 patients with Hunt and Hess grade 4–5.

Efficacy of intervention was evaluated by the administration of transcranialDoppler ultrasound and clinically by modified Rankin scale. Multipletreatments (2–8 times). Dynamic selection of a dose (25–100 mg.)

The degree of spasm was determined angiographically. According to the degreeof spasm: mild - up to 30%, moderate - 30–60%, severe - 60–100%. Dosage wasselected accordingly. When assessing the correlation between the outcome ofthe disease and the severity of the angiospasm detected during angiography,a significantly worse result was obtained in the near future in the case ofa narrowing of the vessel diameter in at least one basin by more than 70%(p = 0.02). When choosing other criteria for assessing angiospasm (thedegree less than 70%, only in the M1 MCA segment), correlation could not beidentified.

All patients showed decrease in the linear velocity of blood flow accordingto ultrasound in the postoperative period.

Conclusion: Endovascular administration of Verapamil fortreatment of cerebral vasospasm is a safe technique (procedure-relatedcomplications - 3.6%), which allows to achieve a decrease in blood flowvelocity (effect of injection is short-lived) and positively affects theoverall recovery of such patients, including patients with the severity ofHunt and Hess grade 4–5.

O2-20-4

Endovascular treatment at the acute stage for ruptured blood blisteraneurysms

∼Clinical results of consecutive 7 cases∼

Osamu Masuo¹, Jun Isozaki¹, Kana Takase¹, Yoshiaki Tetsuo¹, Arisa Umesaki², Yoshikazu Matsuda²

¹Department of Neuroendovascular surgery, Yokohama MunicipalCitizen's Hospital

²Department of Neurosurgery, Showa University, Tokyo, Japan

Purpose: The treatment of blood blister aneurysms (BBAs) hasstill been controversial due to angioarchitectural characteristics. Weretrospectively evaluated clinical results including follow up results ofruptured BBAs treated with endovascular procedure.

Materials&Methods: Consecutive 7 patients were treated atour hospital between January 2015 and December 2022. The group included3males and 4females, ranging in age from 25 to 63 years old (average45years). All patients developed subarachnoid hemorrhage, ranging from 1 to4 (average 2.7) in WFNS score. The mean duration from the onset to procedureis 6.4days (range 1–12days).

Results: One patient was treated by the internal trappingwithout bypass surgery, because of the severe parent artery narrowing. Inother 6 patients, stent assisted coil embolization was underwent. In onepatient, significant intraventricular hemorrhage occurred after ventriculardrainage following the endovascular treatment. In all cases, there were nothromboembolic complication during periprocedural period. In two patients,the additional stent assisted coil embolization was performed because ofaneurysmal recurrence. All patients have experienced no rebleeding duringfollow up period (average 35months).

Conclusion: We suggest that stent assisted coil embolization forruptured blister aneurysms is safe and effective from a view point ofprevention of rebleeding.

O2-20-5

The role of endovascular treatment for ruptured aneurysm involvinganterior spinal artery at the craniocervical junction

Katsuhiro Mizutani^1,2, Takenori Akiyama¹, Hideyuki Tomita², Masahiro Toda¹

¹Department of Neurosurgery, Keio University, School ofMedicine

²Department of Neurosurgery, Ashikaga Red Cross Hospital

The ruptured aneurysm at the craniocervical junction (CCJ) involving theanterior spinal artery (ASA) is rare and consists of heterogenous lesionswith variable clinical entities. The standard therapeutic strategy for thelesions has not been well-established. Despite the advance in modernneurointervention, the endovascular treatment for this specific lesion hasbeen described in only a few reports. Here, we report the three cases with aruptured aneurysm on pial tributary of ASA at CCJ, which were subsequentlytreated by transarterial glue injection or coil embolization. Theendovascular treatment can be therapeutic option particularly for theserupture aneurysms. Either embolic agent coil or glue can be effectivedepending on the type of etiology and the surrounding vasculatureanatomy.

O2-20-6

Endovascular treatment of ruptured blood blister-like aneurysms withoverlap stenting strategy-feasibility of hybrid overlap stenting-

Hitoshi Hasegawa, Tomoaki Suzuki, KouheiShibuya, Haruhiko Takahashi, Yukihiko Fujii

Department of Neurosurgery, Brain Research Institute, Niigata University

Purpose: To evaluate clinical outcomes and angiographic resultsafter endovascular treatment of blood blister-like aneurysms (BBAs) withoverlap stenting strategy.

Materials & Methods: Fourteen patients (7 men, 7 women; meanage, 51 years) with ruptured BBAs of internal carotid artery underwentendovascular treatment with overlap stenting strategy. Technical detailsincluding type of deployed stent and posttreatment outcomes wereretrospectively evaluated. Dual antiplatelet agents were administrated inall patients. Mean follow-up period was 15 months.

Results: Initial treatment underwent at the acute stage (n = 9)and subacute/chronic stage (n = 5) (mean period, 9 days from onset). 12patients (85%) were treated with overlap stenting (OS). In all cases,deployed stents (mean 2.4 stents, range 1–5 stents) were closed-cell type(Enterprise or LVIS), including flow diverters (Pipeline) in 2 patients.Hybrid OS (HOS) which means deployment of combination with different stentswere chosen in 8 patients. The technical success rate of stents applicationwas 100%. Endosaccular coil embolization were used concomitantly in 10patients. Major recanalization after the treatment occurred in 6 patients(immediately 5, long-term 1). 2 patients (33%) recurred among initial HOSgroup (n = 6), but 4 (50%) of non-HOS group (n = 8). Retreatment withadditional stenting and/or coiling were performed in all 6 recurrent cases,resulting in complete obliteration. Symptomatic vasospasm was appeared inonly one case waiting for elective treatment. There were no rebleedingevents after the treatment. 2 patients had experienced procedure-relatedcomplication, 1 had in-stent thrombosis during the procedure and 1 had minorstroke just after treatment. 13 patients (93%) had favorable outcomes(modified Rankin scale, 0–2) at the discharge. During follow-up period,there were no recanalization in all angiographic available cases.

Conclusion: Endovascular treatment with overlap stentingstrategy was technically feasible and safe procedure for ruptured BBAs. HOSmight have more benefits of certain flow diversion effects, resulting in animmediate hemostasis and long-term durability of aneurysms. However, itseemed to be necessary to make an angiographic close follow-up due to detectmajor recanalization and avoid rebleeding events.

O3-1-1

Flow diversion at the neck: early single-center experience with theintrasaccular flow diverter Contour NeuroVascular System.

Technical considerations, drawbacks and early outcome.

Nicola Cavasin, Umberto Amedeo Gava, EnricoCagliari

Department of Neuroradiology, Ospedale dell’Angelo

PURPOSE: Endovascular approach has become in many centres thefirst therapeutic choice for the treatment of intracranial aneurysms butdespite ever improving rates of successful treatments, there are still someaneurysm subtypes burdened with unsatisfying occlusion rates afterendovascular procedures. Among these, wide-necked bifurcation aneurysms haveshown particularly low rates of complete occlusion on long term follow-ups.The Contour NeuroVascular System (CS) is a new intra-saccular device. It canbe defined as an “intra-saccular flow diverter” because it's positionedentirely inside the aneurysmal sac but creates a flow-divertion at the levelof the neck without the intrasaccular mesh component of the flowdisruptors.

We report our preliminary experience with this device mainly focusing on thetechnical aspects and nuances, addressing the encountered problems anddiscussing potential solutions and we present the early follow-up.

MATERIALS & METHODS: We retrospectively reviewed ourpatients who received endovascular treatment for saccular intracranialaneurysms with a CS in our centre between October 2021 and March 2022. Thedecision to use the CS was made according to the features of the aneurysms,specifically an unfavourable neck-to-dome ratio or a wide neck. Twotechniques were used: a stand-alone CS deployment in elective cases and aCS-assisted coiling in the ruptured ones. The degree of aneurysms occlusionwas evaluated according to the modified Raymond Roy Occlusion Scale.

RESULTS: By the time the abstract was drafted 10 patients havebeen treated with a CS for wide-necked intracranial aneurysms in ourInstitution. Eight patients had incidental aneurysms and were treated on anelective basis and two presented with a subarachnoid hemorrhage and weretreated the day of admission in the acute setting. No intraproceduralipsilateral stroke, aneurysmal ruptures or technical complications occurred.We’ve faced one device displacement at the early follow-up, without clinicalconsequences, that required a retreatement with an adjunctive device. Thefollow-up ranges from 3 to 9 months. Four aneurysms are completely occluded(one after retreatment), one is still patent and five have small neckremnants.

CONCLUSIONS: The treatment of both unruptured and rupturedwide-necked intracranial aneurysms with the CS is technically feasible. Thedevice is easily deployed and possibly resheathed if needed withoutfriction. Some technical tips and tricks have to be used in order to avoiddevice displacements or incomplete aneurysm occlusions. In our series noclinical complication occurred. Large series are needed to evaluate the longterm occlusion rate and the possible complications but we think that in someselected cases this new tool can be a valuable help in some challengingsubtypes of aneurysms.

O3-1-2

Radiation exposure and contrast agent dose comparison for WEB deviceversus stent assisted coil embolization for treatment of unrupturedbifurcation aneurysms

Jin Wook Baek¹, Sung Tae Kim², Hae Woong Jeong¹, Young Gyun Jeong², Jieun Roh³

¹Department of Diagnostic Radiology, Inje University Busan PaikHospital, Busan, Korea

²Department of Neurosurgery, Inje University Busan Paik Hospital,Busan, Korea

³Department of Diagnostic Radiology, Pusan National UniversityYangsan Hospital, Busan, Korea

Purpose: The purpose of this study was to compare the radiationdose, fluoroscopy time, procedure time, and total amount of contrast agentin each group when treating unruptured bifurcation aneurysms with WEB deviceor stent assisted coil embolization.

Materials and Methods: From the time the WEB device becameavailable in Korea to the present (2021.8 ∼ 2022.03), all unrupturedbifurcation aneurysms treated in our hospital with WEB device and stentassisted coil embolization were analyzed. Patients’ age, sex, aneurysmvolume, size, dome/neck ratio, radiation dose, fluoroscopy time, proceduretime and total amount of contrast agent were retrospectively reviewed andanalyzed statistically.

Results: During this period, total 15 unruptured, bifurcationaneurysms were treated with WEB device or stent assisted coilembolization(SAC) in our hospital. Among them, there were 5 cases of usingWEB device and 10 cases of SAC. There were no statistically significantdifferences in age, sex, aneurysm volume, size, and dome/neck ratio betweenthe two groups (p > 0.05). Regarding variables: radiation dose WEB(1529.4mGy ± 313.91) VS. SAC (3353.4 ± 1102.79) (p < 0.001); Fluoroscopytime WEB (29.44 ± 5.67) VS. SAC (81.43 ± 24.20) (p < 0.001); proceduretime WEB (73.2 ± 18.19) VS. SAC (105.5 ± 21.83) (p = 0.013); and contrastdose WEB (95.4 ± 6.80) VS. SAC (131.8 ± 22.57) (p = 0.001).

Conclusion: The WEB device group had statistically significantlylower radiation and total amount of contrast agent compared to the SACgroup. Fluoroscopy and procedure time were statistically significantlyshorter in the WEB group.

O3-1-3

Our first case experience of Woven EndoBridge (W-EB) device withconfirmation of optimal size using a tailor-made 3D model

Yuki Ebisudani, Jun Haruma, Kenji Sugiu,Tomohito Hishikawa, Masafumi Hiramatsu, Kazuhiko Nishi, Yoko Yamaoka, YuSato, Ryu Kimura, Hisanori Edaki, Masato Kawakami, Isao Date

Department of Neurological Surgery, Okayama University Faculty of Medicine,Dentistry and Pharmaceutical Sciences

Introduction: Woven EndoBridge (W-EB) device was introduced inJapan in 2020. It is the only intrasaccular flow disruptor device in thetreatment of cerebral aneurysms. To maximize the effectiveness of the W-EB,optimal size selection is an important factor. However, the device exchangeratio is about 30% in the W-EB procedure. This means that optimal sizeselection is difficult and the key point for the W-EB deployment.

We have made a tailor-made 3D hollow vascular model using a patient's datafor preoperative simulation in the endovascular treatment of cerebralaneurysms. We can easily simulate the endovascular procedure using thismodel. This is also useful to test the devices in similar clinical settings.We applied this method for our first case of the W-EB.

Case: A 74-year-old man. A left middle cerebral artery (MCA)bifurcation aneurysm was found by brain checkup. In the preoperativemeasurements, the dome/neck ratio is 1.1, the average aneurysm width is5.2 mm, and the smallest aneurysm height is 4.2 mm. After precisemeasurement of the aneurysm, we predicted the optimal W-EB size will be SL6/3 mm or 6/4 mm.

We made a 3D hollow MCA aneurysm model using real patient imaging data.

In our preoperative simulation, we compared 3 sizes of W-EB including 6/3 mm,6/4 mm, and 7/3 mm. First, the 6/3 mm W-EB was obviously small. Second, the6/4 mm W-EB fits the aneurysm, but we confirmed that the lower side of theWEB had deviation to the MCA inferior branch. Third, the 7/3 mm W-EB was bigand could not expand enough in the aneurysm. Thus, we choose the 6/4 mmW-EB.

In the actual procedure, the W-EB deployment was safely performed as ourpreoperative simulation including its deviation to the MCA inferior branch.Therefore we performed balloon angioplasty to put the W-EB into the properposition. Finally, our procedure was performed successfully and had nocomplications.

Conclusion: We successfully performed the first case of the W-EBdeployment. Preoperative simulation using a tailor-made 3D vascular model isuseful for not only procedure simulation but optimal size selection of theW-EB. The preoperative simulation needs support from the company, but it maycontribute to a safer procedure and medical cost reduction.

O3-1-4

PulseRider use in unruptured middle cerebral artery aneurysms

Shuhei Egashira¹, Naoto Kimura², Tetsuya Hayashi², Arata Nagai², Kiyotaka Oi¹, Hiroki Uchida², MIchiko Yokosawa², Ryosuke Doijiri¹, Takayuki Sugawara²

¹Department of Neurology, Iwate Prefectural Central Hospital,Morioka, Japan

²Department of Neurosurgery, Iwate Prefectural Central Hospital,Morioka, Japan

Purpose:- Middle cerebral artery aneurysms are often challengingto treat with conventional intracranial coil embolization due to the complexpositioning of the aneurysm and the parent artery and the size of the neck.The PulseRider aneurysm neck reconstruction device (PulseRider[Cerenovus,Irvine, California, USA]) is a novel neck bridging stent specificallydesigned to treat bifurcation aneurysms. The PulseRider may facilitatestent-assisted coil embolization for middle cerebral artery aneurysms.However, There have been few prior studies on the usefulness of thePulseRider for middle cerebral artery aneurysms, and only six middlecerebral artery aneurysms were included in the initial post-marketing studyof this device. Although not indicated in the United States, the PulseRideris available for wide-neck middle cerebral artery aneurysms in Japan.Information on the early results of its use is essential. We aimed toinvestigate the clinical characteristics, efficacy, and safety of PulseRiderstent-assisted coil embolization for middle cerebral artery aneurysms.

Materials and Methods:- From November 2020 to April 2022, sevenpatients with middle cerebral artery aneurysms were treated withPulseRider-assisted coil embolization at Iwate Prefectural Central Hospital.Clinical characteristics and the efficacy and safety of Pulse Riderstent-assisted coil embolization for middle cerebral artery aneurysms wereretrospectively investigated by chart review and imaging.

Results:- One man and six women were included, ranging from 56to 73 years (mean 66 years). Aneurysm diameters were medium (5–10 mm) in 6patients and small (<5 mm) in 1 patient, all with necks >4 mm ordome-neck ratios <2. Multiple aneurysms were seen in 4 patients.Preoperative and postoperative antithrombotic therapy was dual antiplatelettherapy with aspirin and clopidogrel in 6 of 7 patients and warfarin andaspirin in 1 patient with atrial fibrillation. The degree of initialocclusion using the Raymond-Roy occlusion classification grade was class Iin 1 case, 2 in 1 case, 3a in 2 cases, and 3b in 2 cases. Regarding theability to retain the coil, the PulseRider alone was capable of subsequentcoil embolization in four patients, but two patients with hybrid stentingrequired additional stenting. As for thrombotic events, one patient had aspotty high signal on Diffusion-Weighted Images postoperatively, although itwas asymptomatic. There were no hemorrhagic events. All patients weredischarged home with a modified Rankin Scale of 0 or 1. No death or strokeoccurred within three months postoperatively.

Conclusion:- We report a small but promising case series ofpatients with broad neck middle cerebral artery aneurysms treated with thePulseRider device.

O3-1-5

Woven Endobridge (WEB) for wide-neck bifurcation aneurysms:consideration on efficacy and future direction based on initialexperiences of 40 consecutive cases in a Japanese single center

Ichiro Nakahara, Shoji Matsumoto, Jun Morioka,Akiko Hasebe, Jun Tanabe, Sadayoshi Watanabe, Kenichiro Suyama

Department of Comprehensive Strokology, Fujita Health University School ofMedicine

Introduction: Endovascular treatment for wide-neck bifurcationaneurysms (WNBAs) such as basilar top, anterior communicating artery, andmiddle cerebral artery often require complex techniques such as Y-stentingwith specific numbers of ischemic complications. The endosaccular flowdisruptor device, Woven Endobridge (WEB), was developed in 2011, andconsiderable information from clinical experience has been accumulated.However, the significance of this device for the WNBA has not yet beenestablished so far. We present the initial results of WEB for WNBAs in asingle center since WEB was introduced in Japan and consider the efficacy ofthis device and future direction.

Materials and Methods: Materials are consecutive cases of fortyWNBAs treated by WEB since January 2021. The location of the aneurysmconsists of BA top 6, Acom 17, MCA 11, and ICA 6. The age was 65.4 years old(mean;39–84), male gender 20, maximum aneurysm size 6.9 mm (mean;4.9–14.2)，neck size 4.3 mm (mean;2.4–9.5), dome-neck ratio 1.3 (mean;0.8–1.9), andpresentation included unruptured asymptomatic 20, unruptured symptomatic 1,ruptured acute 8, ruptured chronic 1. Clinical course and imaginginformation were reviewed retrospectively by the medical record.

Results: Deployment of WEB was successful in every case(technical success rate: 100%). 9/40 cases are required to exchange the sizeof WEB (sizing failure rate 23%). The adjunctive technique employed includedballoon assist in 6/40 (15%), stent assist in 6/40 (15%), and dual WEB in1/40 (2.5%). The ischemic complication was 3/40 (2.5%; TIA 2, minor stroke1), and hemorrhagic complication was 1/40 (2.5%; SAH by microguide wirebranch perforation for rescue stenting after WEB deployment). All of themwere asymptomatic at the discharge (mRS 0). One re-treatment case wasexperienced for an irregular shape MCA aneurysm with marginal recurrenceoutside of WEB, which was treated with coiling after a 3-months follow-up.Follow-up DSA is performed at least at 3-months and 12-months, withincreasing numbers of adequate obliteration, though data is still limiteddue to the short follow-up period.

Discussion and Conclusion: Clinical results of our initialexperience were acceptable, same as previous reports from the EU and US.Long-term follow-up remains unknown, but adequate obliteration increases byexperiences, suggesting a learning curve. However, the size failure ratedoes not decrease over time, indicating the necessity of 3D-model simulationor simulation software such as Sim&Cure before treatment. The mostcritical aspect is not to apply this technology to every WNBAs but to define“WEBable” aneurysm with a high expectancy of adequate occlusion andlong-term durability.

O3-1-6

PulseRider-assisted treatment of intracranial aneurysms in theSTERLING registry

Reade Andrew De Leacy^1,6, Ajit S Puri^2,6, Robert M Starke^3,6, Brian T Jankowitz^4,6, Albert Yoo⁶, Florent Gariel⁶, Shady Jahshan⁶, Zsolt Kulcsar⁶, Clemens Schirmer⁶, Cyril Chivot⁶, Jay Howington⁶, Guglielmo Pero⁶, Tom Yao⁶, Adam Polifka⁶, Avery Evans⁶, Osama O Zaidat^5,6

¹Department of Neurosurgery, Icahn School of Medicine at MountSinai, New York, NY, USA

²Department of Radiology, University of Massachusetts, Worcester,MA, USA

³Department of Neurological Surgery, University of Miami MillerSchool of Medicine, Miami, Florida, USA

⁴University of Pennsylvania, Philadelphia, Pennsylvania, USA

⁵Department of Neuroscience, Mercy Health St Vincent MedicalCenter, Toledo, OH, USA

⁶STERLING Registry Investigators

Purpose: We present outcomes of PulseRider (Cerenovus, Irvine,CA) assisted coil embolization of brain aneurysms in routine clinicalpractice included in the STERLING registry.

Materials and Methods: STERLING (NCT03642639) is a prospective,global registry of endovascular treatment of intracranial aneurysms withGalaxy and MicrusFrame coils (Cerenovus, Irvine, CA). PulseRider cases fromSTERLING were included in this interim analysis. A total of 17 subjects(mean age 64.4 ± 8.69 years, 12 female) in the Registry have been treatedwith the PulseRider device. Primary outcome measures were core-lab assessedmodified Raymond-Roy (mRR) occlusion at final procedural angiogram, andwhere available, at 6 months ( + /-3 months) or 1 year (COVID allowedwindow: −3 months/ + 1.5 years). Safety outcomes were procedure- anddevice-related adverse events.

Results: All cases were unruptured aneurysms and two wereretreatments of previously coiled aneurysms. All aneurysms had saccularmorphology, 14/15 (93.3%) were wide neck and 13/15 (86.7%) were at abifurcation. Target aneurysm locations included basilar artery (6/15,40.0%), MCA bifurcation (4/15, 26.7%), ACA (3/15, 20%), ICA terminus (1/15,6.7%), and M2 (distal to bifurcation, 1/15, 6.7%), with a mean parent vesseldiameter of 2.65 ± 0.440mm. PulseRider was successfully implanted with theability to retain the coil mass in all cases. Mean packing density was29.7 ± 11.32%. Adequate occlusion (mRR I or II) was achieved in 86.7%(13/15) cases immediately post procedure, 100% (3/3) at 6 moths, and 75%(3/4) at 1 year. There were no intraprocedural ruptures, no symptomaticthromboembolic events, and no device related SAEs through the maximum followup. 87.5% (7/8) subjects had mRS 0–2 at 1 year. There were no aneurysmretreatments.

Conclusion: In this interim analysis of the ongoing STERLINGregistry, treatment of intracranial aneurysms with the PulseRider device inconjunction with embolization using Galaxy and MicrusFrame coils showedexcellent safety outcomes and high rates of adequate occlusion and goodclinical outcome.

O3-2-1

Short- and long-term outcomes of mechanical thrombectomy in acuteischemic stroke patients with active and inactive cancer

Takeshi Yoshimoto¹, Junpei Koge², Kanta Tanaka³, Masayuki Shiozawa², Naruhiko Kamogawa², Tetsu Satow⁴, Manabu Inoue^2,3, Hiroharu Kataoka⁴, Masatoshi Koga², Kazunori Toyoda², Masafumi Ihara¹

¹Department of Neurology, National Cerebral and CardiovascularCenter

²Department of Cerebrovascular Medicine, National Cerebral andCardiovascular Center, Suita, Japan

³Division of Stroke Care Unit, National Cerebral andCardiovascular Center, Suita, Japan

⁴Department of Neurosurgery, National Cerebral and CardiovascularCenter, Suita, Japan

Purpose: We aim to investigate the difference in mechanicalthrombectomy (MT) outcome for cancer-related stroke (CRS) with active andinactive cancer.

Methods: Of the consecutive acute ischemic stroke (AIS) patientsadmitted to our institute from 2010 to 2021, patients with cancer whoreceived MT within 24 h of onset and were enrolled. Outcomes including thefavorable outcome (modified Rankin Scale score of 0 to 2) at 3 months,1-year, and death within 3 months or 1-yearwere assessed between patientswith active and inactive cancer among patients with cancer. The rate offirst pass effect (FPE, extended Thrombolysis in Cerebral Infarction[eTICI]2c/3 after first pass) and final eTICI 2c/3 achievement were also assessed.Active cancer was defined as a cancer that was diagnosed within 6 months;required chemotherapy or surgical treatment within 6 months; or wasrecurrent, metastatic, or inoperable.

Results: Of 59 patients (26 women; median age, 80 years; medianNIH Stroke Scale score[NIHSS] 17), 19 (32.2%) patients had an active cancer.Patients with active cancer has less atrial fibrillation (47% vs. 78%,P < 0.01) and higher median D-dimer (4.60 μg/mL vs.2.00 μg/mL, P < 0.01). There were no significantdifferences in the favorable outcome at 3 months (26% vs. 45%,P = 0.26) and at 1 year (26% vs. 45%,P = 0.26) between both groups, but death within 3months (32% vs. 5%, P < 0.01) and within 1 year (42% vs.8%, P < 0.01) were more frequent in patients with activecancer than those with inactive cancer.

Conclusions: Long-term clinical outcomes of patients with activecancer were worse than those with inactive cancer.

O3-2-2

Tandem atherosclerotic cervical internal carotid artery occlusion inthe setting of acute ischemic stroke endovascular treatment

Shunsuke Yamashita^1,2,3, Taichiro Imahori^2,3, Junji Koyama³, Kazuhiro Tanaka^2,3, Yusuke Okamura³, Atsushi Arai³, Hirofumi Iwahashi³, Tatsuya Mori³, Takashi Sasayama²

¹Department of Neurosurgery, Yodogawa Christian Hospital, Osaka,Japan

²Department of Neurosurgery, Kobe University Graduate School ofMedicine, Hyogo, Japan

³Department of Neurosurgery, Toyooka Hospital, Hyogo, Japan

Purpose: Concurrent intracranial large vessel occlusion and anextracranial carotid artery steno-occlusive lesion, termed tandem occlusion,is a complex stroke condition with heterogeneity in lesion severity andetiologies. Among tandem occlusions, atherosclerotic cervical internalcarotid artery occlusion (ACICAO) can be challenging because of lesionhardness. We evaluated our experience with treating tandem ACICAO in acuteischemic stroke with endovascular treatment (EVT).

Materials and Methods: In total, 154 consecutive patients whounderwent EVT for acute anterior circulation stroke at our institute wereretrospectively reviewed. Patients with tandem ACICAO were analyzed in thisstudy. ACICAO was defined as cervical internal carotid artery occlusion dueto an atherosclerotic plaque based on angiography findings. Early on in thiscohort, percutaneous transluminal angioplasty (PTA) and carotid arterystenting (CAS) were performed before treating the intracranial lesion (CASfirst-antegrade approach). Towards the end of this cohort, only PTA wasperformed before intracranial lesion treatment (PTA first-antegrade approachwithout emergent CAS). Procedures, recanalization rates, complications, andprognoses were evaluated.

Results: During the study period, a total of 154 patientsunderwent EVT for acute anterior circulation large vessel occlusion at ourinstitute, of whom 10 (6%) were patients with tandem ACICAO. Of the 10patients (6%) with ACICAO, in one patient the cervical lesion could not bepassed; however, in the remaining nine patients the lesion was passedthrough successfully. In all cases, the lesions were very hard and requiredPTA to allow passage of further devices. Four patients underwent emergentCAS before the intracranial procedure, while the remaining five underwentPTA alone. After mechanical thrombectomy for the remaining intracranialocclusion, eight patients (80%) achieved successful recanalization (modifiedthrombolysis in cerebral infarction score 2b or 3). However, one patient hadmassive subarachnoid hemorrhage during the procedure, and another patientdeveloped massive intracranial hemorrhage after EVT. Thus, symptomaticintracranial hemorrhage occurred in these two patients (20%) who underwentemergent CAS, and both died within 24 h. Four of the five patients whoinitially underwent PTA alone subsequently underwent staged endarterectomyor CAS for residual stenosis. The patient in whom the cervical lesion couldnot be passed and another with reocclusion after PTA alone underwent arescue bypass procedure due to persistent ischemic symptoms. After 90 days,four patients (40%) were functionally independent (modified Rankin scalescore 0–2).

Conclusion: Our experience suggests that EVT for ACICAO istechnically feasible; however, it involves the risk of severalcharacteristic complications. These features should be fully recognized forsuccessful treatment. The PTA-first antegrade approach may reduce the riskof complications.

O3-2-3

Underlying atherosclerotic lesions in cerebral large-vesselocclusions: clinical backgrounds, radiological findings, and treatmentoutcomes

Tomoyoshi Kuribara^1,2, Shinya Kohyama², Akio Teranishi², Eisuke Tsukagoshi², Hiroki Sato², Yu Kinoshita², Satoshi Iihoshi², Shinichi Takahashi³, Hiroki Kurita⁴

¹Department of Neurosurgery, Tokorozawa Central Hospital,Tokorozawa, Saitama, Japan

²Department of Endovascular Neurosurgery, Saitama MedicalUniversity International Medical Center, Hidaka, Saitama, Japan

³Department of Neurology and Cerebrovascular Medicine, SaitamaMedical University International Medical Center, Hidaka, Saitama, Japan

⁴Department of Cerebrovascular Surgery, Saitama Medical UniversityInternational Medical Center, Hidaka, Saitama, Japan

Objectives: Mechanical thrombectomy using a standard device hasbeen effective for acute cerebral large-vessel occlusions, particularlythose due to cardiogenic embolism. However, evidence for those withunderlying atherosclerotic lesions is lacking. In this study, we evaluatedthe predictive factors, treatment details, and outcomes of acute cerebrallarge-vessel occlusions with underlying atherosclerotic lesions in patientswho underwent mechanical thrombectomy.

Materials and Methods: We retrospectively analyzed consecutivepatients with acute large-vessel occlusions who underwent mechanicalthrombectomy at our institution between August 2014 and May 2021. Predictivefactors of underlying atherosclerotic lesions were evaluated usingunivariate and multivariate analyses. In addition, treatment details andoutcomes were evaluated and compared with those of other etiologies.

Results: Among 322 included patients, 202 (62.7%) were males and65 (20.2%) had underlying atherosclerotic lesions. Multivariate analysisidentified dyslipidemia, lack of arterial fibrillation documented onadmission, smoking, internal carotid artery lesions, and stenosis ≥ 25% innon-occluded large vessels as predictive factors of underlyingatherosclerotic lesions. Regarding treatment for underlying atheroscleroticlesions, the need for percutaneous transluminal angioplasty, stentplacement, medical therapy, and longer procedure time were observed, whilesuccessful reperfusion rates, favorable outcomes, and mortality rates showedno significant differences with those of other etiologies.

Conclusion: Coexisting diseases and radiological findings wereuseful for predicting underlying atherosclerotic lesions. Furtherunderstanding these characteristics may lead to the early detection ofunderlying atherosclerotic lesions, optimal treatment strategies, and betteroutcomes.

O3-2-4

Clinical outcomes of recanalization therapy in Cancer-relatedstroke

Yuki Kamiya^1,2, Yoshifumi Miyauchi², Ayako Kuriki², Arisa Tomioka¹, Tomokazu Sekine¹, Wataro Tsuruta¹

¹Department of Endovascular Neurosurgery, Toranomon Hospital,Tokyo, Japan

²Department of Neurology, Showa University Koto Toyosu Hospital,Tokyo, Japan

Background: Cancer-related stroke (CRS) is generally known tohave a poor clinical outcome.

Although the efficacy and safety of recanalization therapy for CRS patientsremains unclear, there are some reports that both intravenous thrombolysis(IVT) and mechanical thrombectomy (MT) improve in-hospital mortality andhome discharge. This study aims to investigate the clinical outcomes ofrecanalization therapy in CRS.

Methods: We retrospectively analyzed consecutive acute ischemicstroke patients that were treated with recanalization therapy (intravenousthrombolysis (IVT) and/or mechanical thrombectomy (MT)) from 2014 to 2021 atour single center. The indication criteria for recanalization therapy didnot include the prognosis of cancer, and the subjects were patients with mRSscore of 0–3 before the onset of stroke or before invasive treatment ofcancer.

Results: Of the 419 consecutive patients (median 74 years old,39% of female, median NIHSS scores 14 points, median ASPECTS scores 8points) who were treated with recanalization therapy, 21 patients (5%) hadCRS. Of the 21 patients of CRS, 15 were transferred from one majordesignated cancer center in our neighborhood. Compared to 398 no-CRSpatients, CRS patients was younger and had a high proportion of female (66years old and 57% of female), but there was no difference in otherbackground characteristics. IVT was performed in 5 (24%) of 21 CRS patients,which was lower than 201 (51%) of no-CRS patients. There was no differencein the proportion of MT performed (81%, 70%), median recanalization time(254 min, 244 min), median procedural time (63 min, 53 min), recanalizationrate (mTICI2b-3; 82%, 87%, mTICI2c-3; 59%, 65%), and symptomatic ICH (5%,2%) between CRS and no-CRS groups. The 90-day outcome of CRS group wasfavorable (mRS score of 0–2) in 5 (25%) and deaths (mRS score of 6) in 11(55%), which were significantly higher compared to no-CRS groups (35; 9%,p < 0.05), but stoke-related death were 3 patients (15%) and the otherswere cancer-related death, and in-hospital death at our center were only 2stoke-related (10%).

Conclusions: From this result, it can be said thatrecanalization therapy could be performed efficiently and safely for CRSpatients. The total mortality is high, but stoke-related mortality is low,so it is considered to be meaningful to spend the life expectancy of cancerwithout death from a sudden stroke.

O3-2-5

The safety and validity of endovascular thrombectomy for acuteischemic stroke in patients with cancer: single center report.

Keiko Kitazawa¹, Miyako Koyama¹, Nomi Suzuki², Hiroshi Ohara², Yasushi Ito¹

¹Department of Neurosurgery, Shinrakuen Hospital

²Department of Neurology, Shinrakuen Hospital

Purpose: There is not enough evidence of safety and validity forendovascular thrombectomy (EVT) for acute ischemic stroke (AIS) in patientswith cancer. We evaluated successful recanalization rate, hemorrhagic changeafter EVT, and clinical outcome of AIS patients treated by mechanicalthrombectomy with cancer or without cancer.

Methods: Records of all patients received EVT for AIS inanterior circulation between January 2019 and December 2021 were screened.We defined the patients with cancer as the patients who were diagnosed withcancer and were undergoing the treatment or refused treatment for thatcancer. We compared with the patients with cancer (cancer group: CG) and thepatients without cancer(non-cancer group: NCG) in the successfulrecanalization (TICI 2b/3), hemorrhagic change after EVT, good clinicaloutcome (modified Rankin scale (mRS) 0–3 at 3 months and mortality at 3months.

Results: There were 6 patients in CG and 51 in NCG receivingEVT. In CG, the sites of origins of cancer were lung, esophagus, stomach,ovaries, appendix and unknown origin with multiple metastasis in liver. 4 of6 in CG interrupted taking anticoagulant or antiplatelet at the onset of AISbecause of preparation for invasive treatment of cancer or nausea. Theaverage ages were 74 years old in CG and 83 years old in NCG. In CG, therewere 4 men (67%) and in NCG, there were 33 men (65%). The average baselinemRS were 1.0 in CG and 1.6 in NCG. The average baseline Initial NationalInstitute of Health Stroke Scale (NIHSS) were 16.2 in CG and 19.5 in NCG.The successful recanalization rate was 67% in CG and 82% in NCG (P = 0.326).In 4 of 6 patients of CG, we could achieve the successful recanalization butone patient repeated the occlusion in the same lesion and final TICI was 0.The ratio of hemorrhagic change after EVT was 20% in CG and 39% in NCG(P = 0.64). The good clinical outcome was 33% in CG and 43% in NCG (P = 1).The mortality rate was 33% in CG and 8% in NCG (P = 0.115). In CG, the causeof death was cancer in 5 patients and one was died from AIS. There was nosignificant difference between two groups in these factors.

Conclusion: The ratios of the successful recanalization, theclinical outcome and mortality in CG are tend to poorer than in NCG,although there were no significant differences. The rate of hemorrhagicchange of EVT in CG was not higher than in NCG. EVT for patients with cancermight be safe and suitable as well as for the patients without cancer. It isimportant to make decision as soon as possible when we treat AIS patientsand we might not need to hesitate to perform EVT for patients withcancer.

O3-3-1

Transvenous embolization of CSF-venous fistulas using thedual-microcatheter pressure cooker technique

Donna Parizadeh¹, Olga Fermo², David Miller¹, Thien Huynh¹

¹Department of Radiology, Mayo Clinic, Jacksonville, USA

²Department of Neurology, Mayo Clinic, Jacksonville, USA

Background: Endovascular transvenous embolization is emerging asa highly efficacious minimally invasive treatment for patients withCSF-venous fistulas (CVF) associated with spontaneous intracranialhypotension (SIH). To ensure complete and curative embolization of CVFs, wehave started treating patients with a dual-microcatheter pressure cookertechnique using both coils and balloon-microcatheter in patients with CVFslocated at the thoracolumbar location. We report the details of thispromising technique and describe its treatment efficacy and safety.

Methods: We retrospectively reviewed our series of patients withSIH from CVF who underwent transvenous embolization with or without thepressure cooker technique at the Mayo Clinic, Florida between December2020-March 2022. All CVFs were confirmed on lateral decubitus digitalsubtraction or CT myelography. Procedural details, clinical, and imagingoutcomes for all patients were recorded. Patient clinical and imagingoutcome was determined with 1–3 month post-operative post-global impressionof change (PGIC) and Bern MRI SIH Score respectively.

Results: Twenty procedures were performed among 18 patients(mean[SD] age 58[10] years, 78% female. Pressure cooker technique was usedin 10 (50%) of the procedures with treatment level ranging from T6-L1levels. Coils were deployed in either exiting intercostal/lumbar tributaryveins or ascending lumbar veins adjacent to the foraminal venous plexus inall cases. Technically successful embolization of the foraminal venousplexus and adjacent tributaries was achieved in all cases and there were nocomplications. All ten procedures with pressure cooker technique hadcomplete resolution of clinical symptoms, with all patients reporting “verymuch improved” symptoms on the PGIC scale. Bern SIH score also significantlyimproved post-embolization. This contrasted with conventional embolizationwhere 1 patient did not have clinical or imaging improvement.

Conclusion: Dual-microcatheter pressure cooker embolizationtechnique is highly efficacious and safe treatment for CVF associated withSIH.

O3-3-2

Efficacy and safety of trans-venous embolization of CSF-venous fistulain patients with spontaneous intracranial hypotension

Donna Parizadeh³, Olga Fermo², David Miller¹, Vivek Gupta¹, Prasana Vibhute¹, Todd Rozen², Sanjeet Grewal³, Thien Huynh¹

¹Department of Radiology, Mayo Clinic, Jacksonville, USA

²Department of Neurology, Mayo Clinic, Jacksonville, USA

³Department of Neurosurgery, Jacksonville, USA

Purpose: Endovascular transvenous embolization is a noveltreatment for patients with spontaneous intracranial hypotension (SIH)secondary to CSF-venous fistulas (CVF). The technique was introducedrecently with promising results at a single center. We sought to perform thefirst independent validation of the efficacy and safety of this novelprocedure.

Methods: Data were collected prospectively. Inclusion criteriawas: 1) clinical diagnosis of SIH, 2) definitive diagnosis of CVF on eitherdigital subtraction myelogram or CT myelogram, 3) transvenous embolizationfor treatment of CVF at Mayo Clinic, Florida, between December 2020 - March2022, 4) available clinical and imaging follow-up after the procedure.Clinical symptoms pre- and post-embolization were assessed usingstandardized scores including the Headache Impact Test (Hit-6) and PatientGlobal Impression of Change (PGIC) score. Features of SIH pre- andpost-embolization were assessed using the Bern SIH score on brain MRI.Procedural and post-procedural complications were recorded. Pre-andpost-embolization outcomes were compared with Wilcoxon Signed Rank test

Results: Eighteen patients (mean[SD] age 58[10] years, 78%female) underwent transvenous embolization for treatment of CVF. Median(IQR) follow-up was 3.5(4.5) months for clinical (available for 17 patients)and 2 (8) months for imaging outcomes, available for 17 and 11 patients,respectively. All patients had available one-week PGIC scores which reportedhighest level of satisfaction with the treatment in 95%. Among 17 patientswith available clinical follow-up, headache severity decreased significantlypost-embolization (mean HIT-6 score of 63.1 pre-embolization and 38.2post-embolization, p = 0.001). Of 11 patients with available follow-upimaging, concordant with clinical improvement, post-operative Bern SIH alsosignificantly decreased (mean Bern score of 7.5 pre-embolization and 3.1post-embolization, p = 0.009). One case did not improve in clinical orimaging findings. There were no neurological/hemorrhagic complications. Sideeffects were localized back pain (50%) and rebound headache (55%) whichresolved within one month with medical treatment in all cases.

Conclusion: Transvenous embolization is a highly efficacious andsafe treatment for CVF in patients with SIH.

O3-3-3

Spontaneous intracranial hypotension - the quest for the leak

Tomas Dobrocky¹, Ralph Schär², Christoph Schankin³, Jürgen Beck⁴, Eike Immo Piechowiak¹

¹Institute of Diagnostic and Interventional Neuroradiology,University of Bern, Inselspital, Switzerland

²Department of Neurosurgery, University of Bern, Inselspital,Switzerland

³Department of Neurology, University of Bern, Inselspital, Bern,Switzerland

⁴Department of Neurosurgery, Medical Center — University ofFreiburg, Germany

Spontaneous intracranial hypotension (SIH) is a debilitating medicalcondition caused by the loss of cerebrospinal fluid (CSF) at the level ofthe spine. The most common clinical manifestation of the disease isorthostatic headache, which increases in the upright position and subsidesafter laying down.

Patients with SIH often endure considerable diagnostic delay and mountingmorbidity. Neuroimaging plays a crucial role in diagnosing and monitoringSIH, as it provides objective (albeit often subtle) data in the face ofvariable clinical syndromes and often normal lumbar puncture openingpressure.

Spinal imaging chiefly aims to classify and localize the site of CSF leakageas a ventral dural leak, leaking spinal nerve root diverticulum, or directCSF-venous fistula. The quest for the leak may be the fabled search for theneedle in the haystack, scrutinizing the entire spine for a dural breachoften the size of pin. Precisely locating the site of CSF leakage isfundamental to successful treatment, which is generally a targetedpercutaneous epidural patch or surgical closure when conservative measuresfail to provide long-term relief.

In this review we provide an update on the diagnostic criteria,pathophysiology, and neuroimaging in SIH. We describe the value of brain MRIand provide a comprehensive guide to the diagnostic spine work-up foridentifying and localizing CSF leaks. We highlight the challenges and someclues of the CSF leak quest

O3-3-4

Brain Spontaneous Intracranial Hypotension Score for treatmentmonitoring after surgical closure of the underlying spinal duralleak

Tomas Dobrocky¹, Jan Gralla¹, Christoph Schankin², Jürgen Beck³, Eike Immo Piechowiak¹

¹Institute of Diagnostic and Interventional Neuroradiology,University of Bern

²Department of Neurology, University of Bern, Inselspital, Bern,Switzerland

³Department of Neurosurgery, Medical Center — University ofFreiburg, Germany

Purpose: To assess suitability of the brain MRI-based, SIH score(bSIH) for therapy success monitoring of SIH patients with a proven spinalCSF leak after microsurgical closure of the underlying dural breach.

Methods: This retrospective cohort study included consecutiveSIH patients with a proven spinal CSF leak, investigated at our departmentfrom January 2012 to March 2020. The bSIH score integrates 6 imagingfindings; 3 major (2 points) and 3 minor (1 point), and ranges from 0 to 9,with 0 indicating low and 9 high probability of spinal CSF loss. The scorewas calculated using brain MRI before and after surgical treatment of theunderlying CSF leak. Headache intensity was registered on a numeric ratingscale (NRS) (range: 0–10).

Results: Fifty-two SIH patients (35[67%] female; mean age, 45.3years) with a proven spinal CSF leak were included. The mean bSIH scoredecreased significantly from baseline to after surgical closure of theunderlying dural breach (6.9 vs 1.3, P <.001). Adecrease in the NRS score was reported (8.6 vs 1.2, P<.001).

Conclusions: The bSIH score is a simple tool which may serve tomonitor treatment success in SIH patients after surgical closure of theunderlying spinal dural leak. Its decrease after surgical closure of theunderlying spinal dural breach indicates restoration of an equilibriumwithin the CSF compartment.

O3-3-5

Lens dose reduction by table height adjustment duringthree-dimensional cerebral angiography: phantom and clinicalstudies

Jae-Chan Ryu¹, Jong-Tae Yoon¹, Mi Hyeon Kim¹, Ki Baek Lee², Deok Hee Lee¹, Yunsun Song¹

¹Department of Radiology, Asan Medical Center

²Biomedical Engineering Research Center, Asan Institute for LifeSciences, Asan Medical Center

Purpose: The necessity of lens dose reduction has been ofinterest as the number of neurointerventional procedures is rapidlyincreasing. This study aimed to evaluate the radiation dose to the lensaccording to the table height in three-dimensional rotational angiography(3D-RA).

Materials and Methods: In the phantom study, the radiation doseto the lens was evaluated by placing photoluminescent glass dosimeters (PLD)on the eyes of a Rando head phantom. We measured the dose on variable tableheight positions. The optimal table height was derived in terms of the lensdose and appropriacy of the field of view (FOV). In the clinical study, weenrolled the 20 patients planning to undergo cerebral diagnostic angiographyand who had intracranial aneurysms in bilateral anterior circulations. The3D-RA of both internal carotid arteries was performed using conventional andadjusted (optimal height from the phantom study) positions in each patient,respectively. The lens and overall radiation doses were compared between thegroups using paired T-test The image quality and appropriacy of the FOV werequalitatively evaluated.

Results: In the phantom study, as the table height increased,the radiation dose applied to the lens tended to decrease. Lowering 3 cmfrom the conventional height significantly lowered the lens dose by 77%(1528 vs. 343 µGy). Additionally, it was determined that there would be noproblem in evaluating blood vessels on the adjusted height positionconsidering the FOV of the second reconstruction in routine 3D-RA. Theresults of the clinical study is pending and going to be presented on WFITN2022.

Conclusion: An appropriate increase in the table height cansignificantly reduce the dose to the lens without affecting clinicalvascular evaluation.

O3-3-6

Scoring system to assess proficiency in cerebral angiography forneuroendovascular surgery education

Kouichi Misaki, Takehiro Uno, Taishi Tsutsui,Tomoya Kamide, Mitsutoshi Nakada

Department of Neurosurgery, Kanazawa University, Kanazawa, Japan

Purpose: Cerebral angiography is indispensable for endovascularneurosurgeons. However, there is no established system to evaluate thecompetency of trainees. We established a scoring system and statisticallyanalyzed its usefulness.

Materials and Methods: Endovascular neurosurgeons scored theoperators of 177 cerebral angiography based on ten evaluation items. Thereare ten evaluation items; preoperative procedure explanation, deviceselection, device assembly, guidance to the patient, sheath insertion,reduction of radiation exposure, angiography device, catheter operation,blood contamination and failure occurrence. If there was a problem with eachpoint, it was set to 0 points. Total of 10 points were given. Forendovascular neurosurgery, the success rate of each operator was calculatedfor sheath insertion, guiding catheter and guidewire, microcatheter andguidewire, treatment procedure and its assistant, and puncture sitehemostasis. The correlation between the success rate of each operator andthe angiography score was analyzed by Spearman's rank correlationanalysis.

Results: Nine neurosurgeons participated in angiography andendovascular neurosurgery, with an average total score of 7.82 forangiography and an average score of 0.71–0.89 for each point. The proceduresuccess rate ranged from 78 to 97%, averaging 90%. The total score of theangiography was significantly correlated with the procedure success rate andhad a correlation coefficient of 0.683 (p = 0.042). Among each point in theangiography, the strongest correlation with the procedure success rate wasblood contamination with a correlation coefficient of 0.778 (p = 0.014).

Conclusions: A significant correlation was observed between thetotal score of the angiography and the procedure success rate. Thisevaluation system indicates the proficiency of endovascular treatment. Sinceblood contamination has the strongest correlation with the procedure successrate, preserving the surgical field clear indicates a high degree ofmaturity.

O3-4-1

Intracranial Aneurysm Coiling with the i-ED COIL: Initial Experiencein the United States

Maximilian Jeremy Bazil, Johanna T Fifi,Tomoyoshi Shigematsu

Neurosurgery, Icahn School of Medicine at Mount Sinai

Purpose: Endovascular aneurysmal coiling is a preventativealternative to clipping to avoid aneurysmal rupture. We describe ourexperiences with the i-ED coil (Kaneka; Osaka, Japan), offering a monopolarelectrode detachment system, soft, flexible coils that minimally perturb thedeploying microcatheter (SilkySoft Technology), and longer coils withgeneral, lowmemory structures (Infini and Complex Infini Shaping).

Materials and Methods: We retrospectively reviewed a consecutivecase series of seven (7) intracranial aneurysm patients who received Kanekai-ED Coils since their initial use in our practice (December 2020) andDecember 2021.

Results: Of the seven patients given i-ED coils, 2/7 (28.6%)achieved a RR score of 2 and four (57.1%) achieved a RR score of 1 with onenear-complete fusiform occlusion. We compared the number of coils requiredfor treatments using i-ED coils to total coils for treatment of the 50 mostrecent, non-i-ED coiling patients at our practice. Cases which used i-EDcoils achieved a significantly higher packing density (p < 0.01) thanother cases in our practice. The ratio of percent packing density achievedto coils used was significantly higher (p < 0.05) in the i-ED coil cases(average PD/Coils: 12.37 SD: 5.74) than in the non-i-ED cohort (averagePD/Coils: 7.35 SD: 5.62).

Conclusion: Our initial experience with i-ED coils hasidentified a trend of using fewer coils to achieve a higher packing density.The i-ED coils have shown preliminary success in our cohort. We arecurrently performing a larger case series to investigate these findings morerigorously.

O3-4-2

Treatment outcome of distal non-saccular intracranial aneurysms atSiriraj hospital, Thailand: a retrospective review of a singlecenter

Supachart Chaewchantuek, Pattarawit Withayasuk,Anchalee Churojana, Thaweesak Aurboonyawat, Ekawut Chankaew, BoonrerkSangpetngam

Department of Radiology, Interventional neuroradiology center, Sirirajhospital, Bangkok, Thailand

Purpose: A distal non-saccular intracranial aneurysm (DNSIA) isuncommon. The natural history and principles of management are not wellestablished. Our purpose is to evaluate the outcome of the treatment ofDNSIA in different modalities at Siriraj hospital, Thailand.

Method: A retrospective review of patients who were diagnosed ofDNSIA at Siriraj Hospital between July 2013 and June 2021was performed. Datacollection included patient characteristics, clinical presentations,locations of aneurysms, treatment methods and outcomes. The treatments weresummarized into 4 groups, 1 Endovascular treatment (EVT) with parent arteryocclusion (PAO), 2 EVT with parent artery preservation (PAP), 3 surgery withaneurysmal clipping or trapping, 4 conservative treatment. Patient outcomeswere defined as clinical and imaging outcome. The complications weredetermined immediately after each treatment.

Result: There were 46 patients with 49 DNSIAs from 593 cases(7.7%) of intracranial aneurysms who had diagnosed at our center. Theruptured DNSIAs was revealed at 83.7%. The common etiologies were idiopathic(51%), non-traumatic dissection (20.4%), and mycotic (18.4%). The mostcommon locations were posterior cerebral artery (22%), anterior cerebralartery (18.4%) and equally posterior inferior cerebellar artery (18.4%). Themodalities of treatment were EVT with PAO 49%, EVT with PAP 4.1%, surgery30.6% and conservative management 16.3%. Associated hydrocephalus was foundin 32.7%. From 41 patients who underwent treatment, 90.2% had completeobliteration, 7.3% had aneurysmal recanalization, 2.4% had residual lesion.There was no re-rupture aneurysms during the follow up period (averaged29.37 months). Procedural complications occurred in 7 cases (17.1%), 3/7 hadhemorrhage during surgical clipping and 4/7 had infarction from EVT withPAO. Unfavorable outcome was documented in 5 patients (10.9%), 3/5 were notrelated to treatment procedures. The favorable outcome showed a significantcorrelation with initial low Hunt and Hess scale(p-value = 0.018).

Conclusion: DNSIA were usually recognized with rupture. EVT withPAO was considered to be the initial treatment of choice due to its safe andefficiency. Surgical procedure with distal flow preservation should be thealternative procedure when territory infarction was in concern. Conservativemanagement was recommended for non-ruptured DNSIAs.

O3-4-3

Analysis of the effect of simultaneous endovascular treatment ofvertebrobasilar stenosis combined with ipsilateral vertebrobasilaraneurysm.

Yang Wan xin, Li Jing Wei

Department of Xuanwu Hospital Capital Medical University

OBJECTIVE: To analyze the safety, feasibility and clinicaleffects of simultaneous endovascular treatment of vertebrobasilar stenosiscombined with vertebrobasilar aneurysm.

METHODS: The clinical data of six patients with ipsilateralvertebrobasilar stenosis combined with ipsilateral vertebrobasilar aneurysmwho underwent simultaneous endovascular treatment at the Department ofNeurosurgery, Xuanwu Hospital, Capital Medical University, from 01, 2017 to08, 2020 were collected. All six patients underwent simultaneous stentingand embolization of vertebrobasilar artery stenosis and vertebrobasilarartery aneurysm. The patients’ clinical symptoms, imaging data andcomplications were recorded for the operative period and postoperativeperiod.

RESULTS: Stents were successfully placed in the arterialstenosis in 6 patients, stent-assisted embolization of the aneurysm wasperformed in 5 patients, and multi-catheter embolization was performed in 1patient. One patient had a reduced Barthel index score after surgery, andthe rest had no related complications. At postoperative follow-up at months3, 6, and 12, none of the patients had arterial restenosis, none of theaneurysms had recurrence, and no intracranial hemorrhage, cerebralinfarction, or TIA episode occurred.

CONCLUSION: The technique of simultaneous endovascular treatmentof vertebrobasilar stenosis combined with vertebrobasilar aneurysm is afeasible and relatively safe treatment method.

O3-4-4

Utility of i-ED soft coils and the i-ED-14 Infini coil forembolization of cerebral aneurysms and dual AVFs

Kei Harada, Kohsuke Kakumoto, Shogo Oshikata,Masahito Kajihara

Department of Neurosurgery, Fukuoka Wajiro Hospital

Background: The ED coil-10 was used as an extremely soft coilfor cerebral aneurysm embolization. The coil is improved as “i-ED coil”.I-ED soft coils are soft and suitable for finishing with less kickback. Thei-ED 14 Infini coils are 0.010 to 0.014-inch, less shaped memory, and aresuitable for stent-assisted embolization of cerebral aneurysms. We report ontheir utility.

Materials & Methods: The i-ED coils were used in 101(unruptured 75; ruptured, 26) and 9 dural AVF (T-S 5; CS 4) between January2020 and December 2021 in our hospital.

Results: The i-ED soft coils were mainly used as the finishingcoil, and the i-ED 14 Infini coils were used during stent-assistedembolization. The i-ED 14 Infini coils were suitable for sinus packing ofT-S dAVF, and i-ED 12 Infini coils were easy to fit into complex shapesduring target embolization of the CS dAVF.

Conclusions: The i-ED soft coils are extremely soft and suitablefor the finishing stage of embolization. The i-ED 14 Infini coil seeks theopen space in the aneurysms regardless of the size and shape of the coils(30cm and 50 cm) regardless of the secondary coil diameter can be selected,and suitable for stent-assisted embolization.

O3-4-5

Endovascular treatment of intracranial aneurysms with Galaxy andMicrusFrame coils: interim outcomes in the STERLING registry

Kenji Sugiu¹, Reade A. De Leacy², Ajit S. Puri³, Robert M. Starke⁴, Brian T. Jankowitz⁵, Albert Yoo⁶, Florent Gariel⁷, Shady Jahshan⁸, Zsolt Kulcsar⁹, Clemens Schirmer¹⁰, Cyril Chivot¹¹, Jay Howington¹², Guglielmo Pero¹³, Tom Yao¹⁴, Adam Polifka¹⁵, Avery Evans¹⁶, Osama Zaidat¹⁷

¹Department of Neurological Surgery, Okayama University GraduateSchool of Medecine, Okayama, Japan

²Department of Neurosurgery, Icahn School of Medicine at MountSinai, New York, NY, USA

³Department of Radiology, University of Massachusetts, Worcester,MA, USA

⁴Department of Neurological Surgery, University of Miami MillerSchool of Medicine, Miami, Florida, USA

⁵University of Pennsylvania, Philadelphia, Pennsylvania, USA

⁶Department of Neurology, Texas Stroke Institute, Plano, TX,USA

⁷Department of Neuroradiology, Centre Hospitalier Universitaire deBordeaux | CHU Bordeaux

⁸Department of Interventional Neuroradiology, Galilee MedicalCenter, Galilee, Israel

⁹Department of Neuroradiology, University Hospital of Zurich,Zurich, Switzerland

¹⁰Department of Neurosurgery, Geisinger Medical Center, Danville,PA, USA

¹¹Department of Radiology, Amiens University Hospital, France

¹²Department of Neurosurgery, Memorial Health University MedicalCenter, Savannah, GA, USA

¹³Department of Neuroradiology, ASST Grande Ospedale MetropolitanoNiguarda, Milan, Italy

¹⁴Norton Neuroscience Institute, Norton Healthcare, Louisville,KY, USA

¹⁵Department of Neurosurgery, University of Florida, Gainesville,FL

¹⁶Department of Interventional Neuroradiology, University ofVirginia School of Medicine, Charlottesville, VA

¹⁷Department of Neuroscience, Mercy Health St Vincent MedicalCenter, Toledo, OH, USA

Purpose: To present safety and available long-term outcomes forthe first 450 subjects enrolled in STERLING (NCT03642639) - a prospective,real-world, post-market, international registry of endovascular treatment ofintracranial aneurysms with the Galaxy and MicrusFrame coils (Cerenovus,Irvine, CA, USA).

Materials and Methods: Subjects were enrolled between August2018 and January 2021 at 46 global sites (29 US, 12 EU, 5 Japan) and weretreated according to standard of care at each center. Long-term outcomeswere evaluated at 1-year follow-up (−3/ + 6 months) and at end-of-study (1year −3 months/ + 1.5 years to allow follow-up that may have been missed dueto COVID-19). Aneurysm occlusion was assessed by an independent core labusing the Raymond-Roy (RR) scale.

Results: Among the 450 subjects, mean age 58.8 ± 11.57 years,70.9% (319/450) were female. Aneurysm characteristics included: rupturedstatus in 28.9% (129/446); 85.5% (341/399) anterior and 14.5% (58/399)posterior circulation; 54.8% (217/396) bifurcation, 45.2% (179/396)side-wall location; 97.7% (390/399) saccular, 2% (8/399) fusiform, 0.3%(1/399) dissecting morphology; 23.3% (93/399) small (<5 mm), 71.7%(286/399) medium (≥5 to <13mm), 5% (20/399) large (≥13mm) size; and 78.7%(314/399) were wide-necked. At the 1-year follow-up, 86.1% (87/101) subjectsachieved adequate occlusion (RRI or RRII) without retreatment(87.9%[102/116] at the end of study) and 72.3% (73/101) achieved completeocclusion (RRI; 74.1%[86/116] at the end of study), and 98.1% (102/104) ofthose with unruptured aneurysms achieved good-to-ideal clinical outcome (mRS0–2). There were 3/450 (0.7%) intraprocedural ruptures, 4/450 (0.9%)symptomatic intraprocedural thromboembolic events, and 10 (2.5%)device-related SAEs through the end of study.

Conclusion: Interim analysis of the STERLING registry showedGalaxy and MicrusFrame coils have good angiographic, clinical and safetyoutcomes in a broad range of aneurysm types.

O3-4-6

Withdraw

O3-5-1

Safety and Efficacy of Eptifibatide for endovascular intracranialaneurysm treatment

Tilman Schubert, Hakim Shakir Husain, PatrickThurner, Jawid Madjidyar, Zsolt Kulcsar

Neuroradiology, Zurich University Hospital

Purpose: Despite technical progress and increasing experience ofoperators, the rate of thromboembolic complications during endovascularaneurysm treatment remains at a relatively high rate of about 10% (1).However, only 30% of these complications result in clinically symptomaticevents. One effective group of drugs in treating and preventing embolicevents are GP IIb/IIIa inhibitors (2).

In this study, we report our results concerning safety and efficacy ofepitifibatide in the prevention and treatment of thromboemboliccomplications in ruptured and unruptured aneurysms and propose an algorithmfor eptifibatide administration.

Methods: Over a 3.5-year period at our institution, eptifibatidewas used during 69 endovascular aneurysm procedures in 68 patients. Amongthe procedures were 41 cases of ruptured aneurysms (59%). Reasons forepitifibatide treatment were: clot at the coil surface, clot preventionbefore stent placement and distal emboli. Presence of distal occlusion atthe end of the procedure and intracranial hemorrhage were recorded aspredictors of efficacy and safety.

Results: Eptifibatide was given during 43 coiling procedures, 14placements of a flow-diverter and 12 stent assisted coiling procedures.Treatment indications were: clot at the coil surface in 34 (49%), preventionbefore stent placement in 17 (25%) and embolism in 16 cases (23%).Eptifibatide was given as arterial bolus in 17 (25%), as intravenousinfusion in 15 (22%) and combined in 37 cases (54%). Symptomatic infarctionsoccurred in 7 cases (10%). In two patients (3%), intracranial hemorrhageoccurred (one clinically silent bleeding and one fatal parenchymalhemorrhage).

Conclusion: Based on our experience, we propose an algorithm foreptifibatide administration for endovascular aneurysm treatment based onpatient characteristics as well as the postinterventional angiogram. Thisrisk-estimation based algorithm includes presence of subarachnoid hemorrhage(SAH), severity of SAH, presence of intracerebral hemorrhage extension,acute ischemic injury and additional antithrombotic medication.

O3-5-2

Prasugrel-based antiplatelet treatment for flow-diverting stentimplantation

Hyun-Seung Kang

Neurosurgery, Seoul National University College of Medicine, Seoul NationalUniversity Hospital, Seoul, Korea

Introduction: Antiplatelet therapy is an essential part forsuccessful endovascular treatment of intracranial aneurysms, especially inthe setting of flow-diverting stent (FDS) implantation. Here we report onthe clinical outcomes of prasugrel-based antiplatelet treatment for FDSimplantation in a single institution.

Materials & Methods: During the period from June 2015 toMarch 2022, prasugrel-based antiplatelet therapy was performed in 75patients (78 sessions) undergoing FDS implantation for intracranialaneurysmal diseases. Typical antiplatelet therapy included prasugrel loading(20 mg) on the day before endovascular treatment, and maintenance (5 mg) for1 month in combination with aspirin (100 mg). Dual antiplatelet therapy withclopidogrel/aspirin was maintained for another 5 months, and thenmonotherapy was kept lifelong. The nature of aneurysms were large/giant(>10 to 15 mm), dissecting or fusiform. The disease locations were theinternal carotid artery in 34 (cavernous/paraclinoid in 32, supraclinoid in2), middle cerebral artery in 1, posterior cerebral artery in 3, distalvertebral in 33, vertebrobasilar junction/basilar artery in 3, posteriorinferior cerebellar artery in 1.

Results: There was no thromboembolic complications duringprocedural and periprocedural period. During single antiplatelet therapy,delayed stent thrombosis occurred in 3 patients (one resulted in cerebralinfarction) and, otherwise, ischemic infarction occurred in 1 related to theorifice stenosis of the posterior inferior cerebellar artery. One patientwith a giant (37 mm) paraclinoid aneurysm developed aneurysmal rupture 9days after FDS placement and coiling, resulting in significant morbidity.Follow-up imaging more than 3 months were available in 62, and complete/nearcomplete occlusion could be achieved 51 aneurysms (82.3%).

Conclusion: In our series, short-term prasugrel therapy seemedto provide safety for FDS implantation procedures, eliminating chances ofprocedural/periprocedural thromboembolic events with a minimal risk ofhemorrhage.

O3-5-3

The possibilities of terminating antiplatelet therapy after stentassisted coil embolization of intracranial aneurysm: Long termobservational results of the single center retrospectiveexperience

Shunsaku Goto^1,2, Takashi Izumi¹, Masahiro Nishihori¹, Kojiro Ishikawa¹, Eiki Imaoka¹, Hiroki Matsuno¹, Hayato Yokoyama¹, Tsuyoshi Saito¹, Kento Hanyu¹, Ryuta Saito¹

¹Department of Neurosurgery, Nagoya University Graduate school ofMedicine

²Department of Neurosurgery, Nagoya Medical Center

Purpose: After the stent assisted coil embolization (SACE) ofthe intracranial aneurysms, the protocol of the antiplatelet therapy is notestablished well. Especially, proprieties of terminating single antiplatelettherapies (SAPT) are still controversy. The purpose of this study is toinvestigate the possibilities of terminating SAPT after SACE by analyzingthe long-term result in our institution.

Methods: Patients underwent SACE from 2010 to 2020, and could befollowed for more than 1 year were included. Delayed ischemic complicationrate and hemorrhagic complication rate in the course of follow up wereexamined. Moreover, the risk factors of reducing or terminating theantiplatelet therapy, and results of terminating SAPT were alsoanalyzed.

Results: Two hundred forty patients were included. Average agewas 60.3 years old, and average follow-up period was 46.7months. Symptomaticdelayed ischemic complication was observed in 9 (3.8%) cases, and thedeterioration of the mRS was observed in 3 (1.3%) cases. T or Yconfiguration of the stents is the only risk factor of delayed ischemiccomplication (p < 0.001). Limited to the patients followed up more than 2years, SAPT was terminated in 145/205 (70.7%) cases, and no ischemiccomplication were observed.

Conclusions: Retrospectively analyzing the experience ofterminating the SAPT at the single center, it was possible to safelyterminate the SAPT in patients which ischemic complications didn't not occurand intra aneurysmal signal was stable by MRA who for 2 years in many cases.Y or T configuration of stents are high risk factor of delayed ischemiccomplications, and careful consideration is required for reduction ortermination of antiplatelet drugs.

O3-5-4

Thromboelastography with platelet mapping predicts thromboembolism inpatients underwent neuroendovascular treatment.

Ichiro Nakagawa, Masashi Kotsugi, ShoheiYokoyama, HunSoo Park, Ryosuke Maeoka, Takanori Furuta, Haku Tanaka,Kenta Nakase, Ai Okamoto, Hiromitsu Sasaki, Hiroyuki Nakase

Department of Neurosurgery, Nara Medical University, Nara, Japan

Background: Although inhibition of platelet aggregation isessential to avoid thromboembolic complications for neuroendovasculartreatment, excessive inhibition can result in hemorrhagic complications.There are two commercially available measures of adenosine diphosphate (ADP)dependent platelet inhibition, VerifyNow clopidogrel assay and maximalamplitude (MA) attributable to ADP activity (ADP-MA) derived fromthromboelastography (TEG) with platelet mapping. This study sought tocompare platelet function during the perioperative period ofneuroendovascular treatment using TEG6s and VerifyNow.

Method: From November 2020 to January 2022, 102 patients whounderwent neuroendovascular treatment including cerebral aneurysm treatmentand carotid artery stenting (CAS) were retrospectively evaluated. Dualantiplatelet drugs, aspirin 100 mg, clopidogrel 75 mg, or cilostazol 200 mgdaily, were administered preoperatively. The platelet function was measuredfrom the day before treatment to 3 months after the treatment, and ADP-MA,ADP %inhibition, P2Y12 reaction unit (PRU), and PRU %inhibition wereperformed simultaneously and multiple times, respectively, to evaluate thecorrelation between the two assays and their relationship to positivepostoperative DWI findings and perioperative complications.

Results: A total of 266 times in which both tests were performedsimultaneously in all 102 cases. There were significant positivecorrelations ADP-MA / ADP %inhibition and PRU / PRU %inhibition in cerebralaneurysm treatment (n = 56; r = 0.478, 0.587, p <0.0001, 0.0001,respectively) and in carotid artery stenting (n = 46; r = 0.499, 0.552, p<0.0001, 0.0001, respectively). In addition, a strong relationship withpostoperative DWI-positive lesions was observed in ADP-MA value (56.4 ± 6.7vs 46.3 ± 11.9, p <0.001) and the ADP %inhibition value (11.0 ± 8.3 vs29.3 ± 21.9, p <0.001).

Conclusion: ADP-MA and ADP %inhibition have been shown to beuseful in detecting antiplatelet drug resistance.

O3-5-5

Reduction of delayed cerebral ischemia after subarachnoid hemorrhageby coil embolization combined with preoperative antiplateletstherapy.

NORIHITO SHIMAMURA¹, Takeshi Katagai², Nozomi Fujiwara², Takao Sasaki², Shouhei Kinoshita², Keita Yanagiya², Kouta Ueno², Ryouta Watanabe², Yu Nomura², Kiyohide Kakuta², Kosuke Katayama³, Masato Naraoka²

¹Department of Neuroendovascular Therapy, Hirosaki UniversityGraduate School of Medicine

²Department of Neurosurgery, Hirosaki University Graduate Schoolof Medicine

³Department of Neurosurgery, Kuroishi General Hospital

Purpose: Cilostazol, fasudil chloride and interventionaltreatment influence the incidence of delayed cerebral ischemia (DCI) afteraneurysmal subarachnoid hemorrhage (SAH). In our institute, administrationof oral antiplatelets is done preoperatively for coiling of rupturedcerebral aneurysm. We retrospectively analyzed changes of DCI over theyears.

Material and Methods: We compared SAH patient cohort in earlyperiod (2008∼2010, n = 152) with that in late period (2018∼2020, n = 141).All patients were treated within 10 days after the onset of SAH. Method ofaneurysm repair was selected after discussion of certificated neurosurgeonand neuro-interventional surgeon. New neurological deficit and/or cerebralinfarction was defined as DCI. Univariate analysis, logistic regressionanalysis and propensity score matching following multivariate analysis weredone for detection of factor that influenced DCI or outcome of SAH.

Results: Age, gender, Hunt-Kosnik grade and Fisher group weresimilar in both periods. Univariate analysis showed that internal carotidartery aneurysm, posterior fossa aneurysm and coiling significantlyincreased in late period. Onset day of DCI in early periods (9.1 ± 0.50 sd.)and in late periods (8.0 ± 0.66 sd.) were similar, but the incidence of DCIsignificantly decreased from 20% to 9.9%. Balloon angioplasty for treatmentof symptomatic vasospasm was increased from 6.3% to 29% (p < 0.05).Recurrent DCI increased from 27% to 38%. Logistic regression analysisrevealed that coiling significantly reduced incidence of DCI. Favorableoutcome (GR and MD) increased from 57% to 64%. Propensity score matchingrevealed that DCI reduced in late period and coiling reduced DCI.

Conclusion: Incidence of DCI decrease to half, but recurrent DCIincrease in this analysis. Coiling combined with preoperative antiplateletsadministration reduce DCI and produce favorable outcome.

O3-5-6

Platelet reactivity predicts subacute flow-diverter thrombosis

Yukiko Enomoto, Yusuke Egashira, HirofumiMatsubara, Kenji Shoda, Toru Iwama

Neurosurgery, Gifu University Graduate School of Medicine

Introduction: The frequency of severe thromboemboliccomplications in flow diverter (FD) placement is about 5%, of which the mostsevere complication is thrombotic occlusion of FDs. We investigated thefrequency of thrombotic obstruction in FD and related factors, focused onplatelet reactivity before procedure.

Method: Clinical outcomes; 1) positive hyperintensity signals onpostoperative DWI, 2) symptomatic ischemic complications, 3) thromboticocclusion of FDs, 4) hemorrhagic complications were investigated in 42patients who underwent FD treatment at our hospital between Oct.2017 andMar.2022. Factors including platelet reactivity related to each complicationwere retrospectively analyzed by univariate analysis (Mann-Whiteny U test(continuous variable) or Fisher's exact test (category variable) using JMP12.0 (SAS institute). Platelet reactivity tests are performed just beforethe procedure using VerifyNow (Werfen, Spain) and a light transmissionplatelet aggregometer (Sysmex, Japan). The values including ARU, PRU, %inhibition and ADP (1uM, 10uM) / collagen (2ug /dl, 5ug / dl) induedaggregation score (APAL, CPAL) were calculated in all patients.

Result: Positive hyperintensity signals on postoperative DWIwere found in 23 cases (54.8%), symptomatic ischemic complications in 3cases (7.1%), hemorrhagic complications in 7 cases (16.7%), and FDthrombosis in 4 cases (9.5%). Delayed complications after 30 days from theprocedures were found in 5 cases (11.9%; TIA after discontinuation ofantiplatelets, 4 cases of intra-FD stenosis). All FD thrombosis occurredsubacute stage (1 h, 4, 8 and 11 days after the procedure).

In the univariate analysis of factors associated with each complication, onlyFD thrombosis was associated with preoperative platelet reactivity; PRU(p = 0.006),% inhibition (p = 0.011) nad APAL (p = 0.028). Collagen-inducedplatelet aggregation score; CPAL (p = 0.067) also showed a tendency. Thecutoff values associated with FD thrombosis were PRU 251,% inhibition 5%,and APAL 6.9, respectively.

Discussion: Preoperative platelet reactivity test values werenot associated with positive hyperintensity signals on postoperative DWI andperioperative ischemic / hemorrhagic complications but were associated withsubacute FD thrombosis.

Conclusion: Perioperative antiplatelet therapy may contributethe prevention of FD thrombosis that occurred after the subacute phase.

It was suggested that it is necessary to continuously evaluate plateletreactivity not only before but also after the procedure.

O3-6-1

Spatially-resolved transcriptomics for investigation of intracranialvessels in a rabbit model.

Matthew David Alexander^1,4, Daniel L Cooke², Chuanzhuo Wang³, Matthew Zabriskie¹

¹Department Radiology and Imaging Sciences, University of Utah

²Department of Radiology and Molecular Imaging, University ofCalifornia San Francisco, San Francisco, CA, USA

³Department of Radiology, Shengjing Hospital of China MedicalUniversity, Shenyang, China

⁴Department of Neurosurgery, University of Utah, Salt Lake City,UT, USA

Purpose: Demonstration of feasibility of spatially-resolvedtranscriptomic (SRT) analysis for acquisition of high-quality data for thestudy of intracranial vessels and cerebrovascular pathophysiology in arabbit model.

Materials and Methods: Two sibling rabbits were euthanized andbrains with intact arteries harvested and then flash frozen in optimalcutting temperature compound. 10-micron thick slices were made. RNAextraction was performed with the RNeasy Mini protocol for purification oftotal RNA and then subjected to RNA integrity number (RIN) calculation usingthe Agilent RNA 6000 Pico kit, confirming RINs exceeding the threshold of 7for the Visium SRT platform. Tissue optimization was performed to determinethe optimum permeabilization duration, which was then used for performanceof gene expression analysis. cDNA libraries generated include geographicbarcode information so that gene expression data can be mapped back to theH&E-stained image to localize the expression traits anatomically. Beforevisualizing STR dots, clearly visible vessels were traced, and geneexpression data for dots each of the traced regions were isolated. Dotswithin the confines of traced regions were labeled and further assigned toartery or vein groups based on histologic appearance. For unsupervisedassessment, k-means clustering analysis was performed using n = 3 clustersfor all tissue and for the vessel-traced regions. Finally, differentialexpression of dots within vessel tracings was examined, comparing geneexpression between arteries and veins.

Results: Tissue optimization demonstrated optimumpermeabilization duration of 24 min. Across the four capture areas, 7039dots were identified with high quality gene expression data. 127 dots wereassigned to the cluster corresponding to vessels by K-means clustering. 69total dots were included in vessel tracing regions. Among these, 62 (89.9%)were assigned to the K-means cluster corresponding to vessels, while 7(10.1%) were assigned to other clusters. Among the top 50 differentiallyexpressed genes when comparing artery and vein dots, the top four genescorresponded to smooth muscle cell components, which are present in arteriesand absent in veins.

Conclusion: Model animals provide opportunities for research andare particularly useful when human tissue cannot be safely or reliablyobtained. Rabbits are a particularly valuable model animal for the study ofcerebrovascular diseases. This study provides proof-of-concept results usingSRT analysis with the Visium platform for the assessment of intracranialvessels in rabbits. These results show that high-quality SRT data can beobtained from rabbit brain samples. Preliminary gene expression analysiswith unsupervised machine learning techniques adequately identified vessels.Further face validity was found in differential expression that correctlydistinguished arteries from veins with gene products expected to beidentified in the former and absent in the latter.

O3-6-2

Histological analysis of the membrane-dura interface in chronicsubdural hematomas

Matthew B Potts², Amr Alwakeal¹, Pouya Nazari¹, Babak S Jahromi¹, Mireille Bitar²

¹Neurological Surgery, Northwestern University Feinberg School ofMedicine

²Pathology, Northwestern University Feinberg School ofMedicine

Purpose: Chronic subdural hematomas (cSDHs) are characterized byan inflammatory membrane that forms over the outer surface of the hematoma.This membrane is vascularized and has been implicated in the development andpersistence of cSDHs. Given the increasing interest in middle meningealartery embolization for the treatment of cSDH, a further understanding ofthe pathobiology of cSDH membranes is warranted. We hypothesized that theoverlying dura is involved in the formation of these membranes and sought tocharacterize the histologic changes within the dura in cases of cSDH treatedwith surgical evacuation.

Materials and Methods: We retrospectively reviewed 13 cases ofsymptomatic cSDH treated with surgical evacuation in which samples of duraand attached cSDH membrane were collected. Specimens were formalin-fixed andparaffin-embedded. Standard H&E-stained sections were obtained for allcases and submitted for routine pathological evaluation. Brain autopsy durasamples from non-cSDH cases were used as controls.

Results: The mean age was 76.8 years and nine patients weremale. Two patients presented with bilateral cSDHs while seven had a historyof trauma preceding diagnosis of the cSDH ranging from two to 12 weeks. Inall cases, histological analysis of the dura-membrane interface revealedcSDH membranes consisting of prominent organizing chronic hematoma withfibroblasts, small blood vessels, chronic inflammation, and hemosiderindeposits. Fresh hemorrhage was often found just beneath the cSDH membrane.Focally pronounced vascular proliferation of small blood vessels was evidentalong the dura-membrane interface. Immunohistochemical analysis in selectcases confirmed the presence of vascular proliferation along thedura-membrane interface, including endothelial cells ( + nuclear ERGstaining) and vascular wall smooth muscle cells ( + cytoplasmic SMAstaining). Such proliferation was not seen in normal control dura samples inbrain autopsy material.

Conclusion: The interface between cSDH membranes and theoverlying dura is characterized by abnormal vascular proliferation. Suchproliferation may be involved in the formation of the cSDH membrane andfurther investigation is warranted.

O3-6-3

Short-Term Outcome of Middle meningeal Artery Embolization as aprimary treatment for Patient with Symptomatic Chronic SubduralHematoma.

Methinee Damaied¹, Nongluk Jakkrit¹, Tiplada Boonchai²

¹Nursing department, Trang hospital

²Deparment of Medicine, Trang hospital

Purpose: Middle meningeal artery (MMA) embolization has beenproposed as an alternative to surgical treatment for selected patients withchronic subdural hematoma (cSDH). Symptomatic cSDH or large cSDH withmidline shift patients were considered surgical evacuation. We presentsafety and efficacy of this treatment for symptomatic cSDH patients in ourhospital.

Materials and methods: Our series includes 8 cases ofsymptomatic cSDH with a hematoma thickness greater than 10 mm or a midlineshift greater than 5 mm, were initial treated by MMA embolization. Sixpatients were 6 male, mean age of 60.5 years and two patients had cSDHbilaterally. Symptoms were including motor weakness (5 cases), ataxia (2cases), and cognitive impairment (1 case). Three patients have been takingantiplatelet at time cSDH was diagnosed. An initial noninvasive brainimaging showed midline shift in 6 patients (median 8.75 mm) and medianhematoma thickness was 22.5 mm.

Results: Under local anesthesia and transfemoral approach, allpatients successfully embolised using PVA 250–335 micron to occlude the MMA.There was no procedure-related complication. Osmotic agent was described in4 patients for increase intracranial pressure. One patient developedprogressive weakness due to pressure effect from hematoma which was improvedafter medication treatment. Short-term follow-up, none of patients requiredsurgical intervention. Six of 8 patients had good clinical outcome definedby modified Rankin Score (mRS) 0–2 at 3months. All patients had a greaterthan 50% reduction in hematoma size at 3 months (median thickness 7 mm). Nomortality was reported.

Conclusion: MMA embolization is safe and effective as an initialtreatment for symptomatic cSDH.

O3-6-4

The dural vascular plexus in subdural hematomas: a pivotalneuro-anatomical structure in their physiopathology and the indirecttarget of their management?

Martin Moïse², Julie Lebeau¹, Pierre Bonnet^3,4, Didier Martin¹, Bernard Otto², Félix Scholtes^1,5

¹Department of Neurosurgery, University Hospital of Liège, Liège,Belgium

²Department of Radiology, University Hospital of Liège, Liège,Belgium

³Department of Urology, University Hospital of Liège, Liège,Belgium

⁴Department of Human Systematic Anatomy, Faculty of Medicine,University of Liège, Liège, Belgium

⁵Department of Neuroanatomy, Faculty of Medicine, University ofLiège, Liège, Belgium

Purpose: Subdural hematomas (SDH) have classically beenattributed to bridging vein rupture. Recent advances in the understanding ofmeningeal microanatomy and the efficacy of meningeal arterial embolizationin the management of chronic SDH (cSDH) could underline the pivotal role ofthe dural vascular plexus (DVP) in both development and treatment ofSDH.

Materials and Methods: First, we report the case of a65-year-old woman presenting with a 2-month history of worsening headache.CT showed bilateral cSDH as well as dilated left parietal cortical veins.Digital substracted angiography (DSA) confirmed the diagnosis of dAVF. Theshunt was directly located onto a tortuous left parietal cortical vein(Cognard type 3) with secondary drainage within the superior longitudinalsinus and was fed by bilateral middle meningeal arteries (MMA). After anunsuccessful transarterial embolization, surgical clipping and section ofthe fistula allowed for dearterialization of the draining vein as proven byvisual examination and peroperative Doppler. Follow-up DSA and CT confirmedthe exclusion of the shunt and the disappearance of the SDHs over thefollowing months.

Second, we illustrate the efficacy of MMA embolization for cSDH through thecase of a 58-year-old man who developed a 2 cm thick left SDH underanticoagulant regimen for deep venous thrombosis. After its termination,imaging follow-up showed recurrent bleeding and development of membranesunder single antiplatelet therapy, in keeping with chronification. Left MMAembolization was performed by selective microparticles injections andfollow-up CT showed significant reduction of the subdural collection and itshyperdense compound.

Discussion: The DVP is a rich capillary network located in thedural border cell layer preferentially found near the midline. It is fed bybranches of the middle meningeal artery and drains into dural sinusesseparately from the connecting end of bridging veins. It could represent acentral hub in subdural collections development and management.

In dAVF, sinus hypertension might increase DVP hydrostatic pressure and thusresult in subdural collection and bleeding. Disconnection of the shunt leadsto pressure normalization within the cortical vein and therefore the sinus,indirectly eliminating the driving factor of DVP hyperpressure. In thesetting of common cSDH, bleeding might be initiated by traction on the innerdural bordel cell layer. Inflammatory response secondary to bleeding resultsin neovascularized membranes responsible of further leakage and microbleeds.MMA embolization might decrease DVP pressure (in addition to membranedevascularization?) and favour cSDH resorption.

Conclusion: We hypothesize the crucial role of the DVP in bothdevelopment and management of subdural collections as depicted by cases ofdAVF-related SDHs and common cSDH treated by MMA embolization. We furtherprovide original anatomical drawings illustrating the underlying convergentmechanisms.

O3-6-5

The clinical course of middle meningeal artery embolization forchronic subdural hematoma with mild symptom

Shunsuke Tanoue^1,2, Kenichiro Ono², Masaya Nakagawa¹, Toru Yoshiura¹, Terushige Toyooka¹, Kojiro Wada¹

¹Department of Neurosurgery, National Defense Medical CollgeHospital, Saitama, Japan

²Department of Neurosurgery, Mishuku Hospital, Tokyo, Japan

Objective: Recently, the usefulness of middle dural arteryembolization (MMAE) for chronic subdural hematoma (CSDH) has been reported,but the clinical course after MMAE-alone treatment remains unclear. Wereport the initial results and postoperative course of MMAE-alone treatmentof CSDH with mild symptom.

Methods: This was a single-center, retrospective, observationalstudy conducted with Ethics Committee approval (Approval No. 2021-8). TheMMAE for previously untreated and unilateral CSDH performed between July2020 and August 2021 was included. The indication at our hospital wasclinical symptoms of headache only, no or very minimal neurological deficit,and hematoma thickness of at most 10 mm or more or midline shift of at least5 mm on radiographic findings. Patients were followed clinically on the dayafter surgery, at 1, 2, 4, and 6 weeks. Patients who could not be followedas scheduled were excluded from the study. We assessed changes in clinicalsymptoms and radiographic characteristics at each follow-up period.

Results: A total of 11 cases were included in the study. Themean age was 74.5 years, 8 were male, and 4 had left lesions. No patientsreceived antithrombotic therapy. Hematoma thickness was 25 mm, midline shiftwas 6.9 mm, and observation period was 210 days (all median values).Finally, symptoms and radiographic findings improved in 8 (72.7%) (6complete, 2 partial) and 11 (78.6%) (5 complete, 6 partial) patients,respectively. It took 29 days for symptoms and 154 days for imaging toimprove completely (both median values), with a trend toward improvementwithin 1 week (p < 0.05). However, symptoms and radiographic findingsworsened in 6 (two were immediately after surgery and four were 1 week aftersurgery) and 8 patients (five were the day after surgery, four were 1 weekafter surgery, and two were overlapping). Rescue evacuation (RE) wasperformed in 3 patients (21.4%). The risk factors of RE were preoperativemidline shift (cut off 8 mm) and increased hematoma on the day afterMMAE.

Conclusion: MMAE-alone treatment is effective in CSDH with mildsymptoms. Both clinical symptoms and imaging findings improved within 1week. However, it is important to note that the disease may worsen after 1week.

O3-6-6

Interventional Neuroradiology at a Private Hospital in Cambodia

Yoshifumi Hayashi^1,2, Kensuke Kato^1,2, Keisuke Miura¹, Shota Ozaki¹, Yoshifumi Okada^1,2, Kousei Yoshimura¹, Junhao Wang¹, Mitsuru Dan¹, Shoji Yamaguchi¹, Manabu Okawada²

¹Department of Neurosurgery, Kitahara International Hospital

²Sunrise Japan Hospital Phnom Penh

Purpose: In 2016, Sunrise Japan Hospital Phnom Penh wasestablished in Cambodia, a country that has not yet had a system to provideadvanced medical services since the civil war in the 1970s. The hospital hasa Neurosurgery and Interventional Neuroradiology department with a full-timeJapanese specialist, who provides diagnosis and treatment while instructingCambodian doctors. In Cambodia, where there are very few insurancesubscribers, the indications for treatment differ from those in Japan. Thefollowing is a breakdown of the interventional neuroradiology treatment atour hospital.

Materials and Methods: Electronic medical record data werecompiled for interventional neuroradiology treatment performed at SunriseJapan Hospital from October 2016 to March 2022.

Results: A total of 33 treatments were performed. They included13 cases of cerebral aneurysm coil embolization, 9 cases of mechanicalthrombectomy, 6 cases of carotid artery stenting, 3 cases of tumorembolization, 1 case of AVM embolization, and 1 case of intracranial PTA. Incerebral aneurysm treatment, 12 patients (92%) had ruptured aneurysms. Theaverage aneurysm size was 5.5 mm, and the average number of coils used was4.3. This tended to be smaller than the average size of 5.9 mm (50 patients)for clipping surgery performed during the same period. Patients with largeaneurysms that were expected to require more coils tended to avoid thecostly endovascular treatment and opted for clipping surgery. Tumorembolization was performed in only 3 cases, but 82 cases of craniotomy wereperformed during the same period. Although more embolization would have beenperformed in Japan, preoperative embolization could not be performed due tothe costAlthough the number of CAS cases was small compared to the situationin Japan, it is thought that the average life expectancy is 70 years and thenumber of internal carotid artery stenosis cases would be still small.In twocases, the patients received tele-consultation during procedures fromspecialists in Japan. About the outcome of procedures, complications inaneurysmal coil embolization patients included intraoperative rupture in onecase and recanalization in two cases. In an AVM patient, post-embolizationhemorrhage occurred, requiring emergency craniotomy. Five patients (56%) hadTICI 2b or higher for mechanical thrombectomy.

Conclusion: Hospitals that can provide treatment locally areessential to improve the prognosis of cerebrovascular diseases. In order tosave more patients in developing countries, it was considered necessary todetermine a treatment method that can obtain a high outcome while limitingthe cost

O3-7-1

Tom Oxley

O3-7-2

Repeated Endovascular Thrombectomy in Patient with Chronic

Aortic Dissection type A presented with Recurrent Left Middle CerebralArtery Occlusion

Nongluk Jakkrit¹, Methinee Damaied¹, Tiplada Boonchai²

¹Nursing department, Trang hospital

²Deparment of Medicine, Trang hospital

Purpose: To demonstrate a case of chronic aortic dissection typeA with recurrent left middle cerebral artery occlusion underwent rEVT.

Materials and methods: Acute large vessel occlusion treated withrepeat endovascular thrombectomy (rEVT) is rare. Few case reports ofendovascular treatment in patient with chronic aortic dissection type A werepublished. We reported A 37-year-old male with history of chronic aorticdissection type A status post graft repair and seven episodes of recurrentminor stroke presented with acute right hemiparesis and global aphasia,suggestive of left middle cerebral artery syndromes. CT scan of brain and CTangiography of brain and neck showed old hypodense lesion at leftparieto-temporal region and mid left M1 occlusion, respectively.

Endovascular thrombectomy via transfermoral approach was performed;successful recanalization (modified thrombolysis in cerebral infarction(mTICI) 3) was achieved without procedure-related complication. His functionoutcome was excellent at 3 months (modified Rankin scale (mRS) 0). Sixteenmonths after first EVT he developed recurrent left middle cerebral arteryocclusion which was successfully treated endovascular thrombectomy.Antiplatelet and anticoagulant were prescribed for secondary strokeprevention.

Results: Functional independent (mRS 1) at 3 months wasachieved, but nevertheless fatal intracerebral hemorrhage developed at 5months after rEVT.

Conclusion: rEVT can be performed safely in patient with chronicaortic dissection type A.

O3-7-3

A case of Non-Convulsive Status Epilepticus diagnosed by ASL and EEGin the acute phase after SAH

Tomohiro Iida, Yusuke Egashira, Yukiko Enomoto,Toru Iwama

Department of neurosurgery, University of Gifu

Purpose: Non-Convulsive Status Epilepticus (NCSE) may occur inthe acute phase of stroke. For the patient with subarachnoid hemorrhage, itis difficult to diagnose it due to the possibility of coexistence withcerebral vasospasm report a case of NCSE presented with aphasia andconsciousness disturbance 8 days after the onset of subarachnoid hemorrhageand was diagnosed using Arterial Spin Labeling(ASL) andElectroEncephaloGraphy(EEG).

Methods: The diagnosis of NCSE was made by using ASL and EEG forneurological symptoms that occurred during the acute phase after SAH.

Results: A 72-year-old woman was brought to our hospital withimpaired consciousness. CT showed subarachnoid hemorrhage caused by rupturedAcom An(WFNS gradeIV), so we underwent coil embolization under generalanesthesia on the same day. She was extubated on the next day, and herconsciousness E4V5M6 and mild right-sided paralysis were observed, but shewas able to eat by herself in the evening, and CT perfusion on day 7confirmed that there was neither hypoperfusion nor hyperperfusion. At day 8,aphasia occurred and after then her consciousness got worse to E4V1M5. Wesuspected ischemic symptoms due to vasospasm, so performed DSA and planed todo intra-arterial infusion of fasudil. The DSA showed some spasm in lt M2,but peripheral vessels were rather dilated, so it was unlikely that thesymptoms were caused by hypoperfusion. After DSA, MRI was performed becauseNCSE was suspected based on peripheral vasodilation findings. The ASL showedhyperperfusion in a part of lt MCA area, and EEG showed epileptic waves inthe same region. We judged the symptom due to NCSE and was started onantiepileptic drugs. The EEG findings improved, and the patient's level ofconsciousness gradually improved.

Conclusion: Neurological symptom during the acute phase ofstroke should be considered ischemic event first, but NCSE should also betaken into consideration when selecting treatment. Not only EEG but also ASLmay be useful in the diagnosis of NCSE.

O3-7-4

Evaluation of an Implantable Cardiac Monitor for Embolic Stroke ofUndetermined Source after Mechanical Thrombectomy

Nao Shimooka¹, Akihiro Nakaya², Makoto Dehara¹, Yasushi Hagihara¹, Haruhiko Kishima³

¹Department of Neurosuragery, Rinku Medical Center, Japan

²Department of Clinical Engineering. Rinku General Medical Center,Japan

³Department of Neurosurgery, Osaka University Graduate School ofMedicine, Japan

Background and Purpose: Patients with embolic stroke ofundetermined source (ESUS) or transient ischemic attack were indwelled andobserved for the presence or absence of atrial fibrillation (AF). Animplantable cardiac monitor (ICM) was introduced in these patients in March2020. In total, 18 cases were indwelled from March 2020 until June 2021, andthe observations were conducted for a period greater than 1 year. One of the18 patients withdrew from the study within 4 months; thus, 17 patients werefollowed up for 1 year. In total, five of the 18 patients underwentmechanical thrombectomy (MT).

All the cases were examined, and particular attention was paid to patientswho underwent MT.

Results: Total AF was detected in 27.8% (5/18) and 52.9% (9/17)of all cases within 3 months and 1 year, respectively. An AF of 2 min orlonger was detected in 27.8% (5/18) of the observed cases within 3 monthsand in 47.1% (8/17) cases within 1 year. In patients who underwent MT, totalAF was detected in 40.0% (2/5) and 80.0% (4/5) of them within 3 months and 1year, respectively. An AF of 2 min or longer was detected in 40.9% (2/5) ofthe patients within 3 months and in 60.0% (3/5) of the patients within 1year. These were found to be higher than those reported in the past,especially in patients who underwent MT.

Conclusion: Although in the future, a number of cases need to beexamined, ICM placement may be strongly recommended for ESUS after MT.

O3-7-5

Development of Machine Learning Models to Predict Probabilities andTypes of Stroke at Prehospital Stage: The Japan Urgent Stroke Triagescore using Machine Learning (JUST-ML)

Kazutaka Uchida^1,2, Junichi Kouno¹, Shinichi Yoshimura¹, Norito Kinjo^1,2, Fumihiro Sakakibara^1,2, Hayato Araki³, Takeshi Morimoto²

¹Neurosurgery, Hyogo Medical University

²Epidemiology, Hyogo Medical University

³Neurosurgery, Araki Neurosurgical Hospital

Purpose: Prehospital prediction models to estimate thelikelihood of several types of stroke (large vessel occlusion[LVO],intracranial hemorrhage, and subarachnoid hemorrhage, and any types ofstroke) should be useful to transfer those with suspected stroke toappropriate facilities. Recently, we had developed and clinically appliedthe prehospital stroke score which had excellent predictive abilities.However, there are still challenges in terms of operation in site.Therefore, we develop a machine learning model (JUST AI) that couldinstantly calculate the probability of each type of stroke at the sametime.

Materials and Methods: We conducted Multi-center retrospectiveand prospective cohort study. The training cohort had eight centers in Japanfrom June 2015 to March 2018, and the test cohort had 13 centers from April2019 to March 2020. We use the three different machine learning algorithms(logistic regression, random forest, XGBoost) to develop models. Mainoutcomes were large vessel occlusion (LVO), intracranial hemorrhage (ICH),subarachnoid hemorrhage (SAH), and cerebral infarction (CI) other than LVO.The predictive abilities were validated in the test cohort with accuracy,positive predictive value, sensitivity, specificity, area under the receiveroperating characteristic curve (AUC), and F score.

Results: A total of 3178 patients were included in the trainingcohort with 337 LVO, 487 ICH, 131 SAH, and 676 CI cases. The developed MLmodels utilized 19 items that were assessable at the prehospital stage. Thetest cohort included 3127 patients with 183 LVO, 372 ICH, 90 SAH, and 577 CIcases. The overall accuracies were 0.65, and the positive predictive values,sensitivities, specificities, AUCs, and F scores were stable in the testcohort. The classification abilities were also fair for all ML models. TheAUCs for LVO of logistic regression, random forests, and XGBoost were 0.89,0.89, and 0.88, respectively, in the test cohort, and these values werehigher than the previously reported prediction models for LVO.

Conclusion: The ML models developed to predict the probabilityand types of stroke at the prehospital stage had superior predictiveabilities. ML could be applied at the prehospital stage for patientssuspected of having acute stroke.

O3-8-1

Timing and quantification of aneurysm total volume, circulatingportion volume and volume of peri aneurysmal edema based on longitudinalMRIs segmentations.

Jean-Christophe GENTRIC^1,4, Mourad CHEDDAD EL AOUNI¹, Elsa MAGRO^2,3, Julien OGNARD^1,2

¹Department of Radiology, Neuroradiology, Brest universityHospital, Brest, France

²LaTIM, INSERM UMR 1101, University of Western Brittany (UBO)

³Department of Neurosurgery, University Hospital of Brest, Brest,France

⁴GETBO, INSERM UMR 1034, University of Western Brittany (UBO)

Purpose: After flow diversion (FD) target aneurysm will presenta decrease of; the aneurysm volume (AV), the volume of the circulatingportion (VCP), and the peri aneurysmal edema (PAE). The goal of this work isto study the timing and the quantification of the decrease of these volumeafter FD implantation.

Material & Method: A retrospective monocentric analysis ofMRI of patients treated by FD for supracentimetric aneurysm has beenperformed between February 2016 to March 2021. AV, VCP & PAE have beensegmented and quantified on 3 MRIs: MRI1 (before FD treatment) MRI2 (firstcontrol during the first year) and MRI3 (last FU MR at least one year afterprocedure). A variation of the volume was judged significant if superior to20%. Comparisons between variable have been performed using the Wilcoxontest VCP/AV ratio has been calculated and compared to MRI1.

Results: 22 patients have been enrolled. AV increase of 3%between MRI1 and MRI2 and decrease of 26% between MRI1 and MRI3. VCP/AVratio decrease of 72% on MRI2 and of 96% on MRI3. PAE was present in 8patients on MRI1. No de novo PEA appears on MRI2 and MRI3. In 1 patient PAEvolume increase (case of residual aneurysm). In the 7 other patients, themean decrease of PAE was 68% on MRI2 and 78% on MRI 3.

Conclusion: From a timeline point of view, the first variable todecrease was the VCP followed by PAE (both observed before one year) whereasAV decrease was only observed after one year. And the mean reduction of theAV was 26% on MR3.

O3-8-2

Clinical Significance of Cytotoxic Lesions of the Corus Callosum inSubarachnoid Hemorrhage Patients: A Retrospective Analysis

Yosuke Moteki^1,2, Tomonori Kobayashi², Koji Yamaguchi¹, Tatsuya Ishikawa¹, Takayuki Funatsu¹, Seiichiro Eguchi¹, Takakazu Kawamata¹

¹Department of Neurosurgery, Tokyo Women's Medical University

²Department of Neurosurgery, Ebina General Hospital

Purpose: Cytotoxic lesions of the corpus callosum are secondarylesions induced by significant increases in cytokine levels in the brain andare associated with subarachnoid hemorrhage (SAH). However, their clinicalsignificance in SAH patients remains unclear.

Materials and Methods: We retrospectively analyzed SAH patientswho were treated in our hospital and evaluated between-group differences inthe backgrounds, clinical findings, and outcomes between SAH patients whodeveloped cytotoxic lesions of the corpus callosum and those who did not. Wefurther compared patients who achieved good outcomes with those who had pooroutcomes. Multivariate logistic regression analysis was used to identifyrisk factors for poor clinical outcomes.

Results: We analyzed 159 SAH patients; 17 patients (10.7%) had acytotoxic lesions of the corpus callosum. Patients with cytotoxic lesions ofthe corpus callosum were more likely to be in a severe condition (WorldFederation of Neurosurgical Societies grading IV-V: odds ratio[OR], 4.53;95% confidence interval[95% CI], 1.60–12.84; P = 0.0042) and have anintraventricular (OR, 5.98; 95% CI, 1.32–27.13; P = 0.0054) or anintraparenchymal hematoma (OR, 3.62; 95% CI, 1.25–10.45; P = 0.023).Patients with cytotoxic lesions of the corpus callosum had a greaterpropensity of a poor outcome three months after onset (modified Rankin scalescore 0–2: OR, 0.22; 95% CI, 0.07–0.66; P = 0.0043). Multivariate analysisconfirmed that cytotoxic lesions of the corpus callosum increased the riskof a poor outcome (OR, 4.39; 95% CI, 1.06–18.1; P = 0.037).

Conclusions: The development of cytotoxic lesions of the corpuscallosum may be related to the extent of hematomas in SAH patients. Althoughthey are usually reversible lesions, the development of cytotoxic lesions ofthe corpus callosum may be a predictor of poor outcomes in SAH patients.

O3-8-3

Non-contrast improved motion-sensitized driven-equilibrium3DT1-weighted black blood magnetic resonance (iMSDE-3D MR) imaging canpredict the occlusion status of intracranial aneurysms after theflow-diverter stent deployment

Takeshi Miyata¹, Taketo Hatano¹, Takenori Ogura¹, Hideo Chihara², Yuji Agawa¹, Takeru Umemura¹, Hiroki Sakamoto¹, Hiroaki Nakajima¹, Yusuke Nakazawa¹, Koji Shiomi¹, Takashi Nagahori¹, Izumi Nagata¹

¹Department of Neurosurgery, Kokura Memorial Hospital

²Department of Neurosurgery, Hikone Municipal Hospital

Purpose: Flow Diverter Stent (FDS) deployment has been shown tobe effective treatment for unruptured intracranial aneurysms (UIAs).However, it is still unelucidated what factors is associated with incompleteocclusion of UIAs after the FDS deployment. Improved motion-sensitizeddriven-equilibrium 3D T1-weighted black blood magnetic resonance (iMSDE-3DMR) imaging is one of the advanced high-resolution MR imaging techniquesused to directly visualize the vessel wall due to strong reduction ofartifacts caused by blood flow and intra-aneurysmal thrombus, leading tohigher quality images. The purpose of this study was to identify predictivefactors associated with complete occlusion of UIAs treated with FDS by usingthe iMSDE-3D MR imaging technique during an observational period.

Materials and Methods: From April 2019 to March 2022, weretrospectively reviewed patients, who underwent FDS deployment without coilembolization at our institution and were followed postoperatively for atleast 6 months. On the cerebral angiography 6 months after the procedure, weevaluated the occlusion status of all UIAs using the O’Kelly-Marottaclassification. The patients whose UIAs had been completely occluded, wereassigned to the occluded group (group A), and the patientswhose UIAs had been incompletely occluded were assigned to be in thepartially occluded group (group B). Morphological parametersexamined were length of aneurysmal neck, dome and height, saccular orfusiform shape. By using the iMSDE-3D MR imaging, the longest and shortestdiameters of the intra-aneurysmal lumen and their mean values (defined as D [mm]), as well as the cross-sectional area of the intra-aneurysmallumen (defined as S [mm²]), were measured at preoperative time point and oneweek after FDS deployment. The reduction rate of the mean diameter (defined asΔD [%]) and the cross-sectional area (defined asΔS [%]) of the intra-aneurysmal lumen to those at the preoperativestatus was also calculated, respectively. Those parameters were comparedstatistically between the two groups.

Results: Of the 51 patients who underwent FDSdeployment during the above period, 14 (7 in groupA and 7 in group B) wereincluded, with a median age at the time of treatment of 66.9[IQR 59.8–72.3]years. There was no significant difference in the maximum diameter of UIAsbetween groups (Group A: 18.4 ± 5.7 mm, Group B:14.8 ± 4.7 mm). In the evaluation by iMSDE-3D MR imaging,ΔD (Group A: 68.5 ± 19.2%, Group B:22.5 ± 21.0%, p < 0.01) andΔS (Group A: 85.9 ± 14.2%, Group B:38.9 ± 25.2%, p < 0.01) were significantly higher in Group A,respectively.

Conclusion: The reduction rate of the mean diameter and thecross-sectional area of the intra-aneurysmal lumen one-week after the FDSdeployment can predict the occlusion status of UIAs six-months after theprocedure. iMSDE-3D MR imaging is useful to evaluate the occlusion status ofUIAs treated with FDS by clearly visualizing the vessel wall of UIAs.

O3-8-4

Morphological factors affecting coil-only embolization of smallunruptured aneurysms

Hiroshi Tenjin¹, Osamu Saito², Kuniaki Matsumoto³, Akio Asai¹

¹Department of Neurosurgery, Kansai Medical University

²Department of Neurosurgery, Shizuoka Red Cross Hospital

³Department of Neurosurgery, Sano Memorial Hospital

Purpose: When small unruptured aneurysms (SUA) are embolized bycoils, manipulation of the microcatheter and coil is limited because oftheir small size. Previous studies suggested that the morphology of theartery and aneurysm is important. In the present study, we clarified themorphological factors affecting coil-only embolization of SUA.

Methods: We retrospectively identified 17 patients who underwentembolization for unruptured aneurysm with a maximum diameter < 5 mm. Weinvestigated the following: 1: the relationships among dome/neck ratio(D/N), height/neck ratio (H/N), height/dome ratio (H/D), projection ofaneurysm-parent artery, and adverse events, 2: immediate and late occlusion,and 3: number of coils.

Results: 1: Adverse events developed in four cases in which theH/D was smaller than 1 (P < 0.01). There was a significant difference inthe rate of adverse events by projection of the aneurysm-parent artery (p< 0.01), 2: Occlusion rate: Immediately after coil embolization, 71%(12/17) were neck remnant; however, 88% (15/17) of SUA became completeocclusion in the follow-up term, and 3: 1.5 ± 0.6 coils were used.

Conclusion: To achieve successful coil-only embolization inSUAs, it is important to select aneurysms for which the projection of theparent artery is suitable for embolizing and the H/D ratio is larger than 1.In SUAs, occlusion develops naturally after coil embolization.

O3-8-5

Usefulness of Non-contrast-enhanced Silent MRA for Cerebral Aneurysmsafter Flow Diverter and PulseRider Treatments

Tomoaki Suzuki, Hitoshi Hasegawa, KoheiShibuya, Haruhiko Takahashi, Yukihiko Fujii

Department of Neurosurgery, Brain Research Institute, Niigata University

Purpose: The aim of this study was to describe the successfulvisualization using a novel non-contrast-enhanced silent magnetic resonanceangiography (MRA) for aneurysms treated with flow diverter (FD) stents andPulseRider, which induced inevitable metal susceptibility artifacts.

Materials and Methods: Silent MRA was performed for 48unruptured intracranial aneurysms treated with flow diverters and PulseRider(Pipeline: 26, FRED: 16, PulseRider: 6), including follow-up sessions. Theimages were compared with time-of-flight (TOF)-MRA and digital subtractionangiography (DSA).

Results: In treatment using FD, 23 cases (54.8%) were treatedwith coil embolization. However, silent MRA could visualize the residualcavity even in the coiled aneurysms much better than TOF-MRA. Chronologicalthrombosis of aneurysms after FD placement can be detected well on silentMRA, equivalent to that on DSA. In treatment using PulseRider, silent MRAcould visualize the flow signal of the residual neck, as well as thearteries of bifurcation, which TOF-MRA failed to visualize. A segment of theproximal marker composed of stainless steel was poorly visualized on silentMRA; however, the other parts of the parent artery were clearlyvisualized.

Conclusion: Silent MRA is feasible for imaging cerebralaneurysms after FD and PulseRider treatments and is superior to TOF-MRA. Ithas the potential to provide visualization of aneurysm occlusion statusequivalent to DSA in a non-invasive manner.

O3-9-1

Outcomes of Mechanical Thrombectomy in Patients with LargeDiffusion-Weighted Imaging Lesions

Jae Hyung Choi¹, Yong Hwan Cho¹, Sang Hyeon Kim², Myong Jin Kang²

¹Department of Neurosurgery, University of Dong-A, Busan,Korea

²Department of Radiology, University of Dong-A, Busan, Korea

Objective: Despite many advancements in endovascular treatment,the benefits of mechanical thrombectomy (MT) in patients with largeinfarctions remain uncertain due to hemorrhagic complications. Therefore, weaimed to investigate the efficacy and safety of recanalization via MT within6 h after stroke in patients with large cerebral infarction volumes (>70mL).

Methods: We retrospectively reviewed the medical data of 30patients with large lesions on initial diffusion-weighted imaging (>70mL) who underwent MT at our institution within 6 h after stroke onset.Baseline data, recanalization rate, and 3-month clinical outcomes wereanalyzed. Successful recanalization was defined as a modified treatment incerebral ischemia score of 2b or 3.

Results: The recanalization rate was 63.3%, and symptomaticintracerebral hemorrhage occurred in six patients (20%). The proportion ofpatients with modified Rankin Scale (mRS) scores of 0–3 was significantlyhigher in the recanalization group than in the non-recanalization group(47.4% vs. 9.1%, p = 0.049). The mortality rate was higher in thenon-recanalization group, this difference was not significant (15.8% vs.36.4%, p = 0.372). In the analysis of 3-month clinical outcomes, onlysuccessful recanalization was significantly associated with mRS scores of0–3 (90% vs. 50%, p = 0.049). The odds ratio of recanalization for favorableoutcomes (mRS 0–3) was 9.00 (95% confidence interval, 0.95–84.90;p = 0.055).

Conclusion: Despite the risk of symptomatic intracerebralhemorrhage, successful recanalization via MT 6 h after stroke may improveclinical outcomes in patients with large vessel occlusion

O3-9-2

Withdraw

O3-9-3

Assessment of futile recanalization after endovascular thrombectomyfor acute large vessel occlusion

Nobutaka Horie, Masahiro Hosogai, MasashiKuwabara, Daiso Ishi, Takahito Okazaki

Department of Neurosurgery, Hiroshima University

BACKGROUND: Endovascular thrombectomy for LVO is an establishedoperation in the acute phase, but a certain percentage of cases have pooroutcome (futile recanalization) despite good recanalization. Weprospectively verified whether the prediction was possible by the cerebralhemodynamics evaluation immediately after recanalization using RapidDSA.

METHODS: Cases with LVO were prospectively enrolled, which metthe indication for thrombectomy in American Heart Association. Preoperativetissue imaging was performed by MR imaging with DWI, MRA, SWAN, and ASL.Immediately after the recanalization, Rapid DSA (Siemens icono) wasperformed to evaluate CVB, Tmax, CBV, as well as hypoperfusion index and CVBindex. We investigated the correlation between these parameters inpostoperative hemorrhagic complications and clinical outcomes after 1 weekand 3 months.

RESULTS: Analysis was performed on 21 consecutive cases. Theaverage age was 80.7 ± 8.5 years, NIHSS 15.7 ± 6.6 at the first visit.Effective reperfusion was 85.6%. Among them, only 33% of Rapid-DSAeliminated the laterality in CBF and Tmax. CBF <30% (P = 0.02), CBV<34% (P = 0.02), and CBV index (P = 0.01) at Rapid-DSA were significantlycorrelated with postoperative ASPECTS. Hemorrhagic complications were HItype 2 and PH type 2 in 2 cases, and the correlation with each parameter ofRapid-DSA was low. The patients with favorable outcomes after 3 months hadsignificantly lower CBF <45%, Tmax> 6 s, CBV <34%, hypoperfusionindex, and higher CBV index.

CONCLUSION: No studies have been conducted on the prediction offutile recanalization after thrombus recovery so far. Rapid DSA not onlypredicts clinical outcomes, but can also help elucidate pathologicalmechanisms immediately after reperfusion, such as vasoparalysis and noreflow.

O3-9-4

DWI ASPECTS Can Detect Patients Who Need Puncture to Recanalizationwithin 30 min: Interim Analysis of K-NET Registry

Tomohide Yoshie¹, Toshihiro Ueda¹, Masafumi Morimoto², Masataka Takeuchi³, Masahiro Yamamoto⁴, Yoshifumi Tsuboi⁵, for the K-NET investigators¹

¹Stroke center, department of Neurology and NeuroendovascularTherapy, St Marianna University Toyoko Hospital, Kawasaki, Japan

²Department of Neurosurgery, Yokohamashintoshi NeurosurgicalHospital, Yokohama, Japan

³Department of Neurosurgery, Seisho Hospital, Odawara, Japan

⁴Department of Neurology, Yokohama Brain and Spine Center,Yokohama, Japan

⁵Department of Neurosurgery, Kawasakisaiwai Hospital, Kawasaki,Japan

BACKGROUND AND PURPOSE: Faster recanalization for acute largevessel occlusion is associated with better clinical outcome, however, it isnot clear whether all patients need faster recanalization. We aimed toinvestigate what is the patients background in whichpuncture-to-recanalization (P-to R) time within 30 min is associated withgood clinical outcome.

MATERIALS AND METHODS: K-NET Registry is a prospective,multicenter, observational registry of acute ischemic stroke patients inKanagawa prefecture. We evaluated the patients with ICA or MCA occlusion whoachieved TICI2B or more recanalization by endovascular thrombectomy.Patients were divided into subgroups according to pre-treatment patients’background; DWI ASPECTS (≤6, 7–8, ≥9), age (<70, 70–85, >85), NIHSS(≤5, 6–10, 11–15, 16–20, ≥21), occlusion site (ICA, MCA) and symptomrecognition to puncture time (≤1.5 h, 1.5–3 h, 3–4.5 h, 4.5–6 h, ≥6 h). Ineach group P-to-R time (<30min, 30–60min, >60min) was compared betweengood and poor clinical outcomes.

RESULTS: 1394 patients were included in this study. In overallanalysis, P-to-R <30min was significantly associated with good clinicaloutcome. Univariate analysis in each subgroup showed P-to-R <30min wassignificantly associated with good clinical outcome in the patients with DWIASPECTS ≤6, age >85 and NIHSS ≥21. In multivariate analysis, P-to-R<30min was not significant independent predictor for good clinicaloutcome, however, the interaction term between P-to-R <30min and DWIASPECTS was a significant predictor for good clinical outcome. Multivariateanalysis in patients with DWI ASPECTS ≤6 showed age, NIHSS and P-to-R<30min were independent predictors for good clinical outcome. Incontrast, only age and NIHSS were independent predictor for good clinicaloutcome in DWI 7–8 and age, NIHSS and symptom recognition to puncture timewere in DWI ≥9.

CONCLUSIONS: Puncture to recanalization wihtin 30 min is apredoctor of good clinical outcome, however, the effect on outcome dependson DWI ASPECTS. Target time from puncture to recanalization is within 30 minin patients with DWI ASPECTS ≤6.

O3-9-5

Prediction of Difficulty in Guiding Catheter Navigation by PunctureSite Evaluation

Sato Masayuki¹, Tsunogae Marie², Sato Daisuke¹, Ogawa Shotaro¹, Torazawa Seiei¹, Ueda Masayuki², Ota Takahiro¹

¹Department of Neurosurgery, Tokyo Metropolitan TAMA Medicalcenter

²Department of Stroke, Tokyo Metropolitan TAMA Medical center

Objective: To predict difficulty in guiding catheter (GC)placement by access route evaluation. To examine whether inner catheter (IC)change prolonged the time to GC placement.

Subjects: Among 198 consecutive patients who underwent acutethrombectomy for acute stroke at our hospital from January 2017 to March2021, 162 patients (82%) who chose to initially use a 9Fr. ballooned GC andJ-type inner catheter for anterior circulation obstruction, and factorsrequiring a change in IC were the study was conducted.

Method: To evaluate the angle by X, Y, and Z and the flexion ofthe common carotid artery by using chest X-ray, puncture site imaging, andGC-guided video images for the puncture site factors (angle of flexion ofthe femoral artery to the internal iliac artery branch, calcification, andaccordion phenomenon), aortic factors (aortic flexion meandering,calcification in the aortic arch, Aorta Type), and flexion of the commoncarotid artery. The presence or absence of calcification was determined andcompared between the IC - modified group and the IC - non-modifiedgroup.

Results: The IC-modified group had a bifurcation angle of 110degrees or less (33% vs. 16%, P = 0.02), accordion phenomenon (61% vs. 18%,P = 0.001), aortic tortuosity (46% vs. 17%, P = 0.002), calcification in theaortic arch (36% vs. 16%, P = 0.01), and Aorta type 3 (63% vs. 6%,P < 0.0001), and flexion of the common carotid artery (58% vs. 12%,P < 0.0001). In addition, GC indwelling was significantly delayed in theIC change group compared to the non-IC change group (36 min vs 13 min,P = 0.01)

Conclusion: When performing thrombus retrieval therapy, GCindwelling difficulty can be predicted from chest x-ray evaluation, flexionand calcification of the puncture site and target vessel imaging, and anearly decision to change inner catheters Early decision to change the innercatheter may shorten the time to GC placement.

O4-1-1

RNA sequencing analysis of endothelium in a patient-specificintracranial aneurysm model

Milan Samarage¹, Yutaro Komuro², Geoffrey Colby¹, Satoshi Tateshima³, Jason Hinman², Naoki Kaneko³

¹Department of Neurosurgery, University of California LosAngeles

²Department of Neurology, University of California Los Angeles

³Department of Interventional Neuroradiology, University ofCalifornia Los Angeles

Purpose: Ruptured intracranial aneurysms are responsible for5–10% of all strokes yet can carry a mortality rate as high as 50%. Thegrowth and rupture of aneurysms is a consequence of complex arterial wallremodeling resulting from complex interactions between cellular biologicalprocesses and hemodynamic factors. We aimed to develop a patient specificin-vitro aneurysm flow model lined with cultured endothelial cells toanalyze the transcriptomic profile of endothelium in varying hemodynamicconditions

Materials and methods: A total of eight aneurysm casts were madeof polydimethylsiloxanes which were created from patients’ 3D rotationalangiographic data in our institutions neurovascular database. Modelsrepresented two morphologies (bifurcation and sidewall aneurysms), fourlocations (middle cerebral artery bifurcation, basilar tip bifurcation,internal cerebral artery-posterior communicating artery sidewall, internalcerebral artery-superior hypophyseal artery sidewall), and two clinicalconditions (stable aneurysms and growing aneurysms). The lumen of the modelswere coated with fibronectin and connected to a peristaltic pump infusing acell suspension of human umbilical vein endothelial cells and culture media.After culturing for 4–7 days to achieve confluent cell growth, specimens ofthe model from the aneurysm and parent artery were separately cut out toextract RNA which was purified and used for RNA sequencing. DESeq2 was usedto analyze differentially expressed genes (DEGs) between aneurysm and parentvessel, bifurcation and sidewall morphologies and growing and stableaneurysms. Bioinformatic analysis was carried out using the gene ontologyenrichment analysis and visualization tool (GORILLA).

Results: A total of 358 DEGs were identified between aneurysmand parent vessel, 222 DEGs were identified between sidewall and bifurcationaneurysm morphologies and 20437 DEGs were identified between growing andstable aneurysms. Genes such as SYNPO, CHSY3 andALKBH8 were found to be significantly upregulated inendothelial cells within the aneurysms while genes such as FABP4,ANGPT2, SMAD6 and ADAMTS18 were found to besignificantly downregulated in comparison with endothelial cells within theparent artery. SMAD6 and ALKBH8 were alsofound to be significantly upregulated and ADAMTS18significantly downregulated in sidewall aneurysms compared to bifurcationaneurysms. SERPINB6 was found to be upregulated andFOXN2 was found to be significantly downregulated ingrowing aneurysms compared to stable aneurysms.

Conclusion: We demonstrate the successful development of aversatile, patient specific, in-vitro pulsatile intracranial aneurysm cellculture model which can be used to study the complex interactions ofendothelial cell biology, specifically the unique transcriptomic profiles ofvarious endothelial cell populations that are subject to varying hemodynamicconditions based on location within the vasculature and in differentaneurysm morphologies.

O4-1-2

Feasibility and Safety of Creating Wide-necked Aneurysm Model UsingElastase with Balloon Angioplasty in Rabbit

Dong-Sung Won^1,2, Mi Hyeon Kim^1,2, Dae Sung Ryu¹, Jeon Min Kang¹, Jung-Hoon Park¹, Deok Hee Lee²

¹Biomedical Engineering Research Center, Asan Institute for LifeSciences, Asan Medical Center

²Department of Radiology, Research Institute of Radiology, AsanMedical Center, University of Ulsan College of Medicine

Background and Purpose: The reliable and safe models of theelastase-induced aneurysm in rabbits have been proposed for preclinicalresearch; however, the neck size control of aneurysms is still challenging.The purpose of this study was to investigate the technical feasibility andsafety of creating a wide-necked aneurysm model using elastase-induced withballoon angioplasty in the rabbit right common carotid artery (RCCA).

Materials and Methods: Fifteen male New Zealand White rabbitswere divided into 3 groups as follow: group A received only elastasestimulus, group B received elastase stimulus with balloon angioplasty, groupC received balloon angioplasty at 4 weeks after creation of aneurysm byelastase stimulus. All rabbits underwent surgical procedure to create theelastase-induced aneurysm at the RCCA. Balloon angioplasty in groups B and Cwas performed to induce wide-neck aneurysm. All rabbits were sacrificed 4weeks after the aneurysmal creation procedure. Size and shape of the createdaneurysm and histological changes were analyzed and compared between thethree groups.

Results: The aneurysmal creation procedures were technicallysuccessful in 14 (93.3%) of 15 rabbits. One rabbit in group A died duringthe surgery. Saccular aneurysm was created in group A and wide-neckedaneurysm was successfully created in groups B and C. The neck size, anddome-to-neck ratio were significantly higher in groups B and C than group A(all p < 0.05). The tunica media thickness, the vesselarea, the luminal area, and the degree of internal elastic laminadestruction were significantly higher in groups B and C than groups A (allp < 0.05).

Conclusion: Creation of the wide-necked aneurysm model usingelastase-induced with balloon angioplasty was technically feasible and safein the rabbit RCCA. Balloon angioplasty after elastase stimulus effectivelyestablished a wide-necked aneurysm as a potential model for reproducing themechanisms of the aneurysm. The created wide-necked aneurysmal modelrepresents a promising to evaluation of endovascular devices forinterventional neuroradiologic practice.

O4-1-3

Concentrations of atherogenic proteins in aneurysm sac are associatedwith wall enhancement of unruptured intracranial aneurysm

Daizo Ishii¹, Yongjun Lu², Edgar A. Samaniego³, David M. Hasan²

¹Department of Neurosurgery, Hiroshima University, Hiroshima,Japan

²Department of Neurosurgery, University of Iowa Hospitals andClinics, IA, USA

³Department of Neurology, University of Iowa Hospitals andClinics, IA, USA

Background and Purpose: MR-vessel wall imaging (VWI) ofunruptured intracranial aneurysms (UIAs) permits visualization of wallstructures. Aneurysm wall enhancement (AWE) was associated withatherosclerotic remodeling of the aneurysm wall accompanied by infiltrationof inflammatory cells, potentially contributing to rupture. Thus, AWE canserve as a novel imaging biomarker for detecting unstable UIAs. The purposeof this study was to determine whether the luminal concentrations ofatherosclerotic proteins in the aneurysm sac were associated with increasedwall enhancement of UIAs in VWI.

Methods: Subjects with one or more UIAs scheduled to undergoendovascular treatment were prospectively recruited. All subjects underwentevaluation using 3T-MRI including pre/post contrast VWI of the UIAs. Bloodsamples were collected from the aneurysm sac and the parent artery duringendovascular procedures. The delta difference in concentration for eachatherosclerotic protein between the aneurysm sac and that of the parentartery was calculated. The presence of AWE was correlated with patientprofile, aneurysm morphology, and the delta difference of each protein.Variables with significant p-values in univariate analyseswere included in the multivariate logistic regression analysis to evaluatethe independent factors for the presence of AWE.

Results: A total of consecutive 45 patients with 50 UIAs wereenrolled. There was no significant difference in patient profile or aneurysmmorphology between UIAs with or without AWE. The delta anti-oxidizedlow-density lipoprotein (LDL) antibody, small dense LDL, andlipoprotein(a)[Lp(a)] were significantly higher in UIAs with AWE comparedwith those without AWE (767.6 ± 1957.1 versus −442.4 ± 1676.3 mIU/mL,p = 0.02, 114.8 ± 397.7 versus −518.5 ± 1344.4 μg/mL,p = 0.04, and −5.6 ± 11.3 versus −28.7 ± 38.5 μg/mL,p = 0.01, respectively). In multivariate logisticregression analysis, the delta Lp(a) was significantly associated with AWE(p = 0.04).

Conclusions: Increased concentrations of atherogenic proteins inthe aneurysm sac were significantly associated with wall enhancement ofUIAs. In the future studies, elucidation of the effect of medications foratherogenic proteins on the wall enhancement of UIAs is warranted.

O4-1-4

Computational fluid dynamics using dual-layer porous media modelingmay predict the outcomes after FRED deployment

Mikiya Beppu^1,2, Masanori Tsuji³, Fujimaro Ishida⁴, Hidenori Suzuki³, Shinichi Yoshimura²

¹Department of Neurosurgery, Saiseikai Noe Hospital, Osaka,Japan

²Department of Neurosurgery, Hyogo College of Medicine, Hyogo,japan

³Department of Neurosurgery, Mie University Graduate School ofMedicine, Mie, Japan

⁴Department of Neurosurgery, Mie Chuo Medical Center, NationalHospital Organization, Mie, Japan

Purpose: We hypothesized that the hemodynamic changes caused bythe placement of a Flow-Redirection Endoluminal Device (FRED) were relatedto the thrombus formation in the aneurysm.

Previously, only Computational fluid dynamics (CFD) using one-layer porousmedia could be used to evaluate the outcome after Pipeline EmbolizationDevice, but a two-layer porous media analysis technique has been developedin conjunction with the stent strut in FRED.

The purpose of this study was to evaluate the angiographic occlusion statusafter FRED deployment with CFD using dual-layer porous media modeling fordecision-making in treatment of large wide-neck aneurysms.

Materials and Methods: The inclusion criteria were as follows:1) saccular internal carotid artery aneurysms with FD treatment using aFRED, 2) follow-up digital subtraction angiography (DSA) performed 6–12months after the procedure, and 3) preoperative patient-specific geometrymodels available on 3-dimensional rotational angiography. A total of 9patients treated with FRED were retrospectively analyzed through CFD usingthe pretreatment patient-specific 3-dimensional rotational angiography.These patients were classified into 2 groups including no-filling andcontrast-filling groups, based on the O’Kelly-Marotta scale. The patientcharacteristics, morphological variables, and hemodynamic parameters werecompared for understanding the outcomes of FRED treatment.

A novel CFD technique using dual-layer porous media modeling has beendeveloped to the simulation of the stent struts that characterize it.

Results: The patient characteristics and morphological variableswere similar between the two groups. Hemodynamic parameters including flowvelocity, wall shear stress, shear rate were lower and residual flow volumewere higher in the no-filling group.

Conclusion: This study described that novel CFD technique with adual-layer porous media may predict the aneurysm-occlusion status after FREDdeployment preoperatively.

O4-1-5

A new method of intracranial aneurysm modeling for stereolithographyapparatus 3D printer using digital imaging and communications inmedicine data

Jun Haruma, Kenji Sugiu, Ryu Kimura, HisanoriEdaki, Yuki Ebisudani, Yu Sato, Yoko Yamaoka, Kazuhiko Nishi, MasatoKawakami, Masafumi Hiramatsu, Tomohito Hishikawa, Isao Date

Department of Neurological Surgery, Okayama University Faculty of Medicine,Dentistry and Pharmaceutical Sciences

Purpose: Recently introduced Three-dimensional (3D) printers cangenerate human anatomic models in the fields of neuroendovascular surgery. Amethod of creating a 3D-printed hollow model of standard triangulatedlanguage (STL) data using the hollow-free application has been reported.Small vascular segments with an inner diameter of 1 mm or less have beenreported to be prone to apparent blockage of short segments, however, as STLdata is difficult to edit in detail. Considering this background, we deviseda new hollow model creation technique. This used the digital imaging andcommunications in medicine (DICOM) data of three-dimensional digitalsubtraction angiograms (3DDSAs) and a workstation (Ziostation2, ZiosoftInc., Tokyo, Japan). This method can preserve the accurate representation ofsmall vascular segments of 1 mm diameter or less.

In this study, we aimed to verify the accuracy of 3D-printed hollow models ofintracranial aneurysms created from DICOM data.

Methods: The 3DDSA data from nine aneurysms were processed toobtain volumetric models suitable for the stereolithography apparatus. The3DDSA data were used to create computer-aided design (CAD) files.Ziostation2 software (Ziosoft Inc.) is used to create CAD files of hollowintracranial vessels and aneurysm models. The 3DDSA data were loaded onto a3D workstation with Ziostation2 software and were automaticallyreconstructed into isotropic data. Our technique is a simplevolume-rendering (VR) method that uses a subtraction technique on twodifferent 3D data sets of a hollow organ. After processing this data, itwere converted into an STL file and output to a 3D printer. We fabricated ahollow intracranial aneurysm model using a Form 3 (Formlabs Inc.,Somerville, MA, USA). The resulting models were filled with iodinatedcontrast media. 3D rotational angiography of the models was carried out, andthe aneurysm geometry was compared with the original patient data. Theaccuracy of the 3D-printed hollow models’ sizes and shapes was evaluatedusing the nonparametric Wilcoxon signed-rank test and the Dice coefficientindex.

Results: The aneurysm volumes ranged from 34.1 to 4609.8 mm3(maximum diameters 5.1–30.1 mm), and no statistically significantdifferences were noted between the patient data and the 3D-printed models(p = 0.4). Shape analysis of the aneurysms and related arteries indicated ahigh level of accuracy (Dice coefficient index value, 88.7–97.3%;mean[ ± standard deviation (SD)], 93.6% ± 2.5%). The vessel wall thicknessof the 3D-printed hollow models was 0.4 mm for the parent and 0.2 mm forsmall branches and aneurysms, almost the same as the patient data.

Conclusion: This method demonstrated that small intracranialvessels and aneurysms can be physically reproduced from a patient's 3DDSA asa 3D-printed model, which could have useful surgical and educationalapplications.

O4-2-1

Improving the patient preparation process in emergent mechanicalthrombectomy by video analysis

Matthew B Potts, Agnes Donnelly, AbdelmageedSanaa, Babak S Jahromi

Neurological Surgery, Northwestern University Feinberg School of Medicine

Purpose: Minimizing door-to-recanalization times is critical inoptimizing outcomes in acute ischemic stroke caused by large vesselocclusion. Much interest has been paid to streamlining the process of workupand management of acute stroke patients, particularly in the emergency room.We previously conducted a quality improvement project at our institution tostudy the process of patient preparation in the angiography suiteimmediately prior to thrombectomy by analyzing video recordings of theangiography suite from the time a patient arrives until the start of MT.Tasks performed were time-stamped and the roles of the participants wererecorded. We now seek to further characterize this process to identifyfactors that may be targets for improved process efficiency.

Materials and Methods: Data from prior video analysis wasretrospectively reviewed. Recorded tasks included items such as patientexamination, intubation, vascular line placement, urinary catheterplacement, groin prep, draping, and equipment table setup. The primaryoutcome was the time of patient arrival in the angiography suite to skinpuncture (angio-to-groin). The number of tasks performed, time to startingindividual tasks, duration of individual tasks, and overall door-to-angiotimes were correlated with angio-to-groin times.

Results: Data from 57 consecutive MT cases were analyzed,comprising 33 transfers from another institution, 12 emergency roompresentations, and 12 inpatient strokes. There was no difference in meanangio-to-groin time between transfers, ED, and inpatient cases (p = 0.2).The mean door-to-angio time was 62.4 + /- 35.3 min, while the meanangio-to-groin time was 16.2 + /- 8.63 min. There was no correlation betweendoor-to-angio and angio-to-groin times. Cases that omitted at least onemajor task had significantly shorter angio-to-groin times (p = 0.03).Specifically, the omission of patient examination, intubation, and vascularline placement led to shorter angio-to-groin times (p = 0.04, p = 0.02,p = 0.02, respectively). Shorter times to starting puncture sitepreparation, urinary catheter placement, and patient draping correlated withshorter angio-to-groin times (R² = 0.53, R² = 0.47,and R² = 0.72, respectively). The duration of individual tasksdid not correlate with angio-to-groin times.

Conclusion: Several tasks performed in the patient preparationfor MT are associated with overall angio-to-groin times, including theoverall number of tasks performed, specific tasks such as patientexamination, intubation, and vascular line placement, and the time tostarting specifical tasks, such as puncture site preparation, urinarycatheter placement, and patient draping. Importantly, door-to-angio times donot correlate with angio-to-groin times, suggesting that a focus onimproving the efficiency of patient preparation in the angiography suite canhelp reduce overall door-to-recanalization times.

O4-2-2

Effect of intravenous thrombolysis on clot extraction duringmechanical thrombectomy in large vessel occlusion ischemicstrokes

João Brandão Madureira¹, Luísa Biscoito¹, Manuel Correia¹, Teresa Pinho Melo², Lia Neto¹, Gonçalo Basílio¹, Paulo Sequeira¹, Pedro Teotónio³, Sofia Reimão¹

¹Department of Neuroimaging, Hospital de Santa Maria - CentroHospitalar Universitário Lisboa Norte

²Department of Neurology, Hospital de Santa Maria - CentroHospitalar Universitário Lisboa Norte

³Department of Radiology, Hospital de Torres Vedras - CentroHospitalar do Oeste

Purpose: Intravenous alteplase before endovascular thrombectomyis the standard of care for acute ischemic stroke patients with large-vesselocclusion in the absence of contraindications. This study aimed to assessthe effect of alteplase administration in the mechanical extraction of theclot, particularly in the clot's fragmentation and migration rates.

Materials and Methods: Single-center, retrospective,observational study comparing bridging with alteplase prior to mechanicalthrombectomy with the non-bridging therapeutical approach in large-vesselocclusion acute ischemic stroke. We analyzed clinical and imaging data of 92patients with acute ischemic stroke of the anterior circulation with largevessel occlusion receiving treatment with mechanical thrombectomy with andwithout alteplase bridging (N = 48 and N = 44, respectively). Migration andfragmentation rates (primary outcomes) were assessed by univariate andmultivariate logistic analysis. The location and density of the clots, clotburden, periprocedural times, reperfusion scores, type of thrombectomytechnique, and number of extraction maneuvers were evaluated.

Results: The rates of clot migration (28.9% versus 10.0%) andfragmentation (54.3% versus 72.7%) were higher in the bridging group.However, no statistical difference between groups was found in multivariateanalysis (p = 0.063 and p = 0.287, respectively). Alteplase administrationdid not influence procedure times, hemorrhagic events during theendovascular procedure, or reperfusion scores. Clot density was positivelyassociated with fragmentation of the clot (adjusted OR 12.12; 95% CI1.39–105.79; p = 0.024).

Conclusion: Our data has shown no evidence of an alteplasedeleterious effect that could discourage the use of thrombolytics prior toEVT. Although bridging therapy may lead to higher clot fragmentation andmigration rates, this does not seem to impair reperfusion. Contrariwise, ithas the additional advantages of potentially dissolving small emboli andachieving reperfusion without the need for further interventions.

O4-2-3

Time from onset to puncture makes a difference of treatment efficacybetween bridging and direct mechanical thrombectomy in acute strokepatients with anterior circulation large vessel occlusion: Post hocanalysis of the SKIP study.

Mikito Hayakawa^1,2,3, Takato Hiramine², Masataka Takeuchi³, Masafumi Morimoto³, Ryuzaburo Kanazawa³, Yohei Takayama³, Yuki Kamiya³, Keigo Shigeta³, Seiji Okubo³, Norihiro Ishii³, Yorio Koguchi³, Tomoji Takigawa³, Masato Inoue³, Hiromichi Naito³, Takahiro Ota³, Noriyuki Kato³, Toshihiro Ueda³, Kazunori Akaji³, Wataro Tsuruta³, Kazunori Miki³, Yasuyuki Iguchi³, Teruyuki Hirano³, Shigeru Fujimoto³, Tomohiro Ohigashi⁴, Kazushi Maruo⁴, Kentaro Suzuki^3,5, Kazumi Kimura^3,5, Yuji Matsumaru^1,2,3

¹Division of Stroke Prevention and Treatment, Faculty of Medicine,University of Tsukuba

²Department of Stroke and Cerebrovascular Diseases, University ofTsukuba Hospital, Tsukuba, Ibaraki, Japan

³SKIP study group

⁴Department of Biostatistics, Faculty of Medicine, University ofTsukuba, Tsukuba, Japan

⁵Department of Neurology, Nippon Medical School Hospital, Tokyo,Japan

Purpose: Direct mechanical thrombectomy (D-MT) has been reportedto be not inferior to bridging mechanical thrombectomy (B-MT), a strategy ofintravenous thrombolysis (IVT) followed by MT, to improve clinical outcomeof acute stroke patients with anterior circulation large vessel occlusion.However, it remained unclear whether the time to MT makes any differences ofefficacy or safety between B-MT and D-MT. The aim of this study was toclarify the association between the time from symptom onset to puncture(O2P) and 90-day functional outcome in patients who underwent D-MT comparedwith B-MT using dataset of the Direct Mechanical Thrombectomy in Acute LVOStroke (SKIP) study.

Materials and Methods: This study was a post-hoc analysis of theSKIP study, a prospective, randomized trial comparing the efficacy andsafety of D-MT and B-MT in acute stroke patients eligible for IVT withocclusion of the internal carotid artery or the middle cerebral artery M1segment at 23 centers in Japan from Jan 2017 to Jul 2019. We compared theproportion of patients who obtained favorable outcome (defined as a modifiedRankin scale[mRS] score 0–2 at 90 days) between the D-MT and B-MT groups ateach quintile value of O2P time. In addition, we defined the threshold O2Ptime with maximum likelihood using logistic regression models, and wecalculated Odds ratios (ORs) with 95% confidence intervals (CIs) ofobtaining favorable outcome in D-MT versus B-MT group in subgroups dividedaccording to the threshold. ORs were assessed using multiple logisticregression analysis adjusted for age, sex, premorbid mRS score, baselineNational Institutes of Health Stroke Scale, baseline Alberta Stroke ProgramEarly CT Score, and successful reperfusion.

Results: A total of 101 patients who underwent D-MT and 103patients who underwent B-MT were included in this analysis. Each OR with 95%CI of obtaining favorable outcome in D-MT group compared with B-MT group infirst (≤ 100 min), second (101–130 min), third (131–165 min), fourth(166–212 min) and fifth (≥ 213 min) quintile of O2P time were 0.65;0.13–3.30, 0.85; 0.22–3.36, 0.92; 0.18–4.56, 0.37; 0.05–3.00, and 7.75;1.32–45.64, respectively. The threshold O2P time with maximum likelihood was225 min, and the proportions of patients who obtained favorable outcome were58% in D-MT group and 61% in B-MT group (OR, 0.79; 95% CI, 0.40–1.56) in thesubgroup of O2P < 224min, and 69% in D-MT group and 25% in B-MT group(OR, 6.59; 95% CI, 1.61–26.93) in the subgroup of O2P ≥ 225 min. There wereno significant differences of any or symptomatic intracranial hemorrhagerates between the D-MT group and B-MT group in the subgroup of O2P ≥ 225 min(50% vs 75%; p = 0.172, and 13% vs 25%; p = 0.357, respectively).

Conclusion: D-MT was significantly associated with favorableoutcome compared with B-MT if the O2P time was 225 min or longer.

O4-2-4

Primary results of intravenous tPA and mechanical thrombectomy foracute ischemic stroke in real-world clinical practice: the KanagawaIntravenous and Endovascular Treatment of Acute Ischemic Stroke registry(K-NET registry)

Toshihiro Ueda¹, Masataka Takeuchi², Masafumi Morimoto³, Yoshifumi Tsuboi⁴, Ryoo Yamamoto⁵, Shogo Kaku⁶, Junichi Ayabe⁷, Takekazu Akiyama⁸, Daisuke Yamamoto⁹, Kentaro Mori¹⁰, Hiroshi Kagami¹¹, Hidemichi Ito¹², Hidetaka Onodera¹³, Tomohide Yoshie¹, Kentaro Tatsuno¹, Satoshi Takaishi¹

¹Department of Strokology and Neuroendovascular Therapy,StMarianna University Toyoko Hospital, Kawasaki, Japan

²Department of Neurosurgery, Seisho Hospital, Odawara, Japan

³Department of Neurosurgery,Yokohama Shintoshi NeurosurgicalHospital, Yokohama, Japan

⁴Department of Neurosurgery, Kawasakisaiwai Hospital, Kawasaki,Japan

⁵Department of Neurology, Yokohama Brain and Spine Center,Yokohama, Japan

⁶Department of Neurosurgery, Neurosurgical East Yokohama Hospital,Yokohama, Japan

⁷Department of Neurosurgery, Yokosuka Kyousai Hospital, Yokosuka,Japan

⁸Department of Neurosurgery, Akiyama Neurosurgical Hospital,Yokohama, Japan

⁹Department of Neurosurgery, Kitasato University Hospital,Sagamihara, Japan

¹⁰Department of Neurosurgery, Yokohama Sakae Kyosai Hospital,Yokohama, Japan

¹¹Department of Neuroendovascular Therapy, Saiseikai YokohamashiTobu Hospital, Yokohama, Japan

¹²Department of Neurosurgery, St Marianna University School ofMedicine, Kawasaki, Japan

¹³Department of Neurosurgery, StMarianna University Yokohama SeibuHospital, Yokohama, Japan

Background and purpose: Endovascular treatment (EVT) for acutelarge vessel occlusion has been proven to be effective in several randomizedcontrolled trials. We conducted a prospective cohort study to evaluate thereal-world efficacy of EVT in patients with acute ischemic stroke.

Methods: We analyzed the Kanagawa Intravenous and EndovascularTreatment of Acute Ischemic Stroke (K-NET) registry, a prospective,multicenter observational study of patients treated by EVT and/orintravenous tissue-type plasminogen activator (tPA). Of the 2488 patientsenrolled from January 2018 to June 2020 at 40 stroke centers in KanagawaPrefecture, Japan, 2316 patients passing central data quality controlevaluated in the primary analyses were included. The primary outcome was agood outcome, which was defined as a modified Rankin Scale (mRS) of 0 to 2at 90 days. Moreover, a favorable outcome was defined as an mRS score of 0–2or no decrease in mRS score. Secondary analysis included predicting afavorable outcome using multivariate logistic regression analysis in 1592patients treated with EVT in anterior circulation occlusion.

Results: EVT and intravenous tPA alone treatments were performedin 1764 and 552 patients, respectively. The median age was 77 years in theEVT group, and the median National Institute of Health Stroke Scale (NIHSS)score was 18. Pretreatment mRS score 0–2 was 87% of patients, and directtransport was 92%. The rate of occlusion in anterior circulation was 90.3%.Successful recanalization was observed in 88.7%. The mediandoor-to-the-needle time was 45 min, the median door-to-puncture time was 62min, the median puncture-to-recanalization time was 45 min, and the medianonset-to-recanalization time was 200 min. Good and favorable outcomes at 90days were 43.4% and 47.7% in the anterior circulation and 41.9% and 47.9% inthe posterior circulation. The overall mortality was 12.6%. Significantpredictors for a favorable outcome were: younger age, low NIHSS score, highAlberta Stroke Program Early Computed Tomography Score, successfulrecanalization, and door-to-puncture time.

Conclusions: EVT in the K-NET registry had a slightly betteroutcome and less mortality compared with previous randomized trials andother registered studies. These results appear to be associated with fastertime from onset to recanalization.

O4-2-5

Utilization of Direct Transfer to Angio Suite for acute ischemicstroke treatment

Yasushi Ito¹, Keiko Kitazawa¹, Naomi Suzuki², Hiroshi Ohara², Jotaro On¹, Miyako Koyama¹

¹Department of Neurosurgery, Shinrakuen Hospital

²Department of Neurology, Shinrakuen Hospital

Purpose: Mechanical thrombectomy (MT) for acute ischemic strokeneeds recanalization as fast as possible. There are several attempts forreducing recanalization time. Direct transfer to angio suite (DTAS) is aprotocol which skips regular CT/MRI and directly transfer patients to angiosuite. Some papers which support effectiveness of DTAS are reportedrecently. DTAS protocol was stated in our institute and result was evaluatedretrospectively.

Materials and Methods: DTAS was performed in day time(8:30–17:15) for patients with suspect of large vessel occlusion (LVO)within 24 h of last known well, with NIHSS≧6. In DTAS protocol, CT/MRI wasskipped and patient was transferred to angio suite directly from emergencyroom. Cone beam CT (CB-CT) was performed first After neglecting bleeding,Rapid Angio using multiphase CB-CT was performed. MT was performed for casewith mismatch of ischemic core and penumbra.

Results: 17 cases of DTAS were performed during period of2021.7.1～2022.4.25. 11 cases were diagnosed as bleeding and received regulartreatment. 6 cases received Rapid Angio. Excluding one case with largeischemic core with poor mismatch, 5 cases were treatment with MT. Averagedoor to puncture (D2P) time of 5 cases was 36.4 min (25～45min). Timereduction tends to be prominent in later cases as stroke team becamefamiliar with DTAS. D2P time of non DTAS protocol during same period was94.3 min in average. No post procedural symptomatic bleeding was observed inDTAS. mRS at discharge were 0 in 2 cases, 1, 3, 4 in 1 case respectively.Reason of majority cases (11/17) was bleeding might be that all patientswere directly transfer to our hospital.

Conclusions: D2P time was shortened with DTAS protocol comparingregular protocol. Contribution for clinical outcome of DTAS needs furtheraccumulation of cases. To be accustomed for DTAS protocol, simulation withstroke team is essential, which may lead to expansion of DTAS in nightperiod.

O4-3-1

Update on the randomized trials within the Treatment Of BrainArteriovenous malformations (TOBAS) Study.

Elsa MAGRO^1,2,7, Jean-Christophe GENTRIC^3,4,7, Tim DARSAUT^6,7, Jean RAYMOND^5,7

¹Neurosurgery, Hospital University of Brest

²LaTIM, INSERM UMR 1101, University of Western Brittany (UBO)

³Department of Radiology, University Hospital of Brest, Brest,France

⁴GETBO, INSERM UMR 1034, University of Western Brittany (UBO)

⁵Department of Radiology, Service of Neuroradiology, CentreHospitalier de l’Université de Montréal (CHUM), Centre de recherche du CHUM(CRCHUM), Laboratoire de Recherche en NeuroRadiologie Interventionnelle(NRI), Montreal, Quebec, CANADA

⁶Division of Neurosurgery, Department of Surgery, University ofAlberta Hospital, Mackenzie Health Sciences Centre, Edmonton, Alberta,Canada

⁷For the TOBAS Collaborative Group

Purpose: TOBAS was designed to manage patients with brain AVMswithin a transparent clinical research context, and was initiated in 2014.TOBAS combines two RCTs and multiple registries of treated or conservativelymanaged patients. The aim of this work is to report the progress of the twoTOBAS RCTs.

Methods: TOBAS is an investigator-led, internationalmulti-center, pragmatic, prospective study. Management is determined usingan algorithm that combines clinical judgment and randomized allocation.Designed to be all-inclusive, the study offers a first RCT (RCT-1)allocating interventional or conservative management to patients eligiblefor both options, stratified according to treatment selected (surgery,stereotactic radiosurgery (SRS), or embolization). TOBAS algorithm isminimize according to presentation (hemorrhagic versus all otherpresentation) and Spetzler-Martin (SM) grade (I-II versus III-V). Thehypothesis of RCT-1 is that interventional management of unruptured brainAVMs suitable for both conservative and curative treatment alternatives willlead to a decrease in the number of poor outcomes (defined as mRS >2)from 25 to 15% at 10 years; 540 randomized patients (270 per group) areneeded. A second RCT (RCT-2) focuses on the role of pre-embolization as anadjunct to surgery or SRS. The hypothesis of RCT-2 is that pre-surgery orpre-radiosurgery embolization of cerebral AVMs can decrease the number oftreatment failures (failure to achieve an angiographic cure withoutdisabling complication) from 20% to 10%; 440 randomized patients (220 pergroup) are needed.

The primary outcome of TOBAS is death from any cause or disabling stroke(modified Rankin Scale (mRS)>2) at 10 years. Other recorded outcomesinclude mortality (all cause), intracranial hemorrhage after enrollment,peri-operative symptomatic complications (within 31 days), and angiographicoutcomes.

Results: TOBAS is currently recruiting in 30 centers in Canada,France, Chile, Brazil, and USA. At the time of data analysis in May 2021,there were 139 patients in RCT-1 (77 in surgery vs observation, 31 inembolization vs observation, and 31 in SRS vs observation). In RCT-2, 99patients have been included (78 surgery with or without pre-embolization,and 9 SRS with or without pre-embolization).

Conclusion: Collaborative efforts in 30 international centersare ongoing. Much more participation in the randomized trials of TOBAS isrequired to obtain meaningful results.

Clinical trial registration: ClinicalTrials.gov Identifier:NCT02098252

O4-3-2

Surgical treatment of brain AVMs: Clinical outcomes of patientsincluded in the registry of a pragmatic randomized trial

Elsa MAGRO^1,2,7, Jean-Christophe GENTRIC^3,4,7, Jean RAYMOND^5,7, Tim DARSAUT^6,7

¹Neurosurgery, Hospital University of Brest

²LaTIM, INSERM UMR 1101, University of Western Brittany (UBO)

³Department of Radiology, University Hospital of Brest, Brest,France

⁴GETBO, INSERM UMR 1034, University of Western Brittany (UBO)

⁵Department of Radiology, Service of Neuroradiology, CentreHospitalier de l’Université de Montréal (CHUM), Centre de recherche du CHUM(CRCHUM), Laboratoire de Recherche en NeuroRadiologie Interventionnelle(NRI), Montreal, Quebec, CANADA

⁶Division of Neurosurgery, Department of Surgery, University ofAlberta Hospital, Mackenzie Health Sciences Centre, Edmonton, Alberta,Canada

⁷For the TOBAS Collaborative Group

Background: The Treatment of Brain Arteriovenous MalformationsStudy (TOBAS) is a pragmatic study that includes two randomized trials andregistries of treated or conservatively managed patients. We report resultsof the surgical registry.

Methods: TOBAS patients are managed according to an algorithmthat combines clinical judgment and randomized allocation. For patientsconsidered for curative treatment, clinicians selected from surgery,endovascular or radiation therapy as the primary curative method, andwhether observation was a reasonable alternative. When surgery was selectedand observation was deemed not reasonable, the patient was not included inthe RCT but placed in the surgical registry. The primary outcome of thetrial is mRS>2 at 10 years (at last follow-up for the current report).Secondary outcomes include angiographic results, peri-operative seriousadverse events, and permanent treatment-related complications leading tomRS>2.

Results: From June 2014 to May 2021, 1010 patients wererecruited in 29 TOBAS centres. Surgery was selected for 229 (44%) of 512patients considered for curative treatment; 77 (34%) were included in thesurgery vs. observation randomized trial and 152 (66%) placed in thesurgical registry. Surgical registry patients included 124/152 (82%)ruptured and 28/152 (18%) unruptured AVMs, with the majority low-gradeSpetzler-Martin 1–2 (118/152 (78%)). Thirteen patients were excluded,leaving 139 patients for analysis. Embolization was performed prior tosurgery in 78/139 (56%) patients. Surgical angiographic cure was obtained in123/139 (89%; 82%-93%) all grade and in 105/110 (95%) low grade AVMpatients. Sixteen patients (12%; 7%-18%) reached the primary safety outcomeof mRS>2, including 11/16 with a baseline mRS of 3 or more due toprevious AVM rupture. Serious adverse events occurred in 29 patients (21%;15%-28%). Permanent treatment-related complications leading to an mRS>2occurred in 6/139 (4%; 2%-9%) patients.

Conclusion: Treatment of brain AVMs in the TOBAS surgicalregistry was safe and effective. The participation of more patients,surgeons and centres in the randomized trials is needed to definitivelyestablish the role of surgery in the treatment of unruptured brain AVMs.

Clinical trial registration: ClinicalTrials.gov Identifier:NCT02098252

O4-3-3

Endovascular treatment of brain AVMs: Clinical outcomes of patientsincluded in the registry of a pragmatic randomized trial

Jean-Christophe GENTRIC^1,4,7, Elsa MAGRO^2,3,7, Tim DARSAUT^6,7, Jean RAYMOND^5,7

¹Department of Radiology, Neuroradiology, Brest universityHospital, Brest, France

²LaTIM, INSERM UMR 1101, University of Western Brittany (UBO)

³Department of Neurosurgery, University Hospital of Brest, Brest,France

⁴GETBO, INSERM UMR 1034, University of Western Brittany (UBO)

⁵Department of Radiology, Service of Neuroradiology, CentreHospitalier de l’Université de Montréal (CHUM), Centre de recherche du CHUM(CRCHUM), Laboratoire de Recherche en NeuroRadiologie Interventionnelle(NRI), Montreal, Quebec, CANADA

⁶Division of Neurosurgery, Department of Surgery, University ofAlberta Hospital, Mackenzie Health Sciences Centre, Edmonton, Alberta,Canada

⁷For the TOBAS Collaborative Group

Background: The role of endovascular treatment in the managementof brain AVM patients remains uncertain. AVM embolization can be offered asstand-alone curative therapy, or as pre-embolization prior to surgery orstereotactic radiosurgery. The Treatment of Brain AVMs Study (TOBAS) is anall-inclusive pragmatic study that comprises 2 randomized trials andmultiple registries.

Methods: Results from the TOBAS curative and pre-embolizationregistries are reported. The primary outcome for this report is death ordependency (mRS >2) at last follow-up. Secondary outcomes includeangiographic results, peri-operative serious adverse events, and permanenttreatment-related complications leading to mRS>2.

Results: From June 2014 to May 2021, 1010 patients wererecruited in TOBAS. Embolization was chosen as primary curative treatmentfor 116 patients, and pre-embolization prior to surgery or stereotacticradiosurgery for 92 patients. Clinical and angiographic outcomes areavailable in 106/116 (91%) and 77/92 (84%) patients, respectively. In thecurative embolization registry, 70% of AVMs were ruptured, and 62% werelow-grade (Spetzler-Martin 1 + 2), while the pre-embolization registry had70% ruptured AVMs, and 58% low-grade AVMs. The primary outcome of death ordisability (mRS>2) occurred in 15 patients (14%; 8%-22%) of the curativeembolization registry and 9 patients (12%; 6%-21%) of the pre-embolizationregistry at 2 years. Embolization alone was confirmed to occlude the AVM in32/106 (30%; 21%-40%) of the curative attempts, and in 9/77 (12%; 6%-21%)patients in the pre-embolization registry. Serious adverse events (SAEs)occurred in 28/106 attempted curative patients ((26%; 18%-35%), including 21new symptomatic hemorrhages (20%; 13%-29%)). Five of the new hemorrhageswere in previously unruptured AVMs (n = 32; 16%; 95%CI: 5%-33%).Pre-embolization patients had 18/77 SAEs ((23%; 15%-34%), including 12 newsymptomatic hemorrhages (16%; 9%-26%). Three of the hemorrhages were inpreviously unruptured AVMs (n = 23; 13%; 95%CI: 3%-34%).

Conclusion: Embolization as a curative treatment for brain AVMswas often incomplete. Hemorrhagic complications were frequent, even when thespecified intent was pre-embolization before surgery or radiosurgery.Endovascular AVM treatment should preferably, where possible, be offered inthe context of a randomized trial.

Clinical trial registration: ClinicalTrials.gov Identifier:NCT02098252

O4-3-4

3-Blood flow and hemodynamics in cerebra arteriovenous malformation (1from 284–286)

Ali Alaraj

O4-4-1

Operative cannulation of the superior ophthalmic vein for embolizationof indirect carotid-cavernous fistulas: surgical techniques and clinicaloutcome

Gahn Duangprasert, Dilok Tantongtip

Neurosurgery, Thammasat University Hospital

Purpose: Endovascular therapy is known as thefirst-line treatment for indirect carotid-cavernous fistulas (CCFs),particularly with a trans-venous embolization. Only when all otherapproaches were exhausted would a direct surgical approach via superiorophthalmic vein (SOV) be proposed as an alternative option. This study aimsto assess the trans-SOV approach to embolization for its safety, efficacy,and viability as a first-line treatment in selected patients withdescription of the microsurgical and endovascular techniques.

Materials and Methods: We retrospectivelyreviewed 16 patients from 2015 to 2021 with indirect CCFs who were treatedusing SOV approach with n-Butyl cyanoacrylate (n-BCA) and coils as the mainembolic materials. The treatment's safety and efficacy were evaluated byocular and neurological improvement, angiographic obliteration, andrecurrence.

Results: From 16 patients, 3 were identifiedwith Barrow type B, and 13 with type D. The n-BCA was used as sole embolicmaterial in 12 cases, and coils were used in 4 cases. A direct SOV approachwas selected as first option in 11 cases. All patients achieved completefistula obliteration and good recovery of the ocular symptoms, accompaniedby excellent cosmetic results. No recurrence was found at the mean follow-upof 26 months.

Conclusions: Utilizing n-BCA and coils as mainembolic materials, the microsurgical dissection for exposure and directcannulation of the SOV as a route for fistula obliteration deliversexcellent clinical outcome with a low rate of complication. Not only is itsafe and effective as an alternative approach, but it can also serve as afirst-line treatment in selected patients.

O4-4-2

Efficacy of Onyx TVE for dural arteriovenous fistula

Takashi Izumi, Masahiro Nishihori, KoujiroIshikawa, Eiki Imaoka, Hiroki Matsuno, Hayato Yokoyama, Keita Suzuki,Ryuta Saito

Neurosurgery, Nagoya University, Graduate School of Medicine, Nagoya,Japan

Objective: Onyx TAE for dural arteriovenous fistula (dAVF) ishighly curative and has the advantage of being applicable to cases withdifficult access to sinus, but there is a risk of cranial nerve palsy andcerebral artery embolization due to the migration of embolic material. Onyxtends to leak into large cavity, and Onyx injection within sinus may beuseful to reduce risk. We report the results of our own case of Onyx TVE atour hospital.

Methods: We examined embolization results and treatmentcomplications in 10 patients who underwent Onyx TVE for dAVF from 2018 to2021.

Result: The average age of the patients was 69 years, 7 males.The location of dAVF was 6 TSS, 1 tent, and 3 multiple sinus. In the Cognardclassification, 2b was 5 cases, 2a + b was 5 cases and 4 was 1 case.Isolated sinus was found in 5 cases. Eight cases were initial treatmentcases. Treatment was performed on Onyx-based TVE in 6 patients. Theremaining 4 cases were 2 cases in which Onyx TVE was added because theycould not be occluded by other embolization methods, and 2 cases in whichvarious embolization methods were combined for multiple shunts. The averageinjection volume of Onyx on TVE was 1.76 ml. Immediately after treatment,complete obliteration was obtained in 7 cases, mild residual in 2 cases, andintentional partial embolization in 1 case. There were no neurologicalcomplications such as cranial nerve paralysis or cerebral infarction, andthere was no migration into the cerebral arteries.

Conclusion: The results of Onyx TVE for dAVF at our hospitalwere excellent in both occlusion rate and safety. Although limited toaccessible cases, Onyx TVE may be a useful option for dAVF with affectedsinuses with severe stenosis or obstruction.

O4-4-3

Recurrence after endovascular treatment for Transverse-sigmoid sinusdural AVFs: a retrospective study

Yuji Kushi¹, Tetsu Satow^1,2, Eika Hamano¹, Taichi Ikedo¹, Koji Shimonaga¹, Akihiro Niwa¹, Kiyofumi Yamada¹, Hirotoshi Imamura¹, Koji Iihara¹, Hiroharu Kataoka¹

¹Department of Neurosurgery, National Cerebral and CardiovascularCenter

²Department of Neurosurgery, Kindai University Faculty ofMedicine

Purpose: The purpose of this study was to clarify the featuresof recurrence after endovascular treatment for transverse-sigmoid sinusdural arteriovenous fistulae (TSdAVF).

Materials and Methods: Patients with TSdAVF who underwentinitial treatment in our institute between April 2005 and April 2021 wereretrospectively collected and analyzed to determine the characteristics ofrecurrent cases.

Results: 48 consecutive patients were included in the study, andthe mean follow-up period was 50.4 months. Recurrence was observed in 5cases (10.4%). The mean interval between treatment and recurrence was 3.6months (2 ∼ 7 months). Borden classification at the initial treatment wastype 2 in 4 and type 1 in 1. At the time of recurrence, two were classifiedas type 2, and 3 cases as type 1, respectively. The initial treatment wasTAE in 1, TAE and TVE (sinus packing: SP) in 1, and TAE and TVE (selectiveTVE for the shunted pouch) in 3. After initial treatment, complete shuntdisappearance was confirmed in 2 and minimal residual shunts were found in3. The types of recurrence were as follows (with some overlapping): 1)emergence of a new feeder in 4, 2) recanalization of the feeder occluded byTAE in 3, 3) relapse of the feeder occluded by TVE in 2, and 4) augmentationof a feeder that was slightly residual at the end of the initial treatmentin 2. The main feeder involved in recurrence was the occipital artery in 4cases. The main site of recurrence was the TS junction in 5 cases. SP wasperformed in 4 out of 5 recurrent cases, and the disappearance of shuntswere confirmed in all cases.

Conclusion: Patients with Borden type 1 or 2 who have difficultywith SP at initial treatment require more careful follow-up for recurrence.In case of recurrence, SP was useful for the shunt elimination.

O4-4-4

Treatment Selection and Outcome of Dural Arteriovenous Fistulas: AComparison Before and After Onyx Introduction

Naoki Akioka¹, Naoya Kuwayama², Daina Kashiwazaki¹, Satoshi Kuroda¹

¹Department of Neurosurgery, University of Toyama, Toyama,Japan

²Department of Neurosurgery, Toyama Red Cross Hospital, Toyama,Japan

Purpose: In Japan, transarterial embolization (TAE) using Onyxfor intracranial dural arteriovenous fistulas (DAVF) was approved forinsurance in 2018. This study examined how the introduction of Onyx haschanged the treatment choices and outcomes.

Materials and Methods: 194 patients underwent endovascularand/or surgical treatments between April 2001 and October 2021. Their meanage was 65.5 years, ranging from 6 to 88 years. We participated in theinvestigator-initiated clinical trial and started treatment using Onyx inFebruary 2014. The number of cases before the introduction of Onyx was 93and after the introduction was 101. The locations of the lesions of beforeOnyx/Onyx era were as follows: transverse sigmoid sinus (TS) 33/40 cases,cavernous sinus (CS) 33/21 cases, spine 6/15 cases, anterior condylarconfluence (ACC) 5/8 cases, the superior sagittal sinus (SSS) 3/8 cases,tent 7/4 cases, and others 8/9 cases. By Borden classification, 37/40 wereType I, 29/21 were Type II, and 27/40 were Type III.

Results: Before the Onyx era, TAE alone was performed in 27%,TVE alone in 27%, and both TAE and TVE in 46%, compared to 69%, 25%, and 6%,respectively, in the Onyx era. In TS lesions, the number of patients treatedwith TAE alone increased significantly in the Onyx era, and the effectiveocclusion rate increased significantly from 66% before the use of Onyx to85% after. All patients with CS and ACC lesions underwent TVE, and allpatients with craniocervical junction lesions underwent surgery, which wasthe same before and after the introduction of Onyx. The complication rate inall lesions was 7.5% before the Onyx era and 2.0% in the Onyx era, whichwere transient skin ulcers caused by Onyx. Of the 51 patients treated withOnyx, recurrence requiring retreatment was observed in 9 patients.

Conclusions: We found that TAE alone significantly increased thenumber of patients treated with Onyx, especially in TS lesions and improvedthe treatment outcome. However, there are some cases in which TVE should bechosen in consideration of efficacy and safety, and therefore, it isnecessary to make an appropriate decision depending on the case.

O4-4-5

Vessel Navigator, advanced 3D roadmap for transvenous embolization ofdural arteriovenous fistula through the occluded sinus

Tomokazu Sekine¹, Wataro Tsuruta¹, Arisa Tomioka¹, Hisayuki Hosoo², Yuki Kamiya¹, Yuji Matsumaru²

¹Department of Endovascular Neurosurgery, Toranomon Hospital,Tokyo, Japan

²Department of Stroke, University of Tsukuba, Ibaraki, Japan

Purpose: Transvenous embolization (TVE) is one of the option fortreating dural arteriovenous fistula(dAVF), but it is not rare proximaland/or distal venous sinuses is occluded or hypoplasty. In this case TVE viaoccluded sinus can be challenging and there is some risk of perforation.Wehave previously reported the usefulness of contrast-enhanced MagneticResonance Imaging(MRI) for obtaining a panoramic view of the occluded sinusand exclude a hypoplasty. Now we would like to introduce the usefulness ofVessel Navigator which is advanced 3D road mapping for approaching toaffected sinus through the occluded sinus.

Materials and Methods: We reviewed cases of TVE for dAVF fromJune 2015 to October 2021 at our institution. And we analyzed preoperativeangiography to evaluate the approach route and venous drainage, andcontrast-enhanced MRI T1 FFE Gd to confirm venous sinus development(hypoplasia or exists) and T1 VISTA BB to assess the patency of the venoussinus. Then we evaluated the ability to reach the affected sinus andcomplications in cases in which Vessel Navigator was used.

Results: Of 89 cases with dAVF, TVE was performed in 37cases.Contrast-enhanced MRI was obtained in 25 cases, except the case which venoussinus was clearly open. And in all 10 cases whose sinus used for approachwas occluded had the contrast-enhanced MRI. The findings of venous sinusocclusion on contrast-enhanced MRI and angiography matched exactly.

Vessel Navigator was used in 9 cases (8 cavernous sinus(CS), 1 anteriorcondylar confluence(ACC)). 6 were used to approach through a occluded sinusand were able to reach the affected sinus in all cases. And 3 were used tohelp approach through a patent sinus and were able to reach the lesion inall cases, too. In one case which is not using Vessel Navigator failed toreach the affected sinus through a occluded sinus. No complications such asvessel perforation were observed in any of the cases.

Conclusion: Vessel Navigator advanced 3D roadmap usingcontrast-enhanced MRI is useful option for TVE of dAVF through a occludedsinus. It makes TVE via occluded sinus more feasible and safe.

O4-5-1

Intralesional Bleomycin injection for venous malformations of head andneck: An evaluation of treatment outcome in Siriraj Hospital,Thailand.

Peerawas Santheerapharp, Jirapong Vongsfak,Vasin Rungruangwuddikrai, Phanuphong Nianphanich, AnchaleeChurojana

Department of Radiology, Faculty of Medicine, Mahidol university

Purpose: Venous malformation (VM) is a type of vascularmalformations which effects only venous system resulting in enlargement ofvenous lakes. Not only cosmetic problem, VM can be painful. Percutaneoussclerotherapy is currently the treatment of choice. Bleomycin is acost-efficient and safe sclerosing agent that has been used to treat VMssuccessfully. This study aims to evaluate the clinical outcomes of patientswith VMs at head and neck region who had treated with intralesionalbleomycin injection (IBI) at Siriraj Hospital, Bangkok, Thailand.

Materials and methods: A retrospective review of patients whohad VMs at head and neck region with IBI treatment between January 2018 toJuly 2021was performed. In each session Bleomycin dose was limited at 15 mg.Patients’demographic data, presenting symptoms, number of IBI sessions withdose accumulation and clinical outcomes were recorded. Patients’outcomeswere defined as pain relief, satisfactory size reduction and complications.The patients who had less than 1 year follow up period after first visitwere excluded.

Results: A total of 91 patients, 33 male and 58 female, with amedian age of 20 years (IQR 8–37), who had treated by IBI were included. Allpatients had visualized lesions and/or palpable mass, 18.9% had associatedpain. The median follow-up period was 22 months (IQR 12.5–36). The mediannumber of IBI sessions was 2 (IQR 1–3) and the median cumulative dose ofbleomycin administered was 25 mg. (IQR 15–45) Satisfactory result of sizereduction was achieved totally 82.4%, and pain relief was obtained in 81%.The only complication was asymptomatic hyperpigmentation, either at lesionsite or remote region, which was found in 17.6%

Conclusion: Intralesional bleomycin injection has proved itssafe and effectiveness, with satisfactory cosmetic outcome and pain relief,without any major complication. We consider IBI to be the initial treatmentof choice for venous malformations at every location of head and neckregion.

O4-5-2

Filum Terminale Arteriovenous Fistulas: Clinical Characteristics,Treatments, and Outcomes

Jiawei Qi, Jingwei Li, Zhenlong Ji, GuilinLi

Department of Neurosurgery, Xuanwu Hospital, Capital Medical University,Beijing, China

Purpose: Filum terminale arteriovenous fistula is a raredisease, and is prone to missed diagnosis and misdiagnosis. Moreover, thenatural history, clinical characteristics, imaging features and long-termoutcomes of patients is unclear. We aim to summarize the clinicalcharacteristics, imaging features and our experience in treatment.

Methods and Methods: From 2001 to 2021, 67 patients with FTAVFtreated in our SAVM study group were retrospectively reviewed. According tothe angioarchitecture, especially the supplied artery, they are divided intosingle feeder group (45 cases) and multiple feeders group (22 cases).Fifty-seven had preoperative MRI, they are divided into three groupsaccording to scope of edema: 0–5 vertebral bodies (16 cases), 6–10 (32cases), more than 10 (9 cases). Their clinical features, radiologicalfindings, treatment, and outcomes were evaluated.

All analyses were performed with SPSS software, Version 20.0(IBM, Armonk, NewYork). Variables are expressed as the mean ± SD, quartile, or number ofpatients (percentage) as appropriate. Descriptive data were compared byusing the χ2 test for proportions and a Mann–Whitney test for continuousmeasurements. Statistical significance was set at P < 0.05.

Results: The mean age was 54.09 ± 11.85 years, and patients inmultiple feeders group were younger than those in single feeder group(50.05 ± 9.95 vs 56.07 ± 12.23, P = 0.034). This lesion is more common inmale (82.1%). The median of duration was 12 (first quartile was 6, thirdquartile was 24) months. The mean preoperative mALS was 5.79 ± 3.13.Patients in single feeder group had higher rate of misdiagnosis (40% vs9.1%, P = 0.009), and low limb weakness is a common complaint (97.8% vs77.3%, P = 0.006). Patients in multiple feeders group complaint about morebowel/bladder dysfunction (90.9% vs 68.9%, P = 0.047) and hypoesthesia(81.8% vs 46.7%, P = 0.006), and more combined with congenital spine andspinal cord malformation (54.5% vs 24.4%, P = 0.015). The recurrence ratewas 6.0% and seems more common in embolization(P = 0.001). For 57 patients,who were divided into three groups according to the scope of edema, the meanpreoperative mALS was 4.94 ± 3.04, 5.41 ± 3.27, 8.33 ± 2.50 (P = 0.031); andthe median mALS at 6 month after operation was 4.5 (first quartile was 3.5,third quartile was 6.5), 3.5(first quartile was 1, third quartile was 7),6(first quartile was 5, third quartile was 8)(P = 0.041), the median mALS atfollow-up was 4(first quartile was 2.5, third quartile was 7), 3.5(firstquartile was 5, third quartile was 8), 6 (first quartile was 5, thirdquartile was 8)(P = 0.038).

Conclusion: Single feeder and multiple feeders are related tothe clinical characteristics of patients. The scope of preoperative spinalcord edema is related to the severity of the disease. Microsurgery andhybrid operation are safe and effective.

O4-5-3

Cerebral proliferative angiopathy: Diagnostic challenge

Hidetsugu Maekawa

Department of Neurosurgery, Nara Prefecture General Medical Center

Purpose: Cerebral proliferative angiopathy (CPA) was introducedas a distinct entity from brain arteriovenous malformation (AVM). To discussthe challenge in differentiating CPA from AVM.

Materials and Method: The images of cases suspected of CPA andpublished cases as CPA are carefully reviewed.

Results: There are vascular lesions mimicking CPA, such as AVMand developmental venous anomaly (DVA). Some AVM induces perinidalangiogenesis and stenosis or occlusion of proximal arteries. DifferentiatingCPA from AVM with these proliferative changes is especially challenging. Apart of DVA, classified as DVA with arteriovenous shunts, accompaniesperilesional dilated capillaries which are the hallmark of CPA.

Conclusions: Making the diagnosis of CPA is notstraightforward.

O4-5-4

Transvenous embolization of direct carotid cavernous fistula viapterygoid plexus: a case report

Ryu Kimura, Masafumi Hiramatsu, Kenji Sugiu,Tomohito Hishikawa, Jun Haruma, Kazuhiko Nishi, Yoko Yamaoka, Yu Sato,Yuki Ebisudani, Hisanori Edaki, Masato Kawakami, Isao Date

Department of Neurological Surgery, Okayama University Faculty of Medicine,Dentistry and Pharmaceutical Sciences

PURPOSE: Endovascular treatment is the mainstay of treatment fordirect carotid cavernous fistulas (dCCF), but endovascular approaches varywidely. In some case reports, transvenous embolization (TVE) of a dCCF isperformed via the pterygoid plexus (PP) as an access route to the cavernoussinus (CS). We show a rare case in which TVE via the PP was possible for adCCF.

Summary of case: An 81-year-old man had a giant aneurysm in theCS of the right internal carotid artery (ICA) incidentally noted on the headMRI two years earlier. He was aware of headache, trigeminal neuropathy, andprogressive diplopia, and was admitted to our hospital. Digital subtractionangiography (DSA) showed dCCF caused by the ruptured ICA aneurysm. The dCCFdrained through the CS to the superior ophthalmic vein, inferior ophthalmicvein, superficial middle cerebral vein, and PP. The balloon occlusion testof the ICA showed no ischemic tolerance, and the patient was at risk of endleak after the abdominal aortic aneurysm treated with a stent graft andcould not undergo dual antiplatelet therapy. We decided to perform TVE toclose the fistula. At the DSA just before treatment, only the drainage routeof the PP was patent and other routes were occluded. The femoral veinapproach was used to reach the aneurysm via the right internal jugular vein,PP, and CS. The shunt point was relatively easy to pass. We performed TVEusing coils and glue, which resulted in the occlusion of the dCCF. The giantaneurysm was not treated. Currently, 14 months have passed since thesurgery. The diplopia is improving, the headache and trigeminal neuropathyare resolved, and there is no recurrence of dCCF in MRI.

Conclusion: The detailed preoperative examination is importantto consider the various venous approaches of the dCCF. The PP can be aneffective approach route to reach the CS.

O4-5-5

Angioarchitecture and clinical features of spinal extraduralarteriovenous shunts: a nationwide retrospective cohort study

Kouhei Nii¹, Hiro Kiyosue², Yasunari Niimi³, Yuji Matsumaru⁴, Shuichi Tanoue⁵, Masafumi Hiramatsu⁶, Ichiro Nakahara⁷, Wataro Tsuruta⁸, Toshiki Endo⁹, Kittipong Srivatanakul¹⁰, Naoki Akioka¹¹, Satomi Ide¹², Hironori Fukumoto¹, Toshio Higashi¹

¹Department of Neurosurgery, Fukuoka University Chikushi Hospital,Chikushino, Japan

²Department of Diagnostic Image Analysis Endowed Chairs, Facultyof Life Sciences Kumamoto University, Kumamoto, Japan

³Department of Neuroendovascular Therapy, St Luke's InternationalHospital, Tokyo, Japan

⁴Division of Stroke Prevention and Treatment, Department ofNeurosurgery, University of Tsukuba, Ibaraki, Japan

⁵Department of Radiology, Kurume University Hospital, Kurume,Japan

⁶Department of Neurological Surgery, Okayama University GraduateSchool of Medicine, Okayama, Japan

⁷Department of Comprehensive Strokology, Fujita Health UniversitySchool of Medicine, Toyoake, Japan

⁸Department of Endovascular Neurosurgery, Toranomon Hospital,Tokyo, Japan

⁹Department of Neurosurgery, Tohoku University Hospital, Sendai,Japan

¹⁰Department of Neurosurgery, Tokai University School of Medicine,Isehara, Japan

¹¹Department of Neurosurgery, Toyama University Hospital, Toyama,Japan

¹²Department of Radiology, Oita University Hospital, Yufu,Japan

Purpose: Spinal extradural arteriovenous shunts (SEAVS) includevarious arteriovenous shunts outside the spinal dura mater. This study aimsto clarify the angiographic and clinical characteristics and propose aclassification of SEAVS by a large cohort study.

Materials and Methods: Patients with SEAVSs treated betweenJanuary 2011 and December 2020 were enrolled from tertiary referralhospitals certified by the Japanese Society of Neuroendovascular Therapy.Angiography, MRI, CT, and the clinical data, including baseline patientcharacteristics, the coexistence of other arteriovenous shunts, treatmentmodality, and clinical outcomes, were reviewed. The angioarchitecturesincluding feeding arteries, locations of AVS, drainage veins, and osseousinvolvement were evaluated by 13 readers to reach a consensus. SEAVSs wereanatomically classified into four types as below; 1) Epidural AVF, 2)Intraosseous AVF, 3) Paravertebral AVF, and 4) Combined AVF composed of atleast two of the epidural, osseous, and paravertebral AVFs.

Result: A total of 123 patients (83 males and 40 females, meanage 66.0 years) with SEAVSs were collected and analyzed. The most frequentsymptom was myelopathy due to spinal venous congestion (69.9%), followed byradiculopathy (17.6%). According to the anatomical classification, theSEAVSs were classified into epidural AVF in 92 (74.8%), intraosseous AVF inone (0.8%), paravertebral AVF in 8 (6.5%), and combined AVF in 22 patients(17.9%). SEAVSs were treated by endovascular technique alone in 97 patients,surgical interruptions of the draining vein in 19, combinations ofendovascular and surgical treatment in 4, and conservative treatment in 3,respectively. Complete occlusion of the shunt was observed in 92 SEAVSs(74.8%), with significantly lower occlusion rates in combined AVFs (31.8%, p< 0.001). Good clinical outcomes were achieved in 81 SEAVSs (65.9%).

Conclusion: Our cohort study demonstrated that the most commontype of SEAVSs was epidural AVF, followed by the combined AVF. Curativetreatment of combined AVFs is still challenging.

O4-6-1

Cerebellar artery arising from the cavernous segment of the internalcarotid artery and persistent trigeminal artery: a spectrum ofincomplete longitudinal fusion

Dong Young Cho¹, Bum-soo Kim³, Yong Sam Shin²

¹Department of Neurosurgery, Ewha Womans University SeoulHospital, Seoul, South Korea

²Department of Neurosurgery, Seoul St Mary's Hospital, Seoul,South Korea

³Department of Radiology, Seoul St Mary's Hospital, Seoul, SouthKorea

Background: The embryological relationship between cerebellararteries originating directly from the cavernous segment of the internalcarotid artery and persistent trigeminal artery is not well understood.

Purpose: To evaluate the incidence and pattern of cerebellararteries originating from the internal carotid artery and persistenttrigeminal artery, and to discuss their probable embryologicalrelationship.

Material and Methods: We reviewed 5113 angiographic studies from5093 patients at our institution over the last eight years, searching forpatients with persistent trigeminal artery and cerebellar arteriesoriginating from a cavernous segment of internal carotid artery (persistenttrigeminal artery variant).

Results: Of the 5093 patients, 27 patients had persistenttrigeminal artery or persistent trigeminal artery variant (0.53%). Twentypatients (6 men, 14 women; median age ¼ 54 years) had persistent trigeminalartery (0.39%). Seven patients (2 men, 5 women, age range ¼ 37–72 years;median age ¼ 57 years) had a persistent trigeminal artery variant withpersistent trigeminal artery terminating in a cerebellar artery withoutdirect connection to the basilar artery (persistent trigeminal arteryvariant; 0.14%). The terminal branch of the persistent trigeminal arteryvariant was an anterior inferior carotid artery in five patients and asuperior cerebellar artery in two patients. Of the seven patients havingpersistent trigeminal artery variant, four patients had another artery fromthe basilar artery to the anterior inferior carotid artery territory. In6/20 patients with persistent trigeminal artery, there was an anteriorinferior carotid artery arising from the persistent trigeminal artery. Oneof these patients showed another arterial branch from the basilar artery tothe anterior inferior carotid artery territory.

Conclusion: Persistent trigeminal artery variant and cerebellararteries originating from the persistent trigeminal artery are both believedto be a spectrum of incomplete fusion of the longitudinal neural arteries.Understanding the precise anatomy is important in diagnostic and therapeuticsettings for related vascular disease.

O4-6-2

DSA overestimates dural sinus diameter: Comparison of the diametermeasured conventionally on DSA and area-based conversion diameter oncontrast-enhanced MR imaging

Mi Hyeon Kim¹, Ki Baek Lee², Jong-tae Yoon¹, Joon Ho Choi¹, Sun Moon Hwang¹, Boseong Kwon¹, Deok Hee Lee¹

¹Department of Radiology, Research Institute of Radiology, AsanMedical Center, University of Ulsan College of Medicine, Seoul 05505, SouthKorea

²Department of Radiologic Technology, Chungbuk Health &Science University, Cheongju, South Korea

Purpose: While performing cerebral venous sinus stenting,accurate measurement of the dural sinus diameter has been a challenge.Oversizing of the stent occurs not infrequently. We hypothesized that wasdue to the dural sinus's triangular shape - not the round shape as weexperience in the arterial stenoses. We thought the most accurate diametercould be calculated by the converted diameter from the cross-sectional areaof the dural sinus on the contrast-enhanced 3D MR image (CE-MRI). This studyaimed to show how much overestimation was occurring on the conventional DSAin the diameter measurement by comparing it with the diameter calculatedfrom the area-based conversion on CE-MRI.

Materials and Methods: From January to December 2021, 20patients who underwent cerebral DSA and CE-MRI within 4 weeks were enrolledin this retrospective analysis. The average age of the study group was63 ± 5 years (53–71 years). On the venous phase of the cerebral DSA, weselected a mid-portion of the downstream superior sagittal sinus (SSS) andmid-portion of the transverse sinus (TS) to measure the representativediameters. The corresponding diameter was calculated from thecross-sectional area measured by drawing an ROI of the dural sinus on theaxial reformatted image for the SSS and coronal reformatted image for the TSfor both sides. Pairwise comparisons were done for the diameter measured onthe DSA (DSA diameter) and the corresponding converted diameter on CE-MR (MRdiameter) for the SSS, right TS, and left TS.

Result: For the SSS, the DSA diameter was 27% larger than the MRdiameter (9.8 ± 1.4 mm vs. 7.1 ± 1.3 mm, P < 0.05). For the right TS, 16%(8.8 ± 3.2 mm vs 7.4 ± 2.0 mm, P < 0.05). For the left TS, 22%(8.4 ± 2.8 mm vs. 6.6 ± 1.3 mm, P < 0.05).

Conclusion: DSA overestimates the diameter of the dural sinusessignificantly. We would like to recommend 10 to 20% undersizing of the stentdiameter or use MR imaging for the profer stent choice.

O4-6-3

The origins and courses of perforating branches through the anteriorperforating substance

Takahiro Ota

Department of Neurosurgery, Tokyo Metropolitan Tama Medical Center

Purpose: Preservation of blood flow in the perforating branchesis essential to avoid complications in the neurointerventions of theseareas. The fact that the perforators penetrating the anterior perforatingsubstance (APS) share its territories and variations prompted us to reviewthis embryological lateral striate artery group to propose a concept as totheir common embryological origin.

Results: The APS lies deep within the Sylvian fissure and isbordered anteriorly by the lateral and medial olfactory chiasm, laterally bythe insular limit, posteriorly by the optic chiasm and temporal lobe, andmedially by a rhomboid shape near the interhemispheric fissure. Arteriespenetrating the APS include the lenticular striate artery (LSA), branches ofA1, the recurrent artery of Heubner (RAH), branches of the internal carotidartery (ICA), and the anterior choroid artery. Embryologically, the branchesof the LSA, A1, and RAH all originate from the lateral striate arteryderived from the lateral olfactory that branched off the cranial division ofthe primitive internal carotid artery. Occasionally, the RAH branches offthe cortical branch of the middle cerebral artery, which is consideredembryologically identical to the accessory MCA; it is also common for theLSA to originate from the accessory MCA, A1, and RAH, all of which arepossible anatomical variants given that all of these branches originate fromthe embryological lateral striate arteries.

Conclusion: All perforating branches through the APS have acommon embryological origin and are named according to their perfusion areasrather than their origins. Preoperative CT angiography and 3D-rotationalangiography can provide important information for preservation of theperforators by examining the origin of the perforating branch in detail.

O4-6-4

Novel angiographical findings of twisted carotid bifurcation based onover 900 sides.

Joji Tokugawa, Kentaro Kudo, Takumi Mitsuhashi,Takashi Mitsuhashi, Makoto Hishii

Department of Neurosurgery, Juntendo University Nerima Hospital

Introduction: Twisted carotid bifurcation (TCB) is a well-knownanatomical variation of the carotid bifurcation in patients undergoingcarotid endarterectomy but has been little investigated in patients withnon-internal carotid artery (ICA) stenosis. This study investigates thecharacteristics of TCB in patients with ICA stenosis and diverse otherpathologies.

Patients and Methods: All conventional cerebral angiographiesperformed in our institute for any reason from January 2012 to December 2018were reviewed. The patients were divided into two groups, the TCB group andanatomically normal non-TCB group, and the basic characteristics of thegroups were analyzed.

Results: Both sides of the carotid bifurcation were clearlyvisualized in 914 sides of 457 patients. TCB was found in 89 patients, 96 of914 sides (10.5%). Among the 96 sides, 81 (84.4%) were right side, and 15(15.6%) were left side. Among the 89 patients, 74 (83.1%) had TCB only onthe right side, 8 (9.0%) only on the left side, and bilateral in 7 (7.9%).TCB was significantly more frequent in older patients (P = .02), femalepatients (P <.001), and patients with ICA stenosis or occlusion at thebifurcation (P = .005).

Conclusions: The prevalence of TCB was 10.5%, and 84.4% of caseswere on the right in patients with diverse pathologies. Older patients,female patients, and patients with ICA stenosis or occlusion are more proneto have TCB.

O4-6-5

Microneuro angiography of the anterior choroidal artery with highresolution cone beam CT.

Michihiro Tanaka, Keisuke Kadooka, TakafumiMitsutake

Neuroendovascular and Neurosurgery, Kameda Medical Center

Object: Microanatomical evaluation of anterior choroidal artery(AChA) was studied based on the technique of superselective angiography withhigh-resolution cone beam CT (CBCT).

Method: Consecutive 116 cases of the intracranial aneurysm and70 cases of the dural AVFs (DAVFs) treated with endovascular procedure wereanalyzed retrospectively. In all cases, conventional DSA and CBCT wereperformed. Among these 116 cases, a total of 12 cases were applied thesuperselective angiography of the anterior choroidal artery (AChA).

The 80-kV high-resolution CBCT were acquired using the 1024 × 1024 pixelsmatrix detector with an 8-inch field of view. The anatomical variation andconfiguration of AChA were analyzed and compared to the microanatomy basedon the cadaver dissection study.

Result: In all 12 cases, the superselevtive angiography from theorifice of AChA was succeeded and visualized the cisternal segment, plexalpoint, uncal branch and choroidal segment. There were two cases of AChAwhich did not provide the uncal branch. The perforators supplying to thegenu of internal capsule and midbrain were not visualized on the 2D-DSA, butwell identified on the CBCT. There were several limitations that theperforators associated with the large aneurysm with the diameter more than15mm could not be visualized the details due to the beam hardeningeffect.

Conclusion: The CBCT with superselective angiography of AChA isfeasible to visualize the entire arterial system of the amygdalohippocampalformation which was around 50 to 100μm diameter of perforators.

Keywords: Superselective angiography, Anterior choroidal artery (AChA), conebeam CT (CBCT)

O4-7-1

A case of spontaneous high-flow vertebral arteriovenous fistulatreated by selective target embolization with double balloon sandwichtechnique

Ryosuke Suzuki^1,2, Nobuyuki Shimizu¹, Yu Iida¹, Kagemichi Nagao¹, Jun Suenaga¹, Tetsuya Yamamoto¹

¹Department of Neurosurgery, Yokohama City University, GraduateSchool of Medicine

²Department of Neurosurgery, Odawara Municipal Hospital

Purpose: Spontaneous vertebral arteriovenous fistula (VAVF) is arare vascular disorder t in which the vertebral artery (VA) trunk orbranches connect directly with the surrounding venous plexus. Typically,Endovascular embolization is difficult due to its complicated anatomicalstructure and the presence of high-flow shunt. Herein, we report a case ofcervical high-flow VAVF treated by target embolization (TE) using the doubleballoon sandwich technique (DBST), with a review of literatures.

Summary of Case: A 70-year-old woman with no history of trauma or connectivetissue disease presented with left tinnitus. MRI showed no abnormal signalchanges in her brain but left sigmoid sinus and left suboccipital cavernoussinus (SCS) was observed in arterial phase on CT angiography. Angiographyrevealed a direct fistula between V2 segment of left VA and surrounding SCSat the C2 vertebra level, and some reflux into the intracranial venous sinusvia left posterior condylar vein from dilated venous pouch next to fistula.No cortical venous reflex was observed because shunt flow mostly drainedanterogradely. The patient received aspirin (100mg daily) and clopidogrel(75mg daily) for 7 days prior to treatment. Under general anesthesia, theright femoral artery and vein were punctured, and 6Fr FUBUKI guidingcatheter (Asahi Intec, Aichi, Japan) was placed in both the left VA and leftinternal jugular vein (IJV). From arterial side, Scepter XC 4mm × 11mm(Microvention, Inc., California, USA) was positioned into left VA adjacentto the fistula, and Excelsior XT-17 (Stryker, MI, USA) was guided into thefistula. Shouryu HR 7mm × 7 mm (Kaneka Medics, Osaka, Japan) was thennavigated into the dilated venous pouch next to the fistula via IJV. Whileboth balloons were inflated to sandwich the fistula, a total of 7 bareplatinum coils (36 cm) were inserted from the jailed XT-17 into the fistula.The VAVF was completely occluded and left VA was well preserved. Hertinnitus disappeared immediately after the treatment.

Conclusion: TE is usually challenging in VAVF cases with largefistula or high-flow shunt, and overfilling of coils can be costly and causenerve compression symptoms. DBST might be useful for TE in high-flow VAVFcases.

O4-7-2

Strategy of Endovascular Therapy for Direct Carotid Cavernous Fistulaeusing Detachable Coils

Ryo Irie¹, Takato Nakajo¹, Shun Takano¹, Tomoaki Terada², Arisa Umesaki³, Sadatoshi Nakayama³, Takaaki Yamazaki⁴, Kousuke Ohshima⁵, Yuta Kawauchi⁶

¹Department of neurosurgery, Kashiwa Tanaka Hospital

²Department of neurosurgery, Showa University Northern YokohamaHospital

³Department of Neurosurgery, Showa University FujigaokaHospital

⁴Department of Neurosurgery, Hakodate Neurosurgery Hospital

⁵Department of Neurosurgery, Ishioka Neurosurgey Hospital

⁶Department of Neurosurgery, AOI International Hospital

Purpose: Direct carotid-cavernous fistulae (CCF) are mainlycaused by head injury, and they often have difficulties in completeobliteration by coil embolization because of their large size fistulae. Weintroduce our therapeutic strategy and clinical results.

Materials and method: This study is a retrospective analysis ofpatients treated with endovascular therapies using coils for direct CCFbetween 2007 and 2022. Nine patients were included. The mean age was 61years (35–86 years). All cases were performed by EVT under generalanesthesia. The transarterial embolization (TAE) or the transvenousembolization (TVE) of cavernous sinus were performed using detachable coils.Three types of treatment shown below were chosen according to the anatomicalcharacteristics of fistulae. 1st: target coil embolization of fistulae underinternal carotid artery (ICA) balloon protection, second :coil embolizationof outflow in addition, and third : sinus packing with coils and liquidembolic material, if necessary. Ideally we chose first strategy, however, wemust chose second or third strategy because of the size of fistula oranatomical difficulty to deploy coils in the cavernous sinus adjacent to thefistulae.

Results: We achieved complete or almost complete obliteration inall cases, preserving the patency of the internal carotid artery. Targetembolization was performed in 4 cases. In 3 cases, outflow or totalcavernous sinus occlusion was added due to insufficient packings of fistulaebecause of the anatomical feature of the fistulae (shallow and wide pouch).2 cases were treated with only outflow occlusion using coils. Onyx was usedin one case to obliterate the space among the coils. No case needed ICAstenting or ICA occlusion, and no procedural complications were encounteredexpect for transient IIIrd, IVth, Vth, VIth nerve palsy. However, theirextraocular movement disorders were completely improved several months afterthe treatment. 2 patients were needed for retreatments because ofrecanalization and incomplete occlusion of the fistulae.

Conclusion: We could obliterate nine cases of direct CCF usingcoils keeping the patency of the ICA by choosing three strategiesappropriately, although additional ONYX embolization was used in onecase.

O4-7-3

Two cases of dural arteriovenous fistula of the optic canal

Hisanori Edaki¹, Masafumi Hiramatsu¹, Kenji Sugiu¹, Hiroyuki Nakashima², Tomohito Hishikawa¹, Jun Haruma¹, Kazuhiko Nishi¹, Yoko Yamaoka¹, Yu Sato¹, Yuki Ebisudani¹, Ryu Kimura¹, Masato Kawakami¹, Isao Date¹

¹Department of Neurological Surgery, Okayama University GraduateSchool, Okayama, Japan

²Department of Neurological Surgery, Okayama Kyokuto Hospital,Okayama, Japan

Introduction: The optic canal is a short canal that runs throughthe wing of the sphenoid bone at the back of the orbit, through which theoptic nerve and ophthalmic artery (OphA) pass. Although there have been somereports of orbital AVF, this optic canal dural arteriovenous fistula (DAVF)has not been reported. We report two rare cases of DAVF with a shunt pointin the optic canal.

Case presentation: Case 1. A 43-year-old male presented withright exophthalmos and chemosis of the right eye. MRI revealed dilation ofthe right superior ophthalmic vein (SOV). CT revealed expansion of the rightoptic canal, and CT angiography revealed a dilated vessel in the right opticcanal. DSA presented that a feeder of the right OphA and the artery of thesuperior orbital fissure (ASOF) flowed into the dilated vein, and a drainerwas drained into the SOV via a tortuous inferior ophthalmic vein (IOV). Weperformed a transvenous embolization approaching to the right IOV via asuperficial temporal vein and SOV. AVF was completely obliterated using withdetachable coils. One month after the operation, the patient's symptoms wererelieved.

Case 2: A 68-year-old male suffered from a visual field defectin the left eye for the past three years. MRI revealed an abnormal vessel inthe left optic canal and intracranial subarachnoid space. A recurrent branchfrom the third segment of intra-orbital OphA and left ASOF flow into thedilated vein in the left optic canal and the first segment of the left basalvein of Rosenthal. Most of the A-V shunt flow from these veins drained intothe vein of Trolard via the deep and superficial middle cerebral veins.There was no intra-orbital drainage. Endovascular treatment was difficultdue to the lack of an access route, so we performed drainer interruption bya direct surgery. Using an extradural approach, the optic canal was openedand the dilated vein was coagulated and cut. Post operative course wasuneventful. There was no improvement in postoperative visual fielddisturbance.

Conclusion: DAVF in the optic canal has not been reported. Inthe present two cases, the feeder and shunt point were common, but thedraining direction was different. The treatment strategy for optic canalDAVF depends on the direction of the drainer's outflow, so it is importantto accurately diagnose the vascular anatomy.

O4-7-4

A systemic characterization of diluted NBCA and Lipiodol mixture;Tension on catheter tip during catheter withdrawal

Toshio Higashi, Kohei Nii

Neurosurgery, Fukuoka University Chikushi Hospital

Purpose: We have reported the usefulness of dilutedlow-concentration NBCA and lipiodol mixture to embolize dural arteriovenousfistulas or brain tumors, mainly performed in the external carotid arterysystem. The mixture of low concentrations of NBCA allows for slower andsafer embolization due to its lower adhesion to the catheter tip. Mixtureswith miriplatin have also been reported to have higher tissuepermeability.

Materials and Methods: Experiment 1: 450ul each of 5% glucose,0.9% NaCl (saline), 8% albumin solution, and bovine blood were incubatedwith an equal volume of NBCA-lipiodol mixture (12.5, 33, 50% NBCA) at 37°Cfor 3 min. The supernatant was discarded and the solids produced wereweighed. Experiment 2: 120 ul of 12.5%, 50% NBCA-lipiodol mixture, and 600ul of 8% albumin solution, respectively, were placed in a small diametertube, the tip (9 cm) of a micro-catheter was implanted and incubated at 37°Cfor 5 min. When pulling out the micro-catheter, the tension applied to theproximal portion of the catheter was measured until the tip detached fromthe tube.

Results: Experiment 1: No solid material was obtained in 5%glucose. In saline, 12.5%, 33%, and 50% NBCA yielded 3.5%, 9.5%, and 14%solids (weight/% volume), respectively, of the total weight of the solution;in bovine blood, 18%, 23%, and 26% solids, respectively; and in 8% albumin,14%, 26%, and 38% solids, respectively. Experiment 2: The maximum tension atmicrocatheter removal in 8% albumin with NBCA-lipiodol mixture in a smalltube was 0.07 N (n = 2) for 12.5% NBCA and 1.29 N (n = 4) for 50% NBCA.

Conclusions: NBCA is considered to initiate polymerization inresponse to hydroxy ions. 5% glucose solution did not cause polymerization,while saline only produced paper-like films. It is suggested thatcross-linking of serum or proteins is necessary for the NBCA-lipiodolmixture to form strong clumps. Therefore, it is necessary to control theblood flow in the target vessel and flush the lumen with 5% glucose beforeembolization. Also, compared to 50% NBCA, the 12.5% NBCA mixture allows thecatheter to be removed with lower tension.

O4-8-1

Perforator Vessel Embolization For Galenic Arteriovenous MalformationAs A Safe And Feasible Therapy.

Maximilian Jeremy Bazil, Johanna T Fifi,Alejandro Berenstein, Tomoyoshi Shigematsu

Neurosurgery, Icahn School of Medicine at Mount Sinai

Purpose: Vein of Galen Malformations (VOGMs) are a rare,congenital, cerebrovascular disorder which accounts for as little as 1% ofvascular malformations (VMs), but a far greater portion of pediatric VMs.Tectal/thalamic AVMs can often present similarly to VOGM and the treatmentcourse is similar. The simplest treatment for this modality is transarterialembolization (TAE).

Methods: We performed a retrospective review of a prospectivelymaintained database of cases in the practice. VOGMs and tectal/thalamic AVMswith embolization of perforator branches were selected for detailed review.Techniques and clinical outcomes throughout the procedure period weredescribed. We outline patient demographics, VOGM/AVM subtype,radiographic/clinical outcomes, complications, and use of provocativetesting with amytal and lidocaine.

Results: A total of 28 patients at our practice were treated fora VOGM (20/28; 71.4%) or tectal/thalamic AVM (8/28; 28.6%) viatrans-arterial embolization (TAE) of a perforator vessel (such as a ThP oran AchA) between January of 2014 and January of 2022. Males were morerepresented than females in our cohort (16 (57.1%) vs 12 (42.9%)). Of these28 patients, 14 (50%) are currently undergoing treatment, 13 (46.4%) haveachieved at least 95% and up to complete cure of the VOGM, and one patient(3.6%) passed away. A total of 46 thalamoperforator embolizations wereperformed during the treatment course of our cohort with an average of 1.64(SD: 1.13) treatments per patient. A total of 20 patients underwentneuromuscular junction monitoring on at least one occasion to ascertainavoidance of eloquent brain in the embolization procedure. This wastypically performed as a selective WADA test with a 2% Xylocaine (Lidocaine)solution and 25mg of Sodium Amytal, but has also included methohexital inlater years. In one case, neuromonitoring revealed that the MEP wavedisappeared for five minutes after two rounds of 2% Xylocaine and 25mgSodium Amytol infusion. This led to termination of embolizing thethalamoperforator.

Conclusion: We found that ThP and AchA embolization are feasibleand effective for achieving cure of VOGM and tectal/thalamic AVM. We reportfavorable, post-procedural outcomes in the majority of our patients;however, as with any embolization within the thalamic region of the brain,caution should always be used due to the risk of stroke (as in one of ourpatients). If safety of a given embolization is in doubt, provocativetesting with neuromonitoring is performed. In the case of the patient whoexperienced a post-procedural stroke, neuromonitoring was performed andMEP/SEP waves were maintained after amytal and lidocaine. To improve safetyof ThP /AchA embolization, we perform intraoperative neurophysiologicalmonitoring of MEP/SEP with sodium amytal/lidocaine. We intend to expand thispractice beyond VOGM and tectal/thalamic AVM into other eloquent AVMs as wehave seen great success in our own clinic and in the literature.

O4-8-2

Evolution Of Transvenous Embolization In Vein Of Galen Malformation: AReview Of Literature.

Maximilian Jeremy Bazil, Johanna Fifi,Alejandro Berenstein, Tomoyoshi Shigematsu

Neurosurgery, Icahn School of Medicine at Mount Sinai

Introduction: Vein of Galen Malformations (VOGM) compriseapproximately 1% of cerebral vascular malformations overall, but a largerpercentage of all pediatric VMs. Treatment/total obliteration of themalformation is challenging, but has evolved and improved greatly since theinception of endovascular treatment for VOGM. In our practice, we are ableto obtain total obliteration in close to 80% of all cases with transarterialembolization (TAE). The remaining 20% of our cases typically have smallarterial contributors that are uncatheterizable. Transvenous embolization(TVE) then becomes an attractive option and several transvenous approacheshave been described.

Methods: We performed a literature review by parameterizing asearch on PubMed with the terms “Transvenous OR Trans-torcular,” “Vein ofGalen Malformation,” and “Treatment.” The 21 articles chosen for detailedreview described the various TVE approaches for VOGM.

Results: An unfavorable outcome refers to an incompleteobliteration of the VOGM or long-term sequelae of VOGM treatment. Across the21 articles reviewed, we identified a total of 107 patients (Figure1). Theten articles which described a TT approach for VOGM were published between1986–2001. The remainder assessed in the review advocated for transfemoral,transjugular, or combination TAE/TVE treatment of VOGMs. The first of thesetransfemoral approach articles was published in 1989 and the most recentarticle describing transfemoral TVE was published in 2022. Historically, theTT approach obtained variable levels of success with reports of successfulresolution of cardiac failure via TT embolization, but much suggests anassociation with poor clinical outcomes. Transfemoral TVE therapy has grownand waned in popularity between 1989 and 2021. Endovascular coils were themost commonly deployed embolic agent in TVE cases. Based on our previousexperience, we presently favor to begin treatment with staged transarterialembolization (TAE) to reduce flow to the lesion as much as possible and,importantly, to shrink the draining vein. This then allows for theperformance of TVE with coils and n-BCA embolization. We translated thistechnique from Chapot et al.'s use of the procedure to treat an AVM bycreating an “anti-reflux plug” by trapping a detachable-tip microcatheterwith coils and glue, followed by embolization with EVOH.

Conclusion: In 1986, Mickle first described TVE of VOGM byplacement of Gianturco stainless steel coils via surgical exposure over thetorcula and direct trans-torcular access to the aneurysmal pouch.Transfemoral TVE with coils was introduced by Van Halbach in 1989 as a lessinvasive alternative to the TT approach. More recently, we have introduced aTVE approach from a transjugular or transfemoral embolization via theretrograde “pressure cooker technique” (PCT). PCT uses a combination ofcoils, liquid embolic agents, and detachable tip microcatheters toretrogradely close the fistulas from the vein.

O4-8-3

Intraoperative Direct Puncture and Embolization through the DrainageVeins for Sacral Vascular Malformation in Hybrid Operating Room: AClinical Pilot Study for Safety and Feasibility

Yongjie Ma^1,2, Hongqi Zhang^1,2, Ming Ye^1,2

¹Xuanwu Hospital,Capital Medical University

²China International Neuroscience Institute

Purpose: To present a novel approach to embolize sacral vascularmalformation and evaluate the feasibility and safety.

Materials and Methods: Intraoperative direct puncture andembolization through the drainage vein was performed in 13 patients (August2016-Octomber 2018) at the Neurosurgical Department, Xuanwu Hospital,Capital Medical University. All the data of 13 patients were prospectivelycollected. Spinal cord function was evaluated according to modified Aminoffand Logue's Scale (mALS) before surgery and at 6 months after treatment.

Results: Among 13 patients with sacral vascular malformation, 10were male. Three patients (3/13, 23.1%) were diagnosed as extraduralarteriovenous fistulas (AVFs)，four cases(4/13, 30.8%) were filum terminaleAVFs, and 6 cases (6/13, 46.1%) were spinal dural arteriovenousfistulas(SDAVFs). Four patients (30.8%) had previous history of operations(3 underwent embolization and 1 underwent microsurgery) before hybridoperations. The rate of immediate angiographic occlusion of the AVMs was100%. No procedural or clinical complications were observed. The mean mALSbefore hybrid operation were 7.15 (range 4–10,SD = 2.48). And the mean mALSat 6 months follow-up were 4.77 (1–9,2.26).

Conclusions: Intraoperative direct puncture and embolizationthrough the drainage veins is feasible and effective to treatment of sacralvascular malformations when strict anatomical selection is respected. Andthis technique may improve cure rates.

O4-8-4

Embolization for arteriovenous malformation in the eloquentarea

Katsuma Iwaki, Koichi Arimura, Soh Takagishi,Tomohiro Okuda, Yuya Koyanagi, Akira Nakamizo, Koji Yoshimoto

Department of Neurosurgery, Kyushu University

Purpose: Treatment of arteriovenous malformation (AVM) in theeloquent area (eloquent AVM) with preserving functional outcome ischallenging because of the risk of post-surgical complications. The purposeof this study was to evaluate efficacy and feasibility of trans-arterialembolization for eloquent AVM.

Materials and Methods: We reviewed 17 consecutive patients witheloquent AVM treated with endovascular embolization from October 2013 toApril 2021 in Kyushu University Hospital. Moreover, we compared these 17patients with 13 eloquent AVM patients performed with resection orstereotactic radiosurgery without embolization.

Results: The mean age was 29.8 years (range 10–57 years), and 8cases were male. The mean size of nidus was 30.3 mm, and Spetzler-Martin(S&M) Grades were II in 1, III in 9, IV in 6 and V in 1 cases,respectively. Following embolization, surgical resection and stereotacticradiosurgery were performed in 10 and 4 cases, respectively, and remaining 3cases were embolization only. After embolization, ischemic complicationswith temporary deterioration of neurological symptoms occurred in 2, andasymptomatic hemorrhagic complication was noted in 1 case, respectively.

Despite, the rate of S&M grade III-V of embolization group wassignificantly higher than without embolization group (94.1% vs 38.5%,p = 0.002), there was no significant difference in good clinical outcome(modified Rankin Scale 0–2) at 90 days after embolization (70.6% vs 61.5%,p = 0.706). Moreover, the rate of good clinical outcome at 1 year afterembolization was significantly higher in embolization group (93.8% vs 61.5%,p = 0.048).

Conclusions: Eloquent AVM with embolization hada better long-term prognosis than without embolization, despite its highS&M grade. Even AVMs located in the eloquent area can have good outcomeswith proper treatment planning and careful procedure.

O4-9-1

Y-configuration stenting for coil embolization of complex intracranialaneurysms: distinguishing to use between “crossing-Y” and“kissing-Y”

Kenichi Sato^1,2, Yasushi Matsumoto², Teiji Tominaga³

¹Department of Neurosurgery, Tohoku Medical and PharmaceuticalUniversity

²Department of Neuroendovascular Therapy, Kohnan Hospital

³Department of Neurosurgery, Tohoku University Graduate School ofMedicine

Objective: Coil embolization with Y-stenting is recognized as asuitable treatment for complex wide-necked aneurysms. Y-stenting comprisescrossing-Y stenting, in which a stent is passed through the interstices ofanother stent, and kissing-Y stenting, in which two stents are arrangedparallelly. The purpose of this study was to elucidate how to distinguish touse between the two Y-stenting techniques.

Methods: Clinical and angiographic data of patients whounderwent coil embolization with Y-stenting at our department wereretrospectively analyzed. Basic characteristics, endovascular procedure,complications, and outcomes were compared between kissing-Y and crossing-Ystenting groups.

Results: Thirty-eight intracranial aneurysms in 38 consecutivepatients were included in this study. Nineteen (50%) patients were treatedwith coil embolization with kissing-Y stenting and 19 (50%) with crossing-Y.Endovascular procedures were successfully performed in all but one patient,in the kissing-Y group, who had stent migration. One (2.6%) hemorrhagerecurred 12 months after coiling with kissing-Y stenting. Angiographicfollow-up (mean, 15.8 months) was available in 35 patients. Adequateocclusion was demonstrated in 14 (77.8%) and 13 (76.5%) patients in thekissing-Y and crossing-Y groups, respectively. Larger, wider-necked, andmore proximal aneurysms were treated with kissing-Y stenting than withcrossing-Y stenting, although there were no significant differences betweenthe groups in complication rates or clinical outcomes.

Conclusions: Kissing-Y and crossing-Y stenting of intracranialaneurysms were both feasible and yielded reasonable angiographic andclinical results. The choice between the kissing-Y or crossing-Y stentingtechnique should be decided according to the angioarchitecture of targetedaneurysms.

O4-9-2

Safety and Efficacy of Neuroform Atlas Stent-Assisted Coiling forVertebral Artery-Posterior Inferior Cerebellar Artery Aneurysms

Tatsuya Ishikawa, Takayuki Funatsu, YosukeMoteki, Seiichiro Eguchi, Koji Yamaguchi, Takakazu Kawamata

Department of Neurosurgery, Tokyo Women's Medical University, Tokyo,Japan

Introduction: Direct surgical intervention for vertebralartery-posterior inferior cerebellar artery bifurcation (VA-PICA) aneurysmsis often challenging, and endovascular treatment has gained increasingattention in recent years. VA-PICA aneurysms usually show a wide neck andmay require stent-assisted coil embolization. However, a differenttherapeutic approach becomes necessary in patients in whom the PICA branchesat a steep angle from the VA or if the PICA is a small vessel.

Methods: We retrieved records of nine consecutive patients withVA-PICA aneurysms from a retrospective data repository, between April 2017and April 2022. Outcomes were analyzed with regard to clinical status.

Results: Three of nine patients underwent emergency operationsfor management of subarachnoid hemorrhage (SAH), and the others underwentelective treatment for unruptured aneurysms. One patient with an unrupturedaneurysm showed recanalization of previous SAH. Five of nine patientsincluding the patient with SAH underwent operations using the simpletechnique, and a stent-assisted technique was used in the remaining threepatients. The Neuroform Atlas stent was used in all three patients whounderwent the stent-assisted procedure. The stent was deployed from thesmall PICA into the VA from the contralateral side, and coiling wascompleted using the jailing technique. In all three cases of stentimplantation, the vessel diameter of the PICA was not 2 mm. All patientsshowed a favorable postoperative course, without PICA occlusion, thrombosis,or recurrence.

Conclusion: VA-PICA aneurysms were treated using simpletechniques; however, some patients required stent-assisted coilembolization. A contralateral approach using the Neuroform Atlas stent issafe and effective. Adequate surgical planning and the application of anappropriate stent-assisted coil embolization technique are important forsuccessful therapeutic outcomes following surgical intervention in thischallenging and rare location of aneurysms.

O4-9-3

Endovascular coil embolization with partially jailed T stenttechnoique for highly difficult cerebral bifurcation aneurysm

Tomoyuki Tsumoto, Eisuke Hirose, Arisa Umesaki,Sadatoshi Nakayama

Department of Neurosurgery, Showa University Fujigaoka Hospital, Kanagawa,Japan

For bifurcation cerebral aneurysms that require branch preservation, pulseriders for neck formation and WEB that blocks blood flow itself into theaneurysms have appeared. However, it is big problem that the indication ofthese devices is limited by the shape of the aneurysm and the anatomy of thebranches. On the other hand, as an evolution of stent assisted embolization,embolization using composite stents is increasing. We will consider thepast, current status, and future of embolization using composite stentsperformed at our facility. The subjects were 17 unruptured aneurysms (mediananeurysm diameter 11.7 mm) who underwent embolization using composite stentin our department from January 2015 to March 2022. Initially, embolizationwas performed with the Y stent technique in 5 cases and with the T stenttechnique in 8 cases. Although there was no significant difference, the Ystent technique tended to have more ischemic complications. In addition,even if the T stent technique was attempted, there were cases in which itwas difficult to align the stent due to the angle of the sub-branch.Therefore, we devised partially jailed T stent technique as a highlyversatile method. Both branches are secured by microcatheter, and a braidedstent is placed from the main branch to the main artery in anticipation offlow diverting effect. After coiling, the stent is dressed to be partiallyjailed in the main artery, minimizing the stent struts floating in thevessel and ensuring the whole neck. From 2021, this method was selected for1 case of partially thrombosed anterior communicating artery aneurysm, 1case of middle cerebral artery aneurysm, and 2 cases of internal carotidartery-posterior communicating artery aneurysm, and the treatment wascompleted in all cases. In one case of thrombotic aneurysm, recurrenceoccurred 6 months after the operation, but it could be dealt with anoverlapped braided stent on the main branch. The other 3 cases had noischemic complications, and the embolization status was stable after anaverage of 8 months after surgery. At present, the indications of pulserider and WEB for bifurcation aneurysms are limited, and in highly difficultbifurcation aneurysms, there is large dependence on composite stents. In thefuture, a highly versatile composite stent treatment with few thromboticcomplications and long-term stable embolic status will be required, andlong-term results of the partially jailed T stent technique areexpected.

O4-9-4

Initial treatment results of coil embolization for unrupturedintracranial aneurysm combined with Neuroform Atlas and undersized themost flexible coils

Katsutoshi Takayama, Kaoru Myouchinn, TakeshiWada

Interventional Neuroradiology / Radiology, Kouseikai Takai Hospital

Objective: Intraprocedural rupture (IPR) is a rare complicationthat can occur during endovascular treatment of unruptured intracranialaneurysms (UIAs). However, it leads to high morbidity and mortality rates.Coil flexibility is considered one of risk factors for IPR. Neuroform Atlas(NA) (Stryker) stents can be deliverable and deployed much easier than otherstents to enable stent assisted coiling (SAC) with a high likelihood. WhenEVT with NA and undersized flexible coils is performed, IPR may be reduced.This study aimed to determine whether SAC using NA and highly flexible coilsfor UIAs can be conducted without IPR.

Material and Methods: We retrospectively analyzed 31consecutivepatients and 32 UIAs (mean age, 67.6 years; female, n = 23) who underwentSAC for UIAs combined with NA stents and undersized the most flexible coilsbetween January 2017 and December 2022. The location of aneurysms was asfollows: internal carotid artery, 12; anterior communicating artery, 5;middle cerebral artery, 7; vertebra artery, 5; basilar artery, 2. Allaneurysms were denovo except two recanalized aneurysm after coiling. Themean size of the aneurysms was 5.1 (range, 3.1–8.6) mm. SAC proceeded usingthe jailing technique. All coils were selected from HyperSoft (MicroVentionTerumo). How to choose the diameter of the first coil was 2 mm diameter orat least 2 mm less than the maximum aneurysm diameter. Technical successrates, immediate angiographic occlusion, rates of IPR and symptomatic strokewithin 30 days, angiographic occlusion at 3 months post-procedure and lateadverse events (frequency of aneurysmal rupture, ipsilateral ischemicstroke, and retreated targeted aneurysms) were assessed.

Results: The technical success rate was 100%, achievingimmediate complete occlusion (CO) by coiling in 87.5% (28/32), neck remnantsin 9.3% (3/32) and residual aneurysm in 3.1% (1/32). No IPR or symptomaticstroke developed within 30 days. During a mean follow-up period of 11.8months, CO persisted in 22/24 (91.7%). Late adverse events occurred in onepatient (retreatment) (3.2%).

Conclusions: The early clinical and angiographic findings of SACfor UIAs combined with an NA stent and undersized flexible coilsdemonstrated favorable results.

O4-9-5

The utility of L-stent technique for embolization of bifurcationaneurysm

Yuichiro Naito, Norio Fujii, YojiNishijima

Department of Neurosurgery, Nishijima Hospital

Background: It is difficult to embolize bifurcation aneurysmsuch as MCA or Acom AN. If we use neck bridge stent, we cannot emblolizesufficiently to side without stent. T-stent technique can cover the neck ofAN completely, but we have to use 2 stents. Half T-stent technique cannotcover the neck comletely. We report L-stent technique which is the method offull neck coverage with single stent, Neuroform Atlas 3. 0/15. The techniqueis that we deploy Atlas from M2 or A2 to M1 or A1, then we push proximaledge of Atlas to opposite M2 or A2 with guide wire, michrocatheter orballoon. So we can cover neck of AN completely with single stent. It isuseful to embolism bifurcation AN.[Method]We treated 7 ANs with L-stenttechnique. 3 Acom ANs and 4 MCA ANs. There are 3 males and 4 females. Agesfrom 49 to 79. We could deploy Atlas all cases successfully and embolism ANcompletely. There are no complication associated with thistechnique.[conclusion]L-stent technique is very useful and safe method toembolism bifurcation AN.

O4-10-1

Mechanical Thrombectomy Up to 24 Hours in Large Vessel Occlusions andInfarct Velocity Assessment

Manabu Inoue^1,2, Takeshi Yoshimoto², Kanta Tanaka¹, Junpei Koge², Naruhiko Kamogawa², Hirotoshi Imamura⁴, Hiroharu Kataoka⁴, Hiroshi Yamagami⁵, Masatoshi Koga², Masafumi Ihara³, Kazunori Toyoda²

¹Devision of Stroke Care Unit, National Cerebral andCardiovascular Center, Suita, Japan

²Department of Cerebrovascular Medicine, National Cerebral andCardiovascular Center, Suita, Japan

³Department of Neurology, National Cerebral and CardiovascularCenter, Suita, Japan

⁴Department of Neurosurgery, National Cerebral and CardiovascularCenter, Suita, Japan

⁵Department of Stroke Neurology, National Hospital OrganizationOsaka National Hospital, Osaka, Japan

BACKGROUND: We retrospectively compared early- (<6 h) versuslate- (6–24 h) presenting patients using perfusion-weighted imaging (PWI)selection and evaluated clinical/radiographic outcomes.

METHODS AND RESULTS: Large vessel occlusion patients treatedwith mechanical thrombectomy from August 2017 to July 2020 within 24 h ofonset were retrieved from a single-center database. PWI was analyzed byautomated software and final infarct volume was measured semi-automaticallywithin 14 days. The primary endpoint was good outcome (modified Rankin Scale0–2 at 90 days). Secondary endpoints were excellent outcome (modified RankinScale 0–1 at 90 days), symptomatic intracranial hemorrhage, and death.Clinical characteristics/radiological values including hypoperfusion volumeand infarct growth velocity (baseline volume/onset-to-image time) werecompared between the groups.

RESULTS: Of 1294 patients, 118 patients were included. Themedian age was 74 years old, baseline National Institutes of Health StrokeScale score was 14, and core volume was 13 mL. The late-presenting group hadmore female patients (67% versus 31%, respectively;P = 0.001). No statistically significant differences wereseen in good outcome (42% versus 53%, respectively;P = 0.30), excellent outcome (26% versus 32%, respectively;P = 0.51), symptomatic intracranial hemorrhage (6.5%versus 4.6%, respectively; P = 0.74), and death (3.2%versus 5.7%, respectively; P = 0.58) between the groups.The late-presenting group had more atherothrombotic cerebral infarction (19%versus 6%, respectively; P = 0.03), smaller hypoperfusionvolume (median: 77 versus 133 mL, respectively; P = 0.04),and slower infarct growth velocity (median: 0.6 versus 5.1 mL/hour,respectively; P = 0.03).

CONCLUSIONS: Early and late time-window patients treated withmechanical thrombectomy by automated PWI selection have similar outcomes,comparable with those in randomized trials, but different in infarct growthvelocities.

O4-10-2

Correlation of cerebral angiography with asymmetrical cortical anddeep/medullary vein signs on T2* in acute ischemic stroke

Keisuke Kadooka, Takafumi Mitsutake, MichihiroTanaka

Department of Neuroendovascular Surgery, Kameda Medical Center

Purpose: In treating acute ischemic stroke (AIS) patients, thedevelopment of collateral flow to the ischemic area and the assessment oftissue at risk, in another word, penumbra are essential. Good leptomeningealcollateral flow is one of the favorable prognostic factors. T2* is sensitiveto deoxyhemoglobin (DHb) which increases according to the increase of OxygenExtraction Fraction in penumbral tissue and can detect an increase of DHb asprominent draining veins. In this study, we made a comparison betweenimmediately preinterventional asymmetrical vein signs on T2* and thefindings in cerebral angiography during mechanical thrombectomy.

Materials and Methods: Clinical and imaging data of 41 patientswith horizontal segment of middle cerebral artery(M1) occlusion whounderwent mechanical thrombectomy were collected. The occlusion sites weredivided into two groups; 1) proximal MCA(M1P) and 2) distal MCA(M1D). Thegrading of angiographic collateral flow was also examined.

Asymmetrical vein signs on T2* were divided into two groups; 1) asymmetricalcortical vein sign (ACVS) and 2) asymmetrical deep/medullary vein sign(ADMVS).

Results: 27 patients had asymmetrical vein signs (16 with onlyasymmetrical cortical vein signs, 2 with only asymmetrical deep/medullaryvein sign, and 9 with both asymmetrical vein signs).

ACVS was the only parameter which indicated angiographic poor collateralsupply with a significant difference (P < 0.001). On the other hand,ADMVS has nothing to do with angiographic collateral grade (p = 0.673).

Regarding to the occlusion site, ADMVS was the only parameter which suggestedthe existence of M1P occlusion (p = 0.016), in other words, involvement oflenticulostriate arteries(LSAs).

Conclusions: In the patients with M1 occlusion, ACVS suggestsangiographic poor collateral supply and ADMVS suggests the involvement ofLSAs. These two asymmetrical vein signs contribute to poor outcome in thedifferent way.

O4-10-3

Treatment strategy for acute ischemic stroke with CT perfusion images(Vitrea)

Satoshi Fujita, Shinya Yoshii, Morito Hayashi,Naoki Kushida, Sho Sato, Nozomi Hirai, Yu Hiramoto, Haruo Nakayama,Keisuke Ito, Norihiko Saito, Satoshi Iwabuchi

Department of Neurosurgery Ohashi medical center, University of Toho

Introduction: For acute ischemic stroke (AIS) due to occlusionof the brain cerebral artery, mechanical thrombectomy (MT) has becomestandard treatment. In recent years, the effectiveness of MT for largecerebral infarction has been reported from Japan, but the efficacy is stillunknown for mild cases and unknown onset time cases. In our hospital, weperform brain CT perfusion images, examine the effectiveness of MT.

Subjects and methods: From November 2019 to October 2021, 45cases of AIS due to occlusion of the anterior circulation were transportedto our hospital. Image evaluation used Vitrea workstation (320 columnsAquilion one, Canon medical systems). This application can evaluate ischemicpenumbra (TTP 5.3 s delay), core volume (CBV 38% down), and at the same timeCT-angiography to evaluate occluded vessels.

Results: Median age of patients 77 years (20–93 years), medianNIHSS 16 (1–28), occluded blood vessels in CCA / ICA 6 cases, M1 17 cases,M2 / M3 18 cases, tandem lesion 4 cases. Conservative treatment in 10 cases,reconstructive intervention in 35 cases (t-PA only: 4 cases, MT only: 13cases, t-PA + MT: 13 cases, attempt 2 cases, emergency carotid arterystenting: 3 cases). There were 14 mild cases with NIHSS 6 or less, 7 withreconstructive intervention, and 7 with conservative treatment. Cases inwhich symptoms progressed tended to have larger penumbra and core than casesin which symptoms did not progress. There were 3 cases with extensiveischemic core (100 or more), and 2 cases underwent MT, but 1 case hadextensive hemorrhagic infarction. 8 cases with unknown onset time were seen,and MT was performed except for one case, but no case had hemorrhagiccerebral infarction.

Conclusion: At our hospital, we are considering a treatmentstrategy based on the core and penumbra obtained from cerebral perfusionimages. Depending on the case, it is important to identify the cases thatshould be avoided MT by using the volume of the penumbra and core. In thefuture, we would like to create a clearer treatment protocol.

O4-10-4

Arterial spin labeling magnetic resonance imaging can identify theocclusion site and collateral perfusion in patients with acute ischemicstroke

KAZUAKI OKAMURA¹, Yoichi Morofuji¹, Yohei Tateishi², Minoru Morikawa³, Tsuyoshi Izumo¹, Akira Tsujino², Takayuki Matsuo¹

¹Department of Neurosurgery, Nagasaki University Graduate Schoolof Biomedical Sciences

²Department of Neurology and Strokology, Nagasaki UniversityGraduate School of Biomedical Sciences

³Department of Radiology, Nagasaki University Graduate School ofBiomedical Sciences

Background and Purpose: Determining the occlusion site andcollateral blood flow is important in acute ischemic stroke. The purpose ofthe current study was to test whether arterial spin labeling (ASL) magneticresonance imaging (MRI) could be used to identify the occlusion site andcollateral perfusion, using digital subtraction angiography (DSA) as a goldstandard.

Methods: Data from 521 consecutive patients who presented withacute ischemic stroke at our institution from January 2012 to September 2014were retrospectively reviewed. Image data were included in this study if:(1) the patient presented symptoms of acute ischemic stroke; (2) MRI wasperformed within 24 h of symptom onset; and (3) DSA following MRI wasperformed (n = 32 patients). We defined proximal intra-arterial sign (IAS)on ASL as enlarged circular or linear bright hyperintense signal within theoccluded artery, and distal IAS as enlarged circular or linear brighthyperintense signals within arteries inside or surrounding the affectedregion. The presence or absence of the proximal IAS and distal IAS wereassessed, along with their inter-rater agreement and consistency with thepresence of occlusion site and collateral flow on DSA images.

Results: The sensitivity and specificity for identifyingocclusion site with ASL were 82.8% and 100%, respectively. Those foridentifying collateral flow with ASL were 96.7% and 50%, respectively. Theinter-rater reliability was excellent for proximal IAS (κ = 0.92; 95%confidence interval, 0.76–1.00) and substantial for distal IAS detection(κ = 0.78; 95% confidence interval, 0.38–1.00).

Conclusions: Proximal IAS and distal IAS on ASL imaging canprovide important diagnostic clues for the detection of arterial occlusionsites and collateral perfusion in patients with acute ischemic stroke.

O4-10-5

Experience on acute stenting in acute ischemic stroke (AIS) due toEmergent Large Vessels Occlusion(ELVO)

TREEPOB SAENGOW, Boonrerk Sangpetngam, AnchaleeChurojana, Pattarawit Wittayasuk, Ekawut Chankeaw, ThaweesakAurboonyawut

Siriraj Center of Interventional Radiology, Faculty of medicine SirirajHospital, Mahidol University

Background: Successful recanalization after failed mechanicalthrombectomy can be achieved by rescue treatment. Multiple modalities ofrescue treatment had been used without a current standard strategy. Acutestenting (AS) is one of those methods. By deploying self-expanding stents inthe affected segment to rescue the unsuccessful recanalization. The stentingprocedure needs perioperative management of antithrombotic drugs, whichraises the concern about hemorrhagic complications after stenting in acuteperiods. This study aims to compare clinical and angiographic outcomes andcomplications between those with acute stenting and without stenting inemergent large vessel occlusion (ELVO).

Materials and Methods: A retrospective review study of all acuteischemic strokes due to emergent large vessel occlusion who underwentemergency endovascular procedures from Jan 2018 to June 2021. Allintracranial ELVO including tandem lesions were enrolled in the study. Thepatients were divided into two separate groups. The acute stenting group(ASG), is the patient with the placement of an intracranial stent torecanalize the occluded vessel, and the non-stenting group (NSG) is thepatient who treats ELVO without performing an acute stenting procedure. Thepatient baseline data, demographic data, imaging data, procedural data,angiographic, clinical outcomes, and complications were recorded andcompared. The protocol for the acute stenting procedure in our institute wasrecorded.

Results: A total of 320 patients with intracranial ELVOsperformed emergent mechanical thrombectomy. Of those, 26 patients (8.12%)were managed with acute stenting. The ASG demonstrated that finalrecanalization occurred in 24(92.31%), the favorable outcome rate was 17/26(65.38%), rate of symptomatic intracranial hemorrhage (sICH) was4/26(15.38%) which is not different to the NSG. Re-occlusion was a factorfor acute stenting (OR, 11.89[95% CI, 3.09–45.70], P <0.001).

Conclusion: Predictors for acute stenting in failedrecanalization after primary mechanical thrombectomy in our study werereocclusion. Both groups demonstrated insignificant statistical differencesin terms of clinical and angiographic outcomes and the rate of sICH. Acutestenting is feasible and safe to perform in failed MT to acquire successfulrecanalization in ELVO.

Keywords: emergent large vessel occlusion, failed mechanicalthrombectomy, rescue treatment, acute stenting

O4-10-6

Impact of RNF213 p.R4810K variant on endovasculartherapy for large vessel occlusion stroke

Takeshi Yoshimoto¹, Kanta Tanaka², Junpei Koge², Satoshi Saito¹, Hiroshi Yamagami³, Yuriko Nakaoku⁴, Kunihiro Nishimura⁴, Eriko Yamaguchi¹, Tetsuya Chiba¹, Daisuke Kawakami⁵, Masayuki Shiozawa², Naruhiko Kamogawa², Tsuyoshi Ohta⁶, Tetsu Satow⁶, Manabu Inoue², Yorito Hattori¹, Kazuo Washida¹, Hiroharu Kataoka⁶, Kazunori Toyoda², Masatoshi Koga², Masafumi Ihara¹

¹Department of Neurology, National Cerebral and CardiovascularCenter

²Department of Cerebrovascular Medicine, National Cerebral andCardiovascular Center, Suita, Japan

³Department of Stroke Neurology, National Hospital OrganizationOsaka National Hospital, Osaka, Japan

⁴Department of Preventive Medicine and Epidemiology, NationalCerebral and Cardiovascular Center, Suita, Japan

⁵Division of Analytical &Measuring Instruments, ShimadzuCorporation, Nakagyo-ku, Kyoto, Japan

⁶Department of Neurosurgery, National Cerebral and CardiovascularCenter, Suita, Japan

Introduction: The ring finger protein 213 gene(RNF213) has been identified as a susceptibility genefor moyamoya disease, and the p.R4810K polymorphism as a founder variantcommonly found in East Asian patients. A recent large case-control studyincluding over 46,958 Japanese subjects reported that theRNF213 p.R4810K variant was a strong risk factor forJapanese cerebral infarction: the variant was found in 5.2% of patients withnon-cardioembolic stroke and in 2.1% of healthy controls.

Mechanical thrombectomy (MT) is a standard treatment for acute ischemicstroke due to occlusion of the internal carotid artery and M1 segment of themiddle cerebral artery, but in East Asians, about 15–25% of LVOs for whichMT was performed were reportedly caused by intracranial atheroscleroticdisease (ICAD). RNF213 p.R4810K variant may be involved tosome extent in ICAD-related LVO of Asian patients undergoing MT. In thisstudy, we aimed to investigate the impact of RNF213p.R4810K variant on EVT for anterior circulation LVO stroke.

Methods: Of the consecutive ischemic stroke patients from 2011to 2021 seen in our institute, patients who underwent EVT for acuteocclusion of the intracranial ICA or M1 segment of MCA and signed a consentform for RNF213genotyping were included. Outcomes wereinstant re-occlusion, final modified Thrombolysis in Cerebral Infarction(mTICI) ≥2b reperfusion, early re-occlusion, and modified Rankin Scale (mRS)score 0–2 at 90 days. Instant re-occlusionwas defined as occurrence ofre-occlusion during the procedure, whereas early re-occlusion asre-occlusion detected on magnetic resonance angiography within 2 weeks afterconfirmation of successful reperfusion at the end of the procedure.

Results: Of the 277 patients (128 women[46.2%]; median age, 76years) analyzed, 10 (3.6%) patients had the RNF213p.R4810Kvariant. The variant carriers were younger (67 years vs. 76 years,P < 0.01), more frequently received angioplasty(40.0% vs. 12.0%, P < 0.01), and more frequently hadintracranial atherosclerotic disease-related LVO as a cause of acute LVO(70.0% vs. 8.6%, P < 0.01) than non-carriers. Thevariant carriers showed higher rates of instant re-occlusion (40.0% vs.5.6%, P < 0.01), but there were no statisticallysignificant inter-group differences for the final mTICI ≥2b reperfusion ratebetween carriers and non-carriers (100.0% vs. 81.6%,P = 0.22). Early re-occlusion was more frequent in thevariant carriers than non- carriers (60.0% vs. 0.4%, P < 0.01) with nointergroup difference in the rate of repeated EVT (67.7% vs. 100.0%,P = 0.71). There were no statistically significant inter-group differencesfor achievement of mRS score 0–2 (60.0% vs. 51.7%,P = 0.75)

Conclusions: Both instant and early re-occlusion were morefrequent in the RNF213 p.R4810K variant carriers who hadreceived EVT for acute anterior circulation LVO than in the non-carriers.Potential impact of RNF213 polymorphism status on EVToutcomes was clarified.

O4-11-1

Effect of flow diverter pore density on early and late aneurysmocclusion rates

Roberto Fisch², Tilman Schubert¹, Patrick Thurner¹, Jawid Madjidyar¹, Vaia Anagnostakou^1,3, Shakir Husain¹, Daniel Toth¹, Isabelle Barnaure¹, Zsolt Kulcsar¹

¹Neuroradiology, University Hospital of Zurich

²University of Zurich

³New England Center for Stroke research, University ofMassachusetts Medical School

Background and objective: Flow diverter (FD) designs arecontinuously developed to address the challenges of optimal deployment andof efficacy in achieving aneurysm healing. This study aims to evaluate theearly and late occlusion and healing rate of aneurysms treated with twodifferent FDs, a 48- (FD48) and a 64- (FD64) wire mesh density design. BothFDs are CoCr alloy structures, and are designed with similar porosity butdifferent pore density (10–14 vs 17–20/mm2 respectively).

Methods: All consecutive patients treated with either of the twoFDs were included in this retrospective analysis of prospectively collecteddata. Acutely ruptured aneurysms were excluded. The MR-tomographic,angiographic and clinical data of 68 patients with a total of 85 aneurysmswere retrospectively analyzed. 47 (55.3%) aneurysms were treated with theFD48 and 38 (44.7%) aneurysms with the FD64 model at 3 and at 12 months.

Results: Epidemiologic characteristics were similar in the twogroups. The median maximal aneurysm diameter was 7.5 mm in the FD48, and 6.3in the FD64 group, the median neck size was 4 and 4.5 mm respectively. Earlyfollow-up MRI was available for 42 aneurysms of the FD48 and 33 of the FD64group. At three months, in the FD48 group 64.3% of the aneurysms werecompletely occluded, 31.0% showed residual filling and 4.8% showed completefilling; in the FD64 group these rates were 72.7%, 24.2% and 3.0%respectively. Late imaging follow-up was available for 39 aneurysms of theFD48 and 32 of the FD64 group. In the FD48 group 33 (84.6%) were completelyoccluded and 6 (15.4%) showed residual filling at mean 425.5 days afterintervention. In the FD64 group these rates were 87.5% and 12.4%respectively at mean 384.5 days after intervention.

Conclusions: Both flow diverters are reliable tools leading toachieving aneurysm healing. At similar porosity, the higher pore densitydesign showed higher occlusion rates at the early stage, whereas this effectwas less apparent in the late follow up. These results may impact FD choiceif quick healing is the goal.

O4-11-2

Longitudinal observation of the aneurysm size after flow diversion:Potential role in the evaluation of the treatment response

YunHyeok Choi¹, Mi Hyeon Kim¹, Boseong Kwon¹, Yunsun Song¹, Jung Cheol Park², Dea Chul Suh¹, Deok Hee Lee¹

¹Radiology, University of Ulsan, Seoul, Korea

²Neurosurgery, University of Ulsan, Seoul, Korea

Purpose: After flow diversion (FD) therapy for the cerebralaneurysms, the current gold standard for the evaluation of the treatmentresponse is DSA by observing the occlusion status of the aneurysm neckalthough other imaging tools, such as CTA or MRA are also commonly used forthat purpose. We thought that cross-section imaging tools might serve moreinformation since they would reveal associated morphologic changes such asthe aneurysm sac itself. The purpose of this study was to observe alongitudinal volume change of the treated aneurysm sac after FD and toreveal any association of aneurysm volume change and aneurysmal occlusionstatus.

Materials and Methods: A total of 84 patients initial treatedwith FD of unruptured aneurysms at Asan Medical Center between 2014 and 2021and having longer than 12 months of imaging follow-up were enrolled. Wecalculated the aneurysm size by simple measurement of X- and Y-axis diameteron the most representative section on the axial CT or MR images obtainedbefore FD, right after FD, and thereafter for the imaging follow-ups. Thetrend of longitudinal aneurysm size change and aneurysm obliteration wasanalyzed.

Results: Patients were a median age of 53 years and the majoritywere women. The mean follow up period was 24.3 months. 53 patients(63%) wassorted to obliteration of the aneurysm during the follow up period. Other 31patients was thought to be in the endothelizing status. And we used variousflow diverter stents; fourty-nine Pipeline, twenty-nine FRED and six othersgroup(Surpass and Streamline). We analyzed datas from Random Intercepts andTrend Model using linear mixed model. Overall outcome was that the size ofthe aneurysm decreases −0.1392mm per day (P < 0.001). And there wassignificant decreasing size trend between the Pipeline group and FREDgroup.(Pr>F 0.03)

Conclusion: Not only the angiographic obliteration of theaneurysm neck but also the volume reduction on the cross-sectional imagingcould also be the good indicators of appropriate aneurysmal healing.

O4-11-3

Recovery of cranial nerve symptoms after flow diversion withoutcoiling for unruptured very large and giant internal carotid arteryaneurysms

Jung Koo Lee¹, Jai Ho Choi¹, Bum-Soo Kim², Yong Sam Shin¹

¹Department of Neurosurgery, Seoul St Mary's Hospital, TheCatholic University of Korea

²Department of Radiology, Seoul St Mary's Hospital, The CatholicUniversity of Korea

BACKGROUND AND PURPOSE: Cranial nerve symptoms, including visualimpairment and ophthalmoplegia, are one of the most common presentations ofvery large and giant (≥15 mm) ICA aneurysms. In this study, we evaluated thetreatment outcomes of flow diversion and conventional coiling in terms ofrecovery from cranial nerve symptoms and postoperative complications.

MATERIALS AND METHODS: Seventy-nine patients with unruptured ICAaneurysms of >15 mm who were treated with flow diversion or conventionalcoiling between December 2009 and December 2020 were retrospectivelyevaluated. We compared the radiologic and clinical outcomes, includingrecovery from cranial nerve symptoms, between the 2 groups.

RESULTS: Twenty-eight of 49 patients (57.1%) treated with flowdiversion and 10 of 30 patients (33.3%) treated with conventional coilinginitially presented with cranial nerve symptoms(P  =  .068). In the clinical follow-up, the symptomrecovery rate was significantly higher in those treated with flow diversion(15[50%] versus 3[25%] with conventional coiling,P  =  .046). Multivariate logistic regression analysisdemonstrated that flow diversion was significantly associated with symptomrecovery (OR, 7.425; 95% CI, 1.091–50.546; P  =  .040). The overallpostoperative complication rate was similar (flow diversion, 10[20.4%];conventional coiling, 6[20.0%], P  =  .965), though fatalhemorrhagic complications occurred only in patients with intradurallylocated aneurysms treated with flow diversion (4[8.2%] versus 0[0.0%] withcoiling, P  =  .108).

CONCLUSIONS: Flow diversion without coiling for very large andgiant ICA aneurysms yielded a higher rate of recovery from cranial nervesymptoms, but it may be related to an increased hemorrhagic complicationrate, especially for intradurally located aneurysms.

O4-11-4

Elongation from the nominal length and longer PED were associated withthe late occlusion and the incomplete occlusion.

Tadashi Sunohara¹, Hirotoshi Imamura², Nobuyuki Sakai¹, Tsuyoshi Ohta¹, Masaomi Koyanagi¹, Masanori Goto¹, Ryu Fukumitsu¹, Nobuyuki Fukui¹, Yuuki Takano¹, Hironori Haruyama¹, Kohich Go¹, Shinji Kajiura¹, Masashi Shigeyasu¹, Kunimasa Teranishi¹, Kento Asakura¹, Ryo Horii¹, Yuuji Naramoto¹, Yasuhiro Yamamoto¹, Rikuo Nishii¹, Satohiro Kawade¹, Chiaki Sakai¹

¹Department of Neurosurgery, Kobe City Medical Center GeneralHospital

²Department of Neurosurgery, National Cerebral and CardiovascularCenter

Background and Purpose: For the treatment of intracranialaneurysms with the Pipeline embolization device (PED), the optimal size orlength for clinical better outcomes was not well studied even though somebenchtop studies reported negative effects of oversize.

To clarify the effects of size and PED dynamics on the outcome in theclinical time course, measurement of the PED was evaluated along with theclinical outcome.

Materials and Methods: In our retrospective, single-centercohort study, 124 anterior circulation unruptured aneurysms in 114 subjectswere treated with the PED. 47 aneurysms in 46 patients without adjunctivecoil embolization or previous materials were enrolled. Patients werefollowed per standardized protocol, and aneurysmal occlusion was recorded.Angiographical outcomes were analyzed. Accurate anatomical measurements ofartery and PED diameter and length were done by Smart CT Vaso ofPHILIPS.

Results: Imaging data were acquired in 97.9% overall andfollow-up data were in 89.3%.

Compared to the nominal size, the PEDs were elongated by an average of 136%immediately after deployment, and the diameters were −15%, −9%, and −17%just proximal to the aneurysm neck, at the aneurysm portion, and just distalto the aneurysm neck, respectively. After 6 months, the length had shortenedto 123%, and the diameter had expanded to −9%, −4%, and −9%, respectively,however, was still smaller than the nominal diameter and still oversized at6 months. Remodeling effects on vascular distortion and flow alteration wereobserved in 100% and 88% of cases, respectively. Multivariate analysisshowed that PED elongation was significantly correlated with incompleteocclusion at 6 months (per 1 mm elongation, OR, 1.1, P = 0.005) but not atfinal follow-up; longer nominal length of the PED was significantlyassociated with incomplete occlusion at final follow-up (per 1 mmelongation, OR, 1.1, P = 0.003).

Conclusion: The measurement data of PED vascular remodeling wasprovided. The elongation of PED from nominal length was associated with lateocclusion and the case of longer PED was associated with incompleteocclusion. PED provides a dynamic vascular remodeling effect and itovercomes oversize disadvantages as predicted before.

O4-11-5

Comparison of Flow Re-direction Endoluminal Device and PipelineEmbolization Device in the treatment of patients with cerebralaneurysms: A single-center, retrospective analysis

Hidetoshi Matsukawa¹, Saujanya Rajbhandari², Kazutaka Uchida², Manabu Shirakawa², Shinichi Yoshimura²

¹Department of Neurosurgery, Takarazuka City Hospital, Hyogo,Japan

²Department of Neurosurgery, Hyogo College of Medicine, Hyogo,Japan

Purpose: Flow Re-Direction Endoluminal Device (FRED) andPipeline embolization device (PED) have gained widespread popularity in thetreatment of cerebral aneurysms in Japan. To date, differences in thetreatment results of these flow diverters remains unknown. The aim of thisstudy is to compare the clinical and radiological results between patientswith cerebral aneurysm treated by FRED and PED.

Materials and Methods: Clinical and radiological characteristicsof patients with cerebral aneurysm who were treated by FRED or PED at ourinstitute between August 2016 and January 2022 were analyzedretrospectively. Clinical outcome was evaluated by a modified Rankin Scalescore (mRS). Clinical and radiological variables were compared between FREDand PED groups. Primary and secondary endpoint was satisfactory aneurysmocclusion within 1 year and mRS 0 to 2 at 90-day. The safety endpoint wasthe incidence of post-treatment aneurysm rupture and neurologic death ormajor stroke (>4 more points on the National Institutes of Health StrokeScale) within 12 months of the procedure.

Results: One hundred ninety-nine patients undertook 215treatments, 168 (84%) female, mean age 62 ± 11 years, were included in thisstudy. Mean aneurysm size and neck length were11.7 ± 6.5 mm and6.9 ± 3.2 mm. There were 183 (85%) aneurysms with saccular and 29 (13%)aneurysms with fusiform morphology, the remaining 3 (1.4%) aneurysms weredissecting. Age and proportion of past medical history (hypertension,dyslipidemia, diabetes mellitus) and adjunctive coiling showed nosignificant difference between two groups. Proportions of male sex (26 (25%)vs 9 (8.1%), p < 0.01), balloon angioplasty (16 (15%) vs 70 (63%), p <0.01), larger aneurysm (>10mm) (35 (34%) vs 81 (74%), p < 0.01),non-saccular shape (22 (22%) vs 10 (10%), p = 0.04), internal carotid arterylocation (75 (72%) vs 109 (98%), p < 0.01) were significantly lower inFRED group. During median follow up period (366 (IQR 204–551) days),satisfactory aneurysm occlusion was observed in 145 of 183 patients (79%).Median follow up period was significantly shorter in FRED group (263 (IQR179–401) days vs 383 (IQR 359–720) days, p < 0.01). Satisfactory aneurysmocclusion observed more frequently in FRED group (crude HR 1.6 (95%confidence interval: 1.1–2.2), p < 0.01) and the difference remainedsignificant after adjustment of age, sex, and size of aneurysm (adjusted HR1.5 (95% confidence interval: 1.1–2.3), p = 0.02). Proportions of secondaryand safety endpoints showed no differences between two groups.

Conclusion: Our results suggested that satisfactory aneurysmocclusion was more frequently observed in patients with cerebral aneurysmtreated by FRED.

O4-12-1

Experimental evaluation of thrombectomy techniques with theTigeretriever, a manually adjustable stent retriever

Ariel Takayanagi^1,2, Taichiro Imahori¹, Hamidreza Saber¹, Lea Guo¹, Naoki Kaneko¹, Satoshi Tateshima¹

¹Interventional Neuroradiology, University of California LosAngeles

²Department of Neurosurgery, Riverside University Health System,Moreno Valley, California, USA

Purpose: The Tigertriever is a novel stent retriever with amanually adjustable diameter. The optimal technique when using theTigertriever has yet to be determined. The location of the aspirationcatheter and the degree of expansion of the Tigertriever can vary. Weperformed an in vitro study using three-dimensional flow models andperformed clot retrieval using the Tigertriever in order to exploreeffective and safe techniques for mechanical thrombectomy.

Methods: In a three-dimensional flow model with moderatetortuosity, we compared six different techniques using the Tigertriever aswell as aspiration only technique (ADAPT). Success rates of clot retrievalof a thrombus placed in the proximal M2 branch. We measured pulling forceduring each technique to determine the amount of force exerted on thevessels during clot retrieval as well as in the absence of clot.

Results: The highest success rate was achieved when theTigertriever was placed in the distal M1 and aspiration catheter wasadvanced to meet the Tigertriever (90%). The success rate was 50% when theaspiration catheter was positioned in the distal M1 and the Tigertriever wasinstead withdrawn to meet the aspiration catheter, regardless of the degreeof expansion or inflation of the stent. The success rate was only 10% whenthe aspiration catheter was placed in the proximal M1 and the Tigertrieverwas left deflated, but increased to 50% when the stent was inflated.

In the absence of clot, the pulling force did not vary significantly. Thepulling force was significantly higher in all techniques when clot waspresent. The pulling force was highest with the techniques that had thehighest success rates, and lowest with the techniques that had the lowestrecanalization rates.

Conclusion: In our in vitro model, we found that theTigertriever had the highest recanalization rate when the aspirationcatheter was advanced to meet the Tigertriever and clot. Distal positioningof the aspiration catheter and retrieval of the Tigertriever while inflatedhad increased success rates. Additionally, we found that the pulling forcewas low in the absence of clot, and highest with techniques that had thehighest success rates, likely due to clot engagement.

O4-12-2

The Neurovasc Envi Stent Retriever - Initial Experience

Pervinder Bhogal

Department of Interventional Neuroradiology, The Royal London Hospital, BartsNHS Trust

Background: Since the publication in 2015 of several seminaltrials (1–5), mechanical thrombectomy (MT) has been widely accepted as thegold standard treatment for acute ischaemic stroke (AIS) caused by largevessel occlusion (LVO). Subsequent studies have demonstrated the benefit ofMT in selected patients in the extended time window with on-going studieslooking at the potential benefit of MT for patients with larger cores andwith more distal occlusions.

Although stent-retrievers are similar in their overall function each has itsown unique physical properties and over the last decade there are have beena variety of advances made in the design of the different devices. TheNeurovasc Envi is a novel segmented design stent-retriever. We report thefirst clinical experience of this new stent-retriever.

Materials and Methods: We performed a retrospective review ofprospectively maintained data to identify all patients treated with theNeurovasc Envi Stent-Retriever from September 2019 to April 2022. Werecorded the baseline clinical and imaging data, including the NIHSS andASPECT score as well clot features such as hyper density and clot length.Procedural data was recorded including number of passes and first passeffect as well as the 90 day mRS.

Results: We identified 20 patients with median age 74, 19 ofwhom had anterior circulation occlusions. the median NIHSS was 15. Themedian ASPECT score was 8 and clot length was 15mm. The final mTICI ≥2b was90% and first pass mTICI≥2b was 65%. There were no major complications fromusing the device. There was a very small SAH in 10% of patients and one caseof SICH.

Conclusion: The Neurovasc Envi is a novel segmentedstent-retriever that has high rates of recanalisation with low rates ofsubarachnoid haemorrhage.

O4-12-3

Treatment of distal intranial occlusion with pREset LITE and LUX stentretriever. A single center experience.

Simone Comelli, Federico Fusaro, Marco Erta,Federica Schirru, Simona Corraine, Antonio Ferrari, Valeria Ledda,Simona Secci, Alberto Fenu

Department of Neuroradiology, ARNAS G.Brotzu

Purpose: Mechanical thrombectomy (MT) is a standard treatmentfor acute ischemic stroke due to large brain vessel occlusion. In the lastyears MT is been use also in small distal branches. In the present study, weassessed the efficacy and the safety of distal MT using the pReset stentretriever.

Materials and Methods: We selected consecutive patients treatedwith pREset LITE and LUX for a distal intracranial at our hospital (ARNAS G.Brotzu Cagliari Sardinia) between January 2021 and December 2021.

Results: 29 patients with 31 distal arterial occlusionsunderwent MT using the pRest stent retriever: n 17 4 × 20 mm (58,6%) and n12 3 × 20 mm (41,4%).

We admitted only patients with NIHSS = > 6.

We perfomed 22 ACM MT in M2 segment (71%), 3 in M3-M4 segment (9,7%), 4 ACAMT in A2-A3 segment (13%) and 2 PCA MT in P2-P3 segment (6,3%).

First pass MT was performed in 20 cases (69%), 3 cases it was necessarysecond pass MT 10.3% and other 3 cases was necessary third pass MT(10.3%).

In 3 cases was observed unsuccessful thrombectomy (10.3%).

Optimal reperfusion (TICI 3) was observed in 16 out of 29 patients (78%) andgood reperfusion (TICI 2 b, c) was observed in 11 of 29 patients.

Focal ischemia within the territory vascularized by the artery occlusion wasobserved in 10 patients (34,5%).

In 8 cases was observed a minimal post-procedura subarachnoid haemorrhage(SAH) without arterial vasospasm.

5 asymptomatic hemorrhages (4.9%) were noted on follow-up imaging (4patechial hemorrhage and 1 parenchymal hematoma).

No vessel rupture were observed.

Overall, good neurological outcome at three months (mRS ≤ 2) was observed in26 (89.6%).

3 patients died for other clinical situation out of ischemic stroke.

Conclusions: Our single-center experience shows that the pResetstent retriever is safe and effective for the recanalization of smalldiameter distal branches feeding eloquent brain areas.

O4-12-4

Eptifibatide in acute stroke due to distal or barely accessiblethrombus for the prevention of appositional thrombus and thrombusdisplacement

Philipp v. Gottberg¹, Victoria Hellstern¹, Alexandru Cimpoca¹, Ali Khanafer¹, Hansjörg Bäzner³, Hans Henkes^1,2

¹Klinik für Neuroradiologie, Klinikum Stuttgart, Stuttgart,Germany

²Medizinische Fakultät, Universität Duisburg-Essen, Essen,Germany

³Klinik für Neurologie, Klinikum Stuttgart, Stuttgart, Germany

PURPOSE: In the last 15 years, new neurointerventionaltechniques and devices have pushed the boundaries of what is possible.However, due to continuous progress and intensified use, situations withthrombus formation or location in hard-to-reach sites are encountered morefrequently. The purpose of this study was to investigate the use of mid-termintravenous eptifibatide in acute stroke due to thrombus in barelyaccessible or distal locations for the prevention of further thrombusapposition and thrombus displacement.

METHODS AND MATERIALS: Data from 25 patients in our institutionwith acute stroke through thrombus in a barely accessible or distantlocation was retrospectively analyzed. The thrombus location was defined asbarely accessible or distant when beyond distal M2-, A2- or P1-branches, forin-device thrombus (e. g. in-flow-diverter thrombus), proximal stenosis orany other kind of disproportion of the risk-benefit relation regardingendovascular therapy. Eptifibatide was given as primary treatment; norecombinant tissue plasminogen activator was given. Eptifibatide dosage wasadapted to body weight; the mean duration of treatment was 69h. MRS score,NIHSS, TICI score before and after Eptifibatide treatment as well asperiprocedural complications and in-hospital major hemorrhagic events wererecorded.

RESULTS: The presenting symptoms were predominantly mild (meanNIHSS 2.2, 0–8). Mean mRS score points on presentation/before eptifibatidetreatment was 2 (0–4) and 1 after treatment (0–5). On Follow-up angiograms,complete dissolution of thrombus or significant melting thrombus withoutremaining stenosis was seen in 72% of patients. No thrombus dislocation andno appositional thrombus was recorded. Between begin and end of eptifibatidetreatment, 24% (n = 6) of patients showed a reduction in the mRS in a meanof 2 score points (1.8, 1–3), 18 patients had an equal mRS score and onepatient worsened from mRS 4 to 5. Mean TICI on presentation was 2b (0–3) and3 (0–3) at the end of treatment. There was no periprocedural death and nomajor hemorrhagic complication in the in-hospital phase.

CONCLUSION: In our population, mid-term intravenous eptifibatideapplication proved to be a safe way to challenge thrombus apposition anddislocation in barely accessible or distant thrombus. Also, at a clearimprovement in TICI, the patient improvement was moderate.

O4-13-1

Safety and Efficacy of Stent-Assisted Coiling of UnrupturedIntracranial Aneurysms Using Low-Profile Stents in Small ParentArteries

Junhyung Kim¹, Hyun Jin Han², Woosung Lee³, Joonho Chung¹, Yong Bae Kim², Keun Young Park², Sang Kyu Park¹

¹Department of Neurosurgery, Gangnam Severance Hospital, YonseiUniversity College of Medicine, Seoul, Korea

²Department of Neurosurgery, Severance Hospital, Yonsei UniversityCollege of Medicine, Seoul, Korea

³Department of Neurosurgery, Ehwa Woman's University SeoulHospital, Seoul, Korea

BACKGROUND AND PURPOSE: Stent-assisted coiling of intracranialaneurysms arising from small vessels (< 2.0 mm) is a common procedure.However, data regarding its treatment outcomes are scarce. This studyevaluated the clinical and radiologic outcomes of stent-assisted coilingusing low-profile stents for aneurysms of small parent arteries.

MATERIALS AND METHODS: From November 2015 to October 2020,sixty-four patients with 66 aneurysms arising from parent arteries of<2.0 mm were treated with stent-assisted coiling using a Low-ProfileVisualized Intraluminal Support Junior (LVIS Jr) or the Neuroform Atlasstent in a single institution. The clinical and radiologic data wereretrospectively reviewed, and the risk factors for procedure-relatedcomplications were evaluated.

RESULTS: The LVIS Jr and Neuroform Atlas stents were used in 22(33.3%) and 44 (66.7%) cases, respectively. Technical success was achievedin 66 cases (100%). Immediate postprocedural aneurysm occlusion gradesassessed by the Raymond-Roy occlusion classification were I (57.6%), II(19.7%), and III (22.7%), respectively. Procedure-related complicationsoccurred in 10 cases (15.2%), with 8 thromboembolic complications (12.1%)and 2 hemorrhagic complications (3.0%). Procedure-related morbidity was 4.5%without mortality.

On multivariate analysis, current smoking (odds ratio = 7.1, P = .021) had astatistically significant effect on procedure-related complications.

CONCLUSIONS: Stent-assisted coiling of intracranial aneurysmswith low-profile stents in small vessels (< 2.0 mm) had a 100% successrate and a 15.2% overall complication rate with 4.5% morbidity. Currentsmoking was a significant risk factor associated with procedure-relatedcomplications.

O4-13-2

Stent-assisted Coil Embolization of Fusiform Vertebral ArteryAneurysms with a Reconstructive Technique

Ryuta Nakae¹, Tomoji Takigawa², Junya Kaneko¹, Yasuhiko Nariai², Yosuke Kawamura², Ryotaro Suzuki², Issei Takano², Masaya Nagaishi², Akio Hyodo², Kensuke Suzuki²

¹Department of Emergency and Critical Care Medicine, NipponMedical School

²Department of Neurosurgery, Dokkyo Medical University SaitamaMedical Center

Purpose: The treatment of intracranial fusiform vertebral arteryaneurysms (FVAAs) with preservation of the parent artery is challenging. Weevaluate the feasibility, safety, and efficacy of stent-assisted coilembolization of FVAAs with a reconstructive technique.

Materials and Methods: We examined perioperative complicationsand outcomes of patients who underwent stent-assisted coil embolization ofFVAA with a reconstructive technique from November 2010 to September 2021.The following procedures were thoroughly performed. Coils were insertedusing the jailing technique. A few loops of coil were inserted into the FVAAbefore stent deployment to stabilize the microcatheter position and toinsert the coil outside of the stent definitely. The microcatheter wasexchanged for a micro-balloon catheter after stent deployment to use aballoon-in-stent technique for preventing coil migration into the stent.

Results: Forty FVAA patients were treated with stent-assistedcoil embolization with a reconstructive technique. Clinical presentationincluded headache in 20 patients (50.0%), SAH in 14 patients (35.0%), masseffect in 2 patients (5.0%), and no symptoms in 4 patients (5.0%). Theappearance of contralateral VA was as follows: normal in 19 patients(47.5%), hypoplasty in 10 patients (25.0%), aplasty in 4 patients (10.0%),dissection in 4 patients (10.0%), PICA-end in 2 patients (5.0%), andpost-parent artery occlusion state in 1 patient (2.5%). A total of 6procedure-related complications (15.0%) were observed, including 3 (7.5%)procedure-related symptomatic ischemic strokes, 1 (2.5%) intra-operativerupture in SAH case, 1 (2.5%) intra-operative PICA occlusion, and 1 (2.5%)asymptomatic stent occlusion. Of the 40 patients, post-procedure DSArevealed complete occlusion in 12 patients (30.0%), near-complete (100–90%)occlusion in 12 patients (30.0%), and incomplete (< 90%) occlusion in 16patients (40.0%). DSA was available in 15 patients at a median of 12 months(range, 1–16 months) whose post-procedure DSA findings were near-complete orincomplete occlusion. The findings revealed complete occlusion in 6 patients(40.0%). There were no patients with delayed aneurysmal rupture andcomplications during the follow-up period (median, 36 months; range, 1–102months). Four patients (10.0%) developed major recanalization and requiredretreatment. Overall, the morbidity and mortality rates at 6 monthspost-procedure was 5.0% (2/40) and 2.5% (1/40), respectively.

Conclusion: Stent-assisted coil embolization of FVAAs with areconstructive technique is feasible, safe, and effective with good short tomid-term angiographic and clinical outcomes. To further improve treatmentresults, thromboembolic complications should be reduced and the cure ratemust be increased by using different stents for each patient.

O4-13-3

Coil embolization of unruptured cerebral aneurysms using stents insmall arteries less than 2 mm in diameter

Tomohiko Ozaki, Tomoki Kidani, Shin Nakajima,Yonehiro Kanemura, Nobuyuki Izutsu, Saki Kawamoto, Kowashi Taki, NaokiNishizawa, Keijiro Murakami, Kouji Kobayashi, Yosuke Fujimi, ToshiyukiFujinaka

Department of Neurosurgery, Osaka National Hospital

Background and Purpose: Data regarding the safety andeffectiveness of stent placement in small vessels (<2 mm in diameter) fortreating wide-necked cerebral aneurysms are limited. This study aimed toreport our experience regarding coil embolization of unruptured cerebralaneurysms using stents (specifically the Neuroform Atlas) in small arteries<2 mm in diameter.

Materials and Methods: Patients with unruptured cerebralaneurysms treated with stent-assisted coil embolization between March 2017and March 2021 in our hospital were included. Patients who required stentdeployment in small vessels (smallest diameter <2 mm) were classified asthe small vessel group (SVG), whereas the other patients were classified asthe large vessel group (LVG).

Results: Of the 137 cerebral aneurysms included in this study,49 aneurysms met the criteria for the SVG, and 88 aneurysms were classifiedinto the LVG. In SVG, 48 (98%) were treated using the Neuroform Atlas and 43aneurysms (87.8%) demonstrated complete occlusion. In LVG, 78 aneurysms(88.6%) demonstrated complete occlusion. In SVG, 2 (4.1%) patients hadin-stent thrombosis during procedures and 5 (10.2%) experienced symptomaticthromboembolic complications, but only 2 (4.1%) had worsening of themodified ranking scale ≥1 at 90 days after embolization. There was nostatistically significant difference in symptomatic thromboembolic events,in-stent thrombosis during procedure and worsening of modified Rankin Scaleat 90 days between 2 groups. In the SVG, 33 patients (67.3%) underwentfollow-up angiography 1 year after embolization. Aneurysm recanalization wasdemonstrated in 2 patients, but these were slight recanalizations and noneed to retreatment. There was no statistically significant difference inaneurysm recanalization rates between 2 groups. In-stent stenosis orocclusion were not observed at follow-up angiography in both groups.Patients with MCA aneurysms had a higher risk of thrombotic events (5/18patients, 27.8%), such as symptomatic thromboembolic complications orintraprocedural in-stent thrombus, than those with other aneurysms (1/31patients, 3.2%), in the small vessel group (p = 0.0167).

Conclusion: Stent-assisted coil embolization for unrupturedcerebral aneurysms using stents, especially the Neuroform Atlas, in smallarteries <2 mm in diameter is effective and feasible, but carefulperioperative attention should be given to thrombotic events during theembolization of MCA aneurysms.

O4-13-4

Stent-assisted coil embolization to treat extracranial carotid arteryaneurysm 13 years after endarterectomy

Masato Kawakami, Jun Haruma, Kenji Sugiu,Tomohito Hishikawa, Masafumi Hiramatsu, Kazuhiko Nishi, Yoko Yamaoka,Yuki Ebisudani, Yu Sato, Hisanori Edaki, Ryu Kimura, Isao Date

Department of Neurological Surgery, Okayama University Graduate School,Okayama, Japan

Purpose: development of extracranial carotid artery aneurysm(ECCA) after carotid endarterectomy (CEA) is a rare complication, occurringin connection with <1% of all CEAs. The main causes are infection, suturefailure, and degeneration of arterial wall or patch. The traditionaltreatment has been operative repair, which can present a significanttechnical challenge owing to reoperative neck inflammation and potentialcranial nerve injuries. Here, we report a case of successful stent-assistedcoil embolization for right noninfectious ECCA.

Summary of a case- a 63-year-old female was admitted to our hospital for a3-cm pulsating mass in her right mid-neck that had gradually increased insize over the preceding 6 months. Doppler examination and digitalsubtraction angiography revealed a large (15 mm) ECCA at the right commoncarotid artery (CCA). Laboratory data concerning the peripheral bloodrevealed no anomalies in the white cells count and in the indices ofinflammation. The patient had a history of CEA with patch angioplasty byDacron at another hospital 13 years previously because of a symptomatic 80%diameter stenosis with transient ischemic attack (TIA). Routine follow-up at2 years after CEA had shown the patient to be doing well with no new TIA orstrokes and computed tomography angiography did not show restenosis oraneurysm formation. However,13 years after CEA, she had ECCA and neededsurgical treatment because of the risk of rupture of the aneurysm. As thepatient refused blood transfusion for religious reasons, stent-assisted coilembolization was considered after a detailed discussion with the patient. ACarotid Wall stent was deployed, and the aneurysm was occluded using 25detachable coils. Nearly complete obliteration of the aneurysm was achievedwhile preserving the parent artery patency. Her neck swelling and pulsationof the mass disappeared 14 days after the initial treatment. Ultrasoundscans 3 months later revealed complete occlusion of the ECCA but also showedstent shortening. Hence, we performed an additional stent placement so as tooverlap the previous stent by 2.5 cm. Six months after initial treatment,carotid duplex ultrasound confirmed a good outcome. Our experience has shownthat the combination of stent plus coil embolization is a successful andviable option in patients with ECCA after CEA.

Conclusion: no gold-standard treatment for ECCA following CEAhas been established to date, though the stent-assisted coil embolizationtechnique is considered the most minimally invasive and effective treatmentmethod for ECCA. We believe that this is less invasive and safer than openrepair in patients without signs of infection and this makes it an excellentchoice for high-risk patients.

O4-13-5

The incidence of delayed ischemic events after stent-assisted coilembolization and their characteristics

Takenori Ogura, Taketo Hatano, Takeshi Miyata,Yuji Agawa, Takeru Umemura, Izumi Nagata

Department of Neurosurgery, Kokura Memorial Hospital, Fukuoka, Japan

Purpose: Although the necessity of antiplatelet therapy (APT) iswidely recognized for prevention of periprocedural ischemic events ofstent-assisted coil embolization (SACE), a limited number of reports havedescribed delayed ischemic events and optimal duration of APT. In thisstudy, we aimed to reveal the incidence of delayed ischemic events afterSACE, and their relation to the de-escalation of APT.

Material and Methods: We analyzed 163 consecutive SACEprocedures performed at our institution between April 2018 and March 2021retrospectively. Delayed events were defined as the events which arose after30 days from the procedure. All of the possible ischemic events related tothe stented vessel territory were included. We examined the incidence of thedelayed ischemic events and their consequences. Subsequently, we evaluatedthe relationship between the onset of the events and the duration ofAPT.

Results: Among 163 procedures, dual antiplatelet therapy (DAPT)was reduced to single antiplatelet therapy (SAPT) in 156 cases (95.7%) andSAPT was discontinued in 101 cases (61.9%). Overall, 7 delayed ischemicevents (4.2%) were observed. 5 events accompanied transient neurologicalsymptom, whereas 2 events were asymptomatic. Among 7 events, 1 eventoccurred during DAPT, 2 events after discontinuation of DAPT, 4 events afterthe discontinuation of APT. Regarding 5 symptomatic events, the events wereobserved median 13 days after APT de-escalation or discontinuation.Diffusion weighted image (DWI) – positive ischemic lesions were recognizedin 3 events, and in-stent thrombosis was verified in only 1 event underangiography. All the events could be well managed with the restart of APT,and none of the events resulted in persistent neurological deficit.

Conclusions: The most of delayed ischemic events were observedafter the de-escalation of APT, although only one definite in-stentthrombosis was included. Although none of the events resulted in morbidity,careful follow-up would be needed at the time of de-escalation ordiscontinuation of APT

O4-14-1

A Novel Swine Model to Evaluate Intra-Operative Arterial CollapseInduced by Aspiration Thrombectomy Using Concurrent Fluoroscopic andTransmural Visualization

Timothy Katsuyuki Shimizu¹, Ichiro Yuki¹, Zachary Weizen Hsu¹, Hemdeep Kaur¹, Earl Steward², Shuichi Suzuki¹

¹Department of Neurosugery, University of California, Irvine

²Department of Surgery, University of California, Irvine

Purpose: Direct aspiration thrombectomy is an effectivetechnique to recanalize large vessel occlusions (LVO) in stroke patients andhas become one of the major techniques. Advancements in technology hasenabled the use of catheters with larger lumens and higher aspirationforces; however, successful reperfusion rate of the first pass still remainsat 57–63%. Here, the first swine model for LVO, which provides directconcurrent fluoroscopic and transmural visualization of real-time vesselresponses during aspiration thrombectomy, was established to investigate themechanism of aspiration thrombectomy failure observed in clinicalsettings.

Materials and Methods: The common carotid artery (CCA) andsuperficial cervical artery (SCA) were surgically exposed in Yorkshire swine(n = 3), and a total of 13 vessels were treated using aspiration catheterswith different inner diameters (0.058, 0.068, and 0.088 inches). The CCAgroup (n = 7) represented large diameter vessels (4–5 mm), and the SCA group(n = 6) represented small diameter vessels (2–3 mm). LVO was reproducedusing a radiopaque clot analog which was injected into each target vesselvia a guiding catheter. To maintain a consistent clot location in the CCAgroup, mild, non-flow-limiting stenosis was created using a 4-0 Prolenesuture. Fluoroscopy and a high-resolution digital microscope camera wereused simultaneously to monitor angiographic and transmural vessel behaviorduring the procedure. The presence or absence of vessel collapse and reverseflow during the procedures as well as vessel diameter, intraluminalpressures proximal and distal to the occlusion site, and pre-andpost-angiographic findings were evaluated.

Results: Both concurrent fluoroscopic and transmuralvisualization were achieved in all treated vessels allowing the observationof real-time arterial wall and clot response in both the large diametervessel group (CCA) and the small diameter vessel group (SCA). The mean bloodpressures distal and proximal to the occlusion site showed no significantdifferences between the two groups. All vessels observed under directvisualization in the SCA group (Mean Diameter: 2.34 ± 0.49mm) showedimmediate vessel collapse during remote aspiration regardless of the inner-lumen-size of the catheter, while clot ingestion was achieved only by directcontact aspiration. None of the vessels in the CCA group (Mean Diameter:5.16 ± 0.54 mm) showed vessel collapse during remote aspiration; however, 5out of 7 vessels showed local reverse flow followed by ingestion of the clotwhen the tip of the catheter was placed near the clot (5–10 mm). The othertwo vessels required direct contact aspiration to achieve clotingestion.

Conclusion: This swine model to analyze arterial vessel behaviorat the SCA and CCA during aspiration thrombectomy may help us understand themechanism of aspiration thrombectomy failure, and it may contribute toimproving the techniques and the development of new aspiration devices.

O4-14-2

Withdraw

O4-14-3

Association of plasma lipid mediators and futile recanalization aftersuccessful endovascular thrombectomy in patients with acute ischemicstroke

Yao Feng, Xin Xu, Liqun Jiao

Department of neurosurgery, xuanwu hospital, Capital Medical University

Background: Cerebral ischemia-reperfusion injury-induced futilerecanalization accounts for ∼50% of acute ischemic stroke (AIS) patients whorecanalized successfully by endovascular thrombectomy (EVT), and there isstill lack of efficient biomarkers for early prediction. Here, we sought todetermine the temporal profile of plasma levels of bioactive lipidmediators[specialized pro-resolving lipid mediators, lipoxin A4 (LXA4) andresolvin D1 (RvD1), and a pro-inflammatory lipid mediator leukotriene B4(LTB4)] and their association with futile recanalization.

Methods: We retrospectively collected blood samples fromconsecutive AIS patients who underwent complete angiographic recanalizationby EVT in the period from May 22, 2019 to August 13, 2020. Plasma levels ofLXA4, RvD1, and LTB4 longitudinally on admission (pre-EVT) and 24 h post-EVTwere measured by enzyme-linked immunosorbent assay. Three-month clinicaloutcome post-EVT was assessed using the modified Rankin Scale (mRS), andfutile recanalization was defined as mRS of 3–6.

Results: In total, 58 consecutive AIS patients and 15 healthysubjects were recruited. Plasma levels of LXA4, RvD1, and LTB4 in AISpatients were significantly increased post-EVT and higher than those ofhealthy controls. Post-EVT LXA4 level, LXA4/LTB4 ratio, RvD1/LTB4 ratio, andΔLXA4 (pre- and post-EVT variation) level were positively, while post-EVTLTB4 level was negatively associated with 3-month clinical outcomes. Of the58 AIS patients, 27 (46.55%) had futile recanalization. Subgroup analysisrevealed that AIS patients with futile recanalization had lower post-EVTLXA4 level, ΔLXA4 level, and LXA4/LTB4 ratio, but higher post-EVT LTB4 levelthan those with effective recanalization. Multiple logistic regressionanalysis demonstrated that post-EVT LXA4 level (adjusted odd ratio[OR]0.994, 95% confidence interval[CI] 0.99-0998), ΔLXA4 level (adjusted OR0.994, 95% CI 0.99–0.998), and post-EVT LXA4/LTB4 ratio (adjusted OR 0.199,95% CI 0.048–0.821) were independent predictors for futile recanalization,which were further confirmed by receiver operating characteristic curveanalysis (area under the curve were 0.7121, 0.6798, and 0.7145,respectively).

Conclusions: These results indicated that the imbalance betweenanti-inflammatory/pro-resolving and pro-inflammatory lipid mediators maycontribute to futile recanalization. The post-EVT plasma LXA4 level, ΔLXA4level, and LXA4/LTB4 ratio may serve as potential biomarkers for futilerecanalization in AIS patients treated with successful EVT.

O4-14-4

Regional disparities in prehospital delay, tPA, and mechanicalthrombectomy of acute ischemic stroke with special reference to arealsocioeconomic status

Hitoshi Fukuda, Yusuke Ueba, Naoki Fukui,Fumihiro Hamada, Motonobu Nonaka, Tomohito Kadota, Yu Kawanishi, EiichiNakai, Tetsuya Ueba

Neurosurgery, Kochi University, Kochi, Japan

Purpose: Although healthcare service must be provided equallyregardless of the patients’ residence, regional disparities in treatment ofacute ischemic stroke still exist In this presentation, we demonstrateassociation of areal socioeconomic status with prehospital delay, tPA, andmechanical thrombectomy from a county-wide stroke survey in Kochiprefecture, Japan.

Materials and Methods: Acute ischemic stroke patients, who wereregistered in Kochiacutestroke survey ofonset (KATSUO) registry between September 2012and December 2018, were included. The socioeconomic status of themunicipalities the patients reside in was calculated as areal deprivationindex (ADI), which means disadvantage in social link in the community, fromJapan census 2015. All the municipalities in Kochi prefecture except forCapital Kochi city were divided into quartiles according to their ADI (Q1:least deprived – Q4: most deprived). Association of ADI quartiles withprehospital delay over 4 h, tPA injection, and mechanical thrombectomy wasanalyzed. Regional disparities in improving trends of these outcomes werealso evaluated.

Results: Among 5627 patients meeting the inclusion criteria,3902 (65.8%) revealed prehospital delay over 4 h. Multivariable analysisdemonstrated that increasing ADI quartiles were significantly associatedwith prehospital delay (Q4 vs. Q1, odds ratio 1.64[95% confidence interval1.37–1.96], P < 0.001: P for trend < 0.001). Similartrends were observed in poor clinical outcomes including in-hospitalmortality and being discharged to long-term care. Patients in Q4 areasinappropriately responded to the acute stroke setting, where they activatedemergency medical service more frequently, but most of them were delayedovernight. Moreover, the improving trend in Q4 areas in terms of prehospitaldelay, tPA injection, and mechanical thrombectomy was approximately 2 yearslater than other areas.

Conclusions: Regional disparities in treatment for acuteischemic stroke could be explained by delayed and less prevalent transfer ofcorrect medical information in the socioeconomically disadvantageous areas.More acute ischemic stroke patients may be rescued by intervening sociallinks in the communities.

O4-14-5

Intraarterial therapy of Rho-kinase inhibitor following mechanicalthrombectomy for acute ischemic stroke

Yoichi Morofuji¹, Shinsuke Nakagawa², Tsuyoshi Izumo¹, Takayuki Matsuo¹

¹Department of Neurosurgery, Nagasaki University

²Department of Pharmacology, Fukuoka University

Attempts to develop new drugs for acute ischemic stroke are still struggling;however, mechanical thrombectomy is now at the forefront of the treatment oflarge-vessel acute ischemic stroke. Selective intra-arterial access hasopened a new avenue for neuroprotection in acute ischemic stroke that hasthe potential to maximize the local benefits while minimizing systemiceffects. We investigated the effect of fasudil, rho-kinase inhibitor, onblood-brain barrier (BBB) integrity against ischemia-reperfusion injury. Weused in vitro BBB models with rat primarily cultured BBB-related cells(brain capillary endothelial cells, astrocytes and pericytes), and subjectedcells to either normoxia or 6-h oxygen glucose deprivation (OGD)/24-hreoxygenation. Fasudil inhibited the decreases in TEER induced by 6-hOGD/24-h reoxygenation and decreased the endothelial permeability for sodiumfluorescein through the BBB model. Immunocytochemical and western blotanalyses showed that fasudil increased the expression of claudin-5, the mainfunctional protein of tight junctions under 6-h OGD/24-h reoxygenation aswell as normoxia. Our data indicate that rho-kinase inhibitor fasudilstrengthens the barrier integrity in BBB. Since mechanical thrombectomy isnow the gold standard for acute ischemic stroke treatment, neuroprotectivestrategies via the intra-arterial route are highly anticipated.

O4-15-1

Analyzing Follow-Up Care Compliance Among Patients Diagnosed withUnruptured Cerebral Aneurysms.

Hemdeep Kaur, Ichiro Yuki, Timothy Shimizu,Jordan Xu, Shuichi Suzuki

Department of Neurosurgery, University of California, Irvine (UCI), Orange,USA

Introduction: Studies show that unruptured aneurysm patients whochose conservative management are recommended for periodic follow-upimaging. Studies also suggest that risk of rupture can significantlyincrease if the aneurysm grows, which is defined as a “1 mm or greaterincrease in 1 direction” during follow-up imaging. But, little is knownabout the compliance of proper follow-up care after the initial diagnosis ofthe aneurysm. Also, the diagnosis of an unruptured aneurysm can be made bydifferent providers from multiple services, such as Neurology, Neurosurgery,Radiology, and the Emergency department; thus, it is necessary to analyze acentralized patient database to encompass all services in the institution.Cohort Discovery Tool (CDT) is a software that enables users to conductself-serve queries in the electronic health care data warehouse in ahospital. To investigate the follow-up compliance rate of patients who werepreviously diagnosed with an unruptured aneurysm in our institution, datacollection was performed using CDT software, i2b2, and a retrospectiveanalysis was performed.

Methods: Utilizing the CDT software, i2b2, we identifiedpatients who had been diagnosed with unruptured aneurysm in the past 10years at UCI Medical Center, then conducted medical chart reviews of eachpatient. Patients are excluded from this study when 1) the patient hasreasoning for discontinuation of the follow-up described in the medicalchart 2)deceased, or 3) the wrong diagnosis. Proper follow-up care wasdefined as “scheduled for annual/biannual imaging follow-up since thediagnosis date.” After conducting random sampling of this patient group, thefollow-up visit compliance rate was calculated. Finally, for those whomissed a follow-up visit, an individual telephone interview was conducted toanalyze the reasoning.

Results: Between 2010 and 2020, a total of 3001 patients werediagnosed with at least one unruptured aneurysm at the UCI medical center.Of these, 449 patients were randomly selected for analysis. The follow-upvisit compliance rate was 23%, with 69% of patients being non-compliant and8% being deceased. Of those non-compliant, we performed telephone interviewsfor 211 patients. The reasoning behind missed follow-up was 1) unaware ofthe importance for afollow-up visit (65%), 2) unable to attend due to otherreasonings (22%), and 3) properly followed elsewhere (13%). In addition, 33%of the patients with lack of awareness were diagnosed at the emergencydepartment and never visited the clinic for further patient education.

Conclusion: Retrospective analysis, using CDT software, can bean effective method to find the cohort of unruptured aneurysm patients lostin follow-up. A major reason for non-compliance to follow-up visits was alack of awareness of the significance and necessity of follow-up care.Improved clinical approaches may be required to educate patients and ensureproper understanding of follow-up care.

O4-15-2

Use of Distal Intracranial Catheters for Better Working View ofCerebral Aneurysms Hidden by Parent Artery and/or Its Branches: ATechnical Note

Ehab Adel Mahmoud, Ljubisa Borota, ChristofferNyberg, Samuel Lenell

Neuroradiology, Uppsala University hospital

Background: A good working view is critical for safe andsuccessful endovascular treatment of cerebral aneurysms. In a few cases,endovascular treatment of cerebral aneurysms may be challenging because ofdifficulty in obtaining a proper working view. In this report of 6 cases, wedescribed the advantage of using a distal intracranial catheter (DIC) toachieve better visualization of cerebral aneurysms hidden by a parent arteryand/or its branches.

Methods: Between September 2017 and January 2021, we treated 390aneurysms with endovascular techniques. In six cases in which it wasdifficult to obtain a proper working view, the DIC was placed distally closeto the aneurysm in order to remove the parent artery projection from theworking view and obtain better visualization of the aneurysm. Clinical,procedural outcomes and complications were evaluated.

Results: The position of the DIC was above the internal carotidartery (ICA) siphon in the six cases. All aneurysms were successfullyembolized. Raymond–Roy class 1 occlusion was achieved in all four unrupturedaneurysms, while the result was class 2 in the two ruptured aneurysms.Placement of the DIC was atraumatic without dissections or significantcatheter-induced vasospasm in all patients. Transient dysphasia was seen intwo cases and transient aphasia in one.

Conclusion: Using this technique, we have found it possible tobetter visualize the aneurysm sac and/or neck and thereby treat cases weotherwise would have consider untreatable.

O4-15-3

Withdraw

O4-15-4

Usefulness of high flow microcatheter

Naoto Kimura^1,2, Ryosuke Doijiri², Michiko Yokosawa¹, Kiyotaka Ooi², Shuhei Egashira², Takayuki Sugawara¹

¹Department of Neurosurgery, Iwate Prefectural CentralHospital

²Department of Neurology, Iwate Prefectural Central Hospital

Distal access catheters (DACs) are used to stabilize microcatheters inendovascular treatment, but they may interfere with each other and cause themicrocatheter to slip out. High flow microcatheters (HMC) are available inJapan from two companies, Tactics plus (Technocrat, Aichi., Japan) andGuidepost (Tokai medical, Aichi, Japan), both with an outer diameter of 3.4fr. Inner lumen diameter is 0.040–0.035-inch allows insertion of a 0.021inch catheter, and two HMC can be inserted in parallel into an 8-fr guidingcatheter.

The catheter is useful for coil embolization with adjunctive technique andAVM in a variety of situations.

CASE 1: Coil embolization with stent

Parallel insertion of HFM with 8fr guiding catheter is useful in stent assistcoil embolization. Use of two HFMs prevents the jailing microcatheter fromslipping out form aneurysm during stent deployment through each catheterwithout interference, and the HFM provide support to prevent catheterflexion and facilitate catheter manipulation during stent deployment.

CASE 2: Embolization using a PulseRider

The PulseRider is useful for embolization of T-shape bifurcation aneurysms.However, despite its complicated operation and need for backup, the catheterfor coil embolization requires transcel after implantation. The same asprevious technique, stable embolization can be achieved by using 21catheters to separate the axis of pulse rider deployment and the HMC forcoil implantation.

CASE 3: AVM embolization

ONYX embolization from a distal artery, the catheter may be trapped duringcatheter removal, resulting in vascular pull-out damage. the use of an HFMimproves support in the peripheral artery and allows safe catheterremoval.

Conclusion: Despite its small diameter, the HFM catheter can beinserted with a wide variety of microcatheters. The results suggest thatendovascular treatment can be performed safely by using the catheter in away that is appropriate for the situation.

O4-16-1

Radiological predictors of recurrence after coil embolization forposterior communicating artery aneurysms

Shigeki Takada, Tomonori Ichikawa, NobutakeSadamasa, Waro Taki

Department of Neurosurgery, Stroke Center, Koseikai Takeda Hospital, Kyoto,Japan

Purpose: Flow diverter devices (FDDs) have gained wideacceptance for the treatment of unruptured intracranial aneurysms,especially large aneurysms. During last years, the use of FDDs has widelygrown up and the indication for FDDs is expanding. However, coilembolization is still an important method for aneurysms involving a branch,especially posterior communicating artery (Pcom). The aim of thisretrospective study was to evaluate the radiological predictors ofrecurrence after coil embolization for Pcom aneurysms.

Materials and Methods: Between January 2013 and October 2021, 34Pcom aneurysms in 33 patients were treated at our institution. 23 Pcomaneurysms which were treated with coil embolization and observed >6months with follow − up imaging were included in this study. Theradiological characteristics of Pcom aneurysms were analyzed (Aneurysmalfactors: aneurysm size, aneurysm neck diameter, Aspect ratio, multilobular,Pcom factors: fetal Pcom, Pcom diameter, distance between parent artery andorifice of Pcom).

Results: The mean age of the patients was 68.2 ± 11.1 years old.There were 3 (13%) males and 20 (87%) females. We performed coilembolization for 12 (52.2%) unruptured and 11 (47.8%) ruptured Pcomaneurysms. In the treatment of 22 aneurysms, we used adjunctive technique(Balloon-assisted technique: 12, Stent-assisted technique: 8, Doublecatheter technique: 1, Catheter-assisted technique: 1, Balloon-assisted anddouble catheter technique: 1). Distal access catheter was used in 5 (21.7%)aneurysms. In all cases, there was no postprocedural symptomatic cerebralinfarction in Pcom territory. Of 23 aneurysms, 3 (13.0%) were completeocclusion, 15 (65.2%) were neck remnant, and 5 (21.7%) were dome fillingimmediately after the procedure. At follow-up imaging, 15 (65.2%) werestable or improved (SI), 8 (34.8%) were recurrence (RE) (minor recurrence:4, major recurrence: 4). All of 4 major recurrence were retreated. There wasno significant difference in Pcom factors (fetal Pcom, Pcom diameter,distance between parent artery and orifice of Pcom) between SI group and REgroup. On the other hand, in aneurysmal factors, the aneurysm size was6.84 ± 2.27 mm and 9.80 ± 2.93 mm in SI group and RE group, respectively.The aneurysm neck diameter was 3.92 ± 1.38 mm and 6.17 ± 2.90 mm in SI groupand RE group, respectively. In the logistic regression analysis, significantdifferences were observed in aneurysm size (Odds ratio = 1.57; 95% CI,1.04 − 2.36; P = .031) and aneurysm neck diameter (Odds ratio = 2.11; 95%CI, 1.01 − 4.42; P = .048) between SI group and RE group.

Conclusion: Aneurysm size and neck diameter are radiologicalpredictors of recurrence after coil embolization for Pcom aneurysms,regardless of characteristics of Pcom.

O4-16-2

Coiling and overlapping flow diverters with short term anticoagulationfor aneurysms difficult to cure with flow diverter

Makoto Sakamoto, Tetsuji Uno, Sadao Nakajima,Tomohiro Hosoya, Yuhei Kuwamoto, Atsushi Kambe, MasamichiKurosaki

Division of Neurosurgery, Department of Brain and Neurosciences, Faculty ofMedicine, Tottori University

Purpose: Aneurysms that are difficult to cure with flowdiverters include partially thrombosed giant aneurysms and aneurysms withbranching vessels arising from the aneurysmal sac. We evaluated the safetyand outcomes of these lesions treated with coiling and flow-diverter overlapand short-term low-dose anticoagulation to prevent thromboemboliccomplications.

Materials and Methods: Six patients were included in this study,three with basilar trunk and three with IC-PC aneurysms. The mean age was68.2 years, two males and four females. The pipeline was used in two cases,and FRED was used in four cases. The mean maximum diameter of aneurysms was21 mm. Four patients had neurological symptoms owing to the mass effect ofthe aneurysms. Dual antiplatelet therapy (DAPT) with clopidogrel orprasugrel and aspirin was started 1–3 weeks before the procedure. Coilingwas performed either before two flow diverters were implanted or from ajailed microcatheter after a single flow diverter was implanted. EdoxabanTosylate Hydrate 30mg was orally administered for 1–2 months after theprocedures to prevent branch and perforator occlusion. DAPT was continuedfor six months, and then a single antiplatelet was administered for morethan six months.

Results: Two transient ischemic complications were observed fromthe perioperative period to 6 months postoperatively. A patient with a largepartially thrombosed basilar trunk aneurysm had intraoperative thrombusformation with FRED implantation at the stenotic part of the basilar artery.However, no new ischemic lesions were observed after argatroban infusion andin-stent angioplasty at the stenosis. In one case of IC-PC aneurysm,transient hemiparesis occurred one week after DAPT was reduced to SAPT, butno new ischemic symptoms were observed after changing to DAPT usingcilostazol. In other patients, no new symptoms of neurological deficits wereobserved postoperatively. All patients who were symptomatic preoperativelyhad improvement in symptoms. Short-term follow-up imaging showed no evidenceof blood flow signal in the aneurysm, but shrinkage of the thrombus was notobserved.

Conclusion: The combination of coiling, flow-diverter overlap,and short-term low-dose anticoagulation for aneurysms that are difficult totreat with FD alone was performed without permanent neurologicaldeterioration. Since long-term imaging follow-up was not obtained, we mustverify the safety and efficacy of the combination therapy by accumulatingcases and conducting imaging follow-ups in the future.

O4-16-3

Anatomical flow diversion for intractable large cerebralaneurysms

Wataro Tsuruta, Tomokazu Sekine, Arisa Tomioka,Yuki Kamiya, Yuji Matsumaru

Department of Endovascular Neurosurgery, Toranomon hospital

Background: Flow diverter has significantly improved treatmentoutcome of large and giant aneurysms. This device provides curativeendovascular treatment for wide-necked side-wall aneurysms. While efficacyof flow diverter for bifurcation or branching side-wall aneurysms is likelyto be limited. We take the strategy of anatomical flow diversion (AFD) forintractable large cerebral aneurysms. We report our experiences of treatmentcases with AFD.

Patients & Methods: The concept of AFD is transformationfrom bifurcation or branching side-wall type into non-branching side walltype. Linearization of the parent artery by stenting and intentional branchocclusion as well as aneurysmal coil embolization is performed. Bypasssurgery is also used in combination for intolerance case to branchocclusion. We retrospectively evaluated clinical outcome of intractableaneurysms treated with AFD concept in our institute.

Results: AFD was performed in 7 unruptured large aneurysms.Aneurysmal location is BA top in 2, BA-SCA in one, IC-PC in 3, and ICterminal in one. AFD was adapted for initial treatment in 5 and retreatmentin 2. Mean dome diameter is 17 ± 4.6 mm. Bypass surgery was used in 6(STA-SCA 3, STA-PCA 3). Occluded branches were PCA + SCA in 3, Pcom.A in 3,and ACA A1 in one. Flow diverter was used in 3, Enterprise in 3, andEnterprise + LVIS blue in one. Intra-procedural complication didn't occur inany cases. Post-procedural ischemic complication due to the anteriorchoroidal artery occlusion associated with rapid aneurysmal thrombosis afterflow diverter embolization was occurred in one on 7POD. Six (86%)demonstrated mRS 0 on 3 months follow-up and one with ischemic complicationwas mRS 5. Complete occlusion of all the aneurysms has been maintained onmedian follow-up 60 months.

Conclusion: AFD would be useful for intractable large cerebralaneurysms with high curability, while safety verification is needed.

O4-16-4

Long-term durability and recurrence patterns after endovasculartreatment for basilar tip aneurysms

Tatsuya Shimizu¹, Isao Naito², Naoko Miyamoto², Masanori Aihara¹, Ken Asakura³, Yuhei Yoshimoto¹

¹Department of Neurosurgery, Gunma University

²Department of Neurosurgery, Geriatrics Research Institute andHospital

³Department of Neurosurgery, Japanese Red Cross MaebashiHospital

OBJECTIVE: Treating recurrence after coil embolization ofbasilar tip aneurysm remains challenging even with the development ofendovascular procedures. The present study evaluated long-term durabilityand recurrence patterns after endovascular treatment of basilar tipaneurysms.

METHODS: Data of 116 consecutive patients treated withendovascular therapy at three regional hospitals from 2002 to 2019 wereretrospectively analyzed. Aneurysms were ruptured in 51 cases and unrupturedin 65 cases, with a mean maximal diameter of 7.8 mm (>15 mm in 14patients), and a mean follow-up period of 5.8 ± 4.3 years.

RESULTS: Recurrence was observed in 24 of the 116 patients(21%), and 14 patients were retreated. The 5-year recurrence-free survivalrate was 75.3%. Cox proportional hazards analysis found that recurrencecorrelated significantly with maximal aneurysm diameter ³10 mm(p = 0.001; hazard ratio[HR] 3.95, 95% confidence interval[CI] 1.76–8.90)and incomplete occlusion (p = 0.003; HR 4.43, 95%CI 1.63–12.00). Recurrencepattern was classified into three types: neck type (9 patients), regrowthtype (10 patients) and regrowth type of initially thrombosed aneurysm (3patients). Re-rupture occurred in neck type with de-novo aneurysm formationadjacent to the neck (n = 3) and regrowth type with dome filling(n = 4).

CONCLUSIONS: Recurrence after coil embolization for basilar tipaneurysms is associated with large aneurysm and incomplete occlusion atinitial embolization. Understanding the patterns of recurrence is useful forpredicting recurrence and selecting treatment strategies.

O4-16-5

Evaluation of post embolization recurrence in unruptured basilarartery bifurcation aneurysm

Koji Shimonaga¹, Tetsu Satow^1,2, Eika Hamano¹, Taichi Ikedo¹, Yuji Kushi¹, Hirotoshi Imamura¹, Koji Iihara¹, Hiroharu Kataoka¹

¹Department of Neurosurgery, National Cerebral and CardiovascularCenter

²Department of Neurosurgery, Kindai University Faculty ofMedicine

Background: Endovascular treatment for basilar arterybifurcation aneurysm (BA bif. AN) is associated with a high recurrence rate.Although volume embolization rate (VER) and diameter of the aneurysm havebeen cited as factors for recurrence, there are few studies focused onanatomical factors. In the present study, we retrospectively examinedfactors influencing recurrence of BA bif. AN, focusing on the anatomy of theaneurysm and surrounding vessels.

Material and Methods: A total of fifty consecutive cases withunruptured BA bif. AN coiled at our institution between 2005 and 2019 wereincluded. Recurrence was defined as an exacerbation of at least 1 point onthe Consensus grading scale (Meyers et al. JNIS 2010) during an observationperiod of at least 1 year. The evaluation parameter included maximumdiameter, aspect ratio, VER, outflow angle from basilar artery to bilateralposterior cerebral arteries (outflow angle 1 to P1 with larger diameter,outflow angle 2 to P1 with smaller diameter, and the sum of the two: globaloutflow angle), the presence or absence of posterior communicating arteries,and the presence or absence of adequate packing into the inflow zone.

Results: The mean age was 63.3 (42–81) years, 34 were female.The mean maximum diameter of the aneurysm was 7.2 mm (3.5–13.2 mm), and themean VER was 26.9% (15.8–41.6%). Stent-assisted coil embolization wereconcomitantly in 4 patients (8%). The mean observation period was 94.7months (19∼180 months). Ten of 50 patients (20%) had recurrence, of which 2patients (4%) were retreated. In univariate analysis, outflow angle 1 (84.3°vs. 105.6°; p = 0.01) and global outflow angle (164.4° vs. 192.3°; p = 0.04)were significantly associated with recurrence. No significant differenceswere found for other factors.

Conclusion: The present study showed that recurrence was morelikely to occur in BA bif. ANs with steeper outflow angle to largerbranch.

P1-1

Intracranial Aneurysm Coiling with the i-ED COIL: Initial Experiencein the United States

Maximilian Jeremy Bazil, Johanna T Fifi,Tomoyoshi Shigematsu

Neurosurgery, Icahn School of Medicine at Mount Sinai

Purpose: Endovascular aneurysmal coiling is a preventativealternative to clippingto avoid aneurysmal rupture. We describe ourexperiences with the i-EDcoil (Kaneka; Osaka, Japan), offering a monopolarelectrode detachmentsystem, soft, flexible coils that minimally perturb thedeployingmicrocatheter (SilkySoft Technology), and longer coils withgeneral, lowmemory structures (Infini and Complex Infini Shaping).

Materials and Methods: We retrospectively reviewed a consecutivecase series of seven (7)intracranial aneurysm patients who received Kanekai-ED Coils sincetheir initial use in our practice (December 2020) andDecember 2021.