Distal M1 Research Articles

Combining the deployment of only the distal basket segment of the EMBOTRAP III and an aspiration catheter for M2 occlusions: the ONE-SEG technique.

Endovascular therapy (EVT) for distal medium vessel occlusions requires prioritizing effectiveness and safety. We developed a technique combining the deployment of only the distal basket segment of the EMBOTRAP III and an aspiration catheter (AC) for M2 occlusions, called the "ONE-SEG technique," and evaluated its clinical and technical impacts. This was a retrospective review of 30 consecutive patients with M2 segment middle cerebral artery occlusion treated using the ONE-SEG technique. This method involves deploying the EMBOTRAP III through a microcatheter in only one segment and guiding the AC to the M2 origin or distal M1. The rates of final-pass expanded thrombolysis in cerebral infarction (eTICI) scores of 2c/3 or 2b/2c/3, safety (symptomatic intracranial hemorrhage [sICH]), and clinical outcomes (modified Rankin Scale [mRS] score 0-2, 0-3 at 90 days, and mortality at 90 days) were evaluated. Of the 30 cases, 36.7% were female, and the mean age was 75.6 ± 11.0 years. The ONE-SEG technique was used for 17 cases (56.7%, median NIHSS 10 [5-15.5]) with primary M2 occlusion and 13 cases (43.3%, median NIHSS 20 [14-22.5]) with secondary M2 occlusion after proximal thrombus removal. The successful final reperfusion rate (eTICI 2b/2c/3) was 90% overall (27/30 cases). One case (3.3%) developed sICH with secondary M2 occlusion. At 3 months, mRS scores 0-2 were seen in 64.7% of patients with primary M2 occlusion (11/17 cases) and in 23.1% (3/13 cases) with secondary M2 occlusion. EVT using the ONE-SEG technique appears to be safe and effective for M2 occlusion.

Spontaneous Reduction in the Intermetatarsal Angle in Distal First Metatarsal Osteotomies with No Lateral Head Displacement in Hallux Valgus.

The outcomes of first metatarsal (M1) distal osteotomies in hallux valgus (HV) can be improved, especially for intermetatarsal angle (IMA) correction, which is mainly based on lateral displacement of the M1 head (i.e., translation) through the osteotomy. Conversely, there is a spontaneous reduction in the IMA in first metatarsophalangeal joint (MTP1) arthrodesis. But we do not know whether this can be applied to distal osteotomies. We propose a distal osteotomy, called 3D chevron, which combines supination and varization of the M1 head. This might realign soft tissues around the MTP1, potentially leading to a spontaneous reduction in the IMA by an analogous mechanism to MTP1 fusion. Therefore, our study aimed to assess whether spontaneous reductions in IMAs exist in distal M1 osteotomies in the absence of lateral translations of M1 heads. A prospective continuous series of 25 3D chevrons was performed. Two groups were formed during surgery. Patients requiring no M1 head lateral displacement were included in the "successful correction without translation" group, and patients requiring M1 head lateral displacement were included in the "failed correction without translation" group. Radiographic analysis was performed preoperatively and at 1 year postoperatively. Twenty-two women and three men, with a mean age of 44.8 ± 14.2 years and a mean body mass index of 22.6 ± 4.1 kg/m2, underwent follow-up at one year after surgery. The "successful correction without translation" group was composed of HV with milder deformities (13/25 HVs, median preoperative IMA = 13 (IQR 2)) compared to the "failed correction without translation" group (median IMA = 16 (IQR 2.25) p < 0.001). Spontaneous reductions in IMAs were observed in the "successful correction without translation" group, with a median decrease in the IMA of 6 degrees (CI95%[5.5; 8.0]; p < 0.001) between preoperative and 1-year radiographs. Distal osteotomies allow for spontaneous reduction in the IMA in HV. First metatarsal head translation through an osteotomy should not be considered as the only procedure to correct IMAs in distal osteotomies.

Tenecteplase Versus Alteplase in Medium Vessel Occlusion Ischemic Stroke: A Secondary Analysis of the Alteplase Compared to Tenecteplase Randomized Trial.

The safety and efficacy of tenecteplase in patients with ischemic stroke due to medium vessel occlusion (MeVO) are not well studied. We aimed to compare tenecteplase with alteplase in stroke due to MeVO. Patients with baseline M2-middle cerebral artery (MCA), M3/M4-MCA, P2/P3/P4-posterior cerebral artery (PCA), A2/A3/A4-anterior cerebral artery (ACA) occlusions from the Alteplase Compared to Tenecteplase (AcT) trial were included. Primary outcome was the proportion of 90-day modified Rankin Scale (mRS) 0-1. Secondary outcomes were 90-day mRS 0-2, ordinal mRS, mortality, quality of life measures (EuroQol 5-Dimension 5-Level, EuroQol visual analog scale), and symptomatic intracerebral hemorrhage (sICH). Initial and final successful reperfusion were reported in patients undergoing endovascular thrombectomy (EVT). Among 1,558 patients with available baseline computed tomography angiography; 455 (29.2%) had MeVO of which 27.5% (125/455) were proximal M2; 16.3% (74/455) were distal M2; 35.2% (160/455) were M3/M4; 7.5% (34/455) were A2/A3/A4; and 13.6% (62/455) were P2/P3/P4 occlusions. EVT was performed in 87/455 (19.1%) patients. mRS 0-1 at 90 days was achieved in 37.9% in the tenecteplase versus 34.7% in the alteplase group (adjusted risk ratio [aRR] 1.07; 95% confidence interval [CI] 0.91-1.25). Rates of 90-day mRS 0-2, sICH, and mortality were similar in both groups. No statistical difference was noted in initial successful reperfusion rates (13.0% vs. 7.5%) among the 87 patients who underwent endovascular thrombectomy. However, final successful reperfusion was higher in the tenecteplase group (71.7% vs. 60.0%, aRR 1.29, 95% CI 1.04-1.61). Intravenous tenecteplase had comparable safety, functional outcomes and quality of life compared to intravenous alteplase among patients with MeVO. Among those treated with EVT, tenecteplase was associated with higher successful reperfusion rates than alteplase.

Vascular syndrome predicts the development and course of epilepsy after perinatal stroke.

Epilepsy develops in one third of the patients after perinatal stroke. It is still unclear which vascular syndrome of ischemic stroke carries higher risk of epilepsy. The aim of the current study was to evaluate the risk of epilepsy according to the vascular syndrome of perinatal stroke. The study included 39 children with perinatal arterial ischemic stroke (13 with anterior or posterior trunk of the distal middle cerebral artery occlusion, 23 with proximal or distal M1 middle cerebral artery occlusion and three with lenticulostriate arteria infarction), and 44 children with presumed perinatal venous infarction. Magnetic resonance imaging obtained at the chronic stage was used to evaluate the vascular syndrome of stroke. The median follow-up time was 15.1 years (95% CI: 12.4-16.5 years), epilepsy developed in 19/83 (22.9%) patients. The cumulative probability to be without epilepsy at 15 years was 75.4% (95% CI: 65.8-86.4). The probability of having epilepsy was higher in the group of proximal or distal M1 artery occlusion compared to patients with periventricular venous infarction (HR 7.2, 95% CI: 2.5-26, p = .0007). Patients with periventricular venous infarction had significantly more often status epilepticus or spike-wave activation in sleep ≥85% of it compared to patients with anterior or posterior trunk of the distal middle cerebral artery occlusion (OR = 81; 95% CI: 1.3-5046, p = .029). The emphasis of this study is placed on classifying the vascular syndrome of perinatal stroke and on the targeted follow-up of patients for epilepsy until young adulthood. The risk for having epilepsy after perinatal stroke is the highest in children with proximal or distal M1 middle cerebral artery occlusion. Patients with periventricular venous infarction have a more severe course of epilepsy.

Arterial Tortuosity Is a Potent Determinant of Safety in Endovascular Therapy for Acute Ischemic Stroke

Background Subarachnoid hemorrhage (SAH) associated with vessel injury during endovascular therapy for acute ischemic stroke is a known complication. Arterial anatomy may predispose to increased risk of SAH and technical safety, yet factors such as clot location, arterial size, and tortuosity have not been explored. We examined these anatomic factors with respect to SAH during thrombectomy. Methods Arterial anatomy at the site of occlusion and mechanical thrombectomy during device deployment was detailed by the STRATIS (Systematic Evaluation of Patients Treated With Neurothrombectomy Devices for Acute Ischemic Stroke) core laboratory. Luminal diameters, arterial branching, and segmental tortuosity were measured. Arterial tortuosity was quantified using the distance factor metric. Statistical analyses included descriptive variables of arterial anatomy, with univariable and multivariable modeling to predict SAH. Results Arterial tortuosity in each segment from the proximal cerebral arteries to the site of occlusion was quantified in 790 subjects treated with mechanical thrombectomy in STRATIS. Cumulative arterial tortuosity to the site of vessel occlusion was greater in distal lesions. SAH was clearly linked with more distal thrombectomy ( P = 0.02), occurring in 19.0% of distal M2, 16.7% of M3, 7.3% of distal M1, 5.8% of proximal M2, 2.4% of distal internal carotid artery, and 2.1% of proximal M1. In multivariable analysis after adjusting for arterial diameter at the site of occlusion, arterial tortuosity was a significant predictor of SAH (upper tertile versus 1: odds ratio, 3.08 [95% CI, 1.04–9.09]; P = 0.04), while arterial diameter was unrelated to SAH ( P = 0.30) when accounting for tortuosity. Conclusion This novel analysis of arterial tortuosity and angiographic anatomy during mechanical thrombectomy establishes tortuosity as a determinant of SAH, providing insight for future techniques and innovative device designs.

Association between occlusion location, net water uptake and ischemic lesion growth in large vessel anterior circulation strokes

Ischemic lesion net water uptake (NWU) represents a quantitative imaging biomarker for cerebral edema in acute ischemic stroke. Data on NWU for distinct occlusion locations remain scarce, but might help to improve the prognostic value of NWU. In this retrospective multicenter cohort study, we compared NWU between patients with proximal large vessel occlusion (pLVO; ICA or proximal M1) and distal large vessel occlusion (dLVO; distal M1 or M2). NWU was quantified by densitometric measurements of the early ischemic region. Arterial collateral status was assessed using the Maas scale. Regression analysis was used to investigate the relationship between occlusion location, NWU and ischemic lesion growth. A total of 685 patients met inclusion criteria. Early ischemic lesion NWU was higher in patients with pLVO compared with dLVO (7.7% vs 3.9%, P < .001). The relationship between occlusion location and NWU was partially mediated by arterial collateral status. NWU was associated with absolute ischemic lesion growth between admission and follow-up imaging (β estimate, 5.50, 95% CI, 3.81–7.19, P < .001). This study establishes a framework for the relationship between occlusion location, arterial collateral status, early ischemic lesion NWU and ischemic lesion growth. Future prognostic thresholds for NWU might be optimized by adjusting for the occlusion location.

Variation in Vessel Size and Angiographic Outcomes Following Stent‐Retriever Thrombectomy in Acute Ischemic Stroke: STRATIS Registry

Background Mechanical thrombectomy is established for large‐vessel occlusions in acute ischemic stroke, but the potential role in distal vessel occlusions of medium arteries is less well established. Such medium or distal arterial segments have not been assessed with respect to thrombectomy devices used during endovascular therapy. We conducted an analysis of arterial size, segmental anatomy, and stent‐retriever device performance with respect to vessel size during thrombectomy. Methods The STRATIS registry angiography core laboratory adjudicated the exact location of the occlusion, proximal, and distal device deployment, relationship to arterial bifurcations, and anatomic nomenclature. Arterial diameters were measured at all these sites. Statistical analyses examined the relationship between vessel and stent size, and arterial recanalization using expanded Thrombolysis in Cerebral Infarction reperfusion score. Results Overall, 665 patients with stroke were included following thrombectomy using various Solitaire device sizes, including Solitaire 4×40, Solitaire 6×30, Solitaire 4×20, Solitaire 6×20, and Solitaire 4×15. Arterial diameter at the occlusion site was a median of 2.17 mm (interquartile range [IQR], 1.88–2.60 mm) in the distal M1, 1.67 mm (IQR, 1.47–2.06 mm) in the proximal M2 middle cerebral artery, 1.50 mm (IQR, 1.15–1.61 mm) in the distal M2 middle cerebral artery, 1.24 mm (IQR, 1.11–1.24 mm) in the M3 middle cerebral artery, and 1.88 mm (IQR, 1.49–1.94 mm) in the P1 posterior cerebral artery. Expanded Thrombolysis in Cerebral Infarction 2b to 3 reperfusion was achieved in all M3 or P1 segment occlusions. The rate of first‐pass recanalization was significantly higher in patients with medium (0.75–2 mm) versus large (&gt;2 mm) vessel occlusion (69.5% versus 57.1%; P = 0.003). Conclusion Considerable overlap was noted between arterial sizes at occlusion sites carrying different segmental arterial nomenclature or vessel names. Substantial reperfusion may be achieved with currently available mechanical thrombectomy devices in medium arteries.

Abstract TP201: Impact of Microguide Wire Stiffness on Microcatheter and Aspiration Catheter Navigation in Tortuous Vessels

Background and Purpose: Endovascular therapies require devices to access treatment sites safely and efficiently. Vessel tortuosity often complicates this navigation, increasing the risk of microguide wire (MGW) or microcatheter (MC) kickback, which may result in unstable device movements or sudden drop of devices. This study aims to elucidate the effect of MGW stiffness variability on the trackability of MC and aspiration catheters (AC). Methods: Using two silicone vascular models, we replicated the M2 segment of the middle cerebral artery (MCA) at an 80-degree branch (MCA model, Fig. A) and a severely tortuous internal carotid artery (ICA model, Fig. B). Experiments were conducted under conditions of 37°C, 60 BPM, and an ICA flow rate of 240 mL/min. In the MCA model, the MC (TrevoTrak21) was advanced from the M1 segment to distal M2 while three MGWs (Synchro SELECT Soft, Standard, Support) were placed at distal M2. In the ICA model, the AC (Zoom 71) was advanced from ICA to M1 with MC and MGW at distal M2. Maximum push force and kickback length were measured while TrevoTrack21 or Zoom71 were advanced at 4 mm/sec for 7 runs per device. One-way ANOVA assessed group differences. Results: In the MCA model, when using the Soft MGW, the MC recorded the highest pushing force at 59.3mN and kickback of 29.87mm. Conversely, the Support MGW demonstrated the least pushing force at 38.2mN (P&lt;0.001) and the shortest kickback length at 17.83mm (P&lt;0.001). For the ICA model, differences in forces across the MGW types were less distinct. However, the kickback length with the Soft MGW at 13.78mm was significantly greater than that with the Standard MGW at 6.26mm and the Support MGW at 6.76mm (P=0.026). Conclusion: Our findings suggest that MGWs with higher stiffness offer more stable guidance, requiring less force in both MC and AC navigation. Moreover, increased MGW stiffness consistently leads to shorter kickback lengths, emphasizing its importance in stable device navigation.

Abstract TP133: Clot Burden Score Correlates Best With Hypoperfusion Volume and Predicts Final Infarct ASPECTS&lt;=3 in Anterior Circulation Ischemic Strokes

Purpose: Clot Burden Score (CBS) is a semiquantitative measure of thrombus extent on CTA for proximal anterior circulation strokes whose relationship with perfusion metrics has not been fully explored. CBS has potential added value during stroke triage if perfusion imaging is not available or suboptimal. We aimed to investigate if CBS is (1) correlated to perfusion estimates of infarct core volume, hypoperfusion volume, or collateral status, and (2) a predictor of final infarct extent without reperfusion therapy. Methods: Retrospective analysis included consecutive patients (1) arriving &lt;24 hours from onset, (2) with occlusion in the intracranial ICA, M1, M2, or A1 or combination, (3) with concurrent CTP, and (4) had followup CT or DWI during hospitalization. CBS is a 10-point negative ordinal scale: 2-points subtracted for occlusion of supraclinoid ICA, proximal M1, or distal M1, and 1-point subtracted for occlusion of infraclinoid ICA, A1, or M2. Correlation of CBS with perfusion metrics was evaluated using Spearman's rank test. Final infarct ASPECTS were scored for those without thrombolysis or thrombectomy. Multivariate logistic regression was used to identify predictors of final ASPECTS&lt;=3 (approximating &gt;=100mL). ROC analysis was evaluated to assess performance and optimal thresholds. Results: 222 patients included with median (IQR) age of 75 (65-84) and NIHSS of 18 (11-24). Median CBS was 7 (6-9) and best correlated to Tmax&gt;6s r=-0.579 (hypoperfusion volume), followed by HIR r=-0.401 (collateral status) and rCBF&lt;30% r=-0.306 (core volume), all p&lt;0.001. 71 (32.0%) untreated patients also had median CBS of 7 (6-9). CBS and Tmax&gt;6s had the strongest correlation to final ASPECTS in this subgroup, r=0.637 and r=-0.686 (both p&lt;0.001). 22 of these (30.1%) had final ASPECTS&lt;=3. Multivariate logistic regression including CBS, Tmax&gt;6s, HIR, baseline ASPECTS, and NIHSS showed only CBS as independent predictor of final ASPECTS&lt;=3 (p&lt;0.001). ROC AUC for CBS was 0.902 [95% CI: 0.819-0.985] with optimal threshold of &lt;=6 for sensitivity 86.4% and specificity 81.6%. Conclusion: CBS as a measure of thrombus extent correlates best with baseline hypoperfusion volume on CTP and independently predicts very large final infarcts (ASPECTS&lt;=3) without treatment.

Abstract TP246: Circadian Variability of the Clot Burden Score in Acute Anterior Circulation Ischemic Stroke

Background/Purpose: Fibrinolytic activity in blood plasma displays a circadian rhythm with a drop in the morning hours that may predispose to acute thrombotic events. The Clot Burden Score (CBS) is a semiquantitative measure on CT angiography (CTA) of thrombus extent in proximal anterior circulation strokes that has been correlated with functional outcome. Higher clot burden has also been shown to have lower recanalization rates with intravenous thrombolytics. We aimed to investigate whether CBS is a parameter that displays circadian variability. Methods: We performed a retrospective analysis on consecutive stroke patients presenting &lt;24 hours from symptom onset or last known well (LKW) with an occlusion in the anterior circulation confirmed on CTA. CBS was scored on a 10-point negative ordinal scale with 2-points subtracted for occlusion of the supraclinoid ICA, proximal M1, or distal M1, and 1-point subtracted for occlusion of the infraclinoid ICA, A1, or either M2 branches. No points were subtracted for occlusion distal to A1 or M2. Subjects were grouped into four 6-hour intervals, MORNING: 6:00-11:59, DAY: 12:00-17:59, EVENING: 18:00-23:59, and NIGHT: 0:00-5:59, based on the time of onset/LKW. CBS values were compared between groups using the Kruskal-Wallis test with pairwise comparisons. Results: 240 subjects were included with median age of 75 (IQR 65-84), NIHSS score of 17 (IQR 10-24), and time from onset/LKW to CTA of 5 hours (IQR 2-11). 73 subjects had onset during the MORNING, 56 during the DAY, 86 during the EVENING, and 25 during the NIGHT. The median CBS from MORNING time onset was 6 (IQR 5-9), compared to 7 (IQR 6-9) from the DAY, 7.5 (IQR 6-9) from the EVENING, and 7 (IQR 5-8.5) from the NIGHT. CBS was significantly lower in the MORNING compared to the EVENING, p=0.037. CBS was not significantly different between all other pairwise comparisons, p&gt;0.107. Conclusion: CBS as a measure of thrombus extent in proximal anterior circulation strokes on CTA appears to show circadian variability, with lower scores (higher clot burden) during MORNING onset (6:00-11:59) than the EVENING (18:00-23:59). This may have implications for future studies of chronotherapeutic protocols.

Effect of Intravenous Thrombolysis Prior to Mechanical Thrombectomy According to the Location of M1 Occlusion.

The additive effects of intravenous thrombolysis (IVT) before mechanical thrombectomy (MT) remain unclear. We aimed to investigate the efficacy and safety of IVT prior to MT depending on the location of M1 occlusion. We reviewed the cases of patients who underwent MT for emergent large-vessel occlusion of the M1 segment. Baseline characteristics as well as clinical and periprocedural variables were compared according to the location of M1 occlusion (i.e., proximal and distal M1 occlusion). The main outcome was the achievement of functional independence (modified Rankin Scale score, 0-2) at 3 months after stroke. The main outcomes were compared between the proximal and distal groups based on the use of IVT before MT. Among 271 patients (proximal occlusion, 44.6%; distal occlusion, 55.4%), 33.9% (41/121) with proximal occlusion and 24.7% (37/150) with distal occlusion underwent IVT prior to MT. Largeartery atherosclerosis was more common in patients with proximal M1 occlusion; cardioembolism was more common in those with distal M1 occlusion. In patients with proximal M1 occlusion, there was no association between IVT before MT and functional independence. In contrast, there was a significant association between the use of IVT prior to MT (odds ratio=5.30, 95% confidence interval=1.56-18.05, P=0.007) and functional independence in patients with distal M1 occlusion. IVT before MT was associated with improved functional outcomes in patients with M1 occlusion, especially in those with distal M1 occlusion but not in those with proximal M1 occlusion.

Evaluation of CINA® LVO artificial intelligence software for detection of large vessel occlusion in brain CT angiography

ObjectiveTo systematically evaluate the ability of the CINA® LVO software to detect large vessel occlusions eligible for mechanical thrombectomy on CTA using conventional neuroradiological assessment as gold standard. MethodsRetrospectively, two hundred consecutive patients referred for a brain CTA and two hundred patients that had been subject for endovascular thrombectomy, with an accessible preceding CTA, were assessed for large vessel occlusions (LVO) using the CINA® LVO software. The patients were sub-grouped by occlusion site. The original radiology report was used as ground truth and cases with disagreement were reassessed. Two-by-two tables were created and measures for LVO detection were calculated. ResultsA total of four-hundred patients were included; 221 LVOs were present in 215 patients (54 %). The overall specificity was high for LVOs in the anterior circulation (93 %). The overall sensitivity for LVOs in the anterior circulation was 54 % with the highest sensitivity for the M1 segment of the middle cerebral artery (87 %) and T-type internal carotid occlusions (84 %). The sensitivity was low for occlusions in the M2 segment of the middle cerebral artery (13 % and 0 % for proximal and distal M2 occlusions respectively) and in posterior circulation occlusions (0 %, not included in the intended use of the software). ConclusionsLVO detection sensitivity for the CINA® LVO software differs largely depending on the location of the occlusion, with low sensitivity for detection of some LVOs potentially eligible for mechanical thrombectomy. Further development of the software to increase sensitivity to all LVO locations would increase the clinical usefulness.

Abstract 111: Woven Endo Bridge‐Coil Embolization of a Middle Cerebral Artery Bifurcation Aneurysm with Secondary Lobule

Introduction 18‐36% of all intracranial aneurysms are middle cerebral artery(MCA) bifurcation aneurysms. While some are much higher risk than others, they have an overall low estimated annual rupture rate of 0.36%.(1) MCA bifurcation aneurysms have been historically challenging to treat endovascularly given they often have complex morphology and wide necks. The Woven EndoBridge (WEB) is an ellipsoid embolization device designed to provide intrasaccular flow disruption along the aneurysm neck, which has been proven to be an effective method in treating a wide spectrum of wide‐necked bifurcation aneurysms. Thromboembolism and recanalization are the main concerns in treatment with the WEB device, like any aneurysm treatment approach .(2),(3) Occasionally, irregularities and secondary lobules at the base of the primary aneurysm can have persistent filling despite treatment. Methods We present a case of a right MCA bifurcation aneurysm treated by a WEB device and coil embolization. Results 48‐year‐old female with a medical history significant only for active smoking who presented with sudden onset of the worst headache of her life followed by brief loss of consciousness. No neurological evaluation was sought initially, until 2 weeks later as she continued to experience a moderate‐intensity headache associated with nausea and vomiting with frequent falls. On exam, she was alert and oriented, moving all extremities with full strength. CT head revealed an evolving acute to subacute right MCA infarction with adjacent small volume subarachnoid hemorrhage. CTA head revealed a right MCA bifurcation aneurysm measuring 6 x 6 x 7 mm with irregularity of the wall. Multifocal severe stenosis was noted in the right distal right M1 and right M2 divisions. She underwent a diagnostic subtraction angiography which confirmed an irregular right MCA bifurcation aneurysm measuring 4.3 x 4.5 x 5.7 mm (Figure 1 ‐A,B). While it was believed that the subarachnoid hemorrhage was more likely related to the recent infarct, a decision was made to treat the aneurysm given its relatively large size and irregular shape. Embolization was performed with a WEB SL 6 x 4 mm device (Figure 1: C,D ‐blue arrow). Post‐deployment angiograph showed occlusion of the aneurysm dome but persistent filling of the secondary lobule near the base of the aneurysm. Given this residual lobule filling, a decision was made to continue additional embolization with a hyper soft 3D 2 mm X 2 cm coil(Figure 1: C,D ‐ yellow arrow). Final angiography revealed complete occlusion of the aneurysm. Vasospasm of the distal M2 divisions and multiple M3 branches in the right MCA vascular territory was also noted. Therefore, she was treated with 20 mg of intra‐arterial Verapamil with improvement. She was started on Aspirin 325 mg daily. Daily transcranial dopplers were negative for vasospasm. She remained neurologically stable and was discharged home 5 days after admission ambulating independently. Conclusion With modern advances in endovascular devices, many MCA bifurcation aneurysms can be treated minimally invasively. However, there are some limitations to the WEB since every aneurysm is different and there are a finite number of sizes and shapes available for WEB. This case illustrates that adjunctive coil embolization can successfully occlude a residual secondary base lobule after WEB embolization.

Abstract 205: Efficacy and Safety of Mechanical Thrombectomy for Primary MeVO with Disabling Deficit

Introduction We aimed to evaluate the efficacy and safety of mechanical thrombectomy (MT) for medium vessel occlusion (MeVO) with the disabling deficit. Methods The study period was from January 2011 to December 2022. Inclusion criteria were 1) within 24 hours of stroke onset, 2) prestroke mRS score ≤1, 3) NIHSS score ≥4 or disabling deficit (complete hemianopia (≥2 on NIHSS), severe aphasia (≥2 on NIHSS), visual sensory extinction (≥1 on NIHSS), significant weakness with NIHSS subscore of paralysis ≥2), 4) MeVO (MCA distal M2, M3, ACA A1, A2, A3, PCA P1, P2, and P3). Outcomes were compared between the MT and standard medical treatment (SMT) groups. Outcome was defined as the favorable outcome (mRS score 0‐2 at 90 days), death within 90 days, and symptomatic intracranial hemorrhage (SICH). Results Of all, 192 patients (72 women, median age 78 years, median NIHSS score 11 points) were enrolled, and 76.6% (n=147) had distal M2 occlusion. Compared to the SMT group (n=153), the MT group (n=39) had a significantly larger median Tmax&gt;10 sec volume (median 25 mL vs. 5 mL, P&lt;0.01) and Tmax&gt; 6‐sec volume (61 mL vs. 44 mL, P&lt;0.01), while median NIHSS score (13 vs. 11, P=0.69) and intravenous thrombus (51.6％ vs. 55.3%, P=0.72) were significantly lower in the MT group. There were significantly more patients in the MT group with a favorable outcome (73.7% vs. 54.1%, adjusted odds ratio 2.59 95% confidence interval 1.07‐6.24), death within 90 days (7.9% vs. 3.1%), SICH (5.3% vs. 4.4%) were not significantly different. In subgroup analysis, MT was independently associated with age (&lt;80 years; 1.33, 1.21‐15.57, P=0.222) and neurological severity (NIHSS ≥10 points; 2.79, 1.07‐7.24, P=0.870) for a favorable outcome. Conclusion In MeVO with disabling deficits, MT was independently associated with more favorable outcomes than the SMT group.

Abstract 002: Examining Pulling Force Using Combined Stentreiver and Aspiration Technique in a Medium Vessel Thrombectomy Model

Introduction With the advent of smaller stent retrievers (SR) and aspiration catheters (AC) capable of accessing more distal locations, distal and medium vessel occlusions (DMVO) are emerging as promising targets for endovascular thrombectomy (EVT). However, considering the vulnerability of distal vessels to injury, it is imperative to understand the safety of various frontline techniques in these challenging scenarios. Using a vascular flow model, we sought to investigate the optimal size, strategy, and positioning of a stent retriever and aspiration catheter to minimize the pulling force exerted on the M2 vasculature. Methods We used a silicone vascular flow model with moderate tortuosity that replicated the left‐sided anterior circulation, including middle cerebral artery (MCA) branches in the M2 territory. An 8 French Cook Shuttle guide sheath was inserted coaxially with a Catalyst 7‐132 cm aspiration catheter and TrevoTrak 21 microcatheter. To measure pulling force, an Imada force gauge DST‐1A was placed at the M2 and a DST‐11A at the proximal end of the microcatheter. The Solitaire 4x20 mm Solitaire stent‐retriever was pulled at 4 mm/sec with the AC in the proximal cavernous carotid segment (NoAsp), proximal M1 (M1P), and distal M1 (M1D), a total of 8 times per AC position, using the ingestion technique. The pinching technique was also examined using the 4x20mm stent. Results The average pulling force measured on M2 using the 4x20mm stent was 169.1mN with the AC docked in the proximal NoAsp position, 26.5mN with the AC at M1P, and 23.0mN at M1D (p&lt;0.0001). The difference in pulling force between M1P and M1D was not significant (p=0.472). The average pulling force exerted on M2 from pinching the 4x20mm stent with the AC at M1D, rather than ingestion of the stent at M1D, was 62.9mN. Average pulling force was noted to decrease from the first to the last run in most cases, with an average drop of 26.4% at the fourth run. Conclusion ADAPT and stent‐retrieval have recently been shown to be comparable in DMVO (1), however some studies have suggested a combined approach may reduce bleeding complications compared to stent‐retrieval alone (2). In our in‐vitro model, we demonstrated that positioning the AC in M1 (M1D or M1P) reduced the pulling force exerted by the stent‐retriever on M2 compared with AC placement in the cavernous carotid (NoAsp). The pulling force exerted from pinching the 4x20mm stent with the AC at M1D was higher than with the ingestion technique, for which the explanation is uncertain, but may be due to the additional friction in the M1 segment. Taken together, these findings suggest a combined approach decreases frictional pulling force during stent‐retrieval and is safer than SR alone. We also note that the pulling force of each stent decreased after its third usage, in line with the manufacturer’s instructions for use, which suggest no more than 3 retrievals per stent (3). Future experiments will compare a wider range of techniques using stents of varying sizes to better clarify factors associated with decreased pulling force in EVT.

Abstract 064: The Pushability of Commonly Used Microwires in Neuroendovascular Procedures

Introduction In distal and medium‐vessel occlusions (DMVOs), there are increasing opportunities to deliver devices through tortuous and medium sized arteries. However, this comes at the risk of microwire perforation during distal microcatheter advancement for navigation in these curved, slender vessels, leading to hemorrhagic complications. Currently, microwires with a range of stiffness levels are available. However, it is unclear how the variations in stiffness and the relative positioning of the microwire and microcatheter may affect the force applied to the vessel wall. Few studies have compared objective metrics across different commonly used devices. We sought to compare the pushability of various Synchro Select and Chikai microwires using both proximal and distal support. Methods In a moderate tortuosity, silicone flow model of the middle cerebral artery (MCA) branches, we tested 0.014” nitinol microwires (Synchro Select Soft, Standard, or Support), or 0.014” stainless steel microwires (Chikai, Black, and Black Soft) in a TrevoTrak 21 microcatheter docked either in the proximal M1 segment or distal M2 segment. Applied force was measured using an Imada force gauge DST‐1A at the M2 ten times for each experiment. The slope, measured in mN per mm, of the applied distal force during the maximal pushing period was calculated. Results The average slope of the pushing force within a distal microcatheter was 10.64 mN/mm with a Synchro Soft, 10.85 mN/mm with a Standard, and 15.28 mN/mm with a Support microwire (p &lt; 0.0001). The average slope of the pushing force in a proximal microcatheter was 1.61 mN/mm with a Synchro Soft, 3.15 mN with a Synchro Standard, and 3.87 mN with a Synchro Support microwire (p &lt;0.001). With the Chikai microwires, the average slope of the pushing force within a distal microcatheter was 12.48 mN/mm with a Chikai Black Soft wire, 12.82 mN/mm with a Chikai Black microwire, and 14.11 mN/mm using a Chikai microwire (p=0.801). Within a proximal microcatheter, the average maximal force was 2.42 mN/mm using a Chikai Black Soft wire, 3.16 mN/mm using Chikai Black, and 3.91 mN/mm using the Chikai wire (p &lt; 0.001). Conclusion This study demonstrated that stiffer microwires push the arterial wall with significantly greater force within a microcatheter close to the wall. Pushability of the microwire significantly dropped across all microwires when the microcatheter was positioned more proximally. This is the first known report of the pushability of commonly used microsystems in neuroendovascular procedures.

Abstract 115: Carotid Intraluminal Thrombus Obscuring Underlying Carotid Web: Case Report

Introduction Carotid webs (CaW) have been increasingly recognized as a unique cause of recurrent ischemic strokes.1 They are defined as thin, intraluminal, shelf‐like lesions along the posterior aspect of the carotid bulb.1,2 Despite more awareness and ongoing studies into their pathogenesis, diagnosis, and management,3 they are still overlooked in clinical practice as a primary carotid ischemic etiology. Our case describes a patient with right extracranial internal carotid artery (ICA) thrombus secondary to later‐diagnosed CaW on close follow‐up imaging. Methods We report a 55‐year‐old African American man with history of hypertension, type 2 diabetes mellitus and hyperlipidemia presented with acute onset slurred speech and left facial droop (FP). His last known well was 24 hours prior to presentation, and NIHSS upon arrival was 3 (FP 2, dysarthria 1). CT angiography (CTA) of the head and neck demonstrated a nearly occlusive thrombus of the distal right M2 segment MCA as well as non‐hemodynamic stenosis of the proximal right ICA with possible underlying sidewall filling defect‐appearing lesion concerning for a posterior wall thrombus without underlying atherosclerosis at the bulb or otherwise. The patient was admitted to the neurovascular intensive care unit and started on aspirin and high‐risk heparin drip. His MRI Brain demonstrated multiple acute/subacute right MCA territory strokes, predominately in the right posterior insula, right frontal lobe, and right posterior corona radiata. His stroke workup was otherwise unrevealing, and he was discharged on apixaban 5mg BID. Results Close surveillance follow‐up imaging with CTA head and neck was planned and obtained one month later, which demonstrated resolution of the filling defect that was obscuring the currently visualized underlying right CaW pocket (Figure‐1). The prevalence of CaWs has been reported to be between 1.2% and 2.5% of patients with acute ischemic stroke. CaWs are most frequently seen in younger, female patients, and patients with these lesions are at increased risk of recurrent stroke.4,5 Determining the optimal management for these lesions remains essential, but the available data thus far have not been conclusive. Most patients are treated with antiplatelet therapy, but some elect to treat with anticoagulation due to the focal hemostasis caused by CaWs.6 However, multiple studies have suggested that medical management alone is likely not sufficient in reducing the recurrent stroke risk caused by CaWs.5,7 Neuro‐interventional procedures including carotid artery stenting have been reported as secondary prevention strategies in patients with recurrent strokes.5,7,8 Although data regarding the rate of recurrence of strokes secondary to these lesions remains unclear, the current data does suggest benefit and safety in pursuing carotid stenting to prevent recurrent strokes.5‐8 Conclusion In young patients with proximal ICA thrombosis without underlying atherosclerosis or other conventional stroke risk factors, CaW should be considered among other differentials including hypercoagulable status. Following acute medical management, short‐term surveillance imaging is essential to confirm or rule out the diagnosis. In our case, the patient’s proximal ICA thrombus resolved after short course of anticoagulation and was determined to be secondary to the obscured underlying CaW.

Abstract 188: Rescue Left Middle Cerebral Artery Stenting With Xience Skypoint Everolimus‐Eluting Stent: Technical Report

Introduction Drug‐eluting stent (DES) use in symptomatic intracranial atherosclerosis disease (ICAD) has been described in the literature using different guiding and distal access catheters. We describe a case of deployment of a Xience Skypoint everolimus‐eluting stent (EES) (Abbott Vascular, Abbott Park, Illinois) into a symptomatic stenosed left M1 segment using Armadillo catheter (Q'Apel, Fremont, CA) with a successful result. Methods Case report and review of literature Results 67‐year‐old woman with type II diabetes mellitus, hypertension, hyperlipidemia, and recent admission for transient ischemic attack (resolving right hemiparesis and mild dysnomia in the setting of severe left M1 segment stenosis with discharge on Aspirin, Clopidogrel and Atorvastatin), presented with recurrence of symptoms, and MRI brain showing left basal ganglia acute infarction. No tPA was given low NIHSS and resolution of symptoms. Patient’s aphasia and hemiparesis worsened with segmental hypoperfusion which resolved by maintaining high blood pressures with norepinephrine drip. Decision was made to deploy a drug eluting stent into the stenosed M1 segment. Through femoral access, a 7F long destination sheath was inserted to the left common carotid origin. A 7F Armadillo catheter was then inserted into the left internal carotid artery (ICA) terminus. ASAHI Prowater coronary guidewire was inserted over which Xience Skypoint EES deployment was attempted but was unsuccessful given difficulty traversing the ICA ophthalmic segment. Ultimately, Armadillo catheter was advanced over a Phenom catheter (Medtronic) with good access into the distal M1 segment. The Phenom intermediate catheter was then removed, and the 2.25 mm x 12 mm stent was introduced through the Prowater guidewire into the segment and inflated to a pressure of 8 atm, with restoration of blood flow. Postoperatively, SBP was lowered to prevent reperfusion injury. Patient’s exam stabilized with mild dysnomia and right hemiparesis without any elevated blood pressure requirements. At 5‐months follow‐up, patient’s exam was non‐focal with NIHSS 0 and repeat DSA showed no evidence of stent occlusion and patent M1 segment. Conclusion Xience Skypoint EES can be successful in treating symptomatic MCA stenosis refractory to maximal medical therapy with good long term results.

Can Distal First Metatarsal Supination Osteotomy, Varization Osteotomy, or a Combination of Both Improve HV Surgical Outcomes? Preliminary Results of a Multicenter Randomized Control Trial

Category: Bunion; Midfoot/Forefoot Introduction/Purpose: The outcomes of Hallux Valgus (HV) surgical treatment are perfectible. First ray dysmorphia in HV appears to incorporate a first metatarsal (M1) hyperpronation and a valgus deviation of M1 distal articular surface. Those could play a role in first ray destabilization and misalignment in HV. However, we do not know whether correction of these deformities could improve HV surgical treatment outcomes. Therefore, we performed a study to assess the impact of M1 distal supination osteotomy, M1 distal varization osteotomy, and combination of both on HV clinical and radiological outcomes. We hypothesized that M1 distal supination osteotomies would improve surgical outcomes in HV. Methods: We conducted an IRB-approved multicenter randomized control trial. HV with an indication for surgical correction were included. HV requiring surgery of the lesser metatarsals were excluded. Feet were randomly divided into 4 groups corresponding to 4 different types of surgery (Figure): 1. Control, classical M1 distal chevron. 2. Supination M1 distal chevron 3. Varization M1 distal chevron 4. Combination of the latter two. Preoperative evaluation and 6-months follow-up were performed. Demographics, AOFAS score, complications, and patient satisfaction (Likert Scale) were collected. On conventional weight-bearing radiographs before and 6 months after surgery, we measured the Hallux Valgus Angle(HVA), the Intemetatarsal Angle(IMA) the Distal Metatarsal Articular Angle(DMAA), the Okuda's M1 head shape classification(from round to angular) and the sesamoid position according to Hardy and Clapham. Normality of different variables was assessed using the Shapiro-Wilk test. Groups were compared using ANOVA for normal and Kruskall Wallis for nonnormal variables. Post-hoc pairwise analyses were performed with Dunn-Bonferoni’s test. Results: 100 HV were included. 8 were lost to follow-up. The Control (n=24), Supination (n=20), Varization (n=26) and Combination (n=22) groups were comparable on age, gender, BMI, and preoperative radiological parameters. At 6 months, there was no difference on AOFAS improvement (p=0.39) and patients satisfaction (p=0.14) whereas there were significant differences on HVA (p &lt; 0.001), IMA (p &lt; 0.001), DMAA (p &lt; 0.001), Okuda's classifcation (p &lt; 0.001) and sesamoid position (p &lt; 0.001) between groups. We found lower HVA values for Combination VS Control (p &lt; 0.001), Combination VS Varization (p &lt; 0.001), Supination VS Control (p &lt; 0.001) and Supination VS Varization (p = 0.005). Asymptomatic recurrences (HVA&gt;15°) were present in 5 cases in Control (20.8%), and 2 in Varization (7.7%). Asymptomatic Hallux Varus (HVA &lt; 0°) were present in 4 cases in Combination (18.2%), and 1 in Supination (5%). Conclusion: Distal M1 supination osteotomies showed better improvement in radiological parameters without showing clinical benefit. The combination of supination and varization osteotomies could lead to overcorrection while the classic M1 distal chevron could lead to insufficient corrections. Routinely performing a supination osteotomy in HV surgical management may lead to erroneous correction and we recommend an à la carte treatment. These results are preliminary and we recommend more patients and longer follow-up to confirm these findings.

Partial (SAVE) versus Complete (Solumbra) Stent Retriever Retraction Technique for Mechanical Thrombectomy: A Randomized In Vitro Study.

Mechanical thrombectomy has become a first-line treatment for acute ischemic stroke. Several techniques combining stent retrievers and distal aspiration catheters have been described. We aimed to characterize the efficacy of 2 commonly used techniques according to clot characteristics. Soft (mean stiffness = 95.77 [SD, 5.80] kPa) or stiff (mean stiffness = 205.63 [SD, 6.70] kPa) clots (3 × 10 mm and 2 × 10 mm, respectively) were embolized to the distal M1 segment of the MCA in an in vitro model. The technique was randomly allocated (1:1): stent retriever assisted vacuum-locked extraction (SAVE) versus complete retraction (Solumbra). The primary end point was the percentage of first-pass recanalization. Secondary end points were periprocedural distal embolization measures. A total of 130 mechanical thrombectomies were performed (50 for soft clots and 15 for stiff clots per arm). Overall, the rate of first-pass recanalizaton was 35% with Solumbra and 15% with SAVE (P < .01). For stiff clots, the first-pass recanalizaton was equal for both methods (27%; P = 1.00). With soft clots, the first-pass recanalizaton was higher with Solumbra (38%) than with SAVE (12%; P < .01). When we used soft clots, the maximum embolus size (mean, 1.19 [SD, 0.9] mm versus 2.16 [SD, 1.48] mm; P < .01) and total area of emboli (mean, 1.82 [SD, 2.73] versus 3.34 [SD, 3.2]; P = .01) were also lower with Solumbra than with SAVE. Clot characteristics may influence the efficacy of the thrombectomy technique. In occlusions caused by soft clots, complete retrieval into the distal aspiration catheters achieved higher rates of first-pass recanalizaton and lower embolization.