M1 Segment Research Articles

Outcomes with Endovascular Treatment of Patients with M2 Segment MCA Occlusion in the Late Time Window.

Randomized trials in the late window have demonstrated the efficacy and safety of endovascular thrombectomy in large-vessel occlusions. Patients with M2-segment MCA occlusions were excluded from these trials. We compared outcomes with endovascular thrombectomy in patients with M2-versus-M1 occlusions presenting 6-24 hours after symptom onset. Analyses were on pooled data from studies enrolling patients with stroke treated with endovascular thrombectomy 6-24 hours after symptom onset. We compared 90-day functional independence (mRS ≤ 2), mortality, symptomatic intracranial hemorrhage, and successful reperfusion (expanded TICI = 2b-3) between patients with M2 and M1 occlusions. The benefit of successful reperfusion was then assessed among patients with M2 occlusion. Of 461 patients, 367 (79.6%) had M1 occlusions and 94 (20.4%) had M2 occlusions. Patients with M2 occlusions were older and had lower median baseline NIHSS scores. Patients with M2 occlusion were more likely to achieve 90-day functional independence than those with M1 occlusion (adjusted OR = 2.13; 95% CI, 1.25-3.65). There were no significant differences in the proportion of successful reperfusion (82.9% versus 81.1%) or mortality (11.2% versus 17.2%). Symptomatic intracranial hemorrhage risk was lower in patients with M2-versus-M1 occlusions (4.3% versus 12.2%, P = .03). Successful reperfusion was independently associated with functional independence among patients with M2 occlusions (adjusted OR = 2.84; 95% CI, 1.11-7.29). In the late time window, patients with M2 occlusions treated with endovascular thrombectomy achieved better clinical outcomes, similar reperfusion, and lower symptomatic intracranial hemorrhage rates compared with patients with M1 occlusion. These results support the safety and benefit of endovascular thrombectomy in patients with M2 occlusions in the late window.

Number Needing Review: A Novel Metric to Assess Triage Efficiency of Large Vessel Occlusion Detection Systems

Background Endovascular thrombectomy is the gold‐standard treatment for large vessel occlusions (LVOs). A novel metric is introduced: the number needing review (NNR) to assess the triage efficiency of LVO detection systems. Methods Patients with suspected ischemic stroke and images processed by RapidAI LVO detection software over 6 months were reviewed. Only patients with LVOs of the M1 segment were included. The NNR was calculated for an M1 occlusion. Results Of 559 patients, M1 occlusion was detected in 42 patients (7.5%). RapidAI LVO had a sensitivity of 71%, specificity of 94%, positive predictive value of 49%, and negative predictive value of 92% for M1 occlusion. When gaze deviation and hyperdense sign were combined with RapidAI LVO, the specificity and positive predictive value increased to 100% for an M1 occlusion. A negative RapidAI LVO result combined with a low (<15 mL, T max >6 seconds) or high (<50 mL, T max >6 seconds) T max threshold was found to have a specificity and positive predictive value of 100% for no occlusion. The combination of gaze deviation, hyperdense sign, positive RapidAI LVO, and negative RapidAI LVO with low T max threshold yielded an NNR of 24 per 100 cases. When combined with a negative RapidAI LVO and a high T max threshold, the NNR was 16 per 100 cases. Adding National Institutes of Health Stroke Scale score <7 decreased the NNR to 9 per 100 cases. Conclusion Adding gaze deviation and hyperdense sign to the RapidAI LVO increases the specificity and positive predictive value for an M1 occlusion. When combined with a negative RapidAI LVO detection and either a low or high T max >6 seconds threshold, the NNR is significantly reduced.

Safety and Efficacy of MCA‐M2 Thrombectomy in Delayed Time Window: A Propensity Score Analysis From the STAR Registry

Background Mechanical thrombectomy of middle cerebral artery M2 segment occlusion of the middle cerebral artery has reported safety and efficacy in recent post‐hoc and observational studies. However, there is no known benefit of mechanical thrombectomy for patients with M2 segment occlusions in the delayed time window (>6 hours). Methods The Stroke Thrombectomy and Aneurysm Registry (STAR) is a prospective, multicenter, nonrandomized observational study registry for acute ischemic stroke thrombectomy and aneurysm treatment. We analyzed all patients who underwent mechanical thrombectomy within the late time window (>6 hours from symptom onset) involving isolated M2 occlusions. We used propensity score matching to select a comparison group of patients who underwent mechanical thrombectomy for M1 occlusion in the same time window. Results Of 1083 consecutive patients analyzed, propensity matching yielded 180 well matched M1 and M2 pairs. Baseline demographics were well balanced between the groups (M1 and M2). Alberta stroke program early CT score (7.6±1.7 versus 8.3±1.5; P <0.001) was higher in the M2 group. There was a trend towards less complete recanalization (Thrombolysis in Cerebral Infarction 3) 46.1% versus 39.9% ( P =0.053) in the middle cerebral artery M2 segment cohort. However, successful recanalization (Thrombolysis in Cerebral Infarction 2b‐3) was better in middle cerebral artery M2 segment cohort (85% versus 90.5%; P =0.053). Postprocedural asymptomatic hemorrhage rates were similar (29.4% versus 27.8%; P =0.816), but symptomatic hemorrhage rates were higher in the M1 group (7.2% versus 2.2%; P =0.047). Rates of good clinical outcome (modified Rankin scale 0–2) were similar at final follow‐up (43.9% versus 46.7%; P =0.672). The overall mortality was also similar between the cohorts (12.8% versus 13.9%; P =0.877). Conclusion In our analysis of the Stroke Thrombectomy and Aneurysm Registry, M2 occlusions not only achieved similar rates of recanalization and good functional outcome compared with M1 occlusions in a delayed time window (6–24 hours from last normal) but also had less symptomatic intracranial hemorrhage.

Distal middle cerebral artery aneurysm manifestation against the background of COVID-19

A significant part of distal cerebral aneurysms belongs to the category of complex. Traditional methods of shutting down such aneurysms are not applicable. Treatment tactics remain a subject of debate. The presence of COVID-19 complicates the course of the disease and complicates the routing of the patient to a specialized hospital.Description of the case. A 36-year-old man with COVID-19 developed an ischemic stroke in the territory of the right middle cerebral artery (MСA), clinically manifested by dysarthria and pronounced left-sided hemiparesis. Cerebral angiography (CAG) revealed thrombosis of the parietal branch of the M2 segment of the right MСA with distal filling of the channel from the territory of the left MСA. After 3 months, according to the control CAG, recanalization of the M2 segment of the right MСA and fusiform aneurysm of this segment of the artery were diagnosed. To turn off the aneurysm, an intra-intracranial anastomosis was applied between the upper and lower M2 segments of the right MСA and an extra-intracranial anastomosis between the parietal branch of the right superficial temporal artery and the cortical branch from the territory of the compromised M3 segment of the MСA, the aneurysm was excised. The postoperative period was complicated by reinfection of SARS-CoV-2. After the treatment, the patient was discharged in a satisfactory condition without neurological deficit.Discussion. Resection of an aneurysm with revascularization of the distal bed can be considered as the method of choice in patients with distal aneurysms if it is impossible to apply traditional clipping. The presence of COVID-19 infection increases the risk of thrombotic complications, imposes increased requirements on the technique of performing vascular anastomoses.

Cavernous Malformations: What They Have Taught Us.

Cavernous Malformations: What They Have Taught Us.

Endovascular treatment for acute ischaemic stroke caused by isolated internal carotid artery occlusion: treatment strategies, outcomes, and prognostic factors

To describe the experience of endovascular treatment (EVT) of acute ischaemic stroke caused by isolated internal carotid artery (ICA) occlusion, with emphasis on treatment strategies, outcomes, and prognostic factors. A retrospective examination was performed of 66 consecutive patients with acute moderate-to-severe stroke who underwent EVT for isolated ICA occlusion from July 2016 to June 2021. The modified thrombolysis in cerebral ischaemia (mTICI) score was used to evaluate reperfusion outcomes. A multivariate analysis was performed to identify risk factors associated with poor 90-day outcome (modified Rankin Scale [mRS] 3-6). The National Institutes of Health Stroke Scale (NIHSS) median score of the 66 patients at admission was 15. Twelve patients (18.2%) showed thrombus migration to the M1 segment or proximal M2 during EVT and underwent additional intracranial thrombectomy. Successful reperfusion (mTICI 2b-3) was achieved in 60 patients (90.9%) and complete reperfusion (mTICI 3) in 42 (63.6%). A poor functional outcome was seen in 27 patients (40.9%). The rate of 90-day mortality was 9.1% (6/66). Higher NIHSS scores and a lower Alberta Stroke Program Early CT Score (ASPECTS) were independently associated with poor outcomes. Complete reperfusion was the only treatment factor with a significant predictive value (adjusted odds ratio [OR] 0.03; 95% CI=0.01 to 0.25; p=0.001). Endovascular therapy is safe and effective in patients with acute ischaemic stroke due to isolated ICA occlusion. Prevention of thrombus migration and complete reperfusion should be the aim of EVT.

Safety and efficacy of flow diverter stents in the treatment of middle cerebral artery aneurysms: a single-center experience and follow-up data

This study aims to evaluate the safety and efficacy of flow diverters (FDs) in the treatment of middle cerebral artery (MCA) aneurysms and share the follow-up (F/U) results. The treatment and F/U results of 76 MCA aneurysms treated with the flow re-direction endoluminal device (FRED), FRED Jr., and pipeline embolization device (PED) FD stents were evaluated retrospectively. The aneurysm occlusion rates were compared between FDs, and the integrated and jailed branches were evaluated through follow-ups. The oversizing of the stent was compared between occluded/non-occluded aneurysms and integrated branches. The mean F/U duration was 32 ± 6.3 months, and the mean aneurysm diameter was 4.45 mm. A total of 61 (80.3%) aneurysms were wide-necked; 73 (96.1%) were saccular; 52 (68.4%) were located at the M1 segment; and 36 (45.6%) FREDs, 23 (29.1%) FRED Jr.s, and 19 (24.1%) PEDs were used for treatment. The overall occlusion rates for the 6-, 12-, 24-, 36-, and 60-month digital subtraction angiographies were 43.8%, 63.5%, 73.3%, 85.7%, and 87.5% respectively. The last F/U occlusion rates were 67.6% for FRED, 66.7% for PED, and 60.6% for FRED Jr. (P = 0.863). An integrated branch was covered with an FD during the treatment of 63 (82.8%) aneurysms. A total of six (10%) of the integrated branches were occluded without any symptoms at the last F/U appointment. The median oversizing was 0.45 (0-1.30) for occluded aneurysms, and 0.50 (0-1.40) for non-occluded aneurysms (P = 0.323). The median oversizing was 0.70 (0.45-1.10) in occluded integrated branches and 0.50 (0-1.40) in non-occluded branches (P = 0.131). In-stent stenosis was seen in 22 (30.1%) of the stents at the 6-month F/U and in only 2 (4.7%) at the 24-month F/U. Thus, none of the patients had any neurological deficits because of the in-stent stenosis. Severe in-stent stenosis was seen in two stents. MCA aneurysms tend to be complex, with integrated branches and potentially wide necks. FD stents are safe and effective in the treatment of MCA aneurysms, and the patency of the side and jailed branches is preserved in most cases. Higher occlusion and lower in-stent stenosis rates are seen with longer F/U durations.

Abstract Number ‐ 35: Maximum Euclidean Deflection‐A Novel Metric For Safety Of Neurovascular Devices

Introduction Endovascular thrombectomy (EVT) devices are evolving rapidly to improve safety and efficacy of EVT‐mediated recanalization of large vessel occlusion strokes, and to access medium and distal vessel occlusions. To enable effective comparative analyses, there is a need to develop an objective in‐vitro safety metric for new EVT devices. Methods We utilized three FDA‐approved stent‐retrievers (4 mm diameter; variable lengths) currently available in the United States and deployed them in an in‐vitro ischemic stroke bench model (Sim Agility, Mentice Inc., Sweden). The stent‐retrievers were deployed in the M1 segment of the middle cerebral artery of the model using a system comprised of an 0.014 inch guide wire and 0.021 inch microcatheter. After unsheathing in the M1 segment, in the absence of a blood clot, the microcatheter was withdrawn back into the petrous internal carotid artery, and the whole system was withdrawn as a rate of 5 mm per second. Maximum deflection of the terminal internal carotid was measured in 3 axes using a specialized camera set‐up. Results A total of 3 passes were performed for each stent‐retriever (stent A, stent B, and stent C). Maximum deflection of the terminal internal carotid artery (from resting position to largest displacement during stent‐retrieval withdrawal) was measured in 3 planes and the values were as follows (Table).Maximum Euclidean Deflection (MED) ranged from 6.1 to 9.1 mm. Deflection varied based on 3 stent‐retriever designs and the plane of measurement. Figure demonstrates deflections as seen in Stent A. Conclusions Withdrawing an unsheathed stent‐retriever from the middle cerebral artery leads to significant deflection of the internal carotid artery terminus in an in‐vitro stroke model. The degree of deflection is variable in different planes and varies based on stent‐retriever design. Further studies are required to examine the predictors and impact of the deflection.

Abstract Number ‐ 232: Carotid Webs as an Under‐Reported Etiology of Acute Ischemic Stroke – Current Diagnostic Challenges

Introduction Carotid webs are anatomical variants in the internal carotid artery vasculature that predispose patients to stroke. As of now, optimal treatment has yet to be established given the lack of large, randomized trials. Part of this stems from the fact that carotid webs remain under‐recognized sources of ischemic stroke despite a high rate of reoccurrence. Herein, we aim to shed light on the diagnosis with our respective center’s experience as well as discuss diagnostic challenges associated with carotid webs. Methods We present a case of a 40‐year‐old male with no past medical history who presented to our center after having developed sudden onset left sided weakness and sensory loss, a left homonymous hemianopia, and dysarthria. Vessel imaging confirmed a right middle cerebral artery occlusion, specifically in the M2 segment, in the setting of a right carotid web. Results Once intracerebral hemorrhage was ruled out, tissue plasminogen activator was administered, with improvement in neurologic exam. Mechanical thrombectomy was thus deferred. Review of the MRI brain showed that in addition to an infarct in the right subinsular white matter region, there were scattered multifocal right hemispheric acute to early subacute infarcts raising concern for an underlying embolic etiology. While the right M2 occlusion looked like it had mainly resolved, a new focal non‐occlusive intraluminal thrombus was found in the right carotid bulb on CTA, MRA, and carotid ultrasound, just distal to a small transverse extraluminal carotid web (Figure 1). The decision was made to take the patient for right carotid stenting given that the carotid web served as a high‐risk lesion. A stent was placed in the right carotid artery with no complications, and the patient was continued on dual antiplatelet therapy. Upon being seen in outpatient clinic after discharge, patient had NIHSS score of 0, with no residual deficits, and was continued on DAPT and a statin for secondary stroke prevention. Conclusions Knowing that patients with carotid webs are at increased risk for stroke, recognition and accurate diagnosis of webs is crucial for appropriate treatment. Diagnostic challenges of carotid webs should be highlighted to prevent misdiagnosis. These include heightened awareness of the patient population that is most at risk, radiographic mimics, location of the lesion as a confounder, and rule out of other stroke etiologies. Prompt recognition of this high‐risk vascular lesion using multiple imaging modalities at different time points during the patient’s admission allowed for treatment of the underlying etiology of his stroke. By increasing awareness on the appropriate diagnostic approach for carotid webs, more information can be garnered to elucidate optimal treatment strategies.

Abstract Number ‐ 165: Are Smaller Stentrievers the Answer for Achieving Procedural Success in Distal Vessel Occlusions (DiVO)?

Introduction Distal vessel occlusions (DiVO) represent the next frontier of interventional stroke care. Although many experts agree the current generation of stentrievers appear to be ill‐suited to address challenges presented by DiVO, some practitioners advocate utilizing smaller devices.We sought to examine whether smaller diameter devices (3,4 or 5 mm) had any edge over standard sized 6 mm device. Methods A prospectively maintained neuro‐endovascular database was queried for patients between January 2013 to August 2022. Patients included in the analysis had undergone mechanical thrombectomy of distal circulation defined as M2, M3, P2, P3, A2 and A3 segments of the MCA, PCA, and ACA respectively.Primary outcomes measured were TICI post procedure, mRS at discharge and mRS at 90 days. Results A total of 33 patients with DiVO were identified out of a database containing 826 mechanical thrombectomies. There were no other differences in baseline characteristics such as presentation NIHSS (p = 0.58) or comorbid medical conditions. We found no differences in post procedure recanalization TICI between large device and small devices cohorts (p = 1.00), symptomatic ICH (p = 0.52), mRS at discharge (p = 0.154) and mRS at 90 days (p = 0.22). Conclusions There do not appear to be any clinical or radiographic difference in utilizing smaller diameter stentrievers in setting of DiVO.

Abstract Number ‐ 159: Intubation for Patients Undergoing Mechanical Thrombectomy of DiVOs is Associated with Increased Symptomatic ICH

Introduction Distal vessel occlusions (DiVO) represent the next frontier of interventional stroke care. Some practitioners advocate for intubatingDiVOpatients to facilitate roadmapping techniques and vessel selection to assure procedural success. However, prior work studying thrombectomy in large vessel occlusion (LVO) suggests intubation is associated with worse outcomes. We sought to examine whether this relation also exists inDiVOpatients. Methods A prospectively maintained neuro‐endovascular database was queried for patients between January 2013 to August 2022. Patients included in the analysis had undergone mechanical thrombectomy of distal circulation defined as M2, M3, P2, P3, A2 and A3 segments of the MCA, PCA, and ACA respectively.Primary outcomes measured were NIHSS at 24 hours and at discharge. Secondary outcomes measured was the occurrence of symptomatic ICH post procedure. Results A total of 33 patients fit inclusion criteria among our database containing 826 mechanical thrombectomies. While there were more males in the endotracheal intubation group (p = 0.03), there were no other differences in baseline characteristics such as hypertension, diabetes, or prior antiplatelet medication use. Amongst the intubated cohort, we found increased rate of symptomatic intracerebral hemorrhage (ICH) (p = 0.03), worse NIHSS at 24 hours (p = 0.01), and worse NIHSS at hospital discharge (p = 0.002). Conclusions Endotracheal intubation for mechanical thrombectomy inDiVOpatients also appears to be associated with increased rates of symptomatic ICH which drives worse outcomes at 24 hours and discharge.

First-Pass Effect in M1-Occlusion Stroke Patients Treated with Combined Stent-Retriever/Large-Bore Distal Aspiration Catheter Thrombectomy.

Combined stent-retriever/large-bore distal aspiration catheter (LB-DAC) thrombectomy was recently introduced to treat large-vessel occlusion; however, it is unclear whether larger inner diameters improve outcomes. We compared angiographic and clinical outcomes in patients with occlusions of the M1 segment of the middle cerebral artery treated with mechanical thrombectomy using extra-LB-DAC versus LB-DAC in combination with stent-retrievers. We analyzed consecutive patients with M1 occlusion included in the ROSSETTI registry treated with non-balloon guide catheter combined LB-DAC/stent-retriever thrombectomy between June 2019 and April 2022. We compared demographics, baseline clinical variables, procedural variables, angiographic outcomes, and clinical outcomes [National Institute of Health Stroke Scale score at 24 h (24h-NIHSS) and modified Rankin scale score at 3 months] between patients treated with extra-LB-DAC (Sofia Plus, MIVI Q6, Catalyst7; inner diameter, 0.068″-0.070″) versus LB-DAC (Sofia 5F, MIVI Q5, Catalyst6; inner diameter, 0.055″-0.064″). Primary outcome was the first-pass effect (FPE) rate, defined as near-complete/complete reperfusion (mTICI2c-3) after asingle pass of the device. We included 324patients (extra-LB-DAC, 185, 57.1% patients). Demographics, clinical data, and clinical outcomes were similar between the two groups; however, there was atrend towards improvement in National Institute of Health Stroke Scale score at 24 h (24h-NIHSS) in the cohort treated with extra-LB-DAC 9 points (IQR 4;16 points) vs. 12 points (IQR 4;18 points, P = 0.083). Patients treated with extra-LB-DAC had higher FPE rate (47% vs. 30.9%; P = 0.003) and higher modified FPE (mTICI ≥ 2b after asingle pass) rate (65.9% vs 46.8%; P = 0.001). The use of extra-LB-DAC was an independent factor in predicting FPE (odds ratio 1.982, 95% confidence interval 1.250-3.143, P = 0.004). Our results suggest that in combined LB-DAC/stent-retriever thrombectomy, alarger aspiration catheter inner diameter is associated with higher rates of FPE and mFPE.

Abstract Number ‐ 107: Better Late Than Never? ‐ Stroke Revascularization Beyond Day 10: Case Series And Literature Review

Introduction In the last several years,there has been a paradigm shift in treating patients presenting with large vessel occlusion (LVO) strokes with endovascular therapy (EVT). Currently, the 24‐hour window has been incorporated in acute stroke management guidelines based on trials supporting the selection of patients with evidence of ischemic penumbra on perfusion imaging1,2. No current randomized control trials exist to support very late window EVT (beyond 24 hours) from last seen well (LSW) and its benefits are unknown. Several retrospective studies showed that EVT is safe and feasible up to 6 days from LSW in selected patients who are able preserve a favorable ischemic core to penumbra3, 4, 5. In this study we present a retrospective review of three patients with LVO strokes of the anterior circulation successfully treated between 10–14 days from LSW. We aim to explore the safety, efficiency and positive predictors of very late window EVT. Methods A single center retrospective review of stroke patients was performed. 517 patients with LVO strokes who underwent EVT between January 2018 and December 2021 were screened. 3 patients were found to have EVT performed 24 hours beyond LSW. Patient demographics, characteristics and clinical information were collected by systematic chart review. The primary outcome was functional independence as assessed by the modified Rankin Score (mRS) at 90 days. The safety outcomes included neurological deterioration and symptomatic intracranial hemorrhage, defined as an increase in National Institutes of Health Stroke Scale (NIHSS) of 4 or more). Further, a comprehensive literature review of studies describing very late window EVT cases indexed in PubMed was performed. Results We identifiedthree patients with LVO strokes, treated more than 24 hours from LSW. Patient ages ranged from 75 to 89 years. Baseline NIHSS ranged from 1 to 13. All patients had LVO or stenosis of the anterior circulation (internal carotid artery and/or M1 segment of the middle cerebral artery). All patients had fluctuation in their symptoms with worsening going from a supine position to a sitting position, evidence of ischemic penumbra on perfusion imaging and slow infarct growth on repeat brain imaging. The time from LSW to intervention ranged from 11 to 14 days. Recanalization score ranged from 2B‐3. No patients had intracranial hemorrhage or neurological decline. mRS scores were 2, 4, and 6 at 3 months. The patient who died had preservation of neurological function but died in the hospital due to heart failure. Conclusions We conclude that widening of the EVT time window presents new opportunities to treat a select population of LVO stroke patients. To our knowledge, there are no other reports of EVT in LVO patients beyond 10 days of LSW. Patients who have evidence of large ischemic penumbra, fluctuation of symptoms with change in position or blood pressure, good collateral circulation, and small infarct core that grows slowly on repeat imaging may be reasonable candidates for delayed EVT. More data are needed to inform clinical practice.

Abstract Number: LBA7 Outcomes of Endovascular Thrombectomy Versus Medical Treatment in Ischemic Strokes Secondary to Medium Vessel Occlusion

Introduction Acute ischemic stroke (AIS) from arterial occlusions are treated with emergent endovascular thrombectomy (EVT) when clinically appropriate. Clinical outcomes of EVT in medium vessel occlusion (MVO) compared to large vessel occlusion (LVO) have neither been well established nor compared to alternate medical management. Our aim was to evaluate outcomes of patients with AIS secondary to MVO undergoing EVT. Methods We conducted a retrospective chart review of patients presenting to our comprehensive stroke center with MVO‐associated AIS undergoing EVT or aggressive intra‐arterial thrombolytic treatment with concurrent administration of IV eptifibatide. We assessed occlusion site, NIHSS (presentation, 7 day or discharge, 3 months), modified Rankin Scale (baseline, 90‐day), and intracranial hemorrhage (ICH) rate. MVO was defined as occlusion of pure M2 middle cerebral artery without M1 segment involvement, anterior cerebral artery A1 segment or more distal, and posterior cerebral artery P1 segment or more distal. Mann‐Whitney U test, Fisher exact test statistic, and T‐test statistic were used for analysis. Social science statistics software was used for data analysis. Results From August 2020 to December 2021, out of 175 patients who underwent EVT, 50 had MVO (n = 33 M2 occlusion, n = 12 M3 occlusion, n = 1 for P1, P2, A1, A2, A3 each). Twelve subjects with MVO received aggressive medical management with concurrent IV eptifibatide. Subjects between arms were similar at baseline (median NIHSS 11 [95% CI 10.75, 14.32]; mean age 71.5 [95% CI 69.24, 73.77]; male 48.39% [n = 30]). The difference between initial NIHSS and discharge NIHSS was statistically significant in the EVT arm (Z‐Score = 4.03; p‐value < .00001) but not in the medical arm (Z‐score = 1.96; p‐value 0.05). Hemorrhagic transformation occurred in 28% (n = 14) of EVT arm and 16.67% (n = 2) of medical arm. This was not statistically significant (Fisher value: 0.71). Median 90 day mRS was 1 (95% CI [0.89, 2.11]). The difference between 90 day mRS was not significantly different (Z‐score = ‐1.20; p‐value 0.23). Conclusions In our patient cohort, endovascular therapy was safe in medium vessel occlusion and may have more favorable clinical outcomes as illustrated by higher delta NIHSS in the endovascular thrombectomy group. Larger, prospective studies are needed to validate our results.

Abstract Number ‐ 216: Limb‐Shaking Transient Ischemic Attack in the Setting of Moyamoya Disease

Introduction Moyamoya disease (MMD) is a cerebrovascular disorder characterized by progressive narrowing of the large intracranial arteries, primarily the internal carotid artery (ICA) and its branches, with secondary development of prominent small‐vessel collaterals. Limb shaking is a rare manifestation of transient ischemic attack (TIA) that is characterized by brief, irregular, involuntary jerking of the arms or legs and momentary disorientation without complete loss of consciousness. It is mainly associated with high grade carotid stenosis. In rare cases, limb‐shaking TIA can occur in the setting of MMD. Methods The patient was identified in routine clinical practice. Results A woman in her 50s presented with a six‐year history of progressive weakness below the neck when standing and initiating movement. These episodes were followed by violent shaking of her arms and legs that lasted several seconds to minutes. She reported transient confusion after the events, but no seizure activity was seen on multiple EEGs, and anti‐epileptic drugs (AEDs) failed to alleviate her symptoms. Further neurological workup included a MR angiogram of the brain that was suggestive of MMD. Catheter angiography confirmed bilateral occlusion of the M1 segments of the middle cerebral arteries (MCAs) and the A1 segment of the left anterior cerebral artery (ACA). There was neovascularization in the same territories with significant collateral flow from the posterior circulation. She was diagnosed with bilateral limb‐shaking TIA in the setting of MMD. She recently underwent two revascularization procedures, a left superficial temporal artery (STA) to middle cerebral artery (MCA) bypass and a right sided encephaloduroarteriosynangiosis (EDAS). Conclusions Limb‐shaking TIA is predominantly associated with severe atherosclerotic extracranial carotid artery stenosis. In rare cases, the limb‐shaking episodes are caused by cerebral hypoperfusion secondary to severe stenosis of the ICAs, and their branches, in the setting of moyamoya disease. Treatment of limb‐shaking TIA to prevent further brain ischemia includes adjustment of fluid intake, careful blood pressure management to avoid episodes of relative brain hypoperfusion, and revascularization procedures. Revascularization is also the most effective method of treating MMD and patients will often experience improvement of their symptoms within one year. Early recognition of limb‐shaking TIA in MMD is critical to avoid unnecessary and potentially harmful treatments (e.g. AEDs), provide patients with accurate explanations of their symptoms, and ensure timely administration of the appropriate treatments.

Abstract Number ‐ 234: Bilateral Non‐Painful Stimulus‐Induced Decerebrated Posturing In A Bilateral Pontine Ischemic Stroke: A Case Report

Introduction A 38 year‐old right‐handed female is a fully functional teacher with past medical history of hypertension, type II Diabetes Mellitus, polycystic ovarian syndrome, and infertility. She presented to our emergency department (ER) on the same day she was discharged twice from a local ER for acute onset persistent non‐fluctuating left‐sided weakness and painful bilateral leg spasms that woke her from sleep. Patient had pertinent exam findings of moderate pharyngeal dysarthria, mild right nasolabial flattening, mild weakness of left upper extremity (LUE), and stereotyped, painful tonic extensor posturing of the bilateral lower extremities associated with back arching and extensor response of bilateral toes. NIH Stroke Scale was 10. Methods We conducted a review of patient clinical documentation. Results MRI Brain showed anterior asymmetric bilateral pontine ischemic strokes at the ventral pontomedullary junction. MRA brain with black blood sequencing revealed multifocal vasculopathy at the right V4, mid‐basilar and left M1 segments. An angiogram showed Moya‐moya type collaterals. Tonic posturing and spasms persisted for several hours requiring muscle relaxants and benzodiazepines for symptomatic management. Unfortunately, the patient had worsening LUE weakness, inability to swallow and was found to have total vocal cord paralysis. She was intubated for airway protection and after failing extubation required tracheostomy and percutaneous gastrostomy placement. Initial workup revealed poorly controlled hyperlipidemia (LDL 162) and diabetes (A1c 8.7%), CRP 7–9, hypercoagulable panel and transthoracic echocardiogram were unremarkable. Lumbar puncture was also unremarkable (CSF TNC 2, RBC 3, glucose 116, protein 35, Enterovirus and HSV 1,2 PCR, Streptococcus antigen and VDRL were negative). Anticoagulation was started for an incidental right lower lobe subsegmental pulmonary embolism. Ultimately, the patient was discharged to inpatient rehabilitation (IPR) with a Modified Rankin Scale (mRS) of 4, on day 19th of hospitalization with some improvement in oral intake and decannulation of tracheostomy. Conclusions Movement disorders caused by strokes have been described in the literature. In their majority, they are secondary to a supratentorial injury. There have been some cases published of infratentorial, unilateral lesions that have caused different types of involuntary movements. More specifically, two papers described tonic spasms seen in pontine strokes. To our knowledge, this is a novel description of a case of bilateral pontine ischemic stroke that causes painful tonic spasms associated with decerebrate rigidity or posturing. Our hypothesis is that given the localization of the strokes in the anterior area of the inferior segment of the pons there may be involvement of the corticospinal, corticobulbar, and rubrospinal tracts which may be responsible for this presentation. Posterior circulation strokes can be missed about 9–14% of the time, possibly due to atypical presentations. We believe that presenting this case can help to improve the current available literature on this topic.

Abstract Number ‐ 266: Focal Cerebral CNS Vasculitis due to SARS‐CoV‐2 Infection

Introduction Several neurological manifestations of the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection, including anosmia, encephalopathy, and stroke, have been reported. We report a case of a 42‐year‐old man presenting with ischemic stroke due to cerebral vasculitis in the setting of SARS‐CoV‐2 infection. Methods Case report Results A 42‐year‐old man, recently diagnosed with SARS‐CoV‐2 infection, presented with nonfluent aphasia and right‐sided hemiparesis that started five hours prior. Neurological examination revealed nonfluent aphasia, right‐sided facial palsy, and hemiparesis. Computed tomography (CT) of the head showed left‐sided caudate infarct and early ischemic changes in the left putamen. CT angiography (CTA) revealed occlusion of the proximal left M1 segment. Patient’s symptoms rapidly improved and mechanical thrombectomy was not pursued. Patient was started on dual antiplatelet therapy with aspirin and clopidogrel. Magnetic resonance imaging (MRI) of the brain showed acute infarcts in the left posterior parietal, lentiform nucleus, and frontal cortex. CT of the chest revealed bilateral subsegmental pulmonary emboli. Patient was discharged on apixaban and atorvastatin daily, with mild residual aphasia. A month later, the patient returned with dysarthria and right‐sided paresthesia that began three hours prior. CTA showed severe left proximal M1 stenosis involving a longer segment. He was started on vasopressor. Symptoms resolved within 24 hours with residual mild aphasia. MRI brain revealed multiple foci of cortical infarcts within the left MCA territory with no diffusion/ perfusion mismatch. MRA head showed further pruning of the distal MCA branches within the left sylvian fissure with severe stenosis along the mid‐M1 and minimal flow anteriorly, with contrast enhancement at the site of the stenosis, suggestive of vasculitis. Autoimmune vasculitis panel was unremarkable. Due to suspicion of focal inflammatory vasculopathy related to recent SARS‐CoV‐2 infection, patient was started on intravenous methylprednisolone 1 gram daily for 5 days followed by a prednisone taper. MRA revealed improved blood flow in the left middle cerebral artery and branches. The was discharged on apixaban, aspirin, atorvastatin, and a prednisone taper with mild residual aphasia. Conclusions To our knowledge, this is the first reported case of CNS vasculitis associated with an underlying SARS‐CoV‐2 infection with radiographic improvement of blood flow in the affected vessel within 4 days of treatment with high‐dose steroids. This case supports the use of high‐dose steroids in patients with CNS vasculitis associated with SARS‐CoV‐2 to prevent further stroke burden.

The diagnostic performance of artificial intelligence algorithms for identifying M2 segment middle cerebral artery occlusions: A systematic review and meta-analysis

BackgroundArtificial intelligence (AI)-based algorithms have been developed to facilitate rapid and accurate computed tomography angiography (CTA) assessment in proximal large vessel occlusion (LVO) acute ischemic stroke, including internal carotid artery and M1 occlusions. In clinical practice, however, the detection of medium vessel occlusion (MeVO) represents an ongoing diagnostic challenge in which the added value of AI remains unclear. PurposeTo assess the diagnostic performance of AI platforms for detecting M2 occlusions. MethodsStudies that report the diagnostic performance of AI-based detection of M2 occlusions were screened, and sensitivity and specificity data were extracted using the semi-automated AutoLit software (Nested Knowledge, MN) platform. STATA (version 16 IC; Stata Corporation, College Station, Texas, USA) was used to conduct all analyses. ResultsEight studies with a low risk of bias and significant heterogeneity were included in the quantitative and qualitative synthesis. The pooled estimates of sensitivity and specificity of AI platforms for M2 occlusion detection were 64% (95% CI, 53 to 74%) and 97% (95% CI, 84 to 100%), respectively. The area under the curve (AUC) in the SROC curve was 0.79 (95% CI, 0.74 to 0.83). ConclusionThe current performance of the AI-based algorithm makes it more suitable as an adjunctive confirmatory tool rather than as an independent one for M2 occlusions. With the rapid development of such algorithms, it is anticipated that newer generations will likely perform much better.

‘Y’-Shaped Palmar Common Digital Artery Interposition Bypass in the Treatment of an Infantile M2 Large Aneurysm and Literature Review

Both craniotomy and interventional embolization are difficult and risky to treat complex middle cerebral artery (MCA) aneurysms in infants. Trapping with revascularization is a therapeutic option for giant aneurysms that cannot be clipped or coiled alone. We describe a technical method using revascularization with a natural Y-shaped palmar common digital artery interposition graft that provides a normal variation for a complex MCA aneurysm in an infant with intracerebral hemorrhage at 37 days of age. Conservative treatment was performed at that time. Seven months later, the patient was re-admitted to the hospital and was confirmed a large aneurysm in the M2 segment of the right MCA by cerebral angiography. A natural artery palmar common digital artery Y-graft was used as the graft and anastomosed to the M2 and both M3 trunks. The symptoms improved after surgery, and the mRS score of the patient was 1 after 5 years of follow-up. The palmar common digital artery can be an option for intracranial revascularization bypass in complex intracranial aneurysms.

Abstract 138: Hypoperfusion Delay Volume Predicts Early Stroke Recurrence Risk In Symptomatic Anterior Circulation Intracranial Atherosclerotic Disease

Introduction: Data on predictors of early stroke recurrence in patients with symptomatic intracranial atherosclerotic disease (sICAD) is limited. We hypothesized that hypoperfusion delay predicts stroke recurrence within 90-days. Methods: We retrospectively collected all patients hospitalized with anterior circulation sICAD over 3 years (April 2019-April 2022) at a comprehensive stroke center. We collected demographics, clinical risk factors, radiological variables, and treatment strategies. Patients with an indication for anticoagulation such as atrial fibrillation and those with intracranial stenting or angioplasty were excluded. The outcome (verified by two independent reviewers) was recurrent stroke within 90 days in the affected artery. We assessed factors associated with stroke recurrence. We measured the effect of hypoperfusion delay volume on stroke recurrence using Cox-regression models. Results: Out of 131 sICAD hospitalizations during the study period, 66 involved the middle cerebral artery (MCA) M1 segment or intracranial internal carotid artery (ICA) and 44 patients met the inclusion criteria. The mean age was 71 years and 41% were women; 75% were treated with best medical management (dual antiplatelet therapy/high intensity statin therapy); and 75% had baseline perfusion imaging performed. Over 90 days, 11/44 (25%) patients had recurrent stroke. Factors associated with recurrence stroke were no best medical management (15.2% vs. 54.5%, p = 0.02), hypoperfusion Tmax>4 sec mismatch volume (p = 0.003), and hypoperfusion delay Tmax>6 sec mismatch volume (p=0.01). Using Youden’s cutoff for Tmax>4 sec mismatch (13 mL) and for Tmax>6 sec mismatch (5 mL), the risk of recurrent stroke at 90 days in separate models was higher in patients with Tmax>4 sec delay mismatch volume > 13 mL (HR 11.98 95% CI 1.48-96.96 p=0.02) and Tmax>6 sec mismatch volume > 5 mL (HR 4.37 95% CI 1.02-18.82, p=0.048). Effect size of the associations did not meaningfully change after adjusting for best medical management. Conclusion: Hypoperfusion delay is associated with an increased recurrent stroke risk within 90 days in patients with sICAD, despite best medical management. Validation by large prospective studies is warranted.