Acute M1 Occlusion Research Articles

StentRetriever- Aspiration (SRa) vs Direct Aspiration (DA) in the Treatment of Acute M2 Segment Occlusion of Middle Cerebral Artery: A Single Center Randomized Prospective Study

Decision making and patient selection for isolated occlusion of the M2 segment of the middle cerebral artery is challenging, with the efficacy of treatment for such distal occlusions still controversial in recent studies, as occlusion in such small and thin vessels tends to manifest with less severe symptoms initially and hold higher surgical risks. It is even less clear which endovascular technique is more effective for this type of occlusion, with the choice usually left to the radiologist's preference. We conducted a controlled prospective study of consecutive patients presenting to Novara Hospital with an acute M2 occlusion diagnosed at the AngioCt and, following a predetermined randomization, we divided them into two treatment arms with either stent retriever aspiration (SRa) or direct aspiration (DA). All patients were examined on admission, at discharge and after 3 months, and clinical data as well as mRS and NIHSS scale scores were recorded. Our primary aim was to evaluate the difference in recanalization rate in the two groups by comparing the angiographic eTICI obtained with the two techniques. We then investigated whether there were differences in clinical outcomes and complications. Our data confirm a good recanalization rate with an eTICI ≥ 2b in 76.19% of patients in the cohort. An overall good outcome was achieved in 57% of patients as ∆NIHSS and in 50.79% of patients considering mRS. We found no statistically significant difference in recanalization rate nor higher complication rate in either the SRa or DA group. Both techniques are safe, effective and can be considered equally.

Mechanical Thrombectomy for Pediatric Arterial Ischemic Stroke from Acute M2 Occlusion.

Pediatric large-vessel occlusion has a poor natural history. Recent retrospective studies have demonstrated the potential benefits, feasibility, and safety profile of mechanical thrombectomy in children. However, the role of thrombectomy in pediatric M2 occlusions remains uncertain. In this clinical report, we present a multicenter series of 6 pediatric patients with acute M2 occlusion (female = 1, male = 5; age range, 0.9-16.0 years, mean = 9.2). All 6 patients having undergone thrombectomy had excellent clinical outcomes (pediatric mRS = 0-1) at 3 months and final available follow-up (median, 12 months; range, 3-72 months). Factors relevant to treatment decision-making in pediatric M2 occlusions are discussed, including the important role of multidisciplinary team discussions during acute management.

Endovascular treatment for acute M2 occlusion stroke within 6 hours-a retrospective real-world evidence.

We compared the efficacy and safety of endovascular therapy (EVT), intravenous (IV) thrombolysis and conservative treatment in M2 segment occlusion stroke based on a real-world database. We retrospectively analyzed the database of admitted patients with M2 segment occlusion between January 2018 and December 2020. The patients who were eligible for reperfusion treatment were assigned to EVT, IV thrombolysis or conservative treatment according to the exact management proceeding. The primary outcome was a score of 0 and 1 on the modified Rankin scale (mRS) at 90 days. The odds ratio (OR) for the primary outcome was adjusted for age, baseline National Institute of Health Stroke Scale score, and door-to-treatment time. The secondary outcomes were based on a mRS score from 0 to 2 at 90 days and the safety outcomes including symptomatic intracranial hemorrhage, and all-cause mortality. The data were analyzed by the logistical regression model, including baseline adjustments. A total of 109 patients were included. Among them, 42 (38.5%) patients received EVT, 45 (42.5%) received IV thrombolysis and 22 (20.8%) received conservative treatment. The primary outcome based on a mRS score of 0 and 1, occurred in 66.7% of patients in the EVT group and 40% in the IV thrombolysis group (adjusted OR, 1.79; 95% confidence interval [CI], 1.19-2.68; P = 0.01). Symptomatic intracranial hemorrhage occurred in 1 patient (2.3%) in the EVT group and in 2 patients (4.4%) in the IV thrombolysis group (adjusted OR = 0.71, 95% CI: 0.13-4.07). EVT showed better functional outcomes than IV thrombolysis and conservative treatment in moderate to severe acute stoke patients with M2 occlusion. There was no significant difference in the three groups concerning the incidence of symptomatic intracranial hemorrhage.

First-line contact aspiration versus first-line stent retriever for acute ischemic stroke with M2 occlusion: A systematic review and meta-analysis

ObjectiveMechanical thrombectomy is widely used for acute ischemic stroke caused by middle cerebral artery M2 segment occlusion. However, the comparison between contact aspiration (CA) and stent retriever (SR) used as first-line techniques for acute M2 occlusion is still unclear. We aimed to perform a systematic review and meta-analysis on this issue. MethodsThe Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement was followed. Three databases (Pubmed, Embase, and Cochrane) were searched. The Newcastle-Ottawa scale was used to assess the risk of bias for the included studies. We focused on two main outcomes, the final successful reperfusion (modified Thrombolysis in Cerebral Infarction mTICI 2b/3) and 90-day functional independence (modified Rankin Scale score 0–2). The meta-analyses were performed using the random-effects models. ResultsSeven observational studies were included for systematic review. Only one study indicated a superiority of first-line SR in achieving final successful reperfusion, while the other six studies did not show significant difference between these two techniques. And all the seven studies showed comparable proportion of 90-day functional independence. Five studies were available for meta-analysis with 601 patients (239 received first-line CA, 362 received first-line SR). The pooled results also suggested that the proportion of final successful reperfusion (OR=1.18, 95%CI 0.72–1.93, I2 =0%) and 90-day functional independence (OR=1.18, 95%CI 0.82–1.68, I2 =0%) were comparable between these two strategies. ConclusionFor patients with acute M2 occlusion, first-line CA and SR techniques could achieve similar final reperfusion outcomes and 90-day clinical prognosis. Further studies with randomized controlled design are needed.

Abstract 1122‐000181: Collateral Circulation in Ischemic Stroke is Not Determined by Anatomical Variants of the Cerebral Arteries

Introduction : In acute ischemic stroke, collateral circulation determines tissue fate and treatment results. The aim of this study was to evaluate the role of anatomical variations of the Circle of Willis (CoW) in formation of cerebral collateral blood flow in patients with acute M1 occlusion. Methods : This study was a retrospective assessment of radiological examinations of patients with stroke due to middle cerebral artery M1 segment occlusion. All patients underwent mechanical thrombectomy from January 2015 until March 2021. The anatomy of the CoW was assessed on initial CT‐angiography and DSA. CTA was utilized to grade cranial collateral vasculature status and cortical vein opacification score (COVES). Non‐contrast CT scans and ASPECTS scores (using RAPID software) were used to determine the ischemic area. Results : A total of 100 patients were included in the analysis (58 females and 42 males, mean age: 71.6 +/‐ 13.9). We classified the anatomy of the CoW according to its continuity as a full circle. Patients with fully continuous CoW (n = 19) had worse COVES scores than those with CoW incomplete at both anterior and posterior portion (n = 9) (89% vs 68% with COVES 0–2, p = 0.179). No statistically significant results were found when comparing the enhancement of collaterals between these two groups (p = 0.390). The COVES scores were similar for patients with complete and incomplete anterior portions of CoW (77% vs 80% with COVES 0–2, p = 0.812). Patients with incomplete posterior portions of CoW had lower COVES scores than those with complete (80% vs 67% with COVES 0–2, p = 0.206). No statistically significant differences were discovered when comparing different types of the posterior communicating artery (adult, transitional and fetal). Analysis of ischemic areas determined as ASPECTS scores pre‐ and post‐thrombectomy yielded no significant differences between any of the groups. Conclusions : Although certain variants of the CoW have been reported to increase the risk of ischemic stroke, our results show that the anatomy of CoW has no large effect on collateral blood flow during acute M1 occlusion. We presume that the greater role is played by pial arterioles than anatomical variants of major cerebral arteries in cerebral collateral circulation formation. Detailed knowledge about the factors that influence collateral blood flow is crucial as it may aid in identification of patients prone to worse outcomes of ischemic stroke. Anatomical variants of CoW do not play a major role in formation of cerebral collaterals.

Abstract 1122‐000184: Cerebral Arterial Variations in Patients with Ischemic Stroke Undergoing Mechanical Thrombectomy

Introduction : This study aimed to determine what anatomical variants of the Circle of Willis (CoW) and the middle cerebral artery(MCA) are observed in patients with acute M1 occlusion and whether their prevalence differs from that described as “normal” in anatomy textbooks. Methods : We have performed a retrospective assessment of radiological examinations of patients with stroke due to middle cerebral artery M1 segment occlusion. All patients underwent mechanical thrombectomy from January 2015 until March 2021. The anatomy of the CoW was assessed on initial CT‐angiography and DSA. Branches of the MCA were observed on control DSA after recanalization. Results : A total of 100 patients were included in the analysis (58 females and 42 males, mean age: 71.6 +/‐ 13.9). Fully complete CoW was observed in 19% of patients. A total of 10% of patients had an incomplete anterior portion of CoW. In the incomplete anterior portion subgroup, the most common variation was the absence of anterior communicating artery (6% of total hemispheres), followed by the absence of one A1 (3% of total hemispheres). An incomplete posterior portion of CoW was identified in 79% of the patients. The absence of posterior communicating artery (PCoA) was observed in 59 patients. Sixteen patients had adult‐type PCoA, 3 patients had transitional‐type PCoA and 21 patients had fetal‐type posterior cerebral artery (PCA). In the subgroup of patients with fetal‐type posterior circle, 5 patients had no P1 segment of PCA. Anterior temporal branch of MCA was observed in 45% of the patients. Middle cerebral artery bifurcation was found in 80% of hemispheres, and trifurcation in 20%. In the bifurcation subgroup, 26% of MCAs had a dominating upper branch and 18% had a dominating lower branch. A duplicate MCA was observed in one hemisphere. Conclusions : In comparison to normal anatomy described in anatomy textbooks, the population of patients suffering from ischemic stroke due to M1 occlusion had a lower proportion of complete and closed CoW. A foetal type PCoA was observed to be prevalent (21%) in patients suffering from acute M1 occlusion. Detailed anatomical knowledge of anatomical variants of CoW in patients undergoing mechanical thrombectomy is essential for clinicians performing intravascular interventions and may aid procedure planning.

First-Pass Reperfusion by Mechanical Thrombectomy in Acute M1 Occlusion: The Size of Retriever Matters.

Introduction: Single-pass complete reperfusion using stent retrievers has been shown to improve functional outcome in patients with large vessel occlusion strokes. The aim of this study was to investigate the optimal size of stent retrievers to achieve one-pass complete reperfusion by mechanical thrombectomy.Methods: The study evaluated the results of aspiration-assisted mechanical thrombectomy of acute isolated occlusion of the middle cerebral artery in the M1 segment with a novel 5 × 40-mm stent retriever compared to the usual 4 × 20-mm device. Reperfusion status was quantified using the Thrombolysis In Cerebral Infarction (TICI) scale. We hypothesized that thrombectomy of M1 occlusions with 5 × 40-mm stent retriever yields higher rates of complete first-pass reperfusion (FP) (TICI ≥2c after one pass) and successful or modified FP (mFP) (TICI ≥2b after one pass) than thrombectomy with 4 × 20. We included isolated M1 occlusions treated with pRESET 5 × 40 (phenox) as first-choice device for thrombectomy and compared with M1 occlusions treated with pRESET 4 × 20. We excluded patients with additional occlusions or tandem stenosis or who received an intracranial stent or angioplasty as a part of the endovascular treatment.Results: One hundred thirteen patients were included in the 4 × 20 group and 57 patients in the 5 × 40 group. The 5 × 40 group achieved higher FP compared to 4 × 20 group [61.4% (35 of 57 patients) vs. 40.7% (46 of 113), respectively; adjusted odds ratio (OR) and 95% confidence interval (95% CI) = 2.20 (1.08–4.48), p = 0.030] and a higher mFP [68.4%, 39 of 57 patients vs. 48.7%, 55 of 113; adjusted OR (95% CI) = 2.11 (1.04–4.28), p = 0.037]. Frequency of successful reperfusion (TICI ≥2b) was similar in both groups (100 vs. 97.3%), but frequency of complete reperfusion (TICI ≥2c) was higher in the 5 × 40 group [82.5 vs. 61.9%, adjusted OR (95% CI) = 2.47 (1.01–6.04), p = 0.047]. Number of passes to achieve reperfusion was lower in the 5 × 40 group than in the 4 × 20 group [1.6 ± 1.1 vs. 2 ± 1.4, p = 0.033; adjusted incidence rate ratio (95% CI) = 0.84 (0.69–1.03), p = 0.096]. Modified Rankin scale at 90 days was similar in 5 × 40 and 4 × 20 groups.Conclusions: The size of stent retriever matters in acute M1 occlusions treated with aspiration-assisted mechanical thrombectomy. A longer stent retriever with a larger nominal diameter achieves a higher complete and successful FP and higher successful reperfusion compared to a shorter stent retriever.

Endovascular treatment versus intravenous thrombolysis alone in isolated M2 occlusion: a meta-analysis.

Optimal reperfusion strategies for M2 occlusion are still uncertain, with previous studies questioning benefit of mechanical thrombectomy (MT) over intravenous thrombolysis alone (IVT). Here we systematically reviewed and meta-analyzed data from studies comparing IVT alone vs MT with/without previous IVT, to define risk/benefit profile of each paradigm. The study followed PRISMA guidelines. PubMed, EMBASE, and Cochrane Central were searched only for RCTs comparing MT with or without IVT vs IVT alone in adults with acute ischemic stroke and M2 occlusion. Primary endpoint was functional independence at 90 days (modified Rankin Scale<3); secondary endpoints were represented by symptomatic intracranial hemorrhage (sICH) and good recanalization (TICI>2a). Odds ratios for endpoints were pooled with meta-analysis and compared between reperfusion strategies. Seven studies (n=779) were included, all of high quality. Rate of good functional outcome was similar for MT and IVT (62.4% vs 66.3%; OR=0.73; 95%CI: 0.38-1.41; pheterogeneity=0.008) (Fig. 1).sICH was significantly more frequent in the MT group (8.5%) vs IVT group (3%) (OR 2.76, 95%CI 1.19-6.36, pheterogeneity=0.14). Good recanalization (TICI>2a) rate was higher in MT group vs IVT alone group (81.2% vs 51.4%; OR 3.99; 95%CI: 1.98-8.94; pheterogeneity=0.80). IVT alone provides similar clinical benefit compared to MT with/without IVT in cases of M2 occlusion. MT quadruplicates rates of good recanalization, but triplicates risk of sICH. Further trials are needed to define if MT confers any advantage over IVT for M2 occlusion.

Treatment and Outcome in Stroke Patients With Acute M2 Occlusion and Minor Neurological Deficits.

Treatment in stroke patients with M2 segment occlusion of the middle cerebral artery presenting with mild neurological deficits is a matter of debate. The main purpose was to compare the outcome in patients with a minor stroke and a M2 occlusion. Consecutive intravenous thrombolysis (IVT) eligible patients admitted to the Bernese stroke center between January 2005 and January 2020 with acute occlusion of the M2 segment and National Institutes of Health Stroke Scale score ≤5 were included. Outcome was compared between IVT only versus endovascular therapy (EVT) including intra-arterial thrombolysis and mechanical thrombectomy (MT; ±IVT) and between IVT only versus MT only. Among 169 patients (38.5% women, median age 70.2 years), 84 (49.7%) received IVT only and 85 (50.3%) EVT (±IVT), the latter including 39 (45.9%) treated with MT only. Groups were similar in sex, age, vascular risk factors, event cause, or preevent independency. Compared with IVT only, there was no difference in favorable outcome (modified Rankin Scale score, 0-2) for EVT (adjusted odds ratio, 0.96; adjusted P=0.935) or for MT only (adjusted odds ratio, 1.12; adjusted P=0.547) groups. Considering only patients treated after 2015, there was a significantly better 3-month modified Rankin Scale shift (adjusted P=0.032) in the EVT compared with the IVT only group. Our study demonstrates similar effectiveness of IVT only versus EVT (±IVT), and of IVT only versus MT only in patients with peripheral middle cerebral artery occlusions and minor neurological deficits and indicates a possible benefit of EVT considering only patients treated after 2015. There is an unmet need for randomized controlled trials in this stroke field, including imaging parameters, and more sophisticated evaluation of National Institutes of Health Stroke Scale score subitems, neurocognition, and quality of life neglected by the standard outcome scales such as modified Rankin Scale and National Institutes of Health Stroke Scale score.

FLAIR vascular hyperintensity with DWI for regional collateral flow and tissue fate in recanalized acute middle cerebral artery occlusion

PurposeFluid-attenuated inversion recovery (FLAIR) vascular hyperintensity (FVH) extent or FVH-DWI mismatch as a primary influencing factor of clinical outcome in acute ischemic stroke is controversial. This study elucidated the regional pathophysiology and tissue fate in four types of cortical territories classified by the initial FVH and DWI findings in patients with acute proximal middle cerebral artery (M1) occlusion successfully recanalized using mechanical thrombectomy. MethodsWe retrospectively evaluated 35 patients successfully recanalized within 24 h of acute M1 occlusion onset between 2016 and 2019. Each Alberta stroke program early CT score area of M1–M6 were categorized as group A (DWI-, FVH-), B (DWI-, FVH+), C (DWI+, FVH+), or D (DWI+, FVH-). Territorial collateral status was graded on a 4-point scale by initial angiogram. Follow-up head computed tomography (CT) findings on days 2–9 were assessed for the territorial outcome. ResultsOverall, 210 cortical territories were identified; of these, 88 (41.9 %) were categorized into group A; 72 (34.3 %), group B; 37 (17.6 %), group C; and 13 (6.2 %), group D. The rate of territories with good collaterals (grade 2 or 3) significantly decreased in the order of groups as 78.3 %, 62.7 %, 27.6 %, and 0%, respectively (Ptrend <.001). Conversely, the rate of territories with any hypo- or hyper-density on follow-up CT significantly increased in the order of groups as 13.4 %, 23.1 %, 88.5 %, and 85.7 %, respectively (Ptrend <.001). ConclusionCategorization of cortical areas based on the FVH and DWI findings can stratify territorial collateral status and tissue fate.

Cost-effectiveness of endovascular thrombectomy in patients with acute stroke and M2 occlusion

BackgroundThe cost-effectiveness of endovascular thrombectomy (EVT) in patients with acute ischemic stroke due to M2 branch occlusion remains uncertain.ObjectiveTo evaluate the cost-effectiveness of EVT compared with medical management in patients...

Mechanical thrombectomy in acute middle cerebral artery M2 segment occlusion with regard to vessel involvement.

Endovascular treatment (EVT) is an established procedure in patients with acute ischemic stroke due to occlusion of the proximal M1-segment of middle cerebral artery. The assessment of distal thrombectomy in daily clinical routine has not yet been sufficiently evaluated. Patients with M2-segment-occlusions treated by EVT in the local department (January 2012-December 2017) were included (n= 57, mean National-Institutes-of-Health-Stroke-Scale of 11, range 0-20). Patients were grouped according to localization of M2-occlusion (Cohort A (n= 14): central region only, B (n= 24): central region and involvement of frontal vessels, C (n= 19): parietal, occipital, and/or temporal vessels). Differences in proximal (M2-trunk, n= 34) and distal (M2-branches, n= 23) occlusions were also examined. Reperfusion (Thrombolysis-In-Cerebral-Infarction (TICI)), early clinical outcome at discharge (modified Rankin Scale (mRS)), and complications (hemorrhage, new emboli) were noted. Successful reperfusion (TICI2b-3) was found in 49 patients (86.0%). Favorable early clinical outcome (mRS0-2) was achieved in n= 19 (37.7%). Compared to admission, mRS at discharge improved significantly (median (admission) 5 vs. median (discharge) 4, p< 0.001). Early clinical outcome was more favorable in patients with better reperfusion (TICI2b-3: mean mRS 3 ± 1.7 vs. TICI0-2a: mean mRS 4.4 ± 1.4, p= 0.037). Six (10.5%) patients suffered from symptomatic intracranial hemorrhage during treatment or hospitalization. Four patients died (7.0%). No significant differences in favorable clinical outcome (mRS ≤ 2: Cohort A 42.9%, B 50.0%, C 16.7%, p=0.4; χ2-test) or periinterventional complications were found with regard to vessel involvement. EVT in patients with acute M2-occlusion is safe and leads to a significant clinical improvement at discharge. No significant differences in clinical outcome or complications were found with regard to the localization of the M2-occlusion.

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脳灌流画像が有用だった急性中大脳動脈M2 部閉塞血行再建の1 例

Meta-Analysis of Endovascular Treatment for Acute M2 Occlusion.

ObjectiveEndovascular treatment (EVT) outcomes for acute M2 segment of middle cerebral artery occlusion remains unclear because most results are obtained from patients with large artery occlusion in the anterior circulation. The objective of this study was to assess procedural outcomes for acute M2 occlusion and compare outcomes according to thrombus location (M1 vs. M2). MethodsA systematic review was performed for online literature published from January 2004 to December 2016. Primary outcome was successful recanalization rate and symptomatic intracranial hemorrhage (S-ICH) after the procedure. A fixed effect model was used if heterogeneity was less than 50%. ResultsEight articles were included. EVT showed successful recanalization rate of 69.1% (95% confidence interval [CI], 54.9–80.4%) and S-ICH rate of 6.1% (95% CI, 4.5–8.3%). The rates of good clinical outcome at 3 months and mortality were 59.4% (95% CI, 49.9–68.2%) and 14.9% (95% CI, 11.4–19.3%), respectively. According to thrombus location (M1 vs. M2), successful recanalization (odds ratio [OR], 1.539; 95% CI, 0.293–8.092; p=0.610) and S-ICH (OR, 1.313; 95% CI, 0.603–2.861; p=0.493) did not differ significantly. Good clinical outcome was more evident in M2 occlusion after EVT than that in M1 occlusion (OR, 1.639; 95% CI, 1.135–2.368; p=0.008). However, mortality did not differ significantly according to thrombus location (OR, 0.788; 95% CI, 0.486–1.276; p=0.332).ConclusionEVT seems to be technically feasible for acute M2 occlusion. Direct comparative studies between EVT and medical treatment are needed further to find specific beneficiary group after EVT in patient with M2 occlusion.

Implementation of Penumbra-assisted Half-Stent Thrombectomy for Patients with Acute M2 Occlusion:Results of Initial Experiences

The benefits of mechanical thrombectomy(MT)for acute M2 occlusion have remained unclear because of unavoidable device-related complications due to vascular morphological characteristics. We developed a Penumbra-assisted half-stent thrombectomy for achieving secure retrieval of thrombus with minimal damage to the small-caliber vessel. In total, 6 patients were treated with MT for acute M2 occlusion using this technique between November 2016 and May 2017, including 3 men and 3 women, mean age 74.8(51-98)years. The mean baseline National Institutes of Health Stroke Scale score was 17.5(6-32), and Alberta Stroke Program Early Computed Tomography Score-Diffusion-Weighted Imaging was 7.5(6-9). After navigation of the microcatheter through the thrombus in M2 supported by a Penumbra 4MAX as a distal access catheter, the stent retriever(SR)was partially deployed to cover the entire thrombus. The 4MAX was then advanced towards the caudal end of the thrombus, and the SR was pulled back into the 4MAX with simultaneous aspiration of the 4MAX. We used the Trevo XP3 in 5 patients and Revive SE in 1 patient. The mean procedure time from groin puncture to recanalization was 60(54-66)min. Successful recanalization(Thrombolysis in Cerebral Infarction score 2b or 3)was achieved in 5(83%)patients. There were no cases of symptomatic intracranial hemorrhage. Good outcome(modified Rankin Scale score 0 to 2)at 3 months was achieved in 3(50%)patients. Penumbra-assisted half-stent thrombectomy appears to be an effective alternative strategy in MT for acute M2 occlusion.

NIHSS sub-item scores predict collateral flow in acute middle cerebral artery infarction.

The status of collateral vessels has important clinical implications in acute ischemic stroke. To evaluate which components of ischemic symptoms were predictive of pretreatment collateral status, we tested the hypothesis that sub-item scores from the National Institutes of Health Stroke Scale (NIHSS) are associated with leptomeningeal collateral status in acute ischemic stroke with middle cerebral artery (MCA) occlusion. This study included consecutive patients with acute M1 occlusion who underwent revascularization treatment for acute MCA infarction. We evaluated clinical factors and the NIHSS score according to the collateral status assessed by multiphase perfusion computed tomography. Eighty-six patients were included (48 good collateral status, 38 poor collateral status). The patients with poor collateral status were more likely to have a higher total NIHSS score (18 versus 11, p < 0.001) and atrial fibrillation (65.8% versus 41.7%, p = 0.026) than patients with good collateral flow. In a multiple logistic regression, the NIHSS sub-items such as profound "facial palsy" (score 2 versus 0-1) and "visual field defect" (score 2 versus 0-1) were independently associated with poor collateral status. Among the NIHSS sub-items, severe facial palsy and visual field defect were associated with poor collateral status in acute MCA stroke with M1 occlusion. Decision on whether to treat these patients endovascularly should be made more cautiously due to the possibility of a poor outcome.

Endovascular Mechanical Thrombectomy for Acute Middle Cerebral Artery M2 Segment Occlusion: A Systematic Review.

The benefit of endovascular mechanical thrombectomy (EMT) for acute distal occlusions of the middle cerebral artery M2 segment is incompletely defined. The aim of this systematic review is to analyze the recent literature regarding EMT for acute M2 occlusions. We reviewed the literature to identify all studies of patients with acute M2 occlusions who underwent EMT that were published after January 1, 2015. Excellent and good outcomes were defined as modified Rankin Scale score of 0-1 and 0-2, respectively, at 3 months. Successful reperfusion was defined as modified Thrombolysis In Cerebral Infarction (mTICI) score of 2b-3. Eight studies, comprising 630 EMT-treated patients with acute M2 occlusions, were included in the analysis. The median National Institute of Health Stroke Scale score ranged from 10 to 16, and the median Alberta Stroke Program Computed Tomography Score ranged from 9 to 10. Excellent and good outcomes at 3-month follow-up were observed in 40% and 62%, respectively, of patients with acute M2 occlusion who underwent EMT, with a mortality of 11%. Successful reperfusion was achieved in 78% of cases. Postprocedural intracerebral hemorrhage (ICH) occurred in 14% of patients, including a symptomatic ICH rate of 5%. EMT for acute M2 occlusion affords functional independence to most patients, with a modest rate of symptomatic ICH. However, compared with the natural history of distal MCA occlusions, the benefit of M2 thrombectomy using stent retriever or direct aspiration techniques remains unclear.

Alberta Stroke Program Early CT Score Infarct Location Predicts Outcome Following M2 Occlusion.

Although it is generally thought that patients with distal middle cerebral artery (M2) occlusion have a favorable outcome, it has previously been demonstrated that a substantial minority will have a poor outcome by 90 days. We sought to determine whether assessing the Alberta Stroke Program Early CT Score (ASPECTS) infarct location allows for identifying patients at risk for a poor 90-day outcome. We retrospectively analyzed patients with isolated acute M2 occlusion admitted to a single academic center between January 2010 and August 2012. Infarct regions were defined according to ASPECTS system on the initial head computed tomography. Discriminant function analysis was used to define specific ASPECTS regions that are predictive of the 90-day functional outcome as defined as a modified Rankin Scale score of 3-6. In addition, logistic regression was used to model the relationship between each individual ASPECT region with poor outcome; for evaluation and comparison, odds ratios, c-statistics, and Akaike information criterion values were estimated for each region. Ninety patients with isolated M2 were included in the final analysis. ASPECTS score ≤6 predicted poor outcome in this cohort (sensitivity = 0.591, specificity = 0.838, p < 0.001). Using multiple approaches, we found that infarction in ASPECTS regions M3 and M6 were strongly associated with poor functional status by 90 days. Infarction in ASPECTS regions M3 and M6 are key predictors of functional outcome following isolated distal M2 occlusion. These findings will be helpful in stratifying outcomes if validated in future studies.

Abstract TP355: The Threshold of Baseline National Institutes of Health Stroke Scale Score to Predict Favorable Outcome After Medical Therapy in Patients With Acute M2 Occlusion

Objective: Although endovascular therapy is effective in acute ischemic stroke (AIS) patients with occlusion of the internal carotid artery or proximal middle cerebral artery (M1), the benefit are uncertain in those with the occlusion of distal middle cerebral artery (M2). To select the patient with potentially beneficial effects of endovascular therapy, we aimed to establish the threshold of NIHSS score as a predictive factor for favorable outcome in the patient with M2 occlusion treated with medical therapy alone. Methods: Among 2180 AIS patients admitted to our stroke center between October 2011 and February 2015 (ClinicalTrials.gov Identifier: NCT02251665), 72 patients met the following criteria; 1) arrived within 6 hours from the onset, 2) isolated M2 occlusion on MRA, and 3) ASPECTS of ≥ 6 on DWI. Three patients who received endovascular therapy were excluded. We evaluated predictive factors for favorable outcome, defined as a modified Rankin Scale (mRS) &lt;3 or equal to the premorbid mRS at 90 days after the onset. Results: A total of 69 patients (26 women, 79.9±8.6 years old) was analyzed, and favorable outcome was achieved in 38 patients (55%). The favorable outcome group had a younger age (median 78 vs 82, p=0.03) and a lower baseline NIHSS score (9.5 vs 15, p=0.07) than the poor outcome group. Using receiver operating characteristic curves analysis, the optimal cutoff value of NIHSS score to predict favorable outcome was 9 (AUC 0.626). After adjusting for age, sex, onset to door time, and intravenous thrombolysis, NIHSS&lt;9 was an independent predictor of favorable outcome (OR 3.95; 95% CI 1.04-18.22). Conclusion: In AIS patient with M2 occlusion who treated with medical therapy, the baseline NIHSS score &lt;9 was related to favorable outcome.

Manual aspiration thrombectomy using the Penumbra catheter in patients with acute M1 occlusion: A single-center study.

The efficacy and safety of aspiration thrombectomy using Penumbra in acute occlusion of intracranial artery have been proved in many previous studies. Our study aimed to retrospectively assess the efficacy and safety of a manual aspiration thrombectomy using Penumbra in patients with M1 occlusion. We conducted a retrospective review of 70 patients who underwent manual aspiration thrombectomy using Penumbra catheters for treatment of M1 occlusion between January 2012 and December 2014. We evaluated immediate angiographic results and clinical outcomes through review of patient electronic medical records. Male was the dominant sex in this study (M:F = 38:32) and median age was 72 (age range, 36-91). The rate of successful recanalization (TICI grade ≥2 b) was 91.4% (64/70). The successful recanalization rate by single Penumbra was 82.9% (58/70). Six patients were treated in combination with Solitaire stent. Median NIHSS score was 11 (range, 4-20) at admission and was 3 (range 0-23) at discharge. Favorable clinical outcomes (mRS score at three months ≤2) were seen in 42 patients (60%). Two patients were observed to have subarachnoid hemorrhage after the procedure. Another two patients died related to massive symptomatic hemorrhage, brain edema and herniation in the hospital. Manual aspiration thrombectomy appears to be safe and is capable of achieving a high rate of successful recanalization and favorable clinical outcomes in patients with M1 occlusion.