M1 Segment Of Middle Cerebral Artery Research Articles

Tortuosity of middle cerebral artery M1 segment and outcomes after mechanical thrombectomy.

We aimed to quantify the tortuosity of the middle cerebral artery (MCA) and assess its effects on radiological and clinical outcomes in patients with acute MCA occlusions who received mechanical thrombectomy (MT). This retrospective study enrolled 53 patients with acute ischemic stroke due to MCA M1 or M2 segment occlusion who underwent MT using stent retrievers (SRs). Tortuosity index (TI) was defined to quantify the tortuosity of the MCA M1 segment using the following formula: (actual distance / straight distance) × 100. For each patient, four TIs were measured in the anteroposterior and caudal views for both ipsilateral and contralateral sides to the occluded site (TI-APi, TI-APc, TI-CAUi, and TI-CAUc, respectively) using magnetic resonance angiography (MRA) or computed tomography angiography (CTA). We defined the first-pass effect (FPE) as first-pass mTICI classification ≥2b reperfusion. Patients who did not achieve FPE had significantly higher TI-APi (112 vs. 106; P = 0.004), TI-APc (111 vs. 105; P = 0.005), TI-CAUi (110 vs. 105; P = 0.002), and TI-CAUc (110 vs. 105; P = 0.001) than those who achieved FPE. In multivariable analysis, higher TI-APi, TI-CAUi, and TI-APc were independently associated with an increased rate of unsuccessful FPE (odds ratio (OR) [95% confidence interval (CI)]: 1.25 [1.02-1.61], 1.21 [1.01-1.45], and 1.27 [1.03-1.73], respectively). TI-CAUi, TI-APc, and TI-CAUc were also independent predictors of the occurrence of intracranial hemorrhage after MT (OR [95% CI]: 1.15 [1.01-1.38], 1.14 [1.01-1.38], 1.25 [1.02-1.52], respectively). The TIs of the MCA M1 segment on both ipsilateral and contralateral sides were associated with unfavourable outcomes after MT.

Infarct Patterns in Patients With Symptomatic Carotid Webs

Background Carotid webs (CaWs) may explain embolic strokes particularly in young patients with cerebral embolism of otherwise undetermined cause. We aim to describe the radiological patterns of infarction in patients with symptomatic CaWs. Methods Retrospective analysis of a symptomatic CaW database (September 2014–July 2019) from 2 comprehensive stroke centers. Magnetic resonance imaging scans were reviewed independently by 2 blinded raters. Patterns of acute infarction included territorial (involving ≥2 arterial subdivisions), cortical (affecting 1 arterial subdivision), 1or multiple small cortical infarcts, borderzone infarcts (cortical or internal), striatocapsular lacunes (<1.5 cm in size), or ≥1 deep vascular territory (involving subcortical contiguous deep structures). Different concomitant patterns could coexist. Prior strokes and leukoaraiosis severity (modified Fazekas scale) were evaluated. Results Forty symptomatic patients with CaW who had infarction were identified. The median age of patients was 49 years (interquartile range, 41–57 years), 22% were women, and 78% were of Black race. The median National Institute of Health Stroke Scale was 13 (interquartile range, 4–17), noncontrast Alberta Stroke Program Early CT Score was 8 (interquartile range, 7–8), and 13 (33%) patients received intravenous alteplase. Thirty‐four (85%) individuals presented with large vessel occlusion strokes (9% intracranial internal carotid artery, 62% middle cerebral artery M1 segment, 29% M2 segment). Sixty‐three percent of patients had right hemispheric strokes and 85% large vessel occlusion. Most patients (98%) had cortical infarcts: 30% were territorial, 38% affected 1 subdivision, and 63% had ≥1 small cortical infarct. Ten percent of the patients had infarcts involving borderzone areas. Fifteen percent of patients had striatocapsular lacunes, all of which had a concomitant cortical infarction. Five percent of patients had imaging evidence of previous strokes (all cortical and within the CaW vascular territory) and 20% had leukoaraiosis (18% grade 1 and 2% grade 2). Conclusion Acute cerebral infarction attributed to CaW were all compatible with an embolic mechanism. CaW should be considered in the workup of patients with cryptogenic strokes as a potential source of embolism.

Investigation of Current and Super‐Bore 088″ Treatment Strategies of Soft and Stiff Clots at Internal Carotid Artery and Middle Cerebral Artery Occlusion Sites in an In Vitro Thrombectomy Model

Background Various mechanical thrombectomy devices including stent retrievers (STRs), contact aspiration (CA) catheters, and balloon guide catheters (BGCs) are used in both isolation and combination for the treatment of acute ischemic stroke. A new generation of Super‐Bore 088″ aspiration catheters are being trialed clinically. We evaluated the in vitro revascularization performance of current and novel thrombectomy approaches in treating soft (red blood cell–rich) and stiff (fibrin/platelet‐rich) clots at internal carotid artery (ICA) and middle cerebral artery (MCA) occlusion sites. Methods National University of Ireland Galway Research Ethics Committee approved the study. Two human blood clot phenotypes were used to form ICA‐terminus (20‐mm) and MCA–M1 segment (10‐mm) occlusions in an in vitro thrombectomy model. Thrombectomy setups tested were CA: Millipede 088, SOFIA Plus+conventional guide catheter, SOFIA Plus+BGC and C ombination; Millipede 088+STR, SOFIA Plus+BGC+STR, SOFIA Plus+conventional guide catheter+STR. Ten replicates of each experiment were performed totaling 120 tests. Revascularization endpoints were first‐pass effect, final modified Thrombolysis in Cerebral Infarction (mTICI) 2c/3, and procedural‐related distal emboli. Results Millipede 088 CA achieved the highest first‐pass effect rate in ICA‐terminus (60%) and MCA–M1 segment (100%) occlusions and lowest number of procedural‐related distal emboli compared with all other device setups, followed by the combined Millipede 088+STR technique. Amongst the conventional techniques, higher first‐pass effect rates were observed with the combined technique using a BGC (40%) than 6F CA (20%) in ICA‐terminus occlusions whereas the reverse was seen in MCA–M1 segment occlusions, with 6F CA performing better than combined approaches (60% versus 50%). BGCs may provide a revascularization benefit in ICA‐terminus occlusions. Rates of first‐pass effect and final mTICI 2c/3 were better for stiff clots compared with soft clots for all treatment approaches at both occlusion sites. Conclusion Millipede 088 CA was the most effective technique for all clot types and occlusion locations. Across conventional techniques, CA seems to be more effective in MCA–M1 segment occlusions, while the combined technique performed better in ICA occlusions. Clot composition influences the success of each technique.

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.

Balloon expandable Stent utility for early Secondary Prevention of new Cerebral Ischemic events Caused by Intracranial Atherosclerotic Stenosis. Technical Nuances

Objective: Recurrent cerebral ischemic events are estimated to appear in between 12-15% of symptomatic intracranial atherosclerotic disease (ICAD), regardless of the use of leading pharmacological therapies. Balloon expandable stent (balloon mounted coronary stent) could represent a feasible alternative in this disease’s treatment. This study pretends to report the balloon-expandable placement experience in our center. Materials and Methods: A unicentric retrospective study dated between September 2009 and March 2018 was conducted. Patients previously diagnosed with ICAD and symptomatic stenosis treated with balloon-expandable stent were included. Clinical features, morbidity, mortality, short and long-term evolution, and pre-and post-treatment angiographic features were analyzed, as well as a mean 8 years-period follow-up. Data are presented as means, frequencies, and percentages for categorical variables, and ranks for continuous variables. Statistical analysis was carried by IBM SPSS Statistics Base V22.0 (IBM Corporation, Mexico). A Wilcoxon Signed-rank test statistical analysis was performed. Statistical significance was considered when a p-value lesser than 0.05 was measured for every result. Results: A total of 6 patients with 7 affected vessels were treated, with an average age of 62.7 years. Affected and treated vessels were located in the Internal Carotid Artery (ICA) segment in 42.9%, Vertebral Artery (VA) V4 segment in 14.3%, Middle Cerebral Artery (MCA) M1 segment in 28.5%, and Posterior Cerebral Artery (PCA) P1 segment in 14.3%. The incidence of peri-operatory thrombotic events was 0%. Intracranial hemorrhage presented in 0% of cases. Recurrent ischemic or thrombotic events were not reported in a 97-months mean follow-up. 71.4% of patients scored ≤2 in the modified Rankin Score (mRS) pre-treatment, in a 90 day and 12-month follow-up. 100% presented a favorable evolution with mRS ≤2. Restenosis cases were not reported in radiologic control and retreatment was not needed in a 97-month mean follow-up. Conclusions: This study suggests that balloon-expandable stent therapy with some technical endovascular variants for its navigation and placement could be a safe and effective alternative in the treatment of ICAD as a means of cerebral ischemic event early secondary prevention. We propose to consider not to limit endovascular treatment exclusively to those symptomatic ICAD patients refractory to medical-exclusive treatment, as a means to reduce the risk of presenting a new neurological deficit. Further expanded clinical trials are needed to confirm these findings and the advantage of this kind of stents against other kinds reported in the literature.

Machine Learning Automated Detection of Large Vessel Occlusion From Mobile Stroke Unit Computed Tomography Angiography.

Prehospital automated large vessel occlusion (LVO) detection in Mobile Stroke Units (MSUs) could accelerate identification and treatment of patients with LVO acute ischemic stroke. Here, we evaluate the performance of a machine learning (ML) model on CT angiograms (CTAs) obtained from 2 MSUs to detect LVO. Patients evaluated on MSUs in Houston and Los Angeles with out-of-hospital CTAs were identified. Anterior circulation LVO was defined as an occlusion of the intracranial internal carotid artery, middle cerebral artery (M1 or M2), or anterior cerebral artery vessels and determined by an expert human reader. A ML model to detect LVO was trained and tested on independent data sets consisting of in-hospital CTAs and then tested on MSU CTA images. Model performance was determined using area under the receiver-operator curve statistics. Among 68 patients with out-of-hospital MSU CTAs, 40% had an LVO. The most common occlusion location was the middle cerebral artery M1 segment (59%), followed by the internal carotid artery (30%), and middle cerebral artery M2 (11%). Median time from last known well to CTA imaging was 88.0 (interquartile range, 59.5-196.0) minutes. After training on 870 in-hospital CTAs, the ML model performed well in identifying LVO in a separate in-hospital data set of 441 images with area under receiver-operator curve of 0.84 (95% CI, 0.80-0.87). ML algorithm analysis time was under 1 minute. The performance of the ML model on the MSU CTA images was comparable with area under receiver-operator curve 0.80 (95% CI, 0.71-0.89). There was no significant difference in performance between the Houston and Los Angeles MSU CTA cohorts. In this study of patients evaluated on MSUs in 2 cities, a ML algorithm was able to accurately and rapidly detect LVO using prehospital CTA acquisitions.

The clinical and neuroradiological features of patients of coexisting atraumatic convexity subarachnoid hemorrhage and large artery atherosclerosis stroke: A retrospective observational study.

Atraumatic convexity subarachnoid hemorrhage (c-SAH) concomitant with large artery atherosclerosis (LAA) stroke has been rarely discussed in the literature. Our aim in this study is to characterize the clinical and neuroradiological features of patients with LAA stroke and c-SAH.A retrospective study from a single institution was performed between January 2016 and June 2020. Only patients diagnosed with c-SAH and LAA stoke were included in this study. The clinical presentation and neuroimaging finding were summarized by our experienced neurologists.In total, 12 patients (8 men, 4 women), ranging in age from 45 to 75 years, were identified. All of them had cardiovascular risk factors and hypertension was the commonest (50%). Almost all patients presented hemiparesis (91.7%). Other clinical presentations included, dysarthria (41.7%), hemianesthesia (33.3%), facial palsy (33.3%), aphasia (16.7%), and cognitive impairment (8.3%). Internal border-zone (IBZ) infarction and cortical border-zone (CBZ) infarction occurred in 12 and 3 patients, respectively. c-SAH might occurred in different cortical sulcis. Percentages of frontal lobe, parietal lobe and fronto-parietal lobe were 41.7% (n = 5), 25% (n = 3) and 25% (n = 3), respectively. All ischemic lesions were ipsilateral to the sites of c-SAH. High-grade atherosclerotic stenosis of large artery was detected in all patients. The M1 segment of middle cerebral artery (MCA) is the second most common atherosclerotic artery after internal carotid artery (ICA).Our data suggest that LAA stroke is always ipsilateral to the site of c-SAH. Severe atherosclerotic changes can also been seen in the M1 segment of MCA apart from extracranial ICA. Moreover, border zone infarction may be a specific form of infarct when c-SAH is confronted with LAA stroke.

Abstract 1122‐000164: Peri‐embolization Use of Stent Retrievers as a Rescue Tool in Patients with Subarachnoid Hemorrhage

Introduction : Coil migration after endovascular embolization of intracranial aneurysms is one of the periprocedural complications in 2–6% of patients. Stent retriever use is well‐established in treatment of ischemic stroke but has not been well established to address coil retrieval as rescue therapy. We describe three cases with successful removal of migrated coils using stent retrievers. Methods : A retrospective review at a single center university hospital was performed for all Neuro‐endovascular case log from December 2018 to November 2020. Cases of coil migration were reviewed and coil retraction with Stent Retriever with successful coil mass extraction was considered an endpoint. Number of attempts, types of stent retrievers used and time taken for extraction were noted. Results : Case 1: 56‐year‐old female presented with ruptured tri‐lobed 4 × 3 mm Anterior communicating artery aneurysm. Hunt and Hess (H&H) Grade 2. Modified Fisher scale (MFS) 4. Underwent primary coil embolization. Two 2mmx2cm Galaxy Orbit coils were deployed within aneurysm. During deployment of third coil the first two coils displaced out of the aneurysm migrating into left A2 segment. Stryker’s Trevo 3 × 20 mm stent retriever was used for retrieval of coils however they dislodged at the left internal carotid artery (ICA) terminus and migrated distally into the left middle cerebral artery (MCA) M2 superior division. Subsequently, Medtronic’s Solitaire 4 × 40 mm stent retriever was successfully deployed retrieving the migrated coils with full recanalization. Case 2: 64‐year‐old female presented with ruptured 3 × 5.3 mm right posterior communicating artery (Pcom) aneurysm. H&H 5 and MFS 4. Underwent primary coil embolization with placement of Galaxy Orbit 2.5mmx3.5cm coil. On follow up run, coil mass had migrated into the origin of right fetal Pcom. Migrated coil was successfully retrieved using Stryker’s 4 × 40 mm stent retriever with complete recanalization. Case 3: 65‐year‐old female with presented ruptured 8.5 × 6.8 mm right supraclinoid ICA irregular aneurysm. H&H Grade 1. MFS 3. Underwent primary coil embolization with one Galaxy coil (5mm x 10cm) with plan for future flow diversion. Two weeks later, patient experienced acute neurological worsening with new left sided hemiparesis and right gaze deviation. Imaging revealed acute occlusion of right middle cerebral artery M1 segment occlusion with thrombosed migrated coil. Patient underwent retrieval of the coil and superimposed thrombus utilizing Stryker’s Trevo (4*30 mm) stent retriever with resultant full recanalization. Conclusions : These cases demonstrate successful endovascular mechanical removal of migrated coils using stent retrievers. They add to the limited experience of stent retrievers utilization as effective tools for dealing with such complications.

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.

Initial Experience Performing Mechanical Thrombectomy With the CatchView Mini Device for Distal M2 Segment Middle Cerebral Artery Occlusions.

Background: Mechanical thrombectomy (MT) has become the standard of care for acute ischemic stroke due to large vessel occlusion; however, its safety and efficacy in patients with distal strokes remains unclear. In this study, we investigated the safety and efficacy of MT for distal middle cerebral artery (MCA) occlusions using the CatchView Mini (CVM; Balt, Montmorency, France).Methods: This was a prospective single-center analysis of patients with a single MCA-M2 occlusion treated with the CVM device. Consecutive patients were prospectively enrolled from October 2018 to March 2020. Efficacy outcomes included successful recanalization [modified Thrombolysis in Cerebral Infarction (mTICI) 2b/3], procedure times, and number of device passes. Clinical outcomes included National Institutes of Health Stroke Scale Score (NIHSS) at discharge, 90-day functional independence (modified Rankin Scale 0–2) and safety outcomes included hemorrhagic complications, and 90-day mortality.Results: A total of 45 patients (mean age: 74.0 ± 12.6; 53.3% [24/45] female) were included in the study. Upon admission, 33.3% (15/45) of patients were mRS 3–5; and mean NIHSS was 13.2 ± 4.2 Mean time from symptom onset to final angiography was 250.0 ± 83.4 min with a mean intervention duration of 34.0 ± 12.6 min. The mean number of device passes was 1.8 ± 1.5 final mTICI 2b/3 was achieved in 91.1% (41/45) of patients. Eight hemorrhagic complications (17.8%, 8/34) occurred, none of which were symptomatic. At 90-days, 57.8% (26/45) patients were functionally independent and the rate of mortality was 15.6% (7/45).Conclusions: The present analysis demonstrates a low risk profile and high recanalization success for patients with distal M2 occlusions treated with the CVM device.

Is the middle cerebral artery bifurcation aneurysm affected by morphological parameters of bifurcation?

Aneurysm formation is a multifactorial process involving genetic, anatomical and environmental risk factors. A research focusing on the relationship between the presence of aneurysm and the morphology of the arteries will help in the pathogenesis and prediction of intracranial aneurysms. In this study, the relationship between the presence of aneurysm and various morphological parameters of aneurysm-related arteries was evaluated in patients with saccular middle cerebral artery (MCA) bifurcation aneurysm. The archival images of 74 patients (62.2% women) were evaluated retrospectively. In this study, the angle between the ipsilateral MCA M1 segment and the dominant truncus (Φ1), the angle between the M1 segment and the recessive truncus (Φ2), and the bifurcation angle (Φ1 + Φ2) were compared. Bilateral internal carotid artery (ICA), MCA M1 segment, dominant and recessive truncus diameters and these diameters ratios were compared with the aneurysmal side and the contralateral side without aneurysm. When the dominant truncus, recessive truncus angles and bifurcation angle were compared, a significant difference was found on the aneurysmal side (p < 0.0001). In the receiver operating characteristic analysis, when the bifurcation angle of 147.5° was accepted as the limit value, 78.4% sensitivity, 79.7% specificity, 79.5% positive predictive value and 78.7% negative predictive value were determined (area under the curve: 0.85). Our study of the morphological features of arteries associated with MCA bifurcation aneurysms showed that the presence of MCA aneurysms was significantly associated with large bifurcation angles.

Treatment of a Giant Thrombotic M1 Segment Middle Cerebral Artery Aneurysm With Radial Artery Bypass and Distal Occlusion to Create a "Blind Sac" Following Endovascular Failure: 2-Dimensional Operative Video.

The case is of a 36-yr-old male with a previously coiled aneurysm arising from the proximal M1 segment of the middle cerebral artery (MCA) just beyond the internal carotid artery (ICA) bifurcation who presented to our institution with subjective left hemiparesis, headache, and vomiting. Physical exam revealed a left facial droop, but neurological exam was otherwise normal, including full motor strength. Neuroimaging showed a large partially thrombosed aneurysm recurrence, measuring 5.2 cm, with obstructive hydrocephalus. Cerebral angiogram showed filling within a small portion of the aneurysm and marked stenosis of the MCA beyond the neck. A ventriculostomy was placed, and he underwent a pterional craniotomy for high-flow radial artery bypass from the common carotid artery to an M2 branch of the MCA and clip placement. This case demonstrates the creation of a blind sac by placing a clip on the MCA distal to the aneurysm and proximal to the lenticulostriate arteries for the treatment of a giant proximal M1 segment aneurysm. Postoperative digital subtraction angiography shows the MCA distribution, including the lenticulostriate arteries, filling through the radial artery bypass, and anterograde flow through the ICA, which perfuses up to and including the anterior choroidal artery. There is no residual filling of the aneurysm. The patient remained at his neurological baseline postoperatively and required ventriculoperitoneal shunt placement for hydrocephalus. At outpatient follow-up, computed tomography imaging showed decreased size of the thrombosed aneurysm, measuring 4.5 cm, and he had no neurological deficits. The patient gave informed consent for surgery and deidentified video recording of this case.

Middle Cerebral Artery M2 Thrombectomy in the STRATIS Registry.

The safety and benefit of mechanical thrombectomy in the treatment of acute ischemic stroke patients with M2 segment middle cerebral artery occlusions remain uncertain. Here, we compare clinical and angiographic outcomes in M2 versus M1 occlusions in the STRATIS (Systematic Evaluation of Patients Treated With Neurothrombectomy Devices for Acute Ischemic Stroke) Registry. The STRATIS Registry was a prospective, multicenter, nonrandomized, observational study of acute ischemic stroke large vessel occlusion patients treated with the Solitaire stent-retriever as the first-choice therapy within 8 hours from symptoms onset. Primary outcome was defined as functional disability at 3 months measured by dichotomized modified Rankin Scale. Secondary outcomes included reperfusion rates and rates of symptomatic intracranial hemorrhage. A total of 984 patients were included, of which 538 (54.7%) had M1 and 170 (17.3%) had M2 occlusions. Baseline demographics were well balanced within the groups, with the exception of mean baseline National Institutes of Health Stroke Scale score which was significantly higher in the M1 population (17.3±5.5 versus 15.7±5.0, P≤0.001). No difference was seen in mean puncture to revascularization times between the cohorts (46.0±27.8 versus 45.1±29.5 minutes, P=0.75). Rates of successful reperfusion (modified Thrombolysis in Cerebral Infarction≥2b) were similar between the groups (91% versus 95%, P=0.09). M2 patients had significantly increased rates of symptomatic ICH at 24 hours (4% versus 1%, P=0.01). Rates of good functional outcome (modified Rankin Scale score of 0–2; 58% versus 59%, P=0.83) and mortality (15% versus 14%, P=0.75) were similar between the 2 groups. There was no difference in the association of outcome and onset to groin puncture or onset to successful reperfusion in M1 and M2 occlusions. In the STRATIS Registry, M2 occlusions achieved similar rates of successful reperfusion, good functional outcome, and mortality, although increased rates of symptomatic ICH were demonstrated when compared with M1 occlusions. The time dependence of benefit was also similar between the 2 groups. Further studies are needed to understand the benefit of mechanical thrombectomy for M2 occlusions. URL: https://www.clinicaltrials.gov; Unique identifier: NCT02239640.

Diffusion- and Susceptibility Weighted Imaging Mismatch Correlates With Collateral Circulation and Prognosis After Middle Cerebral Artery M1-Segment Occlusion.

Objective: To explore the relation between diffusion-weighted and susceptibility weighted imaging (DWI-SWI) mismatch and collateral circulation or prognosis in patients with occluded M1 segments of middle cerebral artery (MCA).Methods: We enrolled 59 patients with MCA M1-segment occlusion for a retrospective review of baseline clinical and imaging data. As markers of circulatory collaterals, prominent laterality of posterior (PLPCA) and anterior (PLACA) cerebral arteries on magnetic resonance angiography (MRA) studies and a hyperintense vessel sign (HVS) on T2 fluid-attenuated inversion recovery (FLAIR) images were collectively scored. The extent of acute cerebral infarction was then quantified on DWI, using the Alberta Stroke Program Early CT Score (DWI-ASPECTS). Hypointensity vessel sign prominence (PVS) was also evaluated by SWI and similarly scored (SWI-ASPECT) to calculate DWI-SWI mismatch [(DWI-ASPECTS) – (SWI-ASPECTS)], ranging from −10 to 10 points.Results: DWI-SWI mismatch showed significant associations with PLPCA, PLACA, HVS prominence, and collective collateral scores (all, p < 0.05). National Institutes of Health Stroke Scale (NIHSS), DWI-SWI mismatch, and DWI-ASPECTS also differed significantly according to patient prognosis (good vs. poor) after MCA M1-segment occlusion (p < 0.05). In binary logistic regression analyses, NIHSS and DWI-SWI mismatch emerged as independent prognostic factors (p < 0.05).Conclusions: Collateral circulation may be an important aspect of DWI-SWI mismatch, which in this study correlated with prognostic outcomes of MCA M1-segment occlusion.

Points to consider when evaluating three-dimensional digital subtraction angiography of intracranial aneurysms and their effects on treatment

Background/aimIn this study, we aimed to investigate what should be regarded as potential determinants of treatment strategies when evaluating 3D digital subtraction angiography (DSA) images.Material and methodsOur inclusion criteria were as follows: (1) presence of at least one intracranial aneurysm demonstrated by conventional angiography, (2) having both 2D and 3D images, and (3) being over 18 years old. First, two-dimensional (2D) and then 3D angiography images of 226 aneurysms of 150 patients were scanned. Morphological characteristics such as size, configurations, relationship with parent artery, baby counts, and other incidental findings were determined.ResultsOf the 226 aneurysms, 11 (4.9%) were only detected on 3D images. Four of these 11 additional aneurysms were believed to be babies of other aneurysms seen in 2D images. Middle cerebral artery (MCA) M1 segment was the most common localization in terms of missed aneurysms. Of the 28 aneurysms located in the communicating segment of the internal carotid artery, the absolute locations of 7 (25%) could not be detected in 2D images or detected in the wrong location. Of the 24 aneurysms located in the ophthalmic segment, the origin of 8 (33%) could not be clearly identified in 2D images. Truncus relationships of MCAs bifurcation/trifurcation aneurysms were seen in 41 of 63 aneurysms (65%) on 2D images, whereas all were confirmed on 3D images. Fenestrations not seen in 2D images were identified in 3D images of 4 patients (3%).ConclusionThe superiority of 3D images compared to 2D images in determining the morphologic characteristics of intracranial aneurysms has been known for a long time. The contribution of 3D images to the treatment can be summarized as evaluating the parent artery relationship, revealing the number and shapes of aneurysm babies more clearly, detecting fenestrations, and shortening procedure time by finding the correct working angle.

Validation of a Deep Learning Tool in the Detection of Intracranial Hemorrhage and Large Vessel Occlusion.

Purpose: Recently developed machine-learning algorithms have demonstrated strong performance in the detection of intracranial hemorrhage (ICH) and large vessel occlusion (LVO). However, their generalizability is often limited by geographic bias of studies. The aim of this study was to validate a commercially available deep learning-based tool in the detection of both ICH and LVO across multiple hospital sites and vendors throughout the U.S.Materials and Methods: This was a retrospective and multicenter study using anonymized data from two institutions. Eight hundred fourteen non-contrast CT cases and 378 CT angiography cases were analyzed to evaluate ICH and LVO, respectively. The tool's ability to detect and quantify ICH, LVO, and their various subtypes was assessed among multiple CT vendors and hospitals across the United States. Ground truth was based off imaging interpretations from two board-certified neuroradiologists.Results: There were 255 positive and 559 negative ICH cases. Accuracy was 95.6%, sensitivity was 91.4%, and specificity was 97.5% for the ICH tool. ICH was further stratified into the following subtypes: intraparenchymal, intraventricular, epidural/subdural, and subarachnoid with true positive rates of 92.9, 100, 94.3, and 89.9%, respectively. ICH true positive rates by volume [small (<5 mL), medium (5–25 mL), and large (>25 mL)] were 71.8, 100, and 100%, respectively. There were 156 positive and 222 negative LVO cases. The LVO tool demonstrated an accuracy of 98.1%, sensitivity of 98.1%, and specificity of 98.2%. A subset of 55 randomly selected cases were also assessed for LVO detection at various sites, including the distal internal carotid artery, middle cerebral artery M1 segment, proximal middle cerebral artery M2 segment, and distal middle cerebral artery M2 segment with an accuracy of 97.0%, sensitivity of 94.3%, and specificity of 97.4%.Conclusion: Deep learning tools can be effective in the detection of both ICH and LVO across a wide variety of hospital systems. While some limitations were identified, specifically in the detection of small ICH and distal M2 occlusion, this study highlights a deep learning tool that can assist radiologists in the detection of emergent findings in a variety of practice settings.

Safety and efficacy of the Low-Profile Visualized Intraluminal Support stent in treating intracranial atherosclerotic stenosis

PurposeThe performance of the Low-Profile Visualized Intraluminal Support (LVIS) stent deployed following balloon angioplasty is unknown in treating intracranial atherosclerotic stenosis, and this study was to investigate the safety and efficacy of the LVIS stent in treating intracranial atherosclerotic stenosis in the middle cerebral artery M1 segment. MethodsThirty-five patients were enrolled with 35 atherosclerotic stenoses at the M1 segment. The stenosis was about 75% in 16 patients, 80% in 15, and 90% in the rest four. The LVIS stent was used to treat these patients. ResultsThe success rate of stenting was 97.1%. The stenting procedure was failed in one patient because of intraprocedural dissection of the stenotic (75%) segment, resulting in a 30-day periprocedural complication rate of 2.9% (1/35). Before stenting, the stenosis rate ranged 75%–90% (mean 78.9%±4.7%), and after stenting, the diameter of the stented segment was significantly (P<0.0001) increased to 1.5–3.4mm (mean 2.1±0.32mm) ranging 68.2%–100% (mean 94.0%±5.8%) of the normal arterial diameter, with the residual stenosis ranging 0–31.8% (median 4.8%, IQR 2.4%–7.3%). Follow-up was performed at 6–20 months (mean 8.5) after stenting. One patient (2.9%) had occlusion of the stented M1 segment with no symptoms, and two patients (5.7%) had slight asymptomatic instent stenosis (40%) at the M1 segment, with the instent restenosis and occlusion rate of 8.6% (3/35). ConclusionThe braided LVIS stent can be safely applied for treatment of intracranial atherosclerotic stenosis in the middle cerebral artery with good safety and efficacy immediately after stenting and at follow-up.

Evaluating the Velocity and Extent of Cortical Venous Filling in Patients With Severe Middle Cerebral Artery Stenosis or Occlusion.

Objective: To investigate the velocity and extent of cortical venous filling (CVF) and its association with clinical manifestations in patients with severe stenosis or occlusion of the middle cerebral artery (MCA) using dynamic computed tomography angiography (CTA).Methods: Fifty-eight patients (36 symptomatic and 22 asymptomatic) with severe unilateral stenosis (≥70%) or occlusion of the MCA M1 segment who underwent dynamic CTA were included. Collateral status, antegrade flow, and CVF of each patient were observed using dynamic CTA. Three types of cortical veins were selected to observe the extent of CVF, and the absence of CVF (CVF-) was recorded. Based on the appearance of CVF in the superior sagittal sinus, instances of CVF, including early (CVF1), peak (CVF2), and late (CVF3) venous phases, were recorded. The differences in CVF times between the affected and contralateral hemispheres were represented as rCVFs, and CVF velocity was defined compared to the median time of each rCVF.Results: All CVF times in the affected hemisphere were longer than those in the contralateral hemisphere (p < 0.05). Patients with symptomatic MCA stenosis had more ipsilateral CVF- (p = 0.02) and more delayed CVF at rCVF2 and rCVF21 (rCVF2-rCVF1) (p = 0.03 and 0.001, respectively) compared to those with asymptomatic MCA stenosis. For symptomatic patients, fast CVF at rCVF21 was associated with poor collateral status (odds ratio [OR] 6.42, 95% confidence interval [CI] 1.37–30.05, p = 0.02), and ipsilateral CVF- in two cortical veins was associated with poor 3-month outcomes (adjusted OR 0.025, 95% CI 0.002–0.33, p = 0.005).Conclusions: Complete and fast CVF is essential for patients with symptomatic MCA stenosis or occlusion. The clinical value of additional CVF assessment should be explored in future studies to identify patients with severe MCA stenosis or occlusion at a higher risk of stroke occurrence and poor recovery.

Abstract P517: The Effect of Unfavorable Vascular Anatomy on Mechanical Thrombectomy for Middle Cerebral Artery Occlusion Strokes Preliminary Evaluation of the AIM2 Score System

Background: Time to reperfusion remains one of the strongest predictors of outcome in large vessel occlusion strokes (LVOS). Herein, we aim to assess the impact of unfavorable vascular anatomy on mechanical thrombectomy (MT) number of passes and procedural times. Methods: Retrospectively review of a prospective MT database spanning January-July 2018 including acute LVOS involving the middle cerebral artery-M1 segment and available baseline CT angiography. The AIM2 score (Table 1) was applied with patients categorized as favorable (AIM2: 0-2) versus unfavorable (AIM2: &gt;=3) anatomy. The primary outcome was the rate of &lt;3 device passes. Secondary outcomes included procedural times and the rates of successful reperfusion (mTICI2b-3) and 90-day mRS 0-2. Safety measures included rates of sICH and 90-day mortality. Results: Patients with unfavorable anatomy (n=15) were significantly younger (52±19, p=0.02) and had lower rates of hypertension (46% vs 80%, p=0.01) and smoking (0% vs 39%, p&lt;0.001) versus those with favorable anatomy (n=50). Successful reperfusion with &lt;3 passes was more often achieved with AIM2 scores 0-2 vs. ≥3 (84% vs 60%, p=0.04). There were no significant difference in other outcome measures (Table 2). Conclusions: The AIM2 score system represents a simple method for the systematically evaluation of vascular anatomy in MT and correlates significantly with increased number of MT passes.