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Background: Numerous questions regarding procedural details of distal stroke thrombectomy remain unanswered. This study assesses the effect of anesthetic strategies on procedural, clinical and safety outcomes following thrombectomy for distal medium vessel occlusions (DMVOs)., Methods: Patients with isolated DMVO stroke from the TOPMOST registry were analyzed with regard to anesthetic strategies (ie, conscious sedation (CS), local (LA) or general anesthesia (GA)). Occlusions were in the P2/P3 or A2-A4 segments of the posterior and anterior cerebral arteries (PCA and ACA), respectively. The primary endpoint was the rate of complete reperfusion (modified Thrombolysis in Cerebral Infarction score 3) and the secondary endpoint was the rate of modified Rankin Scale score 0-1. Safety endpoints were the occurrence of symptomatic intracranial hemorrhage and mortality., Results: Overall, 233 patients were included. The median age was 75 years (range 64-82), 50.6% (n=118) were female, and the baseline National Institutes of Health Stroke Scale score was 8 (IQR 4-12). DMVOs were in the PCA in 59.7% (n=139) and in the ACA in 40.3% (n=94). Thrombectomy was performed under LA±CS (51.1%, n=119) and GA (48.9%, n=114). Complete reperfusion was reached in 73.9% (n=88) and 71.9% (n=82) in the LA±CS and GA groups, respectively (P=0.729). In subgroup analysis, thrombectomy for ACA DMVO favored GA over LA±CS (aOR 3.07, 95% CI 1.24 to 7.57, P=0.015). Rates of secondary and safety outcomes were similar in the LA±CS and GA groups., Conclusion: LA±CS compared with GA resulted in similar reperfusion rates after thrombectomy for DMVO stroke of the ACA and PCA. GA may facilitate achieving complete reperfusion in DMVO stroke of the ACA. Safety and functional long-term outcomes were comparable in both groups., Competing Interests: Competing interests: JF: Consulting fees from Cerenovus, Medtronic, Phenox, Penumbra, Roche, Tonbridge; participation on a Data Safety Monitoring Board of Stryker and Phenox; stock holdings for Tegus and Vastrax, Associate Editor for JNIS. RC: Consultant and/or proctor for BALT, Stryker, Microvention, Rapid Medical, Siemens Medical Systems. MM: Institutional grants: Balt, Medtronic, MicroVention, Stryker. AG: Proctor/consultant/speaker for Medtronic, Stryker and Penumbra. MM-G: Consultant for Medtronic, Stryker and Balt, Associate Editor for JNIS. FD: Grant from Cerenovus/ Johnson&Johnson, consulting fees from Cerus Endovascular, Balt, Cerenovus/Johnson&Johnson, honoraria for lectures Asahi, Cerenovus/Johnson&Johnson, Acandis, Stryker, Advisory Board Cerenovus Johnson&Johsno, Associate Editor for JNIS. JK: Grants from SAMW/Bangerter, grants from Swiss Stroke Society, and grants from Clinical Trial Unit Bern outside the submitted work. LLLY: Consultant for Stryker, SeeMode, and See-mode, Cerenovus honoraria, Jakarta Neuroupdate honorarium, Research Support from National Medical research Council (NMRC) Singapore and Ministry of Health (MOH). Stock holdings for Cereflo, SNVIS vice president. BT: Grants from ExxonMobil-NUS Research Fellowship for Clinicians. PN: Consultant/Proctor for Balt, Cerenovus, Medtronic, Penumbra, Stryker. AG: Honoraria for lectures from Stryker Neurovascular, Medtronic, Penumbra. BG: grants from the French Ministry of Health and is the primary investigator of the TITAN, DIRECT ANGIO, and IA-RESCUE trial; consulting fees from Air Liquide, MIVI, Medtronic, Microvention, and Penumbra. LM: Compensation as a speaker for Balt Prime. GB: Compensation as a speaker for Balt Prime., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Background and Purpose: Vasospasm is a common complication of endovascular therapy (EVT). There is a lack of understanding of risk factors for periprocedural vasospasm. Here, we aimed to identify factors associated with vasospasm in patients with acute ischemic stroke who undergo EVT., Methods: We conducted a retrospective single-center analysis of patients receiving EVT for anterior circulation vessel occlusion between January 2015 and December 2021. Patients were excluded if they showed signs of intracranial atherosclerotic disease (ICAD) or if they underwent intra-arterial thrombolysis. Study groups were defined as patients developing vasospasm during EVT (V+) and patients who did not (V-). The study groups were compared in univariable analysis. Multivariable regression models were developed to predict the patient's risk for developing vasospasm based on pre-identified potential prognostic factors. The secondary endpoint was clinical outcome defined as the modified Rankin Scale (mRS) difference between pre-stroke mRS and discharge mRS (delta mRS) and likelihood of successful reperfusion (TICI 2b/3)., Results: In total, 132/1768 patients (7.5%) developed vasospasm during EVT. Vasospasm was more likely to occur in EVT with multiple thrombectomy attempts and after several stent retriever maneuvers. Factors associated with developing vasospasm were younger age (OR = 0.967, 95% CI = 0.96-0.98) and lower pre-stroke mRS (OR = 0.759, 95% CI = 0.63-0.91). The prediction model incorporating patient age, pre-stroke mRS, stent retriever thrombectomy attempts, and total attempts as prognostic factors was found to predict vasospasm with good accuracy (AUC = 0.714, 95% CI = 0.709-0.720). V+ patients showed higher median (IQR) delta mRS (2 (1-4) vs 2 (1-3); p  = 0.014). There was no difference in successful reperfusion (TICI 2b-3) between those with or without vasospasm., Conclusion: Vasospasm was a common complication in EVT affecting younger and previously healthy patients. Presence of vasospasm did not reduce the likelihood of successful reperfusion. As independent predictors, patient age, pre-stroke mRS, thrombectomy maneuvers, and stent retriever attempts predict the occurrence of vasospasm during EVT with good accuracy.

Background: Radiological neuro-interventions, especially endovascular stroke treatment (EST), are increasing in case numbers worldwide with increasing occupational radiation exposure. Aim of this study was to define the radiation exposure of neurointerventionalists (NI) during EST and to compare the accumulated dose reaching the left arm with the left temple., Methods: This is a prospective observational study in a tertiary stroke center conducted between 11/2021 and 07/2022. Radiation exposure was measured using real time dosimetry with dosimeters being carried by the NI during EST simultaneously at the left temple and left arm. The effective dose [µSV] per dose area product (DAP) and potential influencing factors were compared in univariate analysis between the two dosimeter positions., Results: In total, 82 ESTs were analyzed with a median DAP of 6179 µGy*m 2 (IQR 3271 µGy*m 2 -11720 µGy*m 2 ). The accumulated dose at the left arm and left temple correlated with the DAP and fluoroscopy time of the EST (DAP and arm: p = 0.01, DAP and temple: p = 0.006). The radiation exposure (RE) showed a wide range and did not differ between the two dosimeter positions (median, IQR arm 7 µSV, IQR 3.1-16.9 µSV, min. 0.3 µSV max. 64.5 µSV) vs. head 7 µSv, IQR 3.2-17.4 µSV, min. 0.38 µSV, max. 48.6 µSV, p = 0.94). Occupational RE depends on the number of thrombectomy attempts, but not the target vessel occlusion location or the NI's body height., Conclusion: Neurointerventionalists experience a generally low but very variable radiation exposure during EST, which depends on the intervention's fluoroscopy time and dose area product as well as thrombectomy attempts but does not differ between left temple and left arm., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Introduction: Endovascular stroke treatment (EST) is commonly performed for acute basilar artery occlusion (BAO). We aimed to identify the role of the exact location of BAO in patients receiving EST regarding the stroke etiology, recanalization success and prediction of favorable clinical outcome., Methods: Retrospective analysis of 191 consecutive patients treated for BAO with EST from 01/2013 until 06/2021 in a tertiary stroke center. Groups were defined according to exact location of BAO in I: proximal third, II: middle third, III: distal third and IV: tip of the basilar artery. Univariate and multivariate analyses were performed for BAO location comparing stroke etiology, recanalization result and favorable clinical outcome according to mRS 0-3 90 days after stroke onset., Results: Occlusion sides types I-IV were evenly distributed (37, 36, 60 and 58 patients). Types I and II were more often associated with large artery atherosclerosis (50 vs. 10 patients, p < 0.001). Distal/tip occlusion (types III/IV) occurred mostly in cardiac embolism or embolic stroke of unknown source (89 vs. 12 in types I/II, p < 0.001). Occlusion site correlated with the underlying stroke etiology (AUC [Area under the curve] 0.89, p < 0.0001, OR [odds ratio] for embolism in type IV: 245). Recanalization rates were higher in patients with distal occlusions (type III/IV OR 3.76, CI [95% confidence interval] 1.51-9.53, p = 0.0076). The BAO site is not predicting favorable clinical outcome., Conclusion: The exact basilar artery occlusion site in patients eligible for endovascular stroke treatment reflects the stroke etiology and is associated with differing recanalization success but does not predict favorable clinical outcome., (© 2022. The Author(s).)

Background Evidence supporting a potential benefit of thrombectomy for distal medium vessel occlusions (DMVOs) of the anterior cerebral artery (ACA) is, to the knowledge of the authors, unknown. Purpose To compare the clinical and safety outcomes between mechanical thrombectomy (MT) and best medical treatment (BMT) with or without intravenous thrombolysis for primary isolated ACA DMVOs. Materials and Methods Treatment for Primary Medium Vessel Occlusion Stroke, or TOPMOST, is an international, retrospective, multicenter, observational registry of patients treated for DMVO in daily practice. Patients treated with thrombectomy or BMT alone for primary ACA DMVO distal to the A1 segment between January 2013 and October 2021 were analyzed and compared by one-to-one propensity score matching (PSM). Early outcome was measured by the median improvement of National Institutes of Health Stroke Scale (NIHSS) scores at 24 hours. Favorable functional outcome was defined as modified Rankin scale scores of 0-2 at 90 days. Safety was assessed by the occurrence of symptomatic intracerebral hemorrhage and mortality. Results Of 154 patients (median age, 77 years; quartile 1 [Q1] to quartile 3 [Q3], 66-84 years; 80 men; 94 patients with MT; 60 patients with BMT) who met the inclusion criteria, 110 patients (median age, 76 years; Q1-Q3, 67-83 years; 50 men; 55 patients with MT; 55 patients with BMT) were matched. DMVOs were in A2 (82 patients; 53%), A3 (69 patients; 45%), and A3 (three patients; 2%). After PSM, the median 24-hour NIHSS point decrease was -2 (Q1-Q3, -4 to 0) in the thrombectomy and -1 (Q1-Q3, -4 to 1.25) in the BMT cohort ( P = .52). Favorable functional outcome (MT vs BMT, 18 of 37 [49%] vs 19 of 39 [49%], respectively; P = .99) and mortality (MT vs BMT, eight of 37 [22%] vs 12 of 39 [31%], respectively; P = .36) were similar in both groups. Symptomatic intracranial hemorrhage occurred in three (2%) of 154 patients. Conclusion Thrombectomy appears to be a safe and technically feasible treatment option for primary isolated anterior cerebral artery occlusions in the A2 and A3 segment with clinical outcomes similar to best medical treatment with and without intravenous thrombolysis. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Zhu and Wang in this issue.

Purpose: Unfavorable vascular anatomy can impede thrombectomy in patients with acute ischemic stroke. The aim of this study was to determine the prevalence of aortic arch types, aortic arch branching patterns and supra-aortic arterial tortuosity in stroke patients with large vessel occlusion., Methods: Computed tomography (CT) and magnetic resonance (MR) images of all stroke patients in an institutional thrombectomy registry were retrospectively reviewed. Aortic arch types and branching patterns of all patients were determined. In patients with anterior circulation stroke, the prevalence of tortuosity (elongation, kinking or coiling) of the supra-aortic arteries of the affected side was additionally assessed., Results: A total of 1705 aortic arches were evaluated. Frequency of aortic arch types I, II and III were 777 (45.6%), 585 (34.3%) and 340 (19.9%), respectively. In 1232 cases (72.3%), there was a normal branching pattern of the aortic arch. The brachiocephalic trunk and the left common carotid artery had a common origin in 258 cases (15.1%). In 209 cases (12.3%), the left common carotid artery arose from the brachiocephalic trunk. Of 1598 analyzed brachiocephalic trunks and/or common carotid arteries, 844 (52.8%) had no vessel tortuosity, 592 (37.0%) had elongation, 155 (9.7%) had kinking, and 7 (0.4%) had coiling. Of 1311 analyzed internal carotid arteries, 471 (35.9%) had no vessel tortuosity, 589 (44.9%) had elongation, 150 (11.4%) had kinking, and 101 (7.7%) had coiling., Conclusion: With 20%, type III aortic arches are found in a relevant proportion of stroke patients eligible for mechanical thrombectomy. Nearly half of the stroke patients present with supra-aortic arterial tortuosity, mostly arterial elongation., (© 2022. The Author(s).)

Purpose: The treatment of vasospasms during endovascular stroke treatment (EST) with intra-arterial nimodipine (NM) is routinely performed. However, the efficacy of resolving iatrogenic vasospasms during the angiographic intervention and the infarct development in follow-up imaging after EST has not been studied yet., Methods: Retrospective single-center analysis of patients receiving EST for anterior circulation vessel occlusion between 01/2015 and 12/2021. The primary endpoint was ASPECTS in follow-up imaging. Secondary endpoints were the clinical outcome (combined endpoint NIHSS 24 h after EST and difference between modified Rankin Scale (mRS) before stroke and at discharge (delta mRS)) and intracranial hemorrhage (ICH) in follow-up imaging. Patients with vasospasms receiving NM (NM+) or not (NM-) were compared in univariate analysis., Results: Vasospasms occurred in 79/1283 patients (6.2%), who consecutively received intra-arterial NM during EST. The targeted vasospasm angiographically resolved in 84% (66/79) under NM therapy. ASPECTS was lower in follow-up imaging after vasospasms and NM-treatment (NM - 7 (6-9), NM + 6 (4.5-8), p = 0.013) and the clinical outcome was worse (NIHSS 24 h after EST was higher in patients treated with NM (median, IQR; NM+: 14, 5-21 vs. NM-: 9, 3-18; p = 0.004), delta-mRS was higher in the NM + group (median, IQR; NM+: 3, 1-4 vs. NM-: 2, 1-2; p = 0.011)). Any ICH (NM+: 27/79, 34.2% vs. NM-: 356/1204, 29.6%; p = 0.386) and symptomatic ICH (NM+: 2/79, 2.5% vs. NM-: 21/1204, 1.7%; p = 0.609) was equally distributed between groups., Conclusion: Intra-arterial nimodipine during EST resolves iatrogenic vasospasms efficiently during EST without increasing intracranial hemorrhage rates. However, patients with vasospasms and NM treatment show higher infarct growth resulting in lower ASPECTS in follow-up imaging., (© 2023. The Author(s).)

Background and Purpose: Prediction of futile recanalization (FR), i.e. failure of long-term functional independence despite full reperfusion in mechanical thrombectomy (MT), is instrumental in patients undergoing endovascular therapy., Methods: Retrospective single-center analysis of patients treated for anterior circulation LVO ensuing successful MT (mTICI 2c-3) between January 2014 and April 2019. FR was defined as modified Rankin Scale (mRS) 90 days after stroke onset > 2 or mRS > pre-stroke mRS. Multivariable analysis was performed with variables available before treatment initiation regarding their association with FR. Performance of the regression model was then compared with a model including parameters available after MT., Results: Successful MT was experienced by 549/1146 patients in total. FR occurred in 262/549 (47.7%) patients. Independent predictors of FR were male sex, odds ratio (OR) with 95% confidence interval (CI) 1.98 (1.31-3.05, p 0.001), age (OR 1.05, CI 1.03-1.07, p < 0.001), NIHSS on admission (OR 1.10, CI 1.06-1.13, p < 0.001), pre-stroke mRS (OR 1.22, CI 1.03-1.46, p 0.025), neutrophile-lymphocyte ratio (OR 1.03, CI 1.00-1.06, p 0.022), baseline ASPECTS (OR 0.77, CI 0.68-0.88, p < 0.001), and absence of bridging i.v. lysis (OR 1.62, 1.09-2.42, p 0.016). The prediction model's Area Under the Curve was 0.78 (CI 0.74-0.82) and increased with parameters available after MT to 0.86 (CI 0.83-0.89) with failure of early neurological improvement being the most important predictor of FR (OR 15.0, CI 7.2-33.8)., Conclusion: A variety of preinterventional factors may predict FR with substantial certainty, but the prediction model can still be improved by considering parameters only available after MT, in particular early neurological improvement., (© 2022. The Author(s).)

For advanced territorial ischemia numerous retrospective and prospective studies have shown a positive effect of mechanical thrombectomy (MT) compared to best medicinal treatment alone. For patients with minor stroke (NIHSS < 6) there is currently a lack of evidence for MT. Appropriate study protocols must differentiate between patients with large vessel occlusion with disproportionately mild symptoms and more distal vascular occlusion and therefore correspondingly fewer clinical symptoms. The role of intravenous lysis treatment before MT as bridging lysis also currently retains its general recommendation, as large studies could not show a uniform noninferiority of MT alone. In addition, the use of intra-arterial lysis after successful MT offers a promising approach, which still needs to be evaluated. Novel aspiration catheters and stent-retrievers as well as competing thrombectomy techniques can be compared by the first pass effect, the successful recanalization with only one attempt at thrombectomy. Contact aspiration and stent-retriever thrombectomy under aspiration are equivalent and established thrombectomy procedures. For the latter, several detailed maneuver tactics are described for improvement of thrombectomy success. Also, in retrospective studies the combination with a balloon-guided catheter promises a further improvement of recanalization results. In the case of failure of supra-aortic vessel probing with inguinal access, radial access and direct carotid puncture are alternative access routes. Recent studies on ICA stenting with tandem occlusions showed a benefit of stents without an increased risk for symptomatic intracranial hemorrhage. The retrograde approach, to first treat the intracranial vessel occlusion and then the carotid stenosis, seems to be advantageous., (© 2022. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Background: The optimal endovascular strategy for reperfusing distal medium-vessel occlusions (DMVO) remains unknown. This study evaluates angiographic and clinical outcomes of thrombectomy strategies in DMVO stroke of the posterior circulation., Methods: TOPMOST (Treatment for Primary Medium Vessel Occlusion Stroke) is an international, retrospective, multicenter, observational registry of patients treated for DMVO between January 2014 and June 2020. This study analyzed endovascularly treated isolated primary DMVO of the posterior cerebral artery in the P2 and P3 segment. Technical feasibility was evaluated with the first-pass effect defined as a modified Thrombolysis in Cerebral Infarction Scale score of 3. Rates of early neurological improvement and functional modified Rankin Scale scores at 90 days were compared. Safety was assessed by the occurrence of symptomatic intracranial hemorrhage and intervention-related serious adverse events., Results: A total of 141 patients met the inclusion criteria and were treated endovascularly for primary isolated DMVO in the P2 (84.4%, 119) or P3 segment (15.6%, 22) of the posterior cerebral artery. The median age was 75 (IQR, 62-81), and 45.4% (64) were female. The initial reperfusion strategy was aspiration only in 29% (41) and stent retriever in 71% (100), both achieving similar first-pass effect rates of 53.7% (22) and 44% (44; P =0.297), respectively. There were no significant differences in early neurological improvement (aspiration: 64.7% versus stent retriever: 52.2%; P =0.933) and modified Rankin Scale rates (modified Rankin Scale score 0-1, aspiration: 60.5% versus stent retriever 68.6%; P =0.4). In multivariable logistic regression analysis, the time from groin puncture to recanalization was associated with the first-pass effect (adjusted odds ratio, 0.97 [95% CI, 0.95-0.99]; P <0.001) that in turn was associated with early neurological improvement (aOR, 3.27 [95% CI, 1.16-9.21]; P <0.025). Symptomatic intracranial hemorrhage occurred in 2.8% (4) of all cases., Conclusions: Both first-pass aspiration and stent retriever thrombectomy for primary isolated posterior circulation DMVO seem to be safe and technically feasible leading to similar favorable rates of angiographic and clinical outcome.

Background and Purpose: Information of collateral flow may help to determine eligibility for thrombectomy. Our aim was to identify CT perfusion-based surrogate parameters of good collateral status in acute anterior circulation ischemic stroke., Materials and Methods: In this retrospective study, we assessed the collateral status of 214 patients who presented with acute ischemic stroke due to occlusion of the MCA M1 segment or the carotid terminus. Collaterals were assessed on dynamic CTA images analogous to the multiphase CTA score by Menon et al. CT perfusion parameters (time-to-maximum, relative CBF, hypoperfusion intensity ratio, and CBV-index) were assessed with RAPID software. The Spearman rank correlation and receiver operating characteristic analyses were performed to identify the parameters that correlate with collateral scores and good collateral supply (defined as a collateral score of ≥4)., Results: The Spearman rank correlation was highest for a relative CBF < 38% volume (ρ = -0.66, P  < .001), followed by the hypoperfusion intensity ratio (ρ = -0.49, P  < .001), CBV-index (ρ = 0.51, P  < .001), and time-to-maximum > 8 seconds (ρ = -0.54, P  < .001). Good collateral status was better identified by a relative CBF < 38% at a lesion size <27 mL (sensitivity of 75%, specificity of 80%) compared with a hypoperfusion intensity ratio of <0.4 (sensitivity of 75%, specificity of 62%), CBV-index of >0.8 (sensitivity of 60%, specificity of 78%), and time-to-maximum > 8 seconds (sensitivity of 68%, specificity of 76%)., Conclusions: Automated CT perfusion analysis allows accurate identification of collateral status in acute ischemic stroke. A relative CBF < 38% may be a better perfusion-based indicator of good collateral supply compared with time-to-maximum, the hypoperfusion intensity ratio, and the CBV-index., (© 2022 by American Journal of Neuroradiology.)

Background: Whether to approach distal occlusions endovascularly or not in medium-sized vessels secondary to proximal large vessel occlusion stroke remains unanswered., Objective: To investigates the technical feasibility and safety of thrombectomy for secondary posterior circulation distal, medium vessel occlusions (DMVO)., Methods: TOPMOST (Treatment fOr Primary Medium vessel Occlusion STroke) is an international, retrospective, multicenter, observational registry of patients treated for distal cerebral artery occlusions. This study subanalysis endovascularly treated occlusions of the posterior cerebral artery in the P2 and P3 segment secondary preprocedural or periprocedural thrombus migration between January 2014 and June 2020. Technical feasibility was evaluated with the modified Thrombolysis in Cerebral Infarction (mTICI) scale. Procedural safety was assessed by the occurrence of symptomatic intracranial hemorrhage (sICH) and intervention-related serious adverse events., Results: Among 71 patients with secondary posterior circulation DMVO who met the inclusion criteria, occlusions were present in 80.3% (57/71) located in the P2 segment and in 19.7% (14/71) in the P3 segment. Periprocedural migration occurred in 54.9% (39/71) and preprocedural migration in 45.1% (32/71) of cases. The first reperfusion attempt led in 38% (27/71) of all cases to mTICI 3. On multivariable logistic regression analysis, increased numbers of reperfusion attempts (adjusted odds ratio (aOR)=0.39, 95% CI 0.29 to 0.88, p=0.009) and preprocedural migration (aOR=4.70, 95% CI,1.35 to 16.35, p=0.015) were significantly associated with mTICI 3. sICH occurred in 2.8% (2/71)., Conclusion: Thrombectomy for secondary posterior circulation DMVO seems to be safe and technically feasible. Even though thrombi that have migrated preprocedurally may be easier to retract, successful reperfusion can be achieved in the majority of patients with secondary DMVO of the P2 and P3 segment., Competing Interests: Competing interests: JF: research support from the German Ministry of Science and Education (BMBF), German Ministry of Economy and Innovation (BMWi), German Research Foundation (DFG), European Union (EU), Hamburgische Investitions-/Förderbank (IFB), Medtronic, Microvention, Philips, Stryker; consultancy appointments; Acandis, Bayer, Boehringer Ingelheim, Cerenovus, Covidien, Evasc Neurovascular, MD Clinicals, Medtronic, Medina, Microvention, Penumbra, Route92, Stryker, Transverse Medical; stock holdings for Tegus. PP: consultant for Penumbra and Ab Medica. AG: has served as proctor/consultant/speaker for Medtronic, Stryker, and Penumbra M. MM-G: consultant of Medtronic, Stryker, and Balt. FD: research support from Cerenovus; consultant for Cerus Endovascular, AB Medica, and Phenox; speaker honorary from Acandis, Cerenovus. JK reports grants from SAMW/Bangerter, grants from Swiss Stroke Society, and grants from Clinical Trial Unit Bern outside the submitted work. LLLY: consultant for Stryker and SeeMode; research support from National Medical Research Council (NMRC) Singapore and Ministry of Health (MOH); stock holdings for Cereflo. PBS: consultant/proctor for Balt, Acandis, Microvention. RC: consultant and/or proctor for BALT, Stryker, Microvention, Rapid Medical, Siemens Medical Systems. PN: consultant/proctor for Balt, Stryker, and Penumbra. KZ: support under the Operational Programme Integrated Infrastructure for the project: TENSION – complementary project, IMTS: 313011W875, co-financed by the European Regional Development Fund., (© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Objectives: Automated CT perfusion mismatch assessment is an established treatment decision tool in acute ischemic stroke. However, the reliability of this method in patients with head motion is unclear. We therefore sought to evaluate the influence of head movement on automated CT perfusion mismatch evaluation., Methods: Using a realistic CT brain-perfusion-phantom, 7 perfusion mismatch scenarios were simulated within the left middle cerebral artery territory. Real CT noise and artificial head movement were added. Thereafter, ischemic core, penumbra volumes and mismatch ratios were evaluated using an automated mismatch analysis software (RAPID, iSchemaView) and compared with ground truth simulated values., Results: While CT scanner noise alone had only a minor impact on mismatch evaluation, a tendency towards smaller infarct core estimates (mean difference of -5.3 (-14 to 3.5) mL for subtle head movement and -7.0 (-14.7 to 0.7) mL for strong head movement), larger penumbral estimates (+9.9 (-25 to 44) mL and +35 (-14 to 85) mL, respectively) and consequently larger mismatch ratios (+0.8 (-1.5 to 3.0) for subtle head movement and +1.9 (-1.3 to 5.1) for strong head movement) were noted in dependence of patient head movement., Conclusions: Motion during CT perfusion acquisition influences automated mismatch evaluation. Potentially treatment-relevant changes in mismatch classifications in dependence of head movement were observed and occurred in favor of mechanical thrombectomy., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Objectives: Artif icial intelligence (AI)-based image analysis is increasingly applied in the acute stroke field. Its implementation for the detection and quantification of hemorrhage suspect hyperdensities in non-contrast-enhanced head CT (NCCT) scans may facilitate clinical decision-making and accelerate stroke management., Methods: NCCTs of 160 patients with suspected acute stroke were analyzed regarding the presence or absence of acute intracranial hemorrhages (ICH) using a novel AI-based algorithm. Read was performed by two blinded neuroradiology residents (R1 and R2). Ground truth was established by an expert neuroradiologist. Specificity, sensitivity, and area under the curve were calculated for ICH and intraparenchymal hemorrhage (IPH) detection. IPH-volumes were segmented and quantified automatically by the algorithm and semi-automatically. Intraclass correlation coefficient (ICC) and Dice coefficient (DC) were calculated., Results: In total, 79 of 160 patients showed acute ICH, while 47 had IPH. Sensitivity and specificity for ICH detection were 0.91 and 0.89 for the algorithm; 0.99 and 0.98 for R1; and 1.00 and 0.98 for R2. Sensitivity and specificity for IPH detection were 0.98 and 0.89 for the algorithm; 0.83 and 0.99 for R1; and 0.91 and 0.99 for R2. Interreader reliability for ICH and IPH detection showed strong agreements for the algorithm (0.80 and 0.84), R1 (0.96 and 0.84), and R2 (0.98 and 0.92), respectively. ICC indicated an excellent (0.98) agreement between the algorithm and the reference standard of the IPH-volumes. The mean DC was 0.82., Conclusion: The AI-based algorithm reliably assessed the presence or absence of acute ICHs in this dataset and quantified IPH volumes precisely., Key Points: • Artificial intelligence (AI) is able to detect hyperdense volumes on brain CTs reliably. • Sensitivity and specificity are highest for the detection of intraparenchymal hemorrhages. • Interreader reliability for hemorrhage detection shows strong agreement for AI and human readers., (© 2021. The Author(s).)

Purpose: We hypothesize that the detectability of early ischemic changes on non-contrast computed tomography (NCCT) is limited in hyperacute stroke for both human and machine-learning based evaluation. In short onset-time-to-imaging (OTI), the CT angiography collateral status may identify fast stroke progressors better than early ischemic changes quantified by ASPECTS., Methods: In this retrospective, monocenter study, CT angiography collaterals (Tan score) and ASPECTS on acute and follow-up NCCT were evaluated by two raters. Additionally, a machine-learning algorithm evaluated the ASPECTS scale on the NCCT (e-ASPECTS). In this study 136 patients from 03/2015 to 12/2019 with occlusion of the main segment of the middle cerebral artery, with a defined symptom-onset-time and successful mechanical thrombectomy (MT) (modified treatment in cerebral infarction score mTICI = 2c or 3) were evaluated., Results: Agreement between acute and follow-up ASPECTS were found to depend on OTI for both human (Intraclass correlation coefficient, ICC = 0.43 for OTI < 100 min, ICC = 0.57 for OTI 100-200 min, ICC = 0.81 for OTI ≥ 200 min) and machine-learning based ASPECTS evaluation (ICC = 0.24 for OTI < 100 min, ICC = 0.61 for OTI 100-200 min, ICC = 0.63 for OTI ≥ 200 min). The same applied to the interrater reliability. Collaterals were predictors of a favorable clinical outcome especially in hyperacute stroke with OTI < 100 min (collaterals: OR = 5.67 CI = 2.38-17.8, p < 0.001; ASPECTS: OR = 1.44, CI = 0.91-2.65, p = 0.15) while ASPECTS was in prolonged OTI ≥ 200 min (collaterals OR = 4.21,CI = 1.36-21.9, p = 0.03; ASPECTS: OR = 2.85, CI = 1.46-7.46, p = 0.01)., Conclusion: The accuracy and reliability of NCCT-ASPECTS are time dependent for both human and machine-learning based evaluation, indicating reduced detectability of fast stroke progressors by NCCT. In hyperacute stroke, collateral status from CT-angiography may help for a better prognosis on clinical outcome and explain the occurrence of futile recanalization., (© 2021. The Author(s).)

Background: Despite complete endovascular recanalization, a significant percentage of patients with acute anterior stroke do not achieve a good clinical outcome. We analyzed optimal thresholds of relevant parameters to discern functional independence after successful endovascular recanalization and test their predictive performance., Methods: Patients with acute anterior ischemic stroke undergoing endovascular treatment between April 2015 and November 2019 were retrospectively analyzed. Only patients with premorbid modified Rankin Scale (mRS) score <3 and complete recanalization (modified Thrombolysis In Cerebral Infarction 2c/3) were included. Optimal thresholds of the most important variables predicting functional independence (mRS 0-2 after 90 days) were calculated using receiver operating characteristic curves and their predictive performance was tested in an independent dataset using machine learning algorithms., Results: Overall, 371 patients met the inclusion criteria. Optimal thresholds for the overall most important variables to predict functional independence were (1) National Institutes of Health Stroke Scale (NIHSS) score ≤5 after 24 hours (area under the curve (AUC) 0.88 (95% CI 0.84 to 0.92)); (2) Alberta Stroke Program Early CT Score (ASPECTS) ≥7 on follow-up CT (AUC 0.72 (95% CI 0.68 to 0.77)); and (3) change in NIHSS score ≥8 after 24 hours (AUC 0.70 (95% CI 0.65 to 0.74)). The performance of these thresholds to predict a good outcome using machine learning in the independent dataset was evaluated for (1) NIHSS score ≤5 after 24 hours (AUC 0.76 (95% CI 0.71 to 0.81)); (2) follow-up ASPECTS ≥7 (AUC 0.64 (95% CI 0.58 to 0.70)); (3) change in NIHSS score ≥8 after 24 hours (AUC 0.61 (95% CI 0.55 to 0.67)); and (4) the combination of all three parameters (AUC 0.84 (95% CI 0.80 to 0.88))., Conclusions: After complete recanalization in acute anterior circulation ischemic stroke, a good long-term outcome could be accurately predicted reaching NIHSS score ≤5 after 24 hours., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

Background and Purpose: To investigate the reliability and accuracy of Alberta Stroke Program Early Computed Tomography Scores (ASPECTS) derived from flatpanel detector computed tomography pooled blood volume maps compared to non-contrast computed tomography and multidetector computed tomography perfusion cerebral blood volume maps., Methods: ASPECTS from pooled blood volume maps were evaluated retrospectively by two experienced readers for 37 consecutive patients with acute middle cerebral artery (MCA) M1 occlusion who underwent flatpanel detector computed tomography perfusion imaging before mechanical thrombectomy between November 2016 and February 2019. For comparison with ASPECTS from non-contrast computed tomography and cerebral blood volume maps, a matched-pair analysis according to pre-stroke modified Rankin scale, age, stroke severity, site of occlusion, time from stroke onset to imaging and final modified thrombolysis in cerebral infarction (mTICI) was performed in a separate group of patients who underwent multimodal computed tomography prior to mechanical thrombectomy between June 2015 and February 2019. Follow-up ASPECTS were derived from either non-contrast computed tomography or from magnetic resonance imaging (in seven patients) one day after mechanical thrombectomy., Results: Interrater agreement was best for non-contrast computed tomography ASPECTS (w-kappa = 0.74, vs. w-kappa = 0.63 for cerebral blood volume ASPECTS and w-kappa = 0.53 for pooled blood volume ASPECTS). Also, accuracy, defined as correlation between acute and follow-up ASPECTS, was best for non-contrast computed tomography ASPECTS (Spearman ρ = 0.86 (0.65-0.97), P  < 0.001), while it was lower and comparable for pooled blood volume ASPECTS (ρ = 0.58 (0.32-0.79), P  < 0.001) and cerebral blood volume ASPECTS (ρ = 0.52 (0.17-0.80), P  = 0.001). It was noteworthy that cases of relevant infarct overestimation by two or more ASPECTS regions (compared to follow-up imaging) were observed for both acute pooled blood volume and cerebral blood volume ASPECTS but occurred more often for acute pooled blood volume ASPECTS (25% vs. 5%, P  = 0.02)., Conclusion: Non-contrast computed tomography ASPECTS outperformed both pooled blood volume ASPECTS and cerebral blood volume ASPECTS in accuracy and reliability. Importantly, relevant infarct overestimation was observed more often in pooled blood volume ASPECTS than cerebral blood volume ASPECTS, limiting its present clinical applicability for acute stroke imaging.

Despite successful recanalization of large-vessel occlusions in acute ischemic stroke, individual patients profit to a varying degree. Dynamic susceptibility-weighted perfusion and dynamic T1-weighted contrast-enhanced blood-brain barrier permeability imaging may help to determine secondary stroke injury and predict clinical outcome. We prospectively performed perfusion and permeability imaging in 38 patients within 24 h after successful mechanical thrombectomy of an occlusion of the middle cerebral artery M1 segment. Perfusion alterations were evaluated on cerebral blood flow maps, blood-brain barrier disruption (BBBD) visually and quantitatively on k trans maps and hemorrhagic transformation on susceptibility-weighted images. Visual BBBD within the DWI lesion corresponded to a median k trans elevation (IQR) of 0.77 (0.41-1.4) min -1 and was found in all 7 cases of hypoperfusion (100%), in 10 of 16 cases of hyperperfusion (63%), and in only three of 13 cases with unaffected perfusion (23%). BBBD was significantly associated with hemorrhagic transformation (p < 0.001). While BBBD alone was not a predictor of clinical outcome at 3 months (positive predictive value (PPV) = 0.8 [0.56-0.94]), hypoperfusion occurred more often in patients with unfavorable clinical outcome (PPV = 0.43 [0.10-0.82]) compared to hyperperfusion (PPV = 0.93 [0.68-1.0]) or unaffected perfusion (PPV = 1.0 [0.75-1.0]). We show that combined perfusion and permeability imaging reveals distinct infarct signatures after recanalization, indicating the severity of prior ischemic damage. It assists in predicting clinical outcome and may identify patients at risk of stroke progression., (© 2021. The Author(s).)

Background and Purpose: To determine reasons for failed recanalization in mechanical thrombectomy (MT) of the posterior circulation., Methods: Retrospective single center analysis of reasons for MT failure in the posterior circulation. Failed MTs were categorized according to the reason for procedure failure in failed vascular access, failed passage of the target vessel occlusion and MT failure after passing the occluded target vessel. Patient characteristics were compared between failed and successful MT., Results: Patients with failed MT (30/218 patients, 13.8%) were categorized into futile vascular access (13/30, 43.3%), abortive passage of the target vessel occlusion (6/30, 20.0%) and MT failure after passing the vessel occlusion (11/30, 36.7%). In 188/218 (86.2%) successful MTs alternative vascular access, local intra-arterial (i.a.) thrombolysis and emergency stent-assisted PTA prevented 65 MT failures. Patients with failed MT showed a higher NIHSS at discharge, a higher pc-ASPECTS in follow-up imaging, a higher mRS 90 days after stroke onset and a high mortality rate of 77.0% (mRS at 90 days, median (IQR): 6 (6-6) vs. 4 (2-6) for successful MT, p-value < 0.001). Co-morbidities and stroke etiology were not different compared to sufficient recanalization with atherosclerotic disease as the leading stroke etiology in both groups., Conclusion: Failure of MT in posterior circulation ischemic stroke patients is associated with a high mortality rate. Reasons for MT failure are diverse with futile vascular access and MT failure after passing the vessel occlusion as the leading causes. Alternative vascular access, local i.a. thrombolysis and stent-assisted PTA can prevent MT failure., (© 2020. The Author(s).)

Importance: Clinical evidence of the potential treatment benefit of mechanical thrombectomy for posterior circulation distal, medium vessel occlusion (DMVO) is sparse., Objective: To investigate the frequency as well as the clinical and safety outcomes of mechanical thrombectomy for isolated posterior circulation DMVO stroke and to compare them with the outcomes of standard medical treatment with or without intravenous thrombolysis (IVT) in daily clinical practice., Design, Setting, and Participants: This multicenter case-control study analyzed patients who were treated for primary distal occlusion of the posterior cerebral artery (PCA) of the P2 or P3 segment. These patients received mechanical thrombectomy or standard medical treatment (with or without IVT) at 1 of 23 comprehensive stroke centers in Europe, the United States, and Asia between January 1, 2010, and June 30, 2020. All patients who met the inclusion criteria were matched using 1:1 propensity score matching., Interventions: Mechanical thrombectomy or standard medical treatment with or without IVT., Main Outcomes and Measures: Clinical end point was the improvement of National Institutes of Health Stroke Scale (NIHSS) scores at discharge from baseline. Safety end point was the occurrence of symptomatic intracranial hemorrhage and hemorrhagic complications were classified based on the Second European-Australasian Acute Stroke Study (ECASSII). Functional outcome was evaluated with the modified Rankin Scale (mRS) score at 90-day follow-up., Results: Of 243 patients from all participating centers who met the inclusion criteria, 184 patients were matched. Among these patients, the median (interquartile range [IQR]) age was 74 (62-81) years and 95 (51.6%) were female individuals. Posterior circulation DMVOs were located in the P2 segment of the PCA in 149 patients (81.0%) and in the P3 segment in 35 patients (19.0%). At discharge, the mean NIHSS score decrease was -2.4 points (95% CI, -3.2 to -1.6) in the standard medical treatment cohort and -3.9 points (95% CI, -5.4 to -2.5) in the mechanical thrombectomy cohort, with a mean difference of -1.5 points (95% CI, 3.2 to -0.8; P = .06). Significant treatment effects of mechanical thrombectomy were observed in the subgroup of patients who had higher NIHSS scores on admission of 10 points or higher (mean difference, -5.6; 95% CI, -10.9 to -0.2; P = .04) and in the subgroup of patients without IVT (mean difference, -3.0; 95% CI, -5.0 to -0.9; P = .005). Symptomatic intracranial hemorrhage occurred in 4 of 92 patients (4.3%) in each treatment cohort., Conclusions and Relevance: This study suggested that, although rarely performed at comprehensive stroke centers, mechanical thrombectomy for posterior circulation DMVO is a safe, and technically feasible treatment option for occlusions of the P2 or P3 segment of the PCA compared with standard medical treatment with or without IVT.

Objective: To quantify radiation exposure (RE) of endovascular stroke treatment (EST) in the anterior circulation per thrombectomy attempt and determine causes for interventions associated with high RE., Methods: A retrospective single-center study of an institutional review board-approved stroke database of patients receiving EST for large vessel occlusions in the anterior circulation between January 2013 and April 2018 to evaluate reference levels (RL) per thrombectomy attempt. ESTs with RE above the RL were analyzed to determine causes for high RE., Results: Overall, n = 544 patients (occlusion location, M1 and M2 segments of the middle cerebral artery 53.5% and 27.2%, carotid artery 17.6%; successful recanalization rate 85.7%) were analyzed. In the overall population, DAP (in Gy cm 2 , median (IQR)) was 113.7 (68.9-181.7) with a median fluoroscopy time of 31 min (IQR, 17-53) and a median of 2 (IQR, 1-4) thrombectomy attempts. RE increased significantly with every thrombectomy attempt (DAP 1 , 68.7 (51.2-106.8); DAP 2 , 106.4 (84.8-115.6); p value 1vs2 , < 0.001; DAP 3 , 130.2 (89.1-183.6); p value 2vs3 , 0.044; DAP 4 , 169.9 (128.4-224.1); p value 3vs4 , 0.001; and DAP 5 , 227.6 (146.3-294.6); p value 4vs5 , 0.019). Procedures exceeding the 90th percentile of the attempt-dependent radiation exposure level were associated with procedural complications (n = 17/52, 29.8%) or a difficult vascular access (n = 8/52, 14%)., Conclusions: Radiation exposure in endovascular stroke treatment is depending on the number of thrombectomy attempts. Radiation exposure doubles when three attempts and triples when five attempts are necessary compared with single-maneuver interventions. Procedural complications and difficult vascular access were associated with a high radiation exposure in this collective., Key Points: • Radiation exposure of endovascular stroke treatment (EST) is dependent on the number of thrombectomy attempts. • Reference levels as means for quality control in hospitals performing endovascular stroke treatment should be defined by the number of thrombectomy attempts-we suggest 107 Gy cm 2 , 156 Gy cm 2 , 184 Gy cm 2 , 244 Gy cm 2 , and 295 Gy cm 2 for 1 to 5 maneuvers, respectively, for EST of the anterior circulation • Cases with high rates of radiation exposure are associated with periprocedural complications and difficult anatomical access as a probable cause for a high radiation exposure.

Purpose: To determine the effect of general anesthesia (GA) versus conscious sedation (CS) on radiation exposure (RE), procedure time (PT), and fluoroscopy time (FT) in patients receiving endovascular stroke treatment (EST) for large vessel occlusions (LVOs) in the anterior circulation., Methods: Retrospective analysis of an institutional review board-approved prospective stroke database of a comprehensive stroke center focusing on RE (as dose area product (DAP) in Gy.cm², median (IQR)), PT, and FT (in minutes, median (IQR)) in patients receiving EST for LVOs of the anterior circulation according to the mode of anesthesia during the intervention., Results: Overall 544 patients were included in this analysis (GA: n=143, CS: n=401). For all included LVOs in the anterior circulation PTs (GA: 69 (44-100); CS: 59 (37-99); p=0.235), FTs (GA: 33 (20-56); CS: 29 (16-51); p=0.286), and RE (DAP, GA: 116.23 (73.47-173.41); CS: 110.5 (68.35-184.65); p=0.929) were comparable. In a subgroup analysis of occlusions of the middle cerebral artery (M1-segment; GA: n=80/544, 14.7%; CS: n=211/544, 38.8%), PTs (GA: 69 (37-101); CS: 54 (35 - 89); p=0.223), FTs (GA: 33 (19-55); CS: 25 (14-48); p=0.264), and RE (DAP, GA: 110.91 (66.8-169.12); CS: 103.8 (63.17-181); p=0.893) were similar., Conclusion: In this retrospective analysis, no effect of the mode of anesthesia on the radiation exposure during EST was detected as GA and CS showed comparable PT, FT, and DAPs., Competing Interests: Competing interests: PAR: reports personal fees from Boehringer Ingelheim, Bayer, BMS, Daiichi Sankyo, and Covidien, outside the submitted work. MM: unrelated: board membership: Codman; consultancy: Medtronic, MicroVention, Stryker; grants/grants pending: Balt*, MicroVention*; payment for lectures Including service on speakers bureaus: Medtronic, MicroVention, Stryker. *Money paid to the institution. MB: activities related to this article: disclosed no relevant relationships. Activities not related to this article: grants and personal fees from Bayer, Codman, Guerbet, Medtronic, and Novartis; grants from the Hopp Foundation, Siemens, and Stryker; personal fees from Braun, Böhringer Ingelheim, Roche, Teva, and Vascular Dynamics. Other relationships: disclosed no relevant relationships. JARP: activities related to the present article: disclosed no relevant relationships. Activities not related to the present article: travel and meeting expenses from Stryker and MicroVention. Other relationships: disclosed no relevant relationships., (© Author(s) (or their employer(s)) 2020. No commercial re-use. See rights and permissions. Published by BMJ.)