To identify patient- and procedure-related factors associated with radiation exposure during middle meningeal artery (MMA) embolization for chronic subdural hematoma (cSDH), with particular focus on embolic agent (particle vs. liquid) and arterial access route (transradial vs. transfemoral). In this retrospective single-center cohort study, we included all patients who underwent MMA embolization for cSDH between February 2021 and October 2025. MMA embolization was performed by fourteen experienced board-certified neuroradiologists. The primary outcome was dose area product (DAP, Gy · cm2). Univariable and multivariable linear regression analyses were performed to assess associations between DAP and age, sex, access route, treated side (unilateral vs bilateral), embolic agent, anesthesia, interventionalist, and guiding catheter. A total of 112 patients (median age 81 years; 20

BACKGROUND:To evaluate the impact of Woven EndoBridge (WEB) device protrusion on the occurrence and number of postprocedural diffusion-weighted imaging (DWI) lesions in patients with unruptured intracranial aneurysms. METHODS:This retrospective single-center study included all consecutive patients with unruptured intracranial aneurysms treated with the WEB device between January 2019 and May 2026. Postprocedural brain MRI, including DWI, was performed within 24-72 hours after treatment. The presence and number of postprocedural DWI lesions, as well as the WEB protrusion, were independently assessed by two experienced board-certified neuroradiologists. Univariable and multivariable linear regression analyses were performed to identify factors associated with the number of postprocedural DWI lesions. Logistic regression analyses were used to assess factors associated with the occurrence of DWI lesions. RESULTS:WEB protrusion was observed in 26/117 patients (22%). Postprocedural DWI lesions occurred in 51/117 patients (44%), without a significant difference between patients with and without protrusion (13/26 (50%) vs 38/91 (42%), P=0.408). However, the mean number of postprocedural DWI lesions was significantly higher in patients with WEB protrusion compared with those without protrusion (4.6±10.2 vs 1.5±3.2, P=0.013). In the multivariable linear regression model, only WEB protrusion was significantly associated with the number of postprocedural DWI lesions (β=3.03 (0.49-5.57), P=0.02). CONCLUSION:WEB protrusion was independently associated with the number of DWI lesions after treatment of unruptured intracranial aneurysms. In contrast, procedure duration was associated with DWI lesion occurrence, whereas repositioning attempts showed no independent association with either lesion occurrence or lesion burden.

The treatment effect of mechanical thrombectomy in patients with mild stroke symptoms and large vessel occlusion remains unclear. Furthermore, it is uncertain whether achieving complete reperfusion (modified Thrombolysis in Cerebral Infarction [mTICI] 3) offers additional clinical benefit compared to incomplete reperfusion (mTICI 2b) in patients with mild stroke. In this retrospective, multicenter analysis, all patients enrolled in the German Stroke Registry—Endovascular Treatment between 2015 and 2023 (n = 18,069) were evaluated. The study included patients with a National Institutes of Health Stroke Scale (NIHSS) score of < 6 and anterior circulation large vessel occlusion. Clinical outcomes were compared between mTICI 2b and mTICI 3. The primary endpoint was excellent functional outcome at 90 days, defined as a modified Rankin Scale (mRS) score of 0–1. Of the 747 included patients, 37

OBJECTIVE:This analysis evaluates the effect of successful reperfusion on functional outcomes after MT, stratified by admission National Institutes of Health Stroke Scale (NIHSS) and Alberta Stroke Program Early CT Score (ASPECTS) as surrogates for clinical-core mismatch, using multicenter registry data. METHODS:Retrospective analysis of patients with anterior circulation stroke undergoing MT enrolled in the German Stroke Registry (2015-2023). Patients were stratified into nine subgroups according to ASPECTS (10; 9-8; ≤ 7) and NIHSS (0-10; 11-15; ≥ 16). The primary endpoint was the rate of good functional outcome (modified Rankin Scale [mRS] of 0-2) at 90 days. Safety outcomes included symptomatic intracranial hemorrhage and mortality. Inverse-probability-weighted regression adjustment (IPWRA) was used to control confounders in observational data. RESULTS:18,069 patients were screened, 5448 met the inclusion criteria (mean age 71.2; 48% female). Successful reperfusion (mTICI 2b-3) was associated with improved functional outcomes in all subgroups, including patients with low NIHSS and high ASPECTS or high NIHSS and low ASPECTS. Largest effects were observed for high clinical-core mismatch (ASPECTS = 10; NIHSS ≥ 16) with 47% (95% Confidence Interval [CI]: 42%-53%) mRS 0-2 after mTICI 3 recanalization compared to 9% (95% CI: 3%-16%) after persistent occlusion, a 38-percentage point increase in good outcome. mTICI 3 was associated with superior outcomes compared to mTICI 2b, particularly in patients with high NIHSS and high ASPECTS. INTERPRETATION:Patients with pronounced clinical-core mismatch derive the greatest benefit from successful reperfusion. Nonetheless, significant functional improvements across all subgroups support more individualized treatment considerations and highlight the need for refined selection criteria.

Background Chronic subdural hematomas (cSDHs) are associated with high recurrence risks following surgical evacuation. The EMBOLISE trial demonstrated that, compared with surgery alone, adjunctive middle meningeal artery embolization (MMAE) significantly reduced reoperation rates. However, given the limitations of the clinical end points of the trial, which may be subject to interrater variability and certain biases, the quantitative imaging metrics need to be evaluated. Purpose To evaluate the prespecified imaging end points of the EMBOLISE trial and assess the long-term resolution of cSDH through quantitative imaging analyses. Materials and Methods EMBOLISE was a multicenter, randomized, interventional trial conducted across 39 U.S. sites between December 2020 and August 2023. Prespecified secondary imaging end points included changes in hematoma volume and thickness and midline shifts from 24 hours to 90 days after the procedure at CT and MRI. The post hoc analyses performed herein extended the assessment to 180 days and included absolute hematoma metrics. Mixed-effects modeling was employed to adjust for confounders. Results Four hundred patients were enrolled in the EMBOLISE study, among whom 352 were included (mean age, 72 years ± 10.4 [SD]; 256 men). The mean cSDH volume was 126 mL at screening, with no intergroup differences. At 90 and 180 days, the MMAE plus surgery group had lower cSDH volumes (20.6 mL vs 28.9 mL [P = .03] and 19.4 mL vs 31.5 mL [P = .04], respectively). Mixed-effects models revealed a 6.9 mL (95% CI: -13.5, -0.40; approximately 25%) greater volume reduction and an 8.4 mL (95% CI: -15.2, -1.6; approximately 30%) lower absolute volume at 90 days in the MMAE group There was no evidence of a difference in the prespecified secondary imaging end points between the groups. Conclusion While the prespecified secondary imaging end points did not significantly differ, the absolute 90- and 180-day hematoma volumes were significantly lower in patients who received MMAE and surgery. Confounder-adjusted mixed-effects analysis indicated a greater reduction in hematoma volume with adjunctive MMAE. ClinicalTrials.gov identifier NCT04402632 © RSNA, 2026 Supplemental material is available for this article. See also the editorial by Ramasamy and Baker in this issue.

Background: Cerebral vasospasm (CV) as a complication after aneurysmal subarachnoid hemorrhage (aSAH) is a major determinant of secondary vasospasm-associated ischemic infarction (SVS-I) and poor outcome. Data on the interplay among the onset of CV, SVS-I, and in-hospital mortality remain limited. Methods: We conducted a retrospective, single-center study including patients admitted with aSAH between January 2016 and May 2024 who developed treatment-relevant CV. The primary outcome was the rate of in-hospital mortality. The relationship between the onset of CV, demographics, imaging, and treatment data and the primary outcome was analyzed using logistic regression. A confounder-adjusted mediation analysis was performed to quantify the extent to which the effect of time to CV onset on in-hospital mortality was mediated by SVS-I. Results: A total of 165 patients with aSAH and treatment-relevant CV were included. The median age was 55 (IQR, 48-64), and 67.2% (111) were female. Of the included patients, 13.3% (22) died during hospitalization. In multivariable logistic regression analysis, earlier onset of treatment-relevant CV (adjusted odds ratio [aOR] 0.79; 95% CI, 0.66-0.95) and the occurrence of SVS-I (aOR 13.47; 95% CI, 2.78-65.3) were associated with the primary outcome. Mediation analysis indicated that SVS-I accounted for 28% of the effect of earlier onset of CV on in-hospital mortality. Conclusions: Twenty-eight percent of the effect of earlier onset of cerebral vasospasm on in-hospital mortality was mediated by secondary ischemic infarction. Targeting patients with early-onset vasospasm and the associated risk of infarction may reduce in-hospital mortality following aneurysmal subarachnoid hemorrhage.

To compare radiation exposure between transradial (TRA) and transfemoral (TFA) access and identify treatment-related factors associated with radiation exposure in endovascular treatment of intracranial aneurysms. This retrospective single-center study analyzed consecutively treated patients receiving endovascular aneurysm treatment (EAT) from May 2023 to April 2025 at the University Medical Center Hamburg-Eppendorf. EAT was performed by nine experienced board-certified neuroradiologists. The primary outcome was the radiation exposure defined as dose area product (DAP) (Gy·cm2). In addition to access route (TRA vs. TFA), patient-related (e.g. age, gender, aneurysm location) and procedure-related (e.g., interventionalist, incidental vs. symptomatic, used device) characteristics were analyzed with regard to radiation exposure using uni- and multivariable linear regression analysis. A total of 209 patients (156 female, 53 male; median age 59 [51–68]) were analyzed. Median DAP was 72.2 (51.6–96.7). Multivariable linear regression analyses revealed that radiation exposure did not differ significantly between TRA and TFA (β = 8.13 [−3.79 to 20.01]; p = 0.18). Stent-assisted coiling (β = 55.82 [34.91–76.74]; p < .001) and female gender (β = −14.95 [−27.5 to −22.41]; p = 0.02) were associated with increased DAP. Further patient- and procedure-related variables were not significantly associated with radiation exposure. In this study, the choice between TRA and TFA had no significant impact on radiation exposure during endovascular aneurysm treatment. Stent-assisted coiling was independently associated with increased radiation exposure during endovascular treatment of intracranial aneurysms. Question Understanding and minimizing radiation exposure in endovascular aneurysm treatment is essential, as the increasing use of transradial access necessitates comparison with the established transfemoral route. Findings Radiation exposure did not differ between transradial and transfemoral access, while higher doses were independently associated with stent-assisted coiling procedures of increased complexity. Clinical relevance Our findings support the safety of transradial access regarding radiation exposure, allowing operators to select the most suitable access route based on patient anatomy and preference without increasing radiation risk.

BACKGROUND:A study was undertaken to investigate the relationship between the vascular access route and the occurrence of diffusion-weighted imaging (DWI) lesions as well as puncture site complications in patients undergoing elective endovascular treatment (EVT) for cerebral aneurysms. METHODS:This retrospective single-center study included all consecutive patients who underwent elective EVT of unruptured cerebral aneurysms via transradial (TRA) or transfemoral (TFA) access between January 2024 and April 2025. Postprocedural MRI was assessed for new DWI lesions. Univariable and multivariable regression analysis was performed to identify predictors for DWI lesions. RESULTS:A total of 199 patients (50.3% TRA, 49.7% TFA) were included. New DWI lesions were detected in 53% of patients. There was no difference in the rates of silent or symptomatic DWI lesions between the two groups (60% vs 50%, P=0.15; and 5% vs 10%, P=0.19, respectively). In a multivariate regression analysis, higher age (aOR 1.04 per year, 95% CI 1.01 to 1.06, P=0.009), longer procedure time (aOR 1.01 per minute, 95% CI 1 to 1.02, P=0.023), and the use of adjunctive techniques such as stent- and balloon-assisted coiling (aOR 6.96, 95% CI 1.73 to 27.99, P=0.006) were independent predictors of postprocedural DWI lesions, while no association was found for the access route. Puncture site complications were comparable between TFA and TRA groups (TRA 3% vs TFA 8%, P=0.12). CONCLUSION:TRA is a safe and feasible alternative to TFA for elective EVT. The risk of postprocedural DWI lesions is primarily influenced by patient age and procedural complexity rather than access route. These findings support the use of TRA in appropriately selected patients, particularly when vascular anatomy or patient preference favors this approach.

The relationship between angiographic success, number of device passes and functional outcome is a topic of clinical interest in endovascular thrombectomy (EVT) for acute ischemic stroke (AIS). This study systematically assessed differential effects of reperfusion levels and device pass counts based on large-scale, multicenter registry data. Patients enrolled in the prospective, multicenter German Stroke Registry between 06/2015–12/2023 were screened. Inclusion criteria were anterior circulation AIS, pre-stroke mRS of 0–1, ≥ 1 passes and availability of clinical data. The primary outcome was functional independence at 90 days. Outcomes were evaluated across different degrees of reperfusion and number of passes employing Inverse Probability Regression Adjustment to control for confounding factors. 6,398 patients fulfilled the inclusion criteria. Single-pass mTICI 3 reperfusion was associated with the highest estimated rate of functional independence (54.3

This study aimed to compare the detection rates and inter-rater agreements of the sagittal T2w-TSE and sagittal short tau inversion recovery (STIR) sequence versus the axial T2w-TSE sequence with full spinal cord coverage in identifying spinal cord lesions in patients with suspected demyelinating diseases and diagnosed multiple sclerosis (MS). 104 patients were prospectively enrolled in this study and underwent MRI, including a sagittal T2w-TSE and STIR sequence, as well as an axial T2w-TSE sequence with full spinal cord coverage. Two experienced neuroradiologists, blinded to clinical parameters, independently evaluated the scans in separate sessions. After blinded readings, raters re-evaluated all sequences to assess if lesions could be retrospectively identified in other sequences. Spinal cord lesions were found in 81 patients. The highest inter-rater reliability was observed for the sagittal T2w-TSE sequence (κ = 0.73, 95

BACKGROUND AND PURPOSE:Cerebral vasospasm remains a strong predictor of poor outcomes after aneurysmal subarachnoid hemorrhage (aSAH). Endovascular treatment of vasospasm can be considered when conservative treatment options are exhausted, but its superiority over standard treatment remains a subject of critical debate. This study focuses on patients with clinically relevant vasospasm after aSAH who underwent endovascular vasospasm treatment and aims to analyze patients' individual risk factors, intensity, and extent of cerebral vasospasm associated with poor functional outcomes after aSAH. MATERIALS AND METHODS:We conducted a retrospective cohort study of consecutive patients with aSAH admitted at a tertiary stroke center between January 2016 and December 2022. Patients with medically refractory cerebral vasospasm necessitating at least 1 endovascular intervention were analyzed. Primary end point was defined as functional outcome defined as modified Rankin Scale (mRS) scores after 6 months. Secondary end point was the occurrence of cerebral infarctions following cerebral vasospasm. RESULTS:Overall, 138 patients received endovascular treatment due to cerebral vasospasm, including 322 treatments, with 78 patients receiving more than 1 endovascular treatment. In 65.2% (90) of patients, cerebral vasospasm developed in both hemispheres; in 16.7% (23), cerebral vasospasm occurred involving the posterior circulation; and in 10.1% (14), percutaneous transluminal angioplasty was performed. Multivariable logistic regression analysis showed an association of higher age (adjusted odds ratio [aOR], 1.05, 95% CI: 1.0-1.1), higher Hunt and Hess grades (aOR, 2.12, 95% CI: 1.38-3.24), the occurrence of rebleeding (aOR, 4.97, 95% CI: 1.0-24.65), and bihemispheric vasospasm (aOR, 4.05, 95% CI: 1.4-11.72) with unfavorable outcome (mRS 3-6). Further analysis showed that higher age (aOR, 1.07, 95% CI: 1.03-1.13) was associated with an increased risk of developing vasospasm-associated infarctions. CONCLUSIONS:Our results indicate an association between bihemispheric cerebral vasospasm and poor functional outcomes after aSAH. This finding supports a more aggressive treatment strategy in patients developing bihemispheric vasospasm to prevent unfavorable disease courses.

BACKGROUND:While thrombectomy benefits patients with large infarcts, it is unclear whether this benefit persists across different levels of reperfusion. AIMS:This study investigates how the degree of reperfusion influences the effectiveness of endovascular thrombectomy (EVT) combined with best medical treatment (BMT), compared to BMT alone, in patients with large infarcts. METHODS:This post hoc analysis of the TENSION trial, a randomized controlled study, assessed EVT versus BMT in patients with extensive infarction (Alberta Stroke Program Early CT Score (ASPECTS) 3-5). Primary outcome was the modified Rankin Scale (mRS) score at 90 days. Secondary outcomes included infarct volume at 24 h, mortality, and symptomatic hemorrhage. Outcomes were stratified by final reperfusion level, measured with the modified thrombolysis in cerebral infarction (mTICI) scale. Confounder-adjusted common odds ratios (cORs) and average treatment effects (ATEs) were estimated using inverse probability weighting with regression adjustment. RESULTS:A total of 246 patients (median age, 74 years (interquartile range (IQR), 65-80); median baseline ASPECTS, 4 (IQR, 3-5)) were included. Compared to BMT alone, unsuccessful EVT (mTICI ⩽ 2a) was not associated with worse functional outcomes (cOR:1.2, 95% CI, 0.95 to 1.52; p = 0.131), higher mortality (ATE: -11.6%; 95% CI, -28.82 to 5.61; p = 0.187), or larger infarct volumes on follow-up (ATE:0.99 mL; 95% CI, -45.30 to 45.32; p = 0.965). First-pass complete reperfusion (mTICI 3) showed the greatest treatment benefit, significantly improving all endpoints, with a cOR of 4.85 (95% CI, 3.74-6.31; p < 0.001) for improved mRS scores and a 29% absolute reduction in mortality. CONCLUSION:In this post hoc analysis of the TENSION trial, unsuccessful EVT did not worsen outcomes compared to BMT alone. The highest benefit of EVT occurred with first-pass complete reperfusion, emphasizing the importance of achieving optimal reperfusion in this vulnerable stroke subgroup. These findings do not justify general treatment recommendations.

Objectives:To date, consistent evidence for consequences of heading in football (soccer) on the structure and function of the brain is lacking, but first studies indicate a potential effect of specific high-magnitude headers. The purpose of this longitudinal, prospective study was to investigate whether potential structural and/or functional alterations within the brain were associated with (high-magnitude) heading. Methods:3T MRI sequences were obtained from active high-level male players before and after an observation period of 17.2 months (median). Cortical thickness and grey matter (GM) volume were investigated on a whole-brain level. Functional connectivity (FC) was analysed in the default mode network (DMN) and salience network (SN). During the observation period, each training and each match was videotaped and evaluated regarding the heading exposure. Significant structural and functional findings were subsequently correlated with specific header characteristics. Results:14 included participants (mean age: 20.36±3.34 years) played 5822 headers. GM volume remained unchanged, whereas cortical thickness decreased minimally from pre-measurement to post-measurement in a left precentral region (mean change: 0.048±0.128 mm; clusterwise p=0.0416). Within the SN, FC increased in one cluster (false discovery rate corrected p=0.026). FC remained stable within the DMN and between DMN and SN. Change from pre-measurement to post-measurement for the significant results did not correlate with heading variables. Conclusion:Our findings may indicate no cumulative effect of heading during the observation period. As these results contrast with cross-sectional findings, more longitudinal, prospective studies with a greater sample size are urgently needed to understand potential heading effects.

BACKGROUND:The optimal anesthetic approach for patients with acute ischemic stroke with large vessel occlusion but low National Institutes of Health Stroke Scale receiving mechanical thrombectomy remains unclear. We aimed to evaluate the association of anesthetic strategies with procedural and clinical outcomes, hypothesizing that conscious sedation/local anesthesia (CS/LA) may offer a more favorable risk-benefit ratio than general anesthesia (GA). METHODS:Multicenter cohort study screening all thrombectomy patients prospectively enrolled in GSR-ET (German Stroke Registry-Endovascular Treatment) across 25 centers between 2015 and 2021. Patients with an admission National Institutes of Health Stroke Scale score of <6 and large vessel occlusion in the anterior circulation underwent 1:1 propensity score matching by their anesthetic strategy during mechanical thrombectomy (CS/LA versus GA). Outcome measures were an excellent functional outcome (modified Rankin Scale score of 0-1 at 90 days) and successful recanalization (modified Thrombolysis in Cerebral Infarction score of 2b-3). RESULTS:Of 13 082 thrombectomy cases, 814 had a National Institutes of Health Stroke Scale <6, of whom 36% received CS/LA and 64% received GA. Before matching, CS/LA patients were less often male (46% versus 54%; P=0.043), had lower National Institutes of Health Stroke Scale scores at admission (median, 3 versus 4; P=0.002), and the M1 segment of the middle cerebral artery was more often occluded (51% versus 39%; P<0.001). After matching, 582 patients were included, and baseline and imaging characteristics were balanced between CS/LA and GA. CS/LA and GA patients achieved similar rates of successful recanalization (85% versus 89%; P=0.14). However, complete recanalization (modified Thrombolysis in Cerebral Infarction score of 3) was less often observed in CS/LA patients (45% versus 61%; P<0.001; adjusted odds ratio, 0.44 [95% CI, 0.30-0.65]; P<0.001). CS/LA patients achieved more often excellent functional outcomes (59% versus 48%; P=0.005; adjusted odds ratio, 1.99 [95% CI, 1.34-2.95]; P=0.001). CONCLUSIONS:In thrombectomy patients with minor stroke, the rate of successful recanalization was comparable between CS/LA and GA. However, our results suggest a more favorable risk-benefit ratio of CS/LA, with an increased rate of excellent functional outcomes.

Background CT perfusion (CTP)-derived baseline ischemic core volume (ICV) can overestimate the true extent of infarction, which may result in exclusion of patients with ischemic stroke from endovascular treatment (EVT). Purpose To determine whether ischemic core overestimation is associated with larger ICV and degree of recanalization. Materials and Methods This retrospective multicenter cohort study included patients with acute ischemic stroke triaged at multimodal CT who underwent EVT between January 2015 and January 2022. The primary outcome was ischemic core overestimation, which was assumed when baseline CTP-derived ICV was larger than the final infarct volume at follow-up imaging. The secondary outcome was functional independence defined as modified Rankin Scale scores of 0-2 90 days after EVT. Successful vessel recanalization was defined as extended Thrombolysis in Cerebral Infarction score of 2b or higher. Categorical variables were compared between patients with ICV of 50 mL or less versus large ICV greater than 50 mL with use of the χ2 test. Adjusted multivariable logistic regression analyses were used to assess the primary and secondary outcomes. Results In total, 721 patients (median age, 76 years [IQR, 64-83 years]; 371 female) were included, of which 162 (22%) demonstrated ischemic core overestimation. Core overestimation occurred more often in patients with ICV greater than 50 mL versus 50 mL or less (48% vs 16%; P < .001) and those with successful versus unsuccessful vessel recanalization (26% vs 13%; P < .001). In an adjusted model, successful recanalization after EVT (odds ratio [OR], 3.14 [95% CI: 1.65, 5.95]; P < .001) and larger ICV (OR, 1.03 [95% CI: 1.02, 1.04]; P < .001) were independently associated with core overestimation, while the time from symptom onset to imaging showed no association (OR, 0.99; P = .96). Core overestimation was independently associated with functional independence (adjusted OR, 2.83 [95% CI: 1.66, 4.81]; P < .001) after successful recanalization. Conclusion Ischemic core overestimation occurred more frequently in patients presenting with large CTP-derived ICV and successful vessel recanalization compared with those with unsuccessful recanalization. © RSNA, 2024 Supplemental material is available for this article.

Overweight/obese patients experience a lower incidence of subarachnoid hemorrhage (SAH) compared to non-overweight patients, even though elevated body mass index (BMI) has been associated with various SAH risk factors. Given that intracranial aneurysms are a primary cause of SAH, a potential protective effect of a high BMI on intracranial aneurysms is likely but remains insufficiently investigated. This population-based MRI study aims to conduct detailed analyses on risk factors associated with the incidence of unruptured intracranial aneurysms (UIA). Retrospective analysis of subjects enrolled in the prospective Hamburg City Health study who underwent intracranial magnetic resonance imaging (MRI) was done. MRI scans were screened for UIA using time-of-flight angiography. Subject data including medical history, laboratory examinations, and risk factors for UIA were collected, and a multivariable logistic regression model was used to investigate the relationship between risk factors and UIA incidence. 2688 subjects (mean (IQR) age, 65 (58–71); 1176 female (43.8

BACKGROUND:There is yet no randomized controlled evidence that mechanical thrombectomy (MT) is superior to best medical treatment in patients with large vessel occlusion but minor stroke symptoms (National Institutes of Health Stroke Scale (NIHSS) <6). Prior studies of patients with admission NIHSS scores ≥6 observed unfavorable functional outcomes despite successful recanalization, commonly termed as futile recanalization (FR), in up to 50% of cases. AIM:The aim of this study is to determine the prevalence of FR in patients with minor stroke and identify associated patient-specific risk factors. METHODS:Our multicenter cohort study screened all patients prospectively enrolled in the German Stroke Registry Endovascular Treatment from 2015 to 2021 (n = 13,082). Included were patients who underwent MT for anterior circulation vessel occlusion with a baseline NIHSS score of <6 and successful recanalization (modified Thrombolysis in Cerebral Infarction (mTICI) scores of 2b-3). FR was defined by modified Rankin Scale (mRS) scores of 2-6 at 90 days. Multivariable logistic regression analysis was conducted to explore factors associated with FR. RESULTS:A total of 674 patients met the inclusion criteria. FR occurred in 268 (40%) patients. Multivariable logistic regression analysis indicates that higher age (adjusted odds ratio (aOR) = 1.04 (95% confidence interval (CI) = 1.02-1.06)), pre-stroke mRS 1 (aOR = 2.70 (95% CI = 1.51-4.84)), transfer from admission hospital to comprehensive stroke center (aOR = 1.67 (95% CI = 1.08-2.56)), longer time from symptom onset/last seen well to admission (aOR = 1.02 (95% CI = 1.00-1.04)), MT under general anesthesia (aOR = 1.78 (95% CI = 1.13-2.82)), higher NIHSS after 24 h (aOR = 1.09 (95% CI = 1.05-1.14)), and symptomatic intracranial hemorrhage (aOR = 16.88 (95% CI = 2.03-140.14)) increased the odds of FR. There was no significant difference in primary outcome between achieving mTICI score of 2b or 3. CONCLUSIONS:Unfavorable functional outcomes despite successful vessel recanalization were frequent in acute ischemic stroke patients with low NIHSS scores on admission. We provide patient-specific risk factors that indicate an increased risk of FR and should be considered when treating patients with minor stroke. DATA ACCESSIBILITY STATEMENT:The data that support the findings of our study are available on reasonable request after approval of the German Stroke Registry (GSR) steering committee.