Safety and Efficacy of Thrombectomy for Distal Medium Vessel Occlusions of the Middle Cerebral Artery

Purpose: Mechanical thrombectomy (MT) for distal medium vessel occlusions (DMVOs) in the middle cerebral artery (MCA) is less established than for large vessel occlusions. This study evaluates the safety and efficacy of MT in DMVOs, comparing it with M1-segment occlusions. Materials and Methods: This retrospective study analyzed 218 patients who underwent MT for isolated M1 (n=123) or distal M2+M3 (n=35) occlusions between January 2020 and August 2023. Outcomes included procedural complications, hemorrhagic events, reperfusion rates, and clinical severity and disability at admission and discharge. Multivariate logistic regression identified predictors of favorable outcomes Results: Median admission National Institutes of Health Stroke Scale (NIHSS) scores were higher in the M1 group (13, interquartile range [IQR]: 8) compared to the distal M2+M3 group (8, IQR: 7; P<0.001), with significant improvements at discharge in both groups (6 [IQR: 8] for M1 and 2.5 [IQR: 5] for M2+M3; P=0.025). Favorable outcomes were more frequent in the M2+M3 group (50.0%) compared to M1 (28.1%; P=0.023). Recanalization rates (modified Thrombolysis in Cerebral Infarction >= 2b) were excellent (>90% in both groups; P=0.300). Procedural complications were rare, with vessel perforations occurring infrequently (M1: 1.6%; M2+M3: 2.9%; P=0.531). Symptomatic intracranial hemorrhage rates were similarly low (2.4% vs. 2.9%; P=0.889). Multivariate analysis identified younger age (P=0.045) and lower NIHSS (P=0.061) as predictors of favorable outcomes in distal occlusions. Conclusion: MT is safe and effective for DMVOs of the MCA, demonstrating significant improvements in clinical outcomes and comparable complication rates to MT for M1-segment occlusions. Given the typically less severe presentations in DMVO and similar risk profiles, careful patient selection and individualized treatment remain critical.