Complete Recanalization in Mechanical Thrombectomy Is Associated with Favorable Functional Outcome for M2 Occlusions

Objective: There are insufficient coherent reports on mechanical thrombectomy (MT) for occlusion of the second segment of the middle cerebral artery (M2 occlusion) in a real-world clinical setting. We evaluated the efficacy and safety of MT for M2 occlusions and compared the primary thrombectomy strategies (stent retriever, aspiration catheter, and combined technique) to analyze factors predicting good functional outcomes. Methods: We evaluated background factors, preprocedural factors, procedural factors, and procedural time for patients who underwent MT for M2 occlusions from our retrospective cohort. According to the modified Rankin Scale (mRS) score three months after MT, patients were divided into good (mRS <= 2) and poor (mRS >= 3) prognosis groups. Results: A total of 29 patients (median age, 78 years; 11 [37.9%] females) were included in the study. In this cohort, rates of successful reperfusion, thrombolysis in cerebral infarction (TICI) 3, postprocedural hemorrhage (PPH), and symptomatic PPH were 82.8, 34.5, 31.0, and 0%, respectively. Good prognoses were achieved in 13 (45%) cases. A prognostic factor of MT for M2 occlusions is TICI 3 from multivariate analysis (OR, 11.7; 95% CI, 1.003-136; p = 0.0497). There was no statistically significant difference in the functional outcome three months after MT based on the choice of the primary thrombectomy strategy. Conclusion: MT for M2 occlusions is a reliable and relatively safe procedure. The presence of TICI 3 was a prognostic factor in this cohort. Future studies are warranted to investigate the optimal thrombectomy strategy for medium vessel occlusion.