Meta-Analysis of Endovascular Treatment for Acute M2 Occlusion

Objective : Endovascular treatment (EVT) outcomes for acute M2 segment of middle cerebral artery occlusion remains unclear because most results are obtained from patients with large artery occlusion in the anterior circulation. The objective of this study was to assess procedural outcomes for acute M2 occlusion and compare outcomes according to thrombus location (M1 vs. M2). Methods : A systematic review was performed for online literature published from January 2004 to December 2016. Primary outcome was successful recanalization rate and symptomatic intracranial hemorrhage (S-ICH) after the procedure. A fixed effect model was used if heterogeneity was less than 50%. Results : Eight articles were included. EVT showed successful recanalization rate of 69.1% (95% confidence interval [CI], 54.9– 80.4%) and S-ICH rate of 6.1% (95% CI, 4.5–8.3%). The rates of good clinical outcome at 3 months and mortality were 59.4% (95% CI, 49.9–68.2%) and 14.9% (95% CI, 11.4–19.3%), respectively. According to thrombus location (M1 vs. M2), successful recanalization (odds ratio [OR], 1.539; 95% CI, 0.293–8.092; p=0.610) and S-ICH (OR, 1.313; 95% CI, 0.603–2.861; p=0.493) did not differ significantly. Good clinical outcome was more evident in M2 occlusion after EVT than that in M1 occlusion (OR, 1.639; 95% CI, 1.135–2.368; p=0.008). However, mortality did not differ significantly according to thrombus location (OR, 0.788; 95% CI, 0.486–1.276; p=0.332). Conclusion : EVT seems to be technically feasible for acute M2 occlusion. Direct comparative studies between EVT and medical treatment are needed further to find specific beneficiary group after EVT in patient with M2 occlusion.