The Role of Flow Diverter Stents in Treating Distal Middle Cerebral Artery Aneurysms: A Systematic Review and Meta-analysis

Purpose Flow diversion has emerged as a key strategy in the treatment of intracranial aneurysms. However, its safety and efficacy in distal middle cerebral artery (MCA) aneurysms remain inadequately characterized. This study aims to update and synthesize the current literature by evaluating occlusion rates, procedural complications, and clinical outcomes associated with flow diversion in this subset. Methods A systematic review and meta-analysis were conducted according to the PRISMA guidelines. Relevant studies published through 2025 were identified through searches of major databases using predefined criteria. A random-effects proportional meta-analysis using R (version 4.4.2) was performed to assess pooled occlusion and complication rates. Heterogeneity was evaluated via I² statistics, and publication bias was assessed via funnel plots. Results Ten studies comprising 128 distal MCA aneurysms treated with flow diverter stents were included. The pooled complete occlusion rate was 87% (101/120; 95% CI: 80–93%), with no observed heterogeneity (I² = 0.0%, p = 0.7997). A sensitivity analysis excluding two large studies revealed an occlusion rate of 81% (48/61; 95% CI: 71–91%), with low heterogeneity. The overall complication rate was 14% (21/128; 95% CI: 8–21%), with the most frequent complications being thromboembolic events, in-stent stenosis, and hemorrhagic complications. Funnel plots did not reveal evidence of publication bias. Conclusion Flow diversion appears to be a promising treatment option for distal MCA aneurysms, offering high rates of complete occlusion with an acceptable complication profile. However, the data remain limited and heterogeneous. Larger prospective studies with standardized outcome reporting are needed to establish its definitive role in this challenging vascular territory.