Propensity Score-Matched Analysis of Endovascular Treatment and Microsurgery for Unruptured Middle Cerebral Artery Aneurysms: Long-Term Outcomes over 6-Year Follow-Up.

Objectives: The choice between endovascular treatment and microsurgery for unruptured intracranial aneurysm (UIA) is influenced by aneurysm location, with middle cerebral artery (MCA) UIAs traditionally requiring surgery. This study compares these treatment modalities using propensity score matching (PSM). Methods: This single-center analysis included adults with saccular MCA UIAs who underwent treatment. PSM incorporated patient and aneurysm characteristics to create comparable groups. Results: Before matching, 124 patients underwent microsurgery and 28 underwent endovascular treatment. With a median follow-up of 76.5 months, 93.4% achieved good functional outcome (modified Rankin Scale [mRS] 0-2), including 117 (93.4%) in the surgical group and 25 (89.3%) in the endovascular group. Complications occurred in 15.3% of surgical and 10.7% of endovascular patients (p > 0.05). Three patients developed subarachnoid hemorrhage post-treatment: two from other aneurysms and one from an endovascularly treated MCA UIA. Proximal location predicted worse outcomes (p = 0.04), whereas distal location was associated with better outcomes (p < 0.01). Ordinal logistic regression revealed no additional associations. After PSM, we did not observe significant between-group differences in complications or mRS at follow-up, and ordinal logistic regression predicting mRS at follow-up revealed no differences. Distal MCA remained associated with better outcomes (p < 0.01). No differences in survival were found between groups before or after PSM (log-rank test p = 0.34 and p = 0.49, respectively). Conclusions: No differences in long-term outcomes or complications were observed in this cohort after endovascular treatment vs. microsurgery. Distal location was the only factor associated with favorable outcomes. At a median follow-up of 6.4 years, most patients achieved good functional outcomes. These results likely reflect individualized treatment selection within an experienced team and should be considered exploratory given limited statistical power and generalizability.