Functional outcomes following treatment of unruptured middle cerebral artery aneurysms: a single-centre comparison of microsurgical vs. endovascular management.

Purpose: Optimal management of unruptured, middle cerebral artery (MCA) aneurysms, remains undetermined between microsurgical clipping and endovascular intervention. This study aims to compare post-operative functional outcomes between microsurgically and endovascularly treated, unruptured MCA aneurysms.

Materials and methods: All cases of unruptured MCA aneurysms undergoing treatment during a 10-year time period were identified and included. Functional status (FS) was measured using the Modified Rankin Scale. FS was assessed pre-treatment and at 1-month, 6-months and 12-months post-treatment. Median FS was compared between groups and relative risk ratios (RR) calculated to compare the risk of post-operative deterioration between the microsurgical and endovascular cohort at each time point. Occlusion and retreatment rates were also compared.

Results: In total, 119 cases of treated, unruptured MCA aneurysms were identified, of which 40 (34%) were managed microsurgically and 79 (66%) endovascularly. Mean age was 55 years (SD ± 11). No significant difference was seen in any demographic domain pre-operatively. 30-day survival in both cohorts was 100%. No significant difference in median FS was seen between the cohorts at any time point post-treatment. There was a significantly increased risk of deterioration in FS amongst the microsurgical cohort at 1-month post-treatment (RR 1.98, 95% CI 1.08 - 3.62, p = 0.03). There was no significant risk of deterioration in FS at either the 6-month nor 12-month time point post-treatment. Complete occlusion in the microsurgical cohort was greater than the endovascular cohort (91% vs. 66%), demonstrating a significantly reduced RR of incomplete occlusion (RR 0.25, 95% CI: 0.08 - 0.77, p = 0.02).

Conclusions: At 1-month post-treatment, the risk of a decline in FS from baseline was almost twice as great in the microsurgical cohort. However, there was no significant difference in the risk of deterioration in FS at 6-months nor 12-months post-treatment.