Endovascular Treatment of Non-Saccular Posterior Circulation Aneurysms: A Comparative Meta-Analysis of Flow Diversion versus Stent-Assisted Coiling

Background Fusiform and giant aneurysms of the posterior circulation carry a dismal natural history.Flow diversion (FD) and stent-assisted coiling (SAC) are the two principal reconstructive endovascular strategies, yet no meta-analysis of direct comparative studies exists to guide selection between them. Methods A PRISMA-compliant systematic review of MEDLINE and Embase (2011-2026) identified comparative studies of adult patients with non-saccular posterior circulation aneurysms reporting outcomes following FD and SAC. Random-effects meta-analyses were performed with the meta package in R (v4.3.3). Two planned sensitivity analyses and leave-one-out analysis assessed robustness. Results Five studies comprising 209 aneurysms (102 FD, 107 SAC) met inclusion criteria. No significant differences were observed between FD and SAC for favorable functional outcome, satisfactory aneurysm occlusion, or ischemic stroke. FD was associated with significantly higher all-cause mortality (OR 2.06; 95% CI 1.11-3.84; p = 0.03), aneurysm rupture (OR 2.59; 95% CI 1.15-5.82; p = 0.03), and in-stent thrombosis (OR 8.15; 95% CI 1.43-46.40; p = 0.03). All three findings demonstrated fragility on sensitivity and leave-one-out testing. Conclusion FD and SAC produce comparable functional outcomes and occlusion rates for non-saccular posterior circulation aneurysms. FD may carry higher mortality, rupture, and in-stent thrombosis, though these signals did not withstand sensitivity analyses and could not be separated from selection bias towards complex aneurysms. These findings support both modalities as viable reconstructive options while underscoring anatomy driven treatment selection and the need for prospective validation.