Flow Diversion for Small Branches and Distal Aneurysms of the Posterior Circulation: A Subanalysis of the Post-FD Registry.

Background: Flow diversion (FD) has emerged as an effective treatment option for intracranial aneurysms. However, there is limited evidence regarding its safety and efficacy specifically for distal and small-artery aneurysms of the posterior circulation. This study aimed to investigate the outcomes of FD for aneurysms arising from the posterior inferior cerebellar artery, anterior inferior cerebellar artery, superior cerebellar artery, and the P2 and P3 segments of the posterior cerebral artery. Methods: This is a subanalysis of the Post-FD (Posterior Circulation Aneurysms Treated With Flow Diversion) registry, highlighting distal aneurysms in the posterior inferior cerebellar artery, anterior inferior cerebellar artery, superior cerebellar artery, and the P2 and P3 segments of the posterior cerebral artery treated with FD. Aneurysm characteristics and patient outcomes were described for the total series, and a more focused analysis comparing fusiform/dissecting versus saccular aneurysms was performed. The primary treatment outcome was complete aneurysm occlusion (Raymond-Roy class 1). Primary safety outcome was major ischemic/hemorrhagic stroke following FD. Secondary outcomes included functional outcome, aneurysm retreatment, and in-stent stenosis. Results: Overall, 36 patients with 36 aneurysms were treated with FD, with a median age of 60.0 years (interquartile range [IQR], 52.8-65.3 years). Of those, 13 were fusiform/dissecting, while 23 were saccular aneurysms. Complete occlusion was achieved in 78.1% for all aneurysms at a median follow-up of 14.0 months (IQR, 9.3-48.6 months). There was a nonsignificant trend in rates of complete occlusion between fusiform/dissecting (91.7%) and saccular aneurysms (70%; P = 0.151). Major stroke was reported in 2 cases (5.6%) and in-stent stenosis in 4 (11.1%), and retreatment was required for 4 aneurysms (11.4%) There was no difference in rates of major stroke, in-stent stenosis, or retreatment between fusiform/dissecting and saccular aneurysms. Conclusion: This study suggests the safety and feasibility of FD for distal aneurysms of the posterior circulation, particularly fusiform/dissecting aneurysms. Further larger-scale studies are warranted to confirm these findings.