Presentation, management, and outcomes of anterior inferior cerebellar artery dissecting and fusiform aneurysms: a systematic review and institutional case series.

Dissecting and fusiform aneurysms of the anterior inferior cerebellar artery (AICA) are rare and poorly characterized lesions. This study provides a comprehensive patient-level synthesis to date, combining a systematic review with institutional data to describe their clinical presentation, diagnostic workup, management strategies, and outcomes. A systematic review was conducted according to PRISMA guidelines. Studies were included if they reported on dissecting or fusiform AICA aneurysms. Individual patient data were extracted and supplemented with a single-institution case series. Outcomes, complications, and radiological evolution were analyzed descriptively. Forty-nine patients from 36 studies and 6 patients from our institution were included in this study. In the systematic review cohort, most aneurysms presented with subarachnoid hemorrhage (n = 38/49, 77.6%). Compressive cranial neuropathies, particularly including the vestibulocochlear system, were common in patients with unruptured aneurysms. Diagnosis often required digital subtraction angiography after the initial non-invasive imaging. Endovascular treatment, most commonly parent artery occlusion, was employed in 61.2% (n = 30/49) of cases. However, ischemic complications occurred in 23.3% (n = 7/30), especially in proximal (A1-A2) lesions. Bypass surgery was reported selectively for proximal aneurysms with inadequate collateral flow. As an alternative surgical approach, decompression or trapping was pursued based on aneurysm morphology or clinical context. Conservative management was typically reserved for select patients with poor-grade SAH, high procedural risk, or patient refusal of intervention. Overall, 81.4% (n = 35/43) of patients with available follow-up achieved good functional outcomes. Management of AICA dissecting and fusiform aneurysms is highly individualized. Endovascular approaches were frequently used to secure ruptured lesions or lesions considered at high risk, but periprocedural ischemic risk in perforator-rich segments remains a notable concern. Bypass procedures were reported in selected proximal aneurysms with limited collateralization. Conservative management was reserved for highly selected high-risk or anatomically inaccessible cases. Clinical trial registration: This study is not a clinical trial.