Distal posterior inferior cerebellar artery aneurysms: clinical features and management

Aneurysms located on the distal portion of the posterior inferior cerebellar artery (PICA) are uncommon, and their underlying pathology, natural history, and clinical management are poorly understood. To clarify these lesions more fully, the authors undertook a retrospective analysis of the clinical features and management results of 22 distal PICA aneurysms in 20 consecutive patients treated at one institution by the same surgeon during the past decade.

The series included 10 men and 10 women (mean age at presentation 51 years). Nine patients presented with only subarachnoid and/or intraventricular hemorrhage (median Hunt and Hess Grade II). In seven patients intracerebellar hemorrhage was also found; two patients presented with pressure effects and two hemorrhages were incidentally discovered. Prominent comorbidities included cigarette smoking (50%) and hypertension (50%). The 13 saccular and nine fusiform distal PICA aneurysms were distributed on the following segments of the PICA: lateral medullary (seven lesions), tonsillomedullary (five lesions), telovelotonsillar (five lesions), and cortical (five lesions). Six oases were associated with cerebellar arteriovenous malformations. Skull-base and far-lateral transcondylar surgical approaches were used to secure the aneurysms in 86% of cases, either by direct clipping (13 lesions), vessel sacrifice (four lesions), or vessel sacrifice plus bypass (two lesions). Two aneurysms were treated using endovascular PICA ablation. Overall outcome at hospital discharge was excellent or good in 70% of cases. At long-term follow up (100% of patients, mean 123 days), an excellent or good outcome had been achieved in 85% of cases.

Depending on the PICA segment that was affected, variations in clipping strategies and surgical exposures aimed at the PICA branch and main trunk preservation were major contributors to good long-term results.