The true distal posterior inferior cerebellar artery aneurysm: Clinical characteristics and strategy for treatment

Objective: A series of aneurysms located at the 4^th or 5 ^th segment of the posterior inferior cerebellar artery (PICA) has not been previously reported in the literature. We report six such cases and analyze their clinical characteristics and outcomes from three different treatment strategies. Material and Methods: We reviewed six patients with a diagnosis of distal PICA aneurysm. The following data were analyzed: age, sex, aneurysm size, Hunt-Hess grade at presentation, angiographic characteristics, and clinical treatment outcome determined by Glascow outcome scores (GOS). Treatments performed included clipping and wrapping, sacrificing the parent arteries of the aneurysms, and selective coiling. Results: Six patients (5 females, 1 male; mean age: 61.2 years; mean aneurysm size: 6.2mm) presented at our facility with subarachnoid hemorrhage (SAH) caused by aneurysm rupture. Two patients presented with Hunt-Hess grades 4 and 5; all others were in Hunt-Hess grades 2 or 3. One patient died before surgery. Treatment outcomes of the surviving five patients were as follows: three patients had GOS of 5, one improved by operation, and another died from re-bleeding after selective coiling. Conclusion: Surgery for the true distal PICA aneurysm results in good clinical outcomes. Clipping or wrapping should be considered as the first choice for treatment, and sacrificing the parent artery of the distal PICA aneurysm is relatively safer than selective coiling. The type of parent artery and particularly the collateralization of its distal part should be considered as an essential factor to take into consideration when choosing a treatment strategy.