Ruptured Aneurysm Originating from a Posterior Inferior Cerebellar Artery Communicating Artery: A Case Report and Review of the Literature.

This report presents a rare case of such an aneurysm arising from such a communicating artery. A 66-year-old woman presented with a subarachnoid hemorrhage located predominantly in the cisterna magna with intraventricular hemorrhage. Angiography showed hypoplasia of the right posterior inferior cerebellar artery. Its vermian territory was supplied by the communicating artery from the posterior medullary segments of the left posterior inferior cerebellar artery. An aneurysm was on that communicating artery itself at a nonbranching site. The aneurysm was trapped the next day. Postoperative computed tomography showed no infarct in the right posterior inferior cerebellar artery territory. Trapping is applicable when other collateral vessels supply the contralateral posterior inferior cerebellar artery territory. J. Med. Invest. 67 : 197-199, February, 2020.