[Dissecting aneurysm of distal posterior inferior cerebellar artery--case report and review of the literature].

A rare case of dissecting aneurysm of distal posterior inferior cerebellar artery (PICA) is reported. A 51-year-old woman was admitted to our hospital complaining of severe headache and nausea. CT scan revealed subarachnoid hemorrhage which was thicker in the posterior fossa. The vertebral angiography demonstrated an aneurysm on the telovelotonsillar segment (Lister's classification) of the left PICA. On the third day, the left suboccipital craniotomy was performed and the fusiform aneurysm was resected. The postoperative course was uneventful. Histological examination of the resected aneurysm showed a dissection between the ruptured elastic lamina and the tunica media. Dissecting aneurysm of distal PICA is still belong to a rare entity. In all three cases found in the literature, the dissecting aneurysms are sited in the anterior medullary segment of PICA. Probably, this is the first report described a dissecting aneurysm on the more distal part-telovelotonsillar segment of PICA. The clinical features, pathogenesis and treatment of intracranial dissecting aneurysms are briefly discussed with reviewing the literature.