[Trapping of ruptured dissecting aneurysm of distal anterior inferior cerebellar artery--case report].

We report a rare case of dissecting aneurysm of the distal anterior inferior cerebellar artery (AICA). A 63-year-old woman who complained of severe headache and nausea was admitted to our hospital. A computed tomography (CT) scan revealed subarachnoid hemorrhage, intraventricular hemorrhage, and acute hydrocephalus. Left vertebral angiogram revealed a dissecting aneurysm at the meatal loop of the distal AICA. On the next day, left suboccipital craniotomy was performed, and the fusiform aneurysm was trapped. The patient did not exhibit cranial nerve palsy after the operation. A left vertebral angiogram obtained after the operation showed that the dissecting aneurysm of the distal AICA had completely disappeared. Dissecting aneurysm of the distal AICA is a rare condition. Thus far, only 9 cases have been reported in the literature. We reviewed these cases and discussed the treatment for and outcome of dissecting aneurysms of the distal AICA.