Dissecting aneurysm of the posterior inferior cerebellar artery.

Dissecting aneurysms of the posterior inferior cerebellar artery are an uncommon cause of stroke in the vertebrobasilar system, but they may also present with subarachnoid bleeding into the posterior fossa in 70% of the cases. Neither magnetic resonance imaging nor vertebral angiography show specific signs. Treatment should be neurosurgical to prevent rebleeding, although few cases have been reported. The authors report a tenth case and the literature is reviewed.