Persistent primitive hypoglossal artery associated with lower basilar artery aneurysm: diagnosis and clinical implications.

An elderly male was evaluated for subarachnoid hemorrhage and found to have a persistent primitive hypoglossal artery with its associated abnormal posterior fossa circulation and a lower basilar artery aneurysm. Angiography findings are described and are corroborated with computed tomography and magnetic resonance imaging. Its surgical and clinical relevance are discussed.