Persistent hypoglossal artery associated with basilar artery aneurysm.

A saccular aneurysm at the tip of the basilar artery in a patient with a persistent hypoglossal artery is reported. The persistent hypoglossal artery was arising from the left internal carotid artery. Both vertebral and posterior communicating arteries were absent bilaterally. The combination of a persistent hypoglossal artery and a basilar bifurcation aneurysm is a very rare occurrence. The anatomy of the cerebral circulation in this unique case is important for surgical planning.