Basilar bifurcation aneurysms associated with persistent primitive hypoglossal artery

We report two cases of ruptured basilar bifurcation aneurysm associated with a persistent primitive hypoglossal artery. Angiograms revealed low-positioned aneurysms; in both cases bilateral vertebral arteries and posterior communicating arteries were hypoplastic or aplastic. Both aneurysms were successfully clipped via subtemporal transtentorial approach through the craniotomy ipsilateral to the side of the primitive hypoglossal artery. The ipsilateral craniotomy and exposure of the cervical carotid artery were helpful for obtaining the proximal control of the basilar artery needed to perform the clipping procedure with safety.