Fusiform superior cerebellar artery aneurysm presenting with contralateral abducens nerve paresis--case report.

A 25-year-old female suddenly developed headache and diplopia. On admission, neurological examination revealed neck stiffness and left abducens nerve paresis. A computed tomographic scan suggested subarachnoid hemorrhage. Left vertebral angiogram showed an aneurysm on the anterior pontine segment of the right superior cerebellar artery (SCA) and marked flexion and meandering of the basilar artery to the left. At surgery, an atherosclerotic, fusiform aneurysm was found through the right subtemporal transtentorial approach, and the right SCA was clipped just proximal to the aneurysm. Thirteen cases of SCA aneurysm have been described in the literature, but none was a fusiform aneurysm.