Abstract
Basilar artery aneurysms are often asymptomatic, though it may cause brainstem ischemia, compression of brainstem or cranial nerves, subarachnoid hemorrhage, and hydrocephalus. We reported a case of basilar top aneurysm causing brainstem infarction and compression of brainstem. A 71 year-old woman with right hemiplegia was admitted to National Hospital Nayoro because of unconsciousness and left hemiparesis. Neurological examination revealed left hemiparesis and right oculomotor palsy as new findings in addition to right hemiplegia. CT scan demonstrated a partially calcified aneurysm at the top of basilar artery, multiple low density lesions in the midbrain, cerebellum, thalamus and putamen, and periventricular hyperlucency. MRI scan showed partial flow void in the aneurysm. The atrophic base of left cerebral peduncle, compressed by the aneu-rysm, seems to be responsible for the right hemiplegia which was recognized previously. Follow-up CT scan demonstrated a low density area surrounded by a ring enhancement in the right upper midbrain which caused left hemiparesis and right oculomotor palsy.
