[A case report of ruptured internal carotid artery aneurysm with contralateral oculomotor nerve paresis].

We report a case of ruptured internal carotid artery aneurysm with contralateral oculomotor nerve paresis. A 69-year-old female experienced a sudden onset of severe headache. Left-sided mydriasis, absence of light reflex, disability of left ocular movement and ptosis were identified. Computed tomography scan revealed massive subarachnoid hemorrhage. Cerebral angiography showed a right internal carotid artery aneurysm. No abnormal finding was observed in the left internal carotid artery or basilar artery. Magnetic resonance imaging did not show thrombosed aneurysm. The oculomotor nerve paresis lasted for ten days. Ruptured right internal carotid artery aneurysm was surgically confirmed and repaired. We speculated that the contralateral oculomotor nerve paresis was the consequence of bloody jet flow from the ruptured aneurysm.