[Intracavernous internal carotid artery aneurysm associated with persistent trigeminal artery variant: case report].

The authors report a case of an intracavernous internal carotid artery aneurysm associated with a persistent trigeminal artery variant (PTAV). A 47-year-old-woman developed a subarachnoid hemorrhage due to the rupture of aneurysm and underwent direct clipping operation. PTAV is basically an anomalous anastomosis between the internal carotid artery and the anterior inferior cerebellar artery. In this patient, the PTAV originated from the C4 portion of the right internal carotid artery and distributed in the territory of the hemispheric branch of the posterior inferior cerebellar artery. There have been only three reported cases of the internal carotid artery aneurysms arising from the crotch of PTAV. It is also unusual that rupture of such a small aneurysm in the cavernous sinus causes subarachnoid hemorrhage. Embryological development of PTAV and possible mechanism of subarachnoid hemorrhage from the intracavernous aneurysm are discussed.