くも膜下出血で発症した中大脳動脈近位部に複雑なAnastomosisを伴う一側内頸動脈欠損症の1例

Agenesis of the Right Internal Carotid Artery Associated with Complicated Anastomosis of Middle Cerebral Artery : a case report

I．はじめに

　内頸動脈欠損症は比較的まれな先天性病変であり，血行動態の異常から高率に脳動脈瘤を合併することが知られている．このためくも膜下出血や脳出血で発症することが多いが，今回われわれはくも膜下出血で発症した右内頸動脈欠損症で，その出血源が中大脳動脈近位部に発達した複雑なanastomosisを呈する異常血管であると思われた興味ある1例を経験したので報告する．

A 57-year-old female was admitted to our hospital because of headache, nausea, and vomiting. Head CT scan demonstrated subarachnoid hemorrhage. Cerebral angiography showed the absence of the right inter-nal carotid artery, and skull base CT of the bone window level revealed the absence of the right carotid canal. The right middle cerebral artery (MCA) and anterior cerebral artery (ACA) were opacified from the left internal carotid artery. The right Al portion was hypoplastic and the distal portion of the right M1 portion was replaced by several minute complicated anastomotic vessels connected to the right M2 portion. The right MCA territory was mainly supplied by collateral flow from the right ACA and the right poste-rior cerebral artery via the leptomeningeal anastomosis. There was neither aneurysm nor arteriovenous malformation. The second angiography, 1 week after the initial angiography, showed the same hemodyna-mic pattern and aneurysms were not found. We diagnosed the patient as agenesis of the right internal caro-tid artery and the etiology of subarachnoid hemorrhage was suspected to be a rupture of the anastomotic vessels between the right M1 and M2.

She was discharged on the 21st hospital day without any neurological deficit.