両側内頸動脈形成不全に合併したCarotid-SCA anastomosis—後交通動脈—後大脳動脈分岐部脳動脈瘤破裂により発症した1例

A Case of Carotid Superior Cerebellar Artery Anastomosis Assocaited with Bilateral Hypoplasia of the Internal Carotid Artery Represented as the Rupture of Posterior Cerebral Artery-Posterior Communicating Artery Aneurysm

I．はじめに

　persistent primitive trigeminal artery（PPTA）は，胎生期脳血管遺残のうちで最も多く，脳血管撮影では，0.1-0.2％の頻度である^14）．内頸動脈—上小脳動脈吻合は，脳底動脈と直接吻合せず一側上小脳動脈に吻合する，PPTAのvariant typeであり，その報告が散見される^1,19）．

　一方，内頸動脈形成不全は，Huber^8）によると，内頸動脈遠位部の非動脈硬化性狭窄性病変であり，いままでに数例の報告があるのみである^{2,4,5,9,11,16）}．

A rare case of a variant type of the persistent primi-tive trigeminal artery associated with bilateral hypopla-sia of the internal carotid artery was reported. Left common carotid arteriography revealed a thin left inter-nal carotid artery terminated at the ophthalmic artery. Right common carotid arteriography showed that a nar-row internal carotid artery gave off several fine vessels to the cavernous portion, and terminated at the right superior cerebellar artery via the prominent persistent primitive trigeminal artery (PTA) . Supraclinoid por- tons of the bilateral internal carotid arteries were not able to be found.