External Carotid-Basilar Anastomosis—頭部外傷にさいして偶然発見された1例

EXTERNAL CAROTID-BASILAR ANASTOMOSIS: REPORT OF A CASE

Ｉ．はじめに

　近年，脳血管写の普及に伴つて，血管奇形を有する症例も容易に発見されることとなり，報告例もまた飛躍的に増加しつつある。なかでも胎生期動脈の遺残としてのprimitive trigeminal, primitive acoustic，あるいはpri—mitive hypoglossal arteryの存在は最近よく知られるところとなり，その臨床的意義もしだいに明らかにされつつある。これら内頸動脈椎骨動脈吻合に比して，外頸動脈—椎骨動脈—吻合症例は，その報告もきわめて少なく，発生学的解釈も不明のままに残されている。われわれも以下に偶然発見された1症例を記載し，若干の考察を加えたいと思う。

Presence of an external carotid-basilar anastomosis was discovered in a case of head injury. According to Hackett et al., it is possible that the external carotid artery may anastomose to the vertebral artery while the former's branches, together with their tri-butary muscles, shift dorsally during foetal develop-ment. If, in such a case, the trunk of the vertebral artery happens to show hypoplasia in the complicated processes of union, absorption, regression, hyper-plasia, etc. of vascular structures during development, the anastomosis between the external carotid artery and the basilar artery may develop as a dominant vascular route, like in the present case.

This type of vascular anomaly is a rare occurrence and so far only 3 cases could be found in the world literature. This anomaly itself has no pathological significance.