Mongolian gerbilの脳底部血管走行と脳梗塞—大脳動脈の血管走行と梗塞巣との関連

RELATIONSHIP OF CEREBRAL VASCULATURE TO INFARCTION FOLLOWING UNILATERAL COMMON CAROTID ARTERY LIGATION IN THE MONGOLIAN GERBILS

I．はじめに

　Levine and Payan^7）はmongolian gerbilの一側総頸動脈結紮によつて同側大脳半球に梗塞病変が発生することを報告し，Willis動脈輪の形成不全と梗塞病変との関係を指摘した。脳底部血管起行に関する初期の報告では，後交通枝形成異常と梗塞病変との関係が論じられてきたが^5,8），Harrisonら^2）の報告以来、梗塞病変は後交通枝の形成異常に加えて，前大脳動脈における前交通枝の形成異常によつてもたらされることがほぼ明らかになつてきた^1,10）。

　著者らは，一側総頸動脈結紮によつて生じる梗塞巣の範囲が個体によつて差があることを見い出し，Willis動脈輪の形成不全に加えて，前大脳動脈の血管走行が梗塞巣の範囲を左右していることに着目した。本実験は梗塞巣の範囲と前大脳動脈の血管走行との関係を明確にし，さらに，梗塞巣の範囲と生存時間あるいは症状との関係を明らかにするとともに，Willis動脈輪形成不全と梗塞病変との関係についても検索した。

Mongolian gerbils have been used an experi-mental model for cerebral ischemia because they are characterized by frequent anomalies of the circle Willis. The purpose of this study is to clarify the relationships between the cerebrovas-cular anatomy and clinical and morphological changes following permanent unilateral common carotid artery ligation.

In the observation of 269 adult gerbils subjected to unilateral ligation of common carotid artery, 57.2% of animals had not definite anastomosis between the anterior cerebral arteries (ACAs) and all of them died within 1 week (sensitive group). The remaining animals which survived had a defi-nite anastomosis between the ACAs (resistant group). All animals in both groups had no effective posterior communicating arteries. The vascular pattern of ACAs distribution was divided into the type I~IV. Type I: One ACA branches to supply the both hemispheres. Type II: Right and leftACAs branch to supply the respective ipsilateral hemisphere. Type III: A specific ACA that ori-ginated from the posteromedian surface of the optic chiasm branches to supply both hemispheres. The incidence of the type I was 44% and that of type II, III and IV was 37%, 9% and 10%, respectively. In the type II, the area of infarction was observed in about 2/3 of the ipsilateral hemisphere. Not only ipsilateral but contralateral infarction was observed in the type I and III. No infarcted area was observed in the type IV. The infarcted areas which varied according to the ACAs distribution were not predictable from the magnitude of is-chemic manifestation such as neurological deficits or survival time.

These findings suggest that the experimental data in gerbils subjected to unilateral ligation of common carotid artery should be analyzed according to the ACAs distribution.