脳底部異常血管網内の動脈瘤の合併—その症例と発生機序に関する考察

A CASE OF AN ANEURYSM ARISING IN ABNORMAL INTRACRANIAL VASCULAR NETWORKS

はじめに

　内頸動脈末端部の狭窄ないし閉塞とともに，脳底部に異常な血管網が認められる一群の疾患が注目されてからすでに10年以上になり，第18回日本医学会総会シンポジウムで工藤^13）は366例を集計して報告した。しかしその病因についてはまだ議論が多く，一定の見解には達していない。

　われわれは本症を3例経験したが，そのち1例で異常血管網内に発生したと思われる動脈瘤が合併していた。このような血管網内の動脈瘤共存例はいままで報告されていないので本症例について報告し，その発生機序について考察を試みた。

A case of an aneurysm arising in abnormal vas-cular networks at the base of the brain is reported.

The 34 year old man has been hemiplegic on the left since the first attack of subarachnoid hemorrhage (SAH) 15 years ago. He had second attack of SAH in Nov. 1970, and he was admitted to ourdepartment 3 weeks later.

On admittion, physical examination was normal except for Wernicke-Mann's posture of the left. Meningeal signs were absent, and cerebrospinal fluid was clear.

Cerebral angiographic findings are as follows :

1) Cervical internal carotid arteires are slendererthan normal, and they are narrowed just above anddistally from the beginning of posterior communi-cating arteries (Fig. 1,2 and 4).

2) Left middle cerebral artery is normal in itscourse except for its narrowing in Mi (Fig. 1,2and 3). Right middle cerebral artery is not visible(Fig. 1 and 4).

3) Ai portion of anterior cerebral artery isopacified bilaterally (Fig. 1), but right pericallosalartery is visualized via rete mirabile anastomosisand engorged anterior and posterior ethmoidalarteries (Fig. 4).

4) Posterior circulation is normal, and anasto-mosis via dorsal percallosal artery is abundant(Fig. 5).

5) Abnormally dilated perforating arteries arederived from A₁ (right), A₁ and M₁ (left), posteriorcommunicating arteries and posterior cerebral art-eries.

6) An ball-shaped aneurysm is found in thebasal vascular networks i. e. probably in the vici-nity of the left basal ganglia (Fig 1,2 and 3).

7) Cerebral angiographies just after the secondSAH revealed moderate vasospasm of the vesselsaround the aneurysm (Fig. 6 and 7).

The authors discussed the genesis of and thecorrelation between the abnormal vascular net-works and the aneurysm. We concluded that theaneurysm arose from one of the dilated perforatingarteries of the abnormal basal vascular networksbecause of its fragility. It is surmised that thefirst SAH was due to the fragility of the vascularnetworks and the second to the ruptured aneurysm.