末梢性巨大脳動脈瘤の2例

Two Cases of Giant Aneurysms Arising from the Distal Segment of the Anterior Cerebral Circulation

I．はじめに

　巨大脳動脈瘤が末梢動脈に生じることは稀で，特にanterior circulation末梢部の巨大血動脈瘤の報告は極めて少ない．今回われわれは中大脳動脈および前大脳動脈の末梢部に生じた巨大脳動脈瘤症例の各1例を経験したので，動脈瘤の増大機序，診断および治療について若干の考察を加えて報告する．

Giant aneurysm arising from the distal segment of the anterior cerebral circulation is extremely rare, and only 14 cases of anterior cerebral circulation aneurysms have been reported in the literature. This report describes two cases of giant intracranial aneurysms, one arising from the distal segment of the middle cerebral artery, and the other from the azygos anterior cerebral artery. Although both of the patients started with intracranial hemor-rhage, their surgical outcomes were good.

The growth mechanisms of each aneurysm are discus-sed based on the clinical and pathological findings. Since the wall of the middle cerebral artery aneurysm showed granulomatous changes with infiltration of many in-flammatory cells, the aneurysmal enlargement is consi-dered to have resulted from chronic inflammation of the wall. In the case of anterior cerebral artery aneurysm, hemodynamic stress through the azygos artery may have caused the giant aneurysm.

Operative indication for giant intracranial aneurysm is controversial. Since the surgical outcomes of reported cases are definitely better than those of the patients with proximal giant aneurysm, we conclude that giant aneurysm arising from the distal segment of the cerebral artery should be treated surgically.