椎骨脳底動脈ｔｈｒｏｍｂｏｓｅｄ ａｎｅｕｒｙｓｍの病態と治療 部分血栓化した巨大本幹脳動脈りゅうの臨床経過と病理所見―慢性解離性脳動脈りゅうの概念―

Abstract

Little is known about the generatic mechanism and long-term clinical course of dolichoectatic aneurysms. We experienced and followed 12 patients with symptomatic partially thrombosed dolichoectatic aneurysms involving the whole vertebral and/or basilar arteries. Based on the clinical data, radiological images and pathological findings, we studied the generatic mechanism of dolichoectatic aneurysms. Twelve aneurysms involved 10 basilar arteries and 2 vertebral arteries. The 10 basilar aneuryms chronically grew to a giant size and finally caused death. Eight patients died of subarachnoid hemorrhage and 2 died of brainstem compression. Seven patients were autopsied. The average time between first diagnosis and death was 3 years and 10 months. The wall of the aneurysm basically consisted of adventitia and thickened intima. Media and internal elastic lamina almost disappeared. Vascular smooth muscle cells, which reproduce extracellular matrix, were diminished, and the wall of the aneuryms consisted almost entirely of loose collagen fiber networks. Early-stage MRI showed intimal flaps and autopsy confirmed dissection of thickened intima. We present the concept of “chronic dissecting aneurysm” regarding the generatic machanism of symptomatic partially thrombosed dolichoectatic aneurysms.