後下小脳動脈末梢部動脈瘤—自験15例の検討

Peripheral Aneurysms of the Posterior Inferior Cerebellar artery—Analysis of 15 cases

I．はじめに

　後下小脳動脈瘤は比較的稀で全頭蓋内の脳動脈瘤の1％以下とされている．そのほとんどは椎骨動脈の後下小脳動脈分岐部に生じ末梢部の動脈瘤は極めて稀である．今回，われわれは過去8年間に後下小脳動脈末梢部動脈瘤を15例経験したので，その臨床症候，診断，治療などにつき検討を加えて報告する．

Peripheral aneurysms of the posterior inferior cere-bellar artery (PICA) are rare. The authors report 15 cases of peripheral PICA aneurysms. Twelve of theaneurysms were discovered after their rupture and two were discovered after rupture of concomitant AVM, and one was detected incidentally. As to the location of aneurysms, more than half of the aneurysms arose at the telovelotonsillar segment. One patient had 2 aneurysms on the same peripheral PICA, which were not obvious on preoperative angiography because the ruptured one was partially thrombosed. Another rare case with aneurysm located at the internal auditory meatus is also reported.

The findings of CT were characteristic, namely hemorrhage in the fourth ventricle without obvious hemorrhage in the basal cisterns, or only within the cerebellar vermian cistern. This phenomenon strongly suggested the possibility of rupture of peripheral PICA aneurysms. As to the surgical results, 10 patients (71%) of the 14 patients had a good recovery, and 1 patient (7%) with nonrupture aneurysm had a fair result due to pre-existing pontine hemorrhage. Three patients (21%) died. Rebleecling occurred in 3 patients, but cerebral vasospasm occurred in only 1 patient.

Consequently, as peripheral PICA aneurysms are likely to he missed, and rebleeding is an unfavorable factor, one should try to demonstrate aneurysms with angiography, by using various methods such as sub-traction or magnification.