第4脳室内出血で発症した後下小脳動脈分枝Choroidal Arteryの脳動脈瘤—2例報告

Choroidal Artery Aneurysms of the Posterior Inferior Cerebellar Artery Presented with Fourth Ventricular Hemorrhage : report of 2 cases

I．はじめに

　後下小脳動脈（PICA）の分枝である脈絡叢動脈（ChA）に発生する動脈瘤は極めて稀であり，渉猟し得た範囲では，現在までに浦西らによる1例が報告されているにすぎない^13）．われわれは，第4脳室内出血で発症し，ChAに発生した脳動脈瘤2例を経験し，手術を施行し双方共に良好な結果を得た．ChAの発生・解剖と脳動脈瘤の出現に関して若干の検討を加えたので報告する．

Two cases involving a ruptured aneurysm in a choroidal branch of the posterior inferior cerebellar arteryare reported here.

Case 1: A 61-year-old woman was admitted after an episode of severe headache with persistent vomit-ing. A CT revealed an intraventricular hemorrhage within the fourth ventricle. An angiography showed ananeurysmal shadow in the choroidal artery branching from the telovelotonsillar segment of the distal pos-terior inferior cerebellar artery (PICA). The operation disclosed a fusiform aneurysm in the choroidalartery which was successfully trapped using Yasargil's mini-clips. The postoperative course was uneventfuland the patient was discharged without any neurological deficit.

Case 2: A 64-year-old woman became unresponsive after complaining of a severe headache. On admis-sion, she was semicomatose with positive bilateral Babinski's sign. A CT scan showed that the fourth andthird ventricles were packed and dilated by a massive hematoma. An angiography demonstrated ananeurysmal shadow in a branch from the PICA with an occlusion of the right vertebral artery. Further-more, the left vertebral artery was also occluded and the basilar artery was fed by collateral circulation.The patient underwent an operation immediately. The fusiform aneurysm was resected after ligation. Herpostoperative course was satisfactory. She was able to go home without neurological deficit. There hasbeen only one article about “pure” choroidal artery aneurysm, reported by Uranishi, et. al in 1994. Theysuggested that the pathogenesis of this lesion could be due to hemodynamic stress. Our two cases also pre-sent the same characteristics, in the shape of the aneurysms as well as in the anomalous structures in theposterior circulation. Our results offer further evidence concerning the pathogenesis of that type of lesion.