脳梗塞発症後，早期にくも膜下出血を呈した中大脳動脈分岐部細菌性破裂脳動脈瘤の1手術例

Early Subarachnoid Hemorrhage from a Bacterial Aneurysm of the Middle Cerebral Artery Bifurcation Following Cerebral Infarction Caused by a Septic Embolism：Case Report

Ⅰ．は じ め に

　感染性心内膜炎に伴う頭蓋内病変は，vegetation由来のseptic embolismによる細菌性脳動脈瘤，脳梗塞，脳炎，髄膜炎，脳膿瘍などが知られている⁴⁾．細菌性脳動脈瘤は末梢性脳動脈に存在し，くも膜下出血や脳出血にて発症することが多い^1,2,7,10)が，中大脳動脈（middle cerebral artery，以下MCA）分岐部に出現し，かつ，虚血症状にて発症することは比較的稀である¹²⁾．われわれはvegetationを塞栓源とする脳梗塞の経過中に，MCA分岐部細菌性動脈瘤により，くも膜下出血および出血性梗塞を呈した1例を経験した．本症例は，細菌性動脈瘤が短期間で急激な病態の変化を来し得る疾患であることを再認識するうえで，貴重な症例であると考えられたので，治療上の問題点を中心に文献的考察を加えて報告する．

　A 38-year-old left-handed male,with a past history of ventricular septal defect,presented to our hospital with complaints of sudden onset of right hemiparesis and restlessness. Computed tomography (CT) showed a hypodense area in the left insular cortex and corona radiata. The symptoms worsened on the next day,and CT demonstrated a new hypodense area in the left temporal lobe. Echocardiography showed vegetation on the mitral valve,so the patient was treated with a high dose of antibiotics under a diagnosis of infective endocarditis. Although the course was uneventful,subarachnoid hemorrhage was observed on the 4th day,which was followed by hemorrhagic infarction. Cerebral angiography revealed an aneurysm of the bifurcation of the middle cerebral artery and occlusion of the superior trunk of the M2 portion. The aneurysm was successfully obliterated,and histological examination established the diagnosis of a bacterial aneurysm caused by septic embolism. Septic embolism originating from infectious endocarditis is likely to be followed by acute hemodynamic changes and fatal events. Therefore,the possibility of bacterial aneurysm should be considered immediately in patients with neurological deficits caused by septic embolism.