中大脳動脈分岐部閉塞に続発した破裂細菌性脳動脈瘤の1手術例

A Surgically Treated Case with a Ruptured Bacterial Aneurysm of the Middle Cerebral Arterial Bifurcation Following Occlusion

　Ⅰ．はじめに

感染性心内膜炎（infective endocarditis:IE）に合併する細菌性脳動脈瘤の大半は中大脳動脈の末梢部に発生する^5,14)．また発症形式としては，脳内出血やくも膜下出血であることが多いことはよく知られている^5,6,11,14)．今回われわれは，右中大脳動脈近位部閉塞による脳梗塞で発症し，その経過観察中に同部に紡錘状動脈瘤が新生して脳内出血とくも膜下出血を生じ，直達手術を施行した1例を経験した．本症例は手術および病理組織学的検査結果から細菌性脳動脈瘤と確認された．このような症例は稀であり，病態や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 56-year-old woman with aortic regurgitation(AR) developd a high fever on April 25th,2003,followed by the sudden onset of left hemiparesis and dysarthria on May 10th,2003. MRI and MRA showed cerebral infarction due to occlusion of the right proximal portion of the middle cerebral artery. Streptococcus was isolated from arterial blood culture at the time of admission and cardiac examination such as echocardiography revealed active infective endocarditis. Cerebral angiography on the 31st day after the onset of symptoms demonstrated a fusiform-shaped aneurysm at the occluded M2 portion of the middle cerebral artery. Despite administration of antibiotics,a small subcortical hematoma was observed in the right temporal lobe surrounding the aneurysm on the 35th day. The direct surgery of aneurysmal trapping and resection was subsequently performed to prevent rebleeding. The sylvian fissure and perianeurysmal area were strongly adherent to granulation tissue and blood clot. After exposing the aneurysm,the dilated portion of the vessel was successfully trapped and resected. Other than residual left hemiparesis,the post-operative course was uneventful. Histological examination confirmed bacterial aneurysm due to bacterial embolization originating from infective endocarditis (IE). We report a rare case having a ruptured bacterial aneurysm of the middle cerebral arterial bifurcation requiring surgery following occlusion due to bacterial embolization after sepsis and meningitis due to infective endocarditis.