多発性細菌性動脈瘤の1例—発生機序について

Multiple Bacterial Aneurysms : case report

I．はじめに

　細菌性心内膜炎に合併する細菌性動脈瘤は中大脳動脈（以下MCA）領域に発生することが圧倒的に多い^{1,11,12,22,28）}．これに比較し内頸動脈（以下ICA）領域では，海綿静脈洞も含めた硬膜外発生の報告は散見されるが^{19,21,23,27）}，硬膜貫通後の発生は比較的稀である．われわれは，細菌性心内膜炎に合併し出血で発症したMCAの細菌性動脈瘤に対し手術を施行したところ，術前に確認できなかったICAの細菌性動脈瘤が術中に破裂し，治療に難渋した症例を経験した．細菌性動脈瘤の発生機転について若干の考察を加え報告する．

A 59-year-old man presented with an internal carotid artery (ICA) bacterial aneurysm which rupturedduring surgery for treatment of another bacterial aneurysm. He had been admitted to our hospital becauseof the recurrence of colon cancer. He had undergone aortic and mitral valve replacement because of clo-sure incompetence due to bacterial endocarditis two months previously. Two months after treatment forcolon cancer, he developed fever, and arterial blood culture demonstrated Staphylococcus epidermidis. Afew clays later, he suddenly suffered severe headache and vomiting, followed by deterioration of conscious-ness. CT showed subarachnoid hemorrhage and angiography showed a saccular aneurysm at the opercularportion of the left middle cerebral artery (MCA). Immediate clipping of the aneurysm was attempted. Thecarotid cistern was opened via a left frontotemporal craniotomy, but an ICA aneurysm, which had notbeen previously recognized, ruptured suddenly. The ICA aneurysm was wrapped with Vascwrap^® withsome difficulty. The MCA aneurysm was then trapped. Postoperatively, the patient continued to be stupor-ous for a few days. Two weeks later, he died of complications caused by pneumonia. Bacterial aneurysm ismore likely to be located in the distribution of the distal arterial tree, mainly in the distribution of theMCA. The difficulty of preoperative diagnosis and the unpredictable clinical course of bacterial aneurysmsare emphasized.