中大脳動脈early branch分岐部動脈瘤の検討

Aneurysms at the Early Branch of Middle Cerebral Artery

Ⅰ．は じ め に

　中大脳動脈瘤は大部分bifurcationに発生するが，少なからず本幹であるM1部にもみられる．M1部より分岐する皮質枝は特に“early branch”と呼ばれているが，この部位においては動脈瘤が皮質枝と穿通枝（レンズ核線条体動脈：LSA）のいずれにも発生し得ることが特徴である．今回われわれは，early branch，特にearly frontal branch分岐部に発生した動脈瘤に注目し，retrospectiveに検討を行った．

The cortical arteries arising from the proximal (M1) segment of the middle cerebral artery (MCA) are called“early branches”. We retrospectively analyzed clinical features in 10 patients with aneurysms located at the early branches of MCA. The incidence of these aneurysms was 9.5% among 95 MCA aneurysms. Patients consisted of 4 males and 6 females. Ages were 33-77 years old (average of 54.4). Four patients presented with subarachnoid hemorrhage (2 of them had intracerebral hematoma). The aneurysms were classified into 2 groups,the group of the early frontal branch (EFB: 7 cases) and the early temporal branch (ETB: 3 cases). All aneurysms were smaller than 6mm in diameter. The surgical treatment was performed through the pterional approach. Poor outcome occurred in 3 ruptured aneurysms of EFB (MD 1,SD 1,and D 1). At surgery,it is necessary to produce the working space by dissecting sylvian fissure sufficiently and to prevent ischemic complication by avoiding injury of the lenticulostriate arteries (LSA).