抄録
We report surgical treatment of 12 aneurysms located at early bifurcation of middle cerebral artery (MCA). The incidence of these aneurysms was 19.4% among 62 MCA aneurysms if the length of prebifurcation M1 of 15 mm or less was designated as the early bifurcation. Eight aneurysms were unruptured, and 4 patients presented with subarachnoid hemorrhage (SAH). The maximum diameter of aneurysms was less than 10 mm in 8 cases and 10 mm to 15 mm in 4 cases. The aneurysms were classified into 2 types: those buried deep in the sylvian fissure (Type I, 8 cases) and those projected anteroinferiorly and caged by deep sylvian veins and the sphenoid ridge (Type II, 4 cases). Small bridging veins were sacrificed in 6 cases to allow wide exposure and safe manipulation, and no venous infarction was encountered postoperatively. Surgical results were excellent in all but 1 patient with SAH where post-SAH hydrocephalus brought about some mental dysfunction. The patient was the only one who developed intraoperative aneurismal rupture.
To accomplish proximal arterial control and optimal neck clipping, meticulous dissection of sylvian fissure was important for Type I cases, whereas extensive but careful drilling of sphenoid ridge and the making of working space around the caged aneurysm were necessary in Type II cases. For the purpose, some small bridging veins were reluctantly sacrificed.
