抄録
An elderly woman suffered rupture of an aneurysm on the anterior cerebral artery, which had developed from the proximal end of a fenestration in the artery. These features were visualized angiographically and confirmed during surgery. Aneurysms rarely develop from fenestrations in the anterior cerebral artery; to date, only eight cases have been reported in the literature. The findings concerning aneurysms associated with fenestration suggest that congenital factors are involved in their pathogenesis.