Ruptured anterior communicating artery aneurysms associated with fenestration of the anterior cerebral artery.

Two patients with ruptured anterior communicating artery aneurysms associated with fenestration of the anterior cerebral artery are reported. In the literature, only 12 angiographic demonstrations of fenestration of the anterior cerebral artery have been reported. All fenestrations were limited to the distal half of the A1 portion, and seven of the 12 cases were associated with aneurysms. The high incidence of coexisting fenestration and aneurysm suggests that congenital factors may play a role in the pathogenesis of cerebral aneurysm.