Ruptured aneurysm arising from the distal end of a proximal A1 fenestration: Case report and review of the literature

Abstract

A 75-year-old female presented with subarachnoid hemorrhage. Angiography revealed a partial duplication (fenestration) in the proximal A1 segment and a ruptured aneurysm at the distal end of A1 fenestration. This congenital anomaly accompanying an aneurysm was associated with duplicated ipsilateral middle cerebral artery (MCA). Congenital defect of the arterial wall and hemodynamic factors at the fenestrated A1 are considered to play a significant role in the development of this aneurysm. The present case is peculiar because not only the ruptured A1 aneurysm was related with the anterior and middle cerebral artery duplication but also the location of A1 fenestration and the origin of A1 aneurysm in a fenestration are quite unusual. Copyright © 2009 The Korean Neurosurgical Society.