Giant saccular distal azygos artery aneurysm: Report of a case and review of literature.

An azygos anterior cerebral artery (ACA) is a rare variant of normal embryogenesis in which confluence of two A1 segments results in a single A2 segment with the absence of anterior communicating artery. The occurrence of an aneurysm at the bifurcation of azygos ACA is rare with few cases reported in the literature. We report a case of a 40-year-old lady who presented with subarachnoid hemorrhage following rupture of a giant, saccular distal azygos ACA aneurysm. Bifrontal craniotomy and clipping of an aneurysm was performed. The clinical significance of azygos ACA and surgical strategies in clipping these aneurysms are discussed with a review of literature.