A rare duplicate origin of the A2 segment associated with a ruptured aneurysm of the anterior communicating artery complex: a case report

Anatomical variations of the anterior communicating artery complex (ACAC) are important for understanding cerebrovascular development and for planning treatment of aneurysms in this region. We report a rare case of duplicate origin of the A2 associated with a ruptured ACAC aneurysm and discuss its possible embryological basis. An 80-year-old woman presented with sudden severe headache, vomiting, and aphasia. Computed tomography (CT) revealed diffuse subarachnoid hemorrhage, and three-dimensional CT angiography demonstrated an aneurysm in the ACAC. Digital subtraction angiography confirmed the aneurysm and revealed an unusual branching pattern of the anterior cerebral artery (ACA). The right A2 segment coursed anteriorly and continued as the callosomarginal artery, whereas the left side showed a bihemispheric ACA with an arterial ring in the infracallosal portion of the A2 segment. The aneurysm was successfully treated with coil embolization. The postoperative course was uneventful, and the patient was transferred for rehabilitation on postoperative day 54. This rare arterial ring, suggesting a duplicate origin of the A2 segment of ACA, may provide insight into the embryological development of the anterior cerebral circulation and may have implications for understanding aneurysm formation and planning treatment.