Anomalous arrangement of the origins of the anterior choroidal and posterior communicating arteries. Case report.

A case of anomalous origin of the anterior choroidal and posterior communicating arteries in a 36-year-old woman with aneurysmal subarachnoid hemorrhage is presented. Preoperative four-vessel angiography revealed a reverse relationship of these vessels, wherein the anterior choroidal artery origin was proximal to the origin of the posterior communicating artery. This arrangement is extremely rare; the only other reported case was in a patient undergoing angiography prior to acoustic neurinoma resection. It is believed that this is the first case reported in a patient with subarachnoid hemorrhage from rupture of an aneurysm arising from a vessel of such anomalous origin.