[Ruptured cerebral aneurysm of the median artery of the corpus callosum (accessory anterior cerebral artery): case report].

A rare case of ruptured cerebral aneurysm of median artery of corpus callosum (accessory anterior cerebral artery: Acc ACA) is reported. A 66-year-old hypertensive female suddenly lost consciousness for 5 minutes and later complained of severe headache. On admission, the next day, consciousness was clear and she showed no neurological deficit except for right motor weakness. CT scan revealed subarachnoid hemorrhage, and carotid angiography showed triplicated anterior cerebral artery with a saccular aneurysm on the Acc ACA. Twenty hours after the onset, an operation was performed to clip the aneurysm neck. Post-operative course was uneventful and she was discharged on the 25th postoperative day without neurological deficits. When the median artery of corpus callosum(MACC), a branch of anterior communicating artery distributes to one or to both hemispheres, it is called Acc ACA. It is thought to be a vascular anomaly and which has an incidence of 20%. However, cases of aneurysm of MACC (or Acc ACA) have not been reported and our case is considered to be the first.