[Anterior cerebral artery dissecting aneurysm associated with fibromuscular dysplasia (FMD): a case report].

We have recently encountered a rare case of anterior cerebral artery dissecting aneurysm, presenting cerebral infarction and subarachnoid hemorrhage, associated with fibromuscular dysplasia (FMD). A 50-year-old woman was admitted to our hospital with complaints of headache and hemiparesis. A right carotid angiogram obtained 9 hours after the onset revealed stenosis and slight dilatation in the A1 portion of the anterior cerebral artery. At 12 hours after the onset, the patient fell into a coma. CT scan showed diffuse subarachnoid hemorrhage. An angiogram had revealed aneurysmal dilatation and double lumen in the A1 portion, but, 34 days after the onset, angiogram showed growth of the aneurysm in the A1 portion and stenosis in the A2 and A3 portions. At 38 days after the onset, the trapping of the dilated aneurysm to prevent rerupture was performed. Pathological diagnosis was concluded to be FMD. We concluded that FMD caused stenosis as well as the formation and rupture of the dissecting aneurysm in the anterior cerebral artery.