[Dissecting aneurysm of the middle cerebral artery: case report].

We present a surgical case of a dissecting aneurysm of the right middle cerebral artery associated with subarachnoid hemorrhage and intracranial hemorrhage. A 61-year-old woman with consciousness disturbance and left hemiplegia was referred to our hospital. She had suffered severe headache for a week. CT scan showed a subarachnoid hemorrhage in the right Sylvian fissure and intracranial hemorrhage in the right putamen. The right carotid angiogram revealed string sign in M1 portion and occlusion at M2 lower branch of the right middle cerebral artery. On the 12th day, we undertook surgery to confirm whether it was a dissecting aneurysm or not. In the operation, it was reddish in the M1 portion corresponding to the "string sign" and dark-purplish in the lower M2 portion corresponding to an "aneurysm-like lesion". To prevent bleeding, the arterial wall in the M1 portion was coated using muscle. Though the left hemiplegia was unchanged, the postoperative course was uneventful. The patient was transferred to another hospital and underwent rehabilitation. There has been no reccurrence during the four years since surgery. The middle cerebral artery dissecting aneurysm is extremely rare. We presented this case with review of the literature.