[Diagnosis and treatment of nontraumatic dissecting aneurysm in the middle cerebral artery].

Two cases of nontraumatic dissecting aneurysm of the middle cerebral artery (MCA) are reported. A 59-year-old woman presented with subarachnoid hemorrhage, mainly in the right sylvian fissure. On admission, the right carotid angiogram revealed a dissecting aneurysm with a double lumen extending from segment M1 to M2 of the right MCA, and an unruptured saccular aneurysm in the right internal carotid artery. Emergency surgery revealed a discolored protrusion of the arterial wall in the right MCA, which was thought to be the cause of her subarachnoid hemorrhage. The protrusion of the arterial wall was clipped and coated with Bemsheet soaked in Biobond. However, disturbance of consciousness persisted and she died of paralytic ileus two months after the operation. The other patient was a hypertensive 33-year-old woman with right hemiparesis and motor dysphasia. CT scans obtained on the day of admission showed no abnormalities. She was treated conservatively with clinical improvement, but CT scans obtained 3 days after the ictus revealed an infarction deep in the left frontal lobe. A left carotid angiogram was made 4 days after ictus and demonstrated severe stenosis of the proximal segment of the left MCA with poor filling of its superior trunk. Despite improvement of her hemiparesis, CT scans obtained 3 weeks after the ictus showed hemorrhagic infarction in the left frontal lobe. Repeat left carotid angiogram revealed a double lumen in the C1 and M1 portions with improvement of the previous severe stenosis of the M1. The 23 reported cases of DA in the MCA with our cases are reviewed and their neuroradiological and clinical features are discussed.