Cerebral dissecting aneurysm and intimal fibroelastic thickening of cerebral arteries. Case report.

A 19-year-old white man developed aphasia and right hemiplegia after several falls while waterskiing. Cerebral angiography displayed a ripple appearance and a "string of beads" sign along the left middle cerebral artery, with occlusion or stenosis of most of its branches. The patient died after 6 days, of transtentorial herniation due to massive left cerebral infarction. At necropsy, the infarct was found to be due to a subintimal dissecting aneurysm of the left middle cerebral artery. Multifocal areas of intimal fibroelastic thickening (IFT) were found not only at the site of dissection, but also in the other cerebral arteries, most prominent at the bifurcations of the vessels. A systematic study of cerebral arteries performed in six control cases revealed that IFT was present in a similar distribution to that seen in the patient described. However, the degree of IFT in this patient was greater than in the controls. Some individuals with excessive IFT may be more susceptible to cerebral dissecting aneurysm under a variety of stresses, especially trauma.