[Wallenberg's syndrome due to a dissecting aneurysm of the vertebral artery].

A 54 year old man without pathologic past history but mild hypertension, obesity and gastric ulcer, presented with a syndrome of Wallenberg. He had complained for five days of progressive and diffuse headache. The neurological condition improved initially, but the patient died suddenly two weeks later. Pathological examination showed no significant alteration except for left ventricular enlargement and mild arteriosclerosis. There was a hemodissection (dissecting aneurysm) of the left vertebral artery next to the inferior oliva. It induced a lateral infarct and a limited dorsal infarct at the middle third level of medulla oblongata. Although the location of the arterial changes is usual, their nature is exceptional. The cause of the arterial hemodissection could not be ascertained: fibrous arterial dysplasia, atherosclerosis or congenital abnormalities of internal elastic layer may be discussed. But no definite conclusion can be reached.