Spontaneous dissection of the carotid artery.

The clinical and radiographic findings in 20 patients with nontraumatic spontaneous dissection of the carotid vessels are reported. In 18 patients, the dissection was limited to the internal carotid artery; the extent of dissection varied. The radiographic findings were pathognomonic. Dissection occurs within the media of the vessel along a plane not present in normal arteries. Fibromuscular dysplasia and hypertension may be predisposing factors in spontaneous dissection of the carotid artery.