Three cases of spontaneous extracranial vertebral artery dissection.

We describe three cases of extracranial vertebral artery dissection that are unusual in both their modes of presentation and their associations with other pathologic conditions. The first patient had Marfan's syndrome and migraine; his dissection was asymptomatic and was diagnosed by chance at the time of repeat angiography following a previous internal carotid artery dissection. The second patient had systemic lupus erythematosus and presented with a subarachnoid hemorrhage attributed to an intracranial vertebral artery dissection by the demonstration of an extracranial dissection. The third patient had a minor basilar artery stroke in which dissection had occurred beside a congenital hemivertebra deformity.