Cervicocranial arterial dissections.

Cervicocranial dissections are an increasingly recognized cause of stroke in the young. When the dissections narrow the vascular lumen, they often alter blood flow enough to cause transient ischemic attacks in the brain. Alterations in the endothelium activate the coagulation cascade, leading to the formation of intramural clot that may embolize distally to cause brain infarction. Pain and neuro-ophthalmic symptoms and signs are common manifestations.