Seen here is carotid artery dissection. Such an event may be the cause for stroke in a young adult. The extracranial portion of the carotid is more frequently involved than the intracranial portion. Dissection is often preceded by trauma, even minor trauma. It may be bilateral or associated with vertebral arterial dissection. Symptoms and signs are subtle and may include headache, facial pain, Horner's syndrome, tinnitus, cranial nerve palsies, or signs of cerebral infarction. An underlying vasculitis or fibromuscular dysplasia may predispose to dissection. Magnetic resonance imaging with magnetic resonance angiography can be helpful in making the diagnosis.