A 26 year old woman presented with a subacute onset of headache, hypertension, and neurologic impairment. Angiography revealed severe extracranial carotid and vertebral artery disease. Long segmental stenoses, lumen irregularities, and aneurysmal dilatations were noted. She improved with medical management and was followed for one year. Because recurrent neurologic symptoms developed, angiography was repeated and disclosed normal vasculature. "Spontaneous dissections" with recovery are the most probable explanation for this phenomenon.