Episodic unilateral mydriasis and migraine.

Seven patients (all female, ranging in age from 5 to 53 years) had typical migraine and episodic unilateral mydriasis. These mydriatic episodes, usually occurring during the headache, lasted from 15 minutes to 24 hours and had occurred for three months to 35 years. Three patients had suffered from car sickness as children and there was a family history of migraine in six. Normal accommodation in five patients, normal responses to pilocarpine in two patients, and a return to normal or near-normal pupillary reaction in five patients with the cessation of headache made pharmacologic blockade unlikely. Although there are several possible neurogenic mechanisms, a parasympatholytic origin appears to be the most likely explanation for the mydriasis. Such episodes are generally benign.