Abstracts

RATIONALE: Studies find an association between migraine and seizures, perhaps due to a common pathophysiological mechanism. In adults, the risk of migraine is more than twice as great among patients with epilepsy compared to those without epilepsy but the time order is not understood.
METHODS: Case-control study of newly diagnosed unprovoked seizures among Icelandic adults, aged 16 years and older. Cases are from a nationwide active surveillance system for seizures with verification by medical records. Unprovoked seizure is defined as a seizure without an identified proximate precipitant. Controls were selected from a computerized registry of all Icelanders born after 1880, as the next two same sex births that were alive, resided in Iceland, and did not have a history of unprovoked seizure on the date of the case[ssquote]s incident seizure. A control could not be a sibling of the case. Symptoms of prior migraine were identified through a standardized questionnaire. Migraine was defined according to accepted criteria.
RESULTS: Migraine was 1.6-fold more common among cases than controls (95% CI=1.1-2.3). It was diagnosed in 68 of 288 cases (24%) and in 96 of 575 controls (17%). Migraine with aura was 2.7-fold more common in cases than controls (95% CI=1.7-4.1) and was diagnosed in 50 cases (17%) and 42 controls (7%). Migraine without aura was not associated with unprovoked seizure (OR=0.7, 95% CI=0.4-1.2). Results will be presented by seizure type and etiology.
CONCLUSIONS: Migraine is associated with an increased risk for unprovoked seizures. This association is entirely due to migraine with aura.
Support: R01 NS 32663