Epidemiology and classification of epilepsy: gender comparisons

Epilepsy is a common disease. The cumulative lifetime risks for epilepsy and for any unprovoked seizure are 3.1% and 4.1%, respectively, in industrialized countries. Estimate of annual incidence of epilepsy are as high as 43 cases per 100,000 of the population in so-called developed countries, and are almost double this figure in the developing world. Within this there is a growing appreciation of gender differences in the epidemiology of epilepsy and of specific epilepsy syndromes. In 1993, the International League Against Epilepsy (ILAE) proposed simplified classification guidelines to facilitate epidemiologic work in epilepsy, and to allow meaningful comparison between studies undertaken at different times and in different parts of the world. Since then, a number of national studies have been completed, adding to the existing data of already well-established databases such as the Rochester Epidemiology Project. There is broad agreement between studies that females have a marginally lower incidence of epilepsy and unprovoked seizures than males. This difference is usually attributed to male's greater exposure to risk factors for lesional epilepsy and acute symptomatic seizures. On the other hand, idiopathic generalized epilepsies (IGEs), which may represent some 15-20% of all epilepsies, are more common among females. Also, the behavior of some common epilepsy syndromes such as mesial temporal sclerosis may differ between genders with isolated auras more common among females and secondary seizure spread more likely in males. Trends toward gender differences are also seen in other important aspects of epilepsy. These include the incidence of status epilepticus (more common in men), incidence of sudden unexpected death in epilepsy (SUDEP), prognosis, and mortality.