The Epidemiology of Epilepsy

Epilepsy is a chronic disease of the brain characterized by an enduring (i.e., persisting) predisposition to generate seizures, unprovoked by any immediate central nervous system insult, and by the neurobiologic, cognitive, psychological, and social consequences of seizure recurrences. Epilepsy affects both sexes and all ages with worldwide distribution. The prevalence and the incidence of epilepsy are slightly higher in men compared to women and tend to peak in the elderly, reflecting the higher frequency of stroke, neurodegenerative diseases, and tumors in this age-group. Focal seizures are more common than generalized seizures both in children and in adults. The etiology of epilepsy varies according to the sociodemographic characteristics of the affected populations and the extent of the diagnostic workup, but a documented cause is still lacking in about 50% of cases from high-income countries (HIC). The overall prognosis of epilepsy is favorable in the majority of patients when measured by seizure freedom. Reports from low/middle-income countries (LMIC; where patients with epilepsy are largely untreated) give prevalence and remission rates that overlap those of HICs. As the incidence of epilepsy appears higher in most LMICs, the overlapping prevalence can be explained by misdiagnosis, acute symptomatic seizures and premature mortality. Studies have consistently shown that about one-half of cases tend to achieve prolonged seizure remission. However, more recent reports on the long-term prognosis of epilepsy have identified differing prognostic patterns, including early and late remission, a relapsing-remitting course, and even a worsening course (characterized by remission followed by relapse and unremitting seizures). Epilepsy per se carries a low mortality risk, but significant differences in mortality rates are expected when comparing incidence and prevalence studies, children and adults, and persons with idiopathic and symptomatic seizures. Sudden unexplained death is most frequent in people with generalized tonic-clonic seizures, nocturnal seizures, and drug refractory epilepsy.