Who Is at Risk for Prolonged Seizures?

This article reviews how long seizures last and how frequently seizures are prolonged, risk factors for prolonged seizures, and a conceptual framework that links them. These data are derived from studies of patients with a first unprovoked seizure, studies of children with febrile seizures, studies of population-based and community-based cohorts with newly diagnosed epilepsy and patients with refractory epilepsy, and treatment trials. Prolonged seizures that exceed 5 to 10 minutes are relatively common, and the key factor in the identification of those at risk is a history of a prior prolonged seizure. A subgroup of patients with seizures is predisposed to prolonged although not necessarily frequent seizures, which are associated with increased morbidity, increased emergency department visits, and a decreased quality of life. This article also addresses criteria used to justify treatment of a seizure once it has continued longer than 5 minutes and the rationale for such treatment.