Febrile seizures are the most common neurologic disorder of infants and young children. They are an age-dependent phenomenon, occurring in 2 to 4 percent of children younger than five years of age.
Simple febrile seizures, defined as generalized seizures lasting less than 15 minutes and not recurring during a 24-hour period, represent the majority of febrile seizures. While they recur in approximately one-third of children during early childhood, they are an otherwise benign phenomenon and are associated with a risk of future epilepsy that is only slightly higher than the general population. Febrile seizures that are focal, prolonged, or recurrent within the first 24 hours are defined as complex. Complex febrile seizures are a more heterogeneous group, associated with a higher risk of recurrence and an increased likelihood of future afebrile seizures.
The risk factors, clinical features, and diagnostic evaluation of febrile seizures are reviewed here. Treatment and prognosis of febrile seizures are discussed separately. The evaluation and management of nonfebrile seizures in neonates, infants, and children are also discussed separately. (See "Treatment and prognosis of febrile seizures" and "Clinical features and electrodiagnosis of neonatal seizures" and "Clinical and laboratory diagnosis of seizures in infants and children".)
A febrile seizure refers to an event in infancy or childhood, usually occurring between three months and five years of age, associated with fever but without evidence of intracranial infection or defined cause . Seizures with fever in children who have suffered a previous nonfebrile seizure are excluded from this definition. Febrile seizures are not considered a form of epilepsy, which is characterized by recurrent nonfebrile seizures [1,2].
Generally accepted criteria for febrile seizures include: