Febrile seizures.

Thirty to 40 percent of children who have a febrile seizure between the ages of six months and six years are at risk for further and more serious febrile seizures and possibly for afebrile seizures. The risk is heightened if the child is less than one year of age and if the seizure lasts more than 20 minutes or is focal rather than generalized. A history of epilepsy in a first-degree relative also increases the risk. The use of long-term phenobarbital therapy is advocated when the seizure is "atypical".