THE RISK OF SEIZURE RECURRENCE AFTER A FIRST UNPROVOKED AFEBRILE SEIZURE IN CHILDHOOD - AN EXTENDED FOLLOW-UP

Objective. To assess the long-term recurrence risks after a first unpr ovoked seizure in childhood. Methods. In a prospective study, 407 chil dren who presented with a first unprovoked seizure were then followed for a mean of 6.3 years from the time of first seizure. Results. One h undred seventy-one children (42%) experienced subsequent seizures. The cumulative risk of seizure recurrence was 29%, 37%, 42%, and 44% at 1 , 2, 5, and 8 years, respectively. The median time to recurrence was 5 .7 months, with 53% of recurrences occurring within 6 months, 69% with in 1 year, and 88% within 2 years. Only 5 recurrences (3%) occurred af ter 5 years. On multivariable analysis, risk factors for seizure recur rence included a remote symptomatic etiology, an abnormal electroencep halogram (EEG), a seizure occurring while asleep, a history of prior f ebrile seizures, and Todd's paresis. In cryptogenic cases, the risk fa ctors were an abnormal EEG and an initial seizure during sleep. In rem ote symptomatic cases, risk factors were a history of prior febrile se izures and age of onset younger than 3 years. Risk factors for late re currences (after 2 years) were etiology, an abnormal EEG, and prior fe brile seizures in the overall group and an abnormal EEG in the cryptog enic group. These are similar to the risk factors for early recurrence . Conclusions. The majority of children with a first unprovoked seizur e will not have recurrences. Children with cryptogenic first seizures and a normal EEG whose initial seizure occurs while awake have a parti cularly favorable prognosis, with a 5-year recurrence risk of only 21% . Late recurrences do occur but are uncommon.