Distribution of epilepsy syndromes in a cohort of children prospectively monitored from the time of their first unprovoked seizure.

PURPOSE: To assess the distribution of epilepsy syndromes and their stability in children.
METHODS: A cohort of 407 children with a first unprovoked seizure was prospectively recruited and followed up for a mean of 9.4 years. Etiology and epilepsy syndromes were classified by using the International League Against Epilepsy (ILAE) guidelines in the 182 children with two or more seizures. Classification was done both at time of second seizure and at last follow-up. Two-year terminal remission also was analyzed by etiology and epilepsy syndrome.
RESULTS: Etiology of epilepsy syndromes was idiopathic in 45 (25%), cryptogenic in 89 (49%), and remote symptomatic in 48 (26%). In the initial classification, 114 (63%) children had a localization-based epilepsy syndrome including idiopathic in 26, cryptogenic in 34, and symptomatic based on localization or etiology in 54. Twenty-one (12%) children had a generalized epilepsy syndrome, including 19 with primary generalized epilepsy. Forty-seven (26%) cases were in the category of undetermined if focal or generalized. At last follow-up, there was a change in either etiology (n = 16) or the final epilepsy syndrome classification (n = 33) or both (n = 15) in 34 (19%) cases. At time of last follow-up, 144 (79%) of the children with epilepsy were in 2-year terminal remission, and 108 (59%) were in 2-year terminal remission without medications. Factors associated with a favorable prognosis included an idiopathic or cryptogenic etiology and having a localization-based idiopathic epilepsy syndrome.
CONCLUSIONS: After two seizures, childhood-onset epilepsy can be classified by etiology and epilepsy syndrome. Prognosis is favorable in the majority of cases. However, the apparent syndrome may change with longer follow-up. The ability to classify these cases early in the clinical course is important if they are to be used for prognostic purposes.