How well can epilepsy syndromes be identified at diagnosis? A reassessment 2 years after initial diagnosis.

PURPOSE: Epilepsy syndromes can be identified very early in the course of a seizure disorder. It is unclear how accurate and resilient such early classifications are. We compared the classification of epilepsy syndromes made previously on the basis of information available at diagnosis with those made 2 years later in a cohort of children with newly diagnosed epilepsy.
METHODS: Children (n = 613) were prospectively identified at the time of initial diagnosis by participating physicians in Connecticut between 1993 and 1997. Classification of epilepsy syndrome according to International League Against Epilepsy guidelines was made previously based on all relevant information available at diagnosis. All cases were reclassified again after 2 years of additional evidence had accumulated. The distributions of syndromes at diagnosis and at 2 years are compared and reasons for changes examined.
RESULTS: After 2 years, syndromes remained the same in 86.3% of the cohort and changes occurred in 13.7% (n = 84). Evolution of the syndrome occurred in 24 children (3.9%), and rectification to the initial diagnosis occurred in 60 children (9.8%). The most common scenario for evolution of a syndrome was from West syndrome (n = 5), undetermined (n = 4), or symptomatic localization-related epilepsy (n = 3) to the Lennox-Gastaut syndrome. The most common rectification of initial classifications involved incompletely classified syndromes (cryptogenic localization-related and undetermined syndromes; n = 36). In a few instances, a fully specified syndrome was reclassified to another apparently unrelated syndrome. In these cases, initial information at diagnosis had been difficult to interpret.
CONCLUSIONS: Epilepsy syndromes can, for the most part, be identified at the time of initial diagnosis. Two years later, rectifications were made in only 9.8% of cases, and most of these involved syndromes that represented incomplete classifications in the first place. Significant changes were rare. The International League Against Epilepsy classification of the epilepsies can be meaningfully applied in epidemiological studies of newly diagnosed pediatric epilepsy.