IDIOPATHIC GENERALIZED EPILEPSY OF ADOLESCENCE - ARE THE SYNDROMES CLINICALLY DISTINCT

Juvenile myoclonic epilepsy, juvenile absence epilepsy, and epilepsy w ith generalized tonic-clonic seizures (GTCS) on awakening are the thre e syndromes of idiopathic generalized epilepsy of adolescent onset cur rently included in the classification of epilepsy syndromes of the Int ernational League Against Epilepsy (ILAE). Although they differ in the ir predominant seizure types, the syndromes share several clinical fea tures, thus giving rise to questions of phenotypic overlap and purity, We studied the clinical features of 101 patients with idiopathic gene ralized epilepsy beginning in adolescence. A standardized interview wa s used to elucidate seizure phenomenology, precipitants, frequency, an d response to treatment. Groups defined by seizure type were compared and their similarities examined. The group with myoclonic but not abse nce seizures (21 patients) corresponded to the ILAE syndrome of juveni le myoclonic epilepsy, whereas those with absences but not myoclonus ( 37 patients) resembled juvenile absence epilepsy. Twenty-six patients shared the features of juvenile myoclonic epilepsy and juvenile absenc e epilepsy. Epilepsy with GTCS on awakening was not a specific syndrom ic entity; 10 patients had this seizure type alone. Seven patients wer e without a syndromic diagnosis. In these patients only GTCS occurred, but neither on awakening nor in the evening period of relaxation. We conclude that whilst syndromes of idiopathic generalized epilepsy of a dolescence can be recognized, the current classification does not incl ude all patients. In addition, the boundaries between the syndromes ar e indistinct, suggesting underlying neurobiological, possibly genetic, relationships.