Severe idiopathic generalized epilepsy of infancy with generalized tonic-clonic seizures.

PURPOSE: While the literature on infantile epilepsies with minor and major seizures is extensive, little consideration has been given to infantile epilepsy with generalized tonic-clonic seizures (GTCS) alone. The aim of the present study was to analyze the data of a large group of patients and their families to obtain further insight into the clinical picture and pathogenesis of this type of epilepsy.

METHODS: The 101 children (58 boys, 43 girls) met the following inclusion criteria: onset of the epilepsy with febrile or afebrile GTCS in the first 5 years of life, absence of primary organic brain lesion or progressive brain disease, severe course with frequent febrile and/or afebrile GTCS, failure of conventional anticonvulsive therapy.

RESULTS: The epilepsy predominantly afflicts normally developed infants, boys and girls being about equally affected. The epilepsy begins with frequent febrile or afebrile GTCS, characteristically of long duration and often with alternating lateralization. In half of the cases additional myoclonic or myoclonic astatic seizures and/or absences occur. The initial GTCS phase is the same in epilepsies with and without minor seizures. Erratic myoclonias are especially characteristic. With advancing age, the symptomatology becomes increasingly polymorphic due to the occurrence of additional simple and complex focal and tonic seizures. Severe impairment of mental development soon after onset is a leading symptom. The overall death rate was 9%. Only 11% of the patients had been seizure-free for at least two years at final examination. The EEG was initially normal and subsequently exhibited diffuse 4-7/s rhythms, and only later spikes and waves of irregular shape (87%). Focal sharp waves occurred transiently in 26%. The family history and EEG of probands and relatives showed the pathogenesis to be decisively determined by genetic factors.

CONCLUSION: Early infantile GTCS epilepsy represents a genetically determined (idiopathic) epileptic encephalopathy. It overlaps with other forms of early childhood epilepsy such as severe myoclonic epilepsy, severe type of myoclonic astatic epilepsy, as well as early childhood absence epilepsy with GTCS.