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Severe idiopathic generalized epilepsy of infancy with generalized tonic-clonic seizures
H Doose1, H Lunau, E Castiglione
1Epilepsy Center, Raisdorf, Germany.
Insights
This study analyzes infantile epilepsy presenting solely with generalized tonic-clonic seizures (GTCS). It reveals a genetic basis and significant developmental impairment, highlighting the need for targeted research in this specific epilepsy subtype.
Area of Science:
- Neurology
- Pediatric Epilepsy
- Clinical Genetics
Background:
- Infantile epilepsies are well-documented, yet those presenting exclusively with generalized tonic-clonic seizures (GTCS) remain understudied.
- Understanding the clinical spectrum and pathogenesis of GTCS-only infantile epilepsy is crucial for accurate diagnosis and management.
Purpose of the Study:
- To investigate the clinical characteristics and genetic underpinnings of infantile epilepsy primarily manifesting with generalized tonic-clonic seizures (GTCS).
- To differentiate this epilepsy subtype from other infantile epileptic syndromes based on clinical presentation, EEG findings, and family history.
Main Methods:
- Analysis of a cohort of 101 children with epilepsy onset before age 5, characterized by frequent febrile or afebrile GTCS.
- Inclusion criteria specified absence of brain lesions and failure of conventional therapies.
- Detailed clinical evaluation, EEG monitoring, and family history assessment were conducted.
Main Results:
- Epilepsy predominantly affected normally developed infants, with onset in early childhood via frequent, prolonged GTCS, often with alternating lateralization.
- Half of cases developed additional seizure types (myoclonic, astatic, absences) as the condition progressed.
- Severe developmental impairment was a common outcome, with a 9% mortality rate and only 11% achieving long-term seizure freedom.
- EEG showed initial normality followed by diffuse rhythms and later irregular spike-wave discharges.
- Genetic factors were identified as the primary determinant of pathogenesis.
Conclusions:
- Early infantile epilepsy characterized by generalized tonic-clonic seizures (GTCS) is a genetically determined epileptic encephalopathy.
- This syndrome shares features with severe myoclonic epilepsy and early childhood absence epilepsy, indicating overlapping etiologies and clinical presentations.
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.