Benign myoclonic epilepsy in infancy with preceding afebrile generalized tonic-clonic seizures in Japan

Area of Science:

• Neurology
• Pediatric Neurology
• Epileptology

Background:

• Benign myoclonic epilepsy in infancy (BMEI) is typically characterized by myoclonic seizures (MS) in infants under three years old.
• While later generalized tonic-clonic seizures (GTCS) are known in BMEI, early GTCS preceding MS have not been recognized.
• This challenges the established diagnostic criteria and understanding of BMEI's early presentation.

Purpose of the Study:

• To describe a cohort of children presenting with early GTCS prior to MS.
• To investigate if these children fit within the spectrum of BMEI.
• To compare their seizure characteristics, outcomes, and developmental trajectories with typical BMEI cases.

Main Methods:

• Case series reporting on seven children with BMEI presenting with GTCS before MS.
• Clinical data collection including seizure types, age of onset, video-polygraphic features of MS, and developmental assessments.
• Longitudinal follow-up to evaluate seizure course and developmental outcomes.

Main Results:

• Seven children presented with recurrent GTCS before the onset of MS, fulfilling other BMEI criteria.
• The age of MS onset, ictal features, and long-term seizure and developmental outcomes were comparable to typical BMEI.
• The early GTCS were transient, often resolving within months and being replaced by MS.

Conclusions:

• Children experiencing early GTCS followed by MS may represent a distinct subgroup of BMEI.
• This finding broadens the clinical spectrum of BMEI, suggesting a more varied early presentation.
• Recognition of this BMEI variant is crucial for accurate diagnosis and management in pediatric epilepsy.