ILAE definition of the Idiopathic Generalized Epilepsy Syndromes: Position statement by the ILAE Task Force on Nosology and Definitions

Abstract

In 2017, the International League Against Epilepsy (ILAE) Classification of Epilepsies described the "genetic generalized epilepsies" (GGEs), which contained the "idiopathic generalized epilepsies" (IGEs). The goal of this paper is to delineate the four syndromes comprising the IGEs, namely childhood absence epilepsy, juvenile absence epilepsy, juvenile myoclonic epilepsy, and epilepsy with generalized tonic-clonic seizures alone. We provide updated diagnostic criteria for these IGE syndromes determined by the expert consensus opinion of the ILAE's Task Force on Nosology and Definitions (2017-2021) and international external experts outside our Task Force. We incorporate current knowledge from recent advances in genetic, imaging, and electroencephalographic studies, together with current terminology and classification of seizures and epilepsies. Patients that do not fulfill criteria for one of these syndromes, but that have one, or a combination, of the following generalized seizure types: absence, myoclonic, tonic-clonic and myoclonictonic-clonic seizures, with 2.5-5.5 Hz generalized spike-wave should be classified as having GGE. Recognizing these four IGE syndromes as a special grouping among the GGEs is helpful, as they carry prognostic and therapeutic implications.

Methodology for classification and definition of epilepsy syndromes with list of syndromes: Report of the ILAE Task Force on Nosology and Definitions

“…Syndromes are divided based on age at onset and on syndrome type (generalized epilepsy syndromes, focal epilepsy syndromes, focal and generalized epilepsy syndromes, and syndromes associated with DEE or progressive neurological deterioration). Position papers that arose from each working group include: IGEs 21 Epilepsy syndromes with onset in neonates and infants (for the purpose of the proposed classification, infancy was defined as the period up to age 24 months) 22 …”

“…The syndromes in the IGE group are discussed in a separate paper, 21 which focuses on important distinguishing features of each, as well as addressing the areas of overlap.…”

“…The latter description and 27 other points added/modified in the revision process were included in the final (third) Delphi survey, which had a response rate of 58/67 (87%), and consensus was reached on all points. The diagnostic criteria and detailed summaries of each syndrome are discussed in the respective position papers 21–24 …”

“…The diagnostic criteria and detailed summaries of each syndrome are discussed in the respective position papers. [21][22][23][24] 4 | DISCUSSION Epilepsy syndromes have been recognized for >50 years, and their identification is critical in guiding investigations, selecting optimal therapy, and assisting with prognostic counseling on seizure outcome and comorbidities. Although both the 1985 and 1989 Classifications of the Epilepsies refer to the existence of syndromes, syndromespecific diagnostic criteria have not been defined and subjected to a formal consensus process.…”

International League Against Epilepsy classification and definition of epilepsy syndromes with onset at a variable age: position statement by the ILAE Task Force on Nosology and Definitions

“…• Generalized epilepsy syndromes, with polygenic etiologies: three of the idiopathic generalized epilepsies (IGEs-juvenile absence epilepsy [JAE], juvenile myoclonic epilepsy [JME], and epilepsy with generalized tonic-clonic seizures alone [GTCA]). 4 • Self-limited focal epilepsy syndromes with presumed complex inheritance: childhood occipital visual epilepsy (COVE) and photosensitive occipital lobe epilepsy (POLE). • Focal epilepsy syndromes with genetic, structural, or genetic-structural etiologies: sleep-related hypermotor (hyperkinetic) epilepsy (SHE), familial mesial temporal lobe epilepsy (FMTLE), familial focal epilepsy with variable foci (FFEVF), and epilepsy with auditory features (EAF).…”