EPILEPSIES BY ETIOLOGY

In recent years there has been a significant expansion in our understanding of the underlying etiologies of the epilepsies, underpinned by advances in modern neuroimaging and genetic testing. As such terminology such as 'idiopathic', 'cryptogenic' and 'symptomatic' are no longer used. Epilepsies are now described more precisely by their specific underlying etiologies. In this section of EpilepsyDiagnosis.org, important epilepsy etiologies are presented, with particular focus on those that are important to recognize and those for whom early recognition and treatment optimizes health outcomes.

Some etiologies are associated with a more diverse clinical phenotype, with variable seizure type(s), age at onset, associated comorbidities and/or prognosis. In other cases, an etiology is associated with a clearly-defined, relatively uniform and distinct clinical phenotype in most affected individuals (clinical presentation, seizure types, comorbidities, course of illness and/or response to specific therapies), as well as consistent EEG, neuroimaging and/or genetic correlates, and in the latter, the term etiology-specific syndrome can be used.

An etiology-specific epilepsy syndrome

An etiology-specific epilepsy syndrome is when a specific etiology for the epilepsy is associated with a clearly-defined, relatively uniform and distinct clinical phenotype in most affected individuals (clinical presentation, seizure types, comorbidities, course of illness and/or response to specific therapies), as well as consistent EEG, neuroimaging and/or genetic correlates.

The following etiology-specific epilepsy syndromes have been defined by the ILAE in 2022:

Neonate/Infant

Variable Age

Mesial Temporal Lobe Epilepsy with Hippocampal Sclerosis (MTLE-HS)
Rasmussen Syndrome (RS)