Epilepsy classification has never been static. The language moved from broad descriptive labels such as grand mal and petit mal to systems based on seizure networks, epilepsy type, syndrome, cause and observable clinical features.
Before formal international classification
Older medical writing used descriptive terms such as grand mal, petit mal, psychomotor seizure and Jacksonian seizure. These labels reflected what clinicians could observe, but they mixed seizure appearance, presumed anatomy and historical convention.
By the mid-twentieth century, EEG made it possible to connect clinical events with electrical patterns, creating pressure for a shared international vocabulary.
The early ILAE systems
The ILAE published early international proposals in the 1960s and revised seizure classifications in 1970 and 1981. These systems increasingly separated partial—later called focal—seizures from generalised seizures.
The 1981 seizure classification and 1989 epilepsy-and-syndrome classification shaped clinical practice for decades.
Why terminology had to change
Terms such as ‘simple partial’ and ‘complex partial’ were widely used but did not always describe consciousness or network involvement accurately. Advances in imaging, genetics, video-EEG and syndrome recognition also made older frameworks increasingly restrictive.
ILAE therefore moved toward classifications that separated seizure type, epilepsy type, syndrome and aetiology.
The 2017 framework
The 2017 seizure classification introduced focal aware and focal impaired-awareness terminology and formalised focal, generalised and unknown-onset categories.
The accompanying Classification of the Epilepsies organised diagnosis across seizure type, epilepsy type and epilepsy syndrome while considering structural, genetic, infectious, metabolic, immune and unknown causes.
The 2025 seizure-classification update
In April 2025 the ILAE updated the operational seizure classification while retaining the four main classes: focal, generalised, unknown whether focal or generalised, and unclassified.
Important changes included removing ‘onset’ from the main class names, replacing awareness alone with consciousness as a classifier, distinguishing classifiers from descriptors, replacing the motor/non-motor split with observable/non-observable manifestations, and describing the chronological sequence of seizure features.
Classification is a clinical tool, not a label for life
A seizure may initially be classified as unknown and later reclassified when EEG, MRI, witness video or additional events provide more information.
The purpose of classification is to improve communication, diagnosis, treatment and research—not to force every seizure into a category before enough evidence exists.
Why historical terminology still appears
Older terms remain important when reading historic medical records, classic research papers and patient notes written under earlier classification systems.
Modern educational material should explain those terms rather than silently treating them as current terminology.
Related reading
Sources and further reading
- ILAE updated classification of epileptic seizures, 2025
- ILAE Classification of the Epilepsies, 2017
- ILAE Definition and Classification resource hub
- ILAE classification timeline commentary
Evidence checked: September 2026.