Understanding seizures and epilepsy
Start with the event, then classify the seizure, then the epilepsy type, and where possible the epilepsy syndrome. Correct classification matters because it influences investigation, prognosis and medicine choice.
A seizure is not the same as epilepsy
A seizure is a transient episode caused by abnormal excessive or synchronous neuronal activity. Epilepsy is an enduring predisposition to unprovoked seizures. Acute symptomatic or provoked seizures can recur without necessarily meaning that a person has epilepsy.
Think in levels
Clinical reasoning moves from seizure type → epilepsy type → epilepsy syndrome → cause. The diagnosis can become more specific over time as history, EEG, imaging and other investigations add information.
The four main seizure classes
The ILAE updated its operational seizure classification in 2025.
Focal
Seizures arising from a network in one hemisphere. Manifestations depend on the brain region involved and may include sensory, autonomic, cognitive, emotional or motor features. Consciousness may be preserved or impaired.
Generalized
Seizures that rapidly engage bilateral networks. Examples include generalized tonic-clonic, absence, myoclonic, tonic, atonic and myoclonic-atonic seizures.
Unknown whether focal or generalized
Used when there is clear evidence of an epileptic seizure but available information is insufficient to decide whether it is focal or generalized.
Unclassified
Used when the event is epileptic but does not fit an available seizure type with enough confidence.
Epilepsy types
A syndrome diagnosis — for example juvenile myoclonic epilepsy, childhood absence epilepsy, temporal lobe epilepsy or Lennox–Gastaut syndrome — can be especially useful because it bundles together characteristic seizure types, EEG patterns, age of onset, prognosis and treatment considerations.
Why classification comes before drug choice
Some medicines are especially suitable for focal epilepsy, some have broader activity, and some can worsen particular generalized seizure types. This is why EpilepsyWise uses the principle “Divide before drugs.”
Go to wise medicine selectionKey references: International League Against Epilepsy (ILAE), Updated Classification of Epileptic Seizures (2025); ILAE Classification of the Epilepsies (2017); ILAE Classification and Definition of Epilepsy Syndromes (2022).