The background is typically normal (outside the postictal period) in the first year of life. Slow activity can appear with age.
Interictal discharges may be seen and may be focal, multifocal or generalized.
EEG abnormality is enhanced by sleep deprivation, in drowsiness and in sleep. Photic and pattern stimulation can precipitate epileptiform abnormality in some patients, with or without associated clinical seizures.
The ictal EEG varies according to the type of seizure, refer to the seizure type for more detail.
CAUTION Slow (<2.5Hz) spike-wave or generalized paroxysmal fast (≥10Hz) activity are not seen consider Lennox-Gastaut syndrome.