The EEG background is normal.
CAUTION Generalized slowing is not seen.
CAUTION Focal slowing seen consistently over one area consider structural brain abnormality.
Generalized spike-and-wave or polyspike-and-wave is seen in the interictal EEG. Half of patients have these abnormalities only in sleep.
CAUTION Although focal spike-and-wave can occur, if seen consistently in one area consider structural brain abnormality.
CAUTION Slow spike-and-wave (<2.5Hz) is not seen consider other epilepsy syndromes.
An intermittent photoparoxysmal response to photic stimulation may be seen.
EEG abnormality is enhanced by sleep deprivation and in sleep. Generalized spike-and-wave often becomes fragmented with sleep deprivation or in sleep. Fragmented generalized spike-and-wave can appear focal or multi-focal but usually is not consistently seen in one area. The morphology of the focal spike-and-wave typically appears similar to the generalized spike-and-wave.
With generalized tonic-clonic seizures, the ictal EEG is often obscured by artifact. Generalized fast rhythmic spikes are seen in the tonic stage. Bursts of spikes and after-coming slow waves are synchronous with clonic jerks. A postictal period of irregular slow activity follows.