Background

The EEG background is normal.

CAUTION Generalized slowing is not seen.

CAUTION Focal slowing seen consistently over one area consider structural brain abnormality.

Interictal

Generalized spike-wave or polyspike-wave at 3-5.5Hz is seen in the interictal EEG. Half of patients have these abnormalities only in sleep.

CAUTION Although focal spike-wave can occur, if seen consistently in one area consider structural brain abnormality.

CAUTION Slow spike-wave (<2.5Hz) is not seen consider other epilepsy syndromes.

Activation

EEG abnormality is enhanced by sleep deprivation, in drowsiness and in sleep.

An intermittent photoparoxysmal response to photic stimulation may be seen.

Generalized spike-wave often becomes fragmented with sleep deprivation or in sleep. Fragmented generalized spike-wave can appear focal or multi-focal but usually is not consistently seen in one area. The morphology of the focal spike-wave typically appears similar to the generalized spike-wave.

Ictal

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.