The background may be normal or show generalized slowing. Background bi-parietal theta is usually seen.
Example of bi-parietal theta.
CAUTION Focal slowing consistently over one area is not seen consider structural brain abnormality.
Generalized spike-and-wave and polyspike-and-wave occur.
CAUTION Focal discharges are not seen consider structural brain abnormality.
Intermittent photic stimulation may trigger generalized spike-and-wave and polyspike-and-wave, and myoclonic-atonic seizures.
EEG abnormality is enhanced by sleep deprivation and by 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.
The myoclonic component is associated with a generalized spike or polyspike. The atonic component is associated with the aftergoing high voltage slow wave.