The background EEG is normal.
The interictal EEG is normal.
Sleep may activate the EEG and generalized spike-and-wave and polyspike-and-wave may occur, with or without accompanying myoclonic jerks clinically. One fifth of patients have photosensitivity, with myoclonic jerks precipitated by photic stimulation. In 10% of patients myoclonic jerks may be activated by sudden noise or touch in either awake or sleep states.
Myoclonic jerks are associated with generalized spike-and-wave or polyspike-and-wave discharges.