The background EEG is normal.
Occipital spike or spike-wave may occur in the resting EEG record. Centrotemporal spikes or generalised spike-wave may co-exist.
Occipital spike- or polyspike-wave is facilitated by eye closure and intermittent photic stimulation. Generalized spike-wave or polyspike-wave (with posterior predominance) may also occur with photic stimulation. EEG abnormality is enhanced by sleep deprivation, in drowsiness and in sleep.
Occipital ictal patterns are seen, contralateral to the visual field containing the visual phenomena. Ictal patterns may spread to the ipsilateral temporal lobe or contralateral occipital lobe.