Photosensitivity and epilepsy.

Photosensitive epilepsy is a well-known condition characterized by seizures in patients who show photoparoxysmal responses on electroencephalography (EEG) elicited by intermittent photic stimulation. Photoparoxysmal responses can be defined as epileptiform EEG responses to intermittent photic stimulation or to other visual stimuli of everyday life and are frequently found in nonepileptic children. The modern technologic environment has led to a dramatic increase in exposure to potential trigger stimuli; nowadays, television and video games are among the most common triggers in daily life. There is ample evidence for genetic transmission of photoparoxysmal responses; systematic family studies have provided data for an autosomal dominant mode of inheritance with age-dependent penetrance for photosensitivity. The age of maximum penetrance is between 5 and 15 years. The prognosis for control of seizures induced by visual stimulation is generally very good. The large majority of patients do not need anticonvulsant therapy, but, when needed, the drug of choice is valproate. Stimulus avoidance and stimulus modification can be an effective treatment in some patients and can sometimes be combined with antiepileptic drug treatment.