Chapter 97 - Visual stimuli, photosensitivity, and photosensitive epilepsy

Summary

Photosensitivity is a broad term and is used both for epileptiform electroencephalography (EEG) discharges and epileptic seizures, evoked by visual stimuli. This chapter makes a distinction between the epileptiform EEG responses to intermittent photic stimulation (IPS), the photoparoxysmal responses (PPRs), and the seizures provoked by visual stimuli in daily life (visually induced seizures). The close association between migraine and idiopathic benign childhood epilepsy and especially with the occipital lobe epilepsies has been well recognized, and a differential diagnosis in some particular case still represents a challenge. The choice of drug treatment will depend on the likelihood of getting seizures evoked by visual stimuli. It depends on age, photosensitivity range, frequency and severity of seizures, and the type of epileptic syndrome as well as on the environment in which the patient lives. Valproate is most effective; 85% of the visually sensitive patients become seizure-free with valproate. Alternatives are levetiracetam and lamotrigine.