Photosensitivity in juvenile myoclonic epilepsy

Photosensitivity is reported to occur in approximately 40% of patients with juvenile myoclonic epilepsy. Our experience suggests that the prevalence i s higher and may be related to both the duration of intermittent photic sti mulation and also the age at which the procedure is undertaken. A two-year retrospective review of all EEGs was undertaken on all children attending a paediatric EEG department to identify those with juvenile myoclonic epilep sy. Photosensitivity was defined as a generalized spike or spike-wave parox ysm occurring at least twice during intermittent photic stimulation. Sixty- one children with a diagnosis of juvenile myoclonic epilepsy with a median age of 13 (range 7-16) years were identified, 55 (90%) of whom were photose nsitive. Eighteen of these 55 patients showed photosensitivity only after f our minutes of continuous photic stimulation. The prevalence of photosensit ivity in juvenile myoclonic epilepsy is likely to be higher than previously reported. When a diagnosis of juvenile myoclonic epilepsy is being conside red, the initial diagnostic EEG should include intermittent photic stimulat ion for up to five minutes, or less if the patient shows evidence of photos ensitivity. The identification of photosensitivity may have important manag ement implications. (C) 2000 BEA Trading Ltd.