Photic- and pattern-induced seizures: a review for the Epilepsy Foundation of America Working Group.
OBJECTIVE
This report summarizes background material presented to a consensus conference on visually provoked seizures, convened by the Epilepsy Foundation of America.


METHODS
A comprehensive review of literature was performed.


RESULTS
Photosensitivity, an abnormal EEG response to light or pattern stimulation, occurs in approximately 0.3-3% of the population. The estimated prevalence of seizures from light stimuli is approximately 1 per 10,000, or 1 per 4,000 individuals age 5-24 years. People with epilepsy have a 2-14% chance of having seizures precipitated by light or pattern. In the Pokemon cartoon incident in Japan, 685 children visited a hospital in reaction to red-blue flashes on broadcast television (TV). Only 24% who had a seizure during the cartoon had previously experienced a seizure. Photic or pattern stimulation can provoke seizures in predisposed individuals, but such stimulation is not known to increase the chance of subsequent epilepsy. Intensities of 0.2-1.5 million candlepower are in the range to trigger seizures. Frequencies of 15-25 Hz are most provocative, but the range is 1-65 Hz. Light-dark borders can induce pattern-sensitive seizures, and red color also is a factor. Seizures can be provoked by certain TV shows, movie screen images, video games, natural stimuli (e.g, sun on water), public displays, and many other sources.


CONCLUSIONS
Recommendations on reducing risk of seizures have been developed by agencies in the United Kingdom, Japan, and the International Telecommunications Union, affiliated with the United Nations. The Epilepsy Foundation of America has developed a consensus of medical experts and scientists on this subject, reported in an accompanying work.
Fisher
Robert S
RS
Department of Neurology and Neurological Sciences, Stanford Medical Center, Stanford, California 94305-5235, USA. rfisher@stanford.edu
Harding
Graham
G
Erba
Giuseppe
G
Barkley
Gregory L
GL
Wilkins
Arnold
A
D002359:Cartoons as Topic; D016288:Computer Terminals; D020195:Epilepsy, Reflex / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control; D008027:Light / Q000009:adverse effects; D010364:Pattern Recognition, Visual / Q000502:physiology; D010775:Photic Stimulation / Q000009:adverse effects; D013690:Television; D014481:United States / Q000453:epidemiology