Sep 19 2005
The Epilepsy Foundation today issued new recommendations for families on how to limit the risk of seizures triggered by flashing images and certain patterns on television, videogames, computers and other video screens.
The recommendations are based upon guidelines in the UK and Japan and are the first published in the US to be based on an expert review of research on photosensitivity (the susceptibility to visual stimulation). The report by Graham Harding of the Clinical Neurophysiology Unit, Aston University, Birmingham, England, and his colleagues, appears in the September issue of the journal Epilepsia, the official journal of the International League Against Epilepsy.
The consensus recommendations, which are published in full on the Epilepsy Foundation website, cover factors such as light intensity, flicker, contrast, duration and pattern, and the technical parameters within these factors that are most likely to provoke seizures in susceptible individuals. Accompanying the report in Epilepsia is an article on the literature and data review conducted for the working group as part of its analysis and recommendations development.
No one knows how many people have had seizures while watching television, surfing the Internet, or playing videogames. But some epileptologists (doctors who treat seizures) have noticed an increase in the number of young people coming to them following these incidents. The Epilepsy Foundation, which has been watching this trend, believes that seizures from visual stimulation are a significant national health problem.
Physicians on the Epilepsy Foundation’s Task Force on Photosensitivity advise that children and young adults 7 to 19 years of age are especially susceptible to visually induced seizures. They report the annual incidence in this age group to be one in 17,500, compared to one in 91,000 in the overall US population. This five-fold increased risk to youth was dramatically highlighted in December 1997 when nearly 700 children were hospitalized in Japan for symptoms that developed while watching a televised Pokemon episode. About 500 of these children had seizures.
Exposure to flashing light and repetitive patterns does not cause epilepsy, the tendency to recurring seizures, according to the experts. Giuseppe Erba, MD, from the Departments of Neurology and Pediatrics at the University of Rochester Medical Center, who led development of the recommendations, said, “Children with undetected epilepsy may have a first recognized seizure while playing or soon after playing a videogame. Some children will have a seizure when exposed to a specific videogame and will not have another seizure unless again exposed to the same stimulus. This doesn’t mean that the videogame caused the epilepsy, but it reveals the vulnerability of individuals who carry the photosensitive trait when they are exposed to visual stimuli capable of triggering the abnormal response. The same increased risk exists for children with known epilepsy who can be photosensitive, as well.”
In a separate report also released today, the Epilepsy Foundation has issued recommendation for industry concerning technical characteristics of light and patterns that might pose a risk to people who are photosensitive. There is no known method to eliminate the risk of visually provoked seizures entirely because of the great variability of what triggers seizures in different individuals. Controlling these factors in videogames is especially difficult.
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