- Color Changes In TV Cartoons Cause Seizures
- A rash of epileptic seizures triggered
by a television cartoon has pinpointed a new type of epilepsy, according
to a report in this month's Annals of Neurology, the scientific journal
of the American Neurological Association and the Child Neurology Society.
- One evening in Japan in 1997, at precisely
6:50 in the evening, 685 people, most of them children, simultaneously
suffered epileptic seizures. The culprit was not difficult to identify:
all were watching the popular animated TV show, "Pocket Monsters."
- Japanese researchers have now found evidence
that the seizures were provoked by rapid changes of blue and red in the
background of the cartoons.
- Flickering lights such as strobe lights
or even the images on a television or video screen are well known as triggers
for epileptic seizures. Patients who experience such seizures are said
to suffer from photosensitive epilepsy.
- Rapid light/dark changes or alternating
high-contrast patterns cause nerve cells in the brain to fire electrical
impulses more rapidly than usual. In people with photosensitive epilepsy,
the resulting "electrical storm" in the brain can lead to muscular
convulsions or loss of consciousness.
- Although photosensitive epilepsy is not
a new phenomenon, the events in Japan appear to be unprecedented.
- "This may be the world's largest
simultaneous occurrence of photosensitive symptoms in children provoked
by viewing a TV program. Therefore, the seizures were considered to be
triggered by a single uniform visual stimulus," said Shozo Tobimatsu,
M.D., a neurologist at Kyushu University in Japan and one of the authors
of the article.
- Tobimatsu and his colleagues studied
4 boys who had suffered seizures during the cartoon. Like many others,
they were not known to suffer from epilepsy, although some had a family
history of epilepsy.
- The researchers measured brain wave responses
as the boys watched the cartoon in color or in black and white. They found
that only 2 of the boys were sensitive to light/dark changes, but that
all 4 boys had abnormal, epilepsy-like brain changes when exposed to the
color version of the cartoon.
- Because the cartoon had a flickering
blue and red background, the researchers also showed the boys rapidly alternating
blue and red images.
- "Rapid color changes between blue
and red in the cartoon were clearly the most important factor compared
with color changes of other kinds and flickering light," said Tobimatsu.
- These results, combined with a report
last year of color-induced seizures in Great Britain, led the Japanese
team to propose a new subcategory of photosensitive epilepsy called chromatic
- Other authors of the report were You
Min Zhang, M.D., and Motohiro Kato, M.D., also of Kyushu University; and
Yasuko Tomoda, M.D., and Akihisa Mitsudome, M.D., of Fukuoka University.
- Note: This story has been adapted from
a news release issued by American Neurological Association for journalists
and other members of the public. If you wish to quote from any part of
this story, please credit American Neurological Association as the original
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