Washington ? The millions of video games sold in the United States this holiday season come with warnings that sometimes are overlooked. They say that the games can trigger seizures in some players, especially children, who have a rare condition known as photosensitive epilepsy.

For these people — perhaps 1 in 4,000 –a video game’s bright flashes and dramatic patterns sometimes can set off an electrical storm of brain signals. The storm in the brain may cause involuntary body movements, involuntary oral or visual responses and blackouts, according to Dr. Edward Novotny, director of the Pediatric Epilepsy Program at the Yale University School of Medicine in New Haven, Conn.

The video game industry does not dispute the possibility. Rather, it stresses that its products do not cause the attacks; at most they trigger them in susceptible people under certain unusual conditions. Pediatric epilepsy experts generally agree, and note, as the industry does, that strobe lights and flickering TVs sometimes can have the same effect.

Some video game players, whether or not they have photosensitive epilepsy, may suffer lesser symptoms such as nausea, eye- or muscle-twitching, loss of awareness, involuntary movements or altered vision, reported Dr. Yukitoshi Takahashi, head of pediatrics at Japan’s Gifu University School of Medicine.

Asked about the phenomenon of seizures, the game makers’ Washington-based trade association, the Interactive Digital Software Assn., provided a prepared statement. It says: “Although photosensitive epilepsy is not caused by the visual media, as a service to consumers, game system and individual game instruction manuals prominently feature epilepsy warnings that are included when each game system and individual software is sold in the United States.”

The statement concluded that “due to pending litigation we cannot comment further at this time.”

Redmond, Wash.-based Nintendo of America, whose products are in 40 million U.S. homes, is the defendant in two pending Louisiana lawsuits. They allege that the industry’s most famous game maker skimped on design, testing and warnings for products that are “inherently and unreasonably dangerous.”

The risk

For players of video games and their parents, it can be hard to know what to make of the link between video games and seizures, or how to minimize the relatively small danger that video games present compared with more common and familiar hazards such as riding bicycles or climbing trees.

By most estimates, 3 to 5 percent of all people who have epilepsy in the United States, which is about 1 percent of the population, can suffer seizures when exposed to bright flickering light. That comes to 84,000 to 140,000 Americans. The number of them who ever experience seizures, let alone seizures while playing video games, is far smaller.

Neurologists who specialize in photosensitive epilepsy say children ages 7 to 19, especially children at puberty, are most susceptible. About 145 million Americans play computer or video games, and roughly half of all Nintendo, PlayStation and X-Box game players are under 18, according to the Interactive Digital Software Assn.

Nintendo of America, which offers the most conspicuous warnings of any maker, advises players to sit as far as possible from the screen. Nintendo also suggests they play on a small-screen TV, take 15-minute breaks every hour and play only in a “well-lit” room.

Dr. Graham Harding, a neurophysiologist at Aston University in Birmingham, England, who specializes in photosensitive epilepsy, expanded on Nintendo’s cautions. The minimum safe distance between screen and player is about 6 feet, Harding said. A small screen is preferable because it flickers less powerfully than a large one, and a “well-lit” room is one with its main lights on.

Warnings

Some critics say the warnings that now are on and in boxes containing new game systems and game manuals also should be shown on the screen at the beginning of each game.

“Children frequently play video games purchased by friends and neighbors. These kids never get a chance to see a warning that is buried in the packaging materials,” reasoned Geoffrey Parmer of the law firm Bales Weinstein in Tampa.

Parmer makes the argument in a case brought by the parents of Dominic Zummo, who are suing Sony and LucasArts over seizures he had while playing a LucasArts “Star Wars” game on Sony’s PlayStation. The Zummos allege that Sony and LucasArts, the system and game maker, respectively, failed to warn adequately of possible seizures or to thoroughly test their products before their sale.

A Catch-22 makes protecting vulnerable players especially difficult, Harding noted.

While Nintendo, for example, warns that anyone who has had a seizure induced by flashing lights or patterns should consult a doctor before playing a video game, Harding said, that doesn’t protect against a first attack. “Warnings are good except for people who don’t know they are photosensitive,” said Harding.

To cope with the problem of first-time seizures, a pair of Italian neurologists suggested in a study published in the journal Epilepsia in 1999 that game makers put warning labels on games that might be especially hazardous.

The study’s researchers, Stefano Ricci and Federico Vigevano, observed the brain activity of 30 people with photosensitive epilepsy while they played 12 different Super Nintendo games that were popular in the mid-’90s. Seventeen of the subjects showed “sensitivity” to video game programs, they reported. The subjects’ distance from the screen was 1 meter, about 40 inches, which the researchers said reflected actual practice.

The games with the most brightly lighted backgrounds and the most light flashes appeared to cause greater activity, the researchers found. They recommended that those games be labeled “potentially dangerous” so that people concerned about photosensitive epilepsy could steer clear of them.

Robert Fellmeth, the executive director of the Children’s Advocacy Institute at the University of San Diego Law School, said only government regulation would assure adequate warnings. Current industry-written warnings are designed to avoid litigation, he said, and to avoid scaring away consumers.

The federal Consumer Product Safety Commission, which has jurisdiction over video games, has received 25 reports of seizures linked to playing video games since 1988, according to its database. Spokesman Ken Giles said the commission was aware of the warnings, but noted that photosensitive seizures were not unique to video games.

Harding, the British neurologist, said photosensitive epileptic seizures could be greatly reduced if game makers adopted the voluntary standards used on British television. Those standards, which apply only to TV programs, ban flashes that occur more than three times per second and flashing that appears on more than a combined 25 percent of the screen. The standards also warn against certain patterns, such as ones with more than five contrasting light-dark pairs of stripes that are large or moving on the screen.

These standards have been adopted in Japan, Russia and by the Disney Co., but only for TV programming.