NEW ORLEANS - Japanese children who had seizures during a “Pokemon” cartoon in 1997 have generally not had another one unless they already had epilepsy, researchers say.

The TV show sent at least 685 Japanese viewers, mostly children, to emergency rooms with symptoms ranging from nausea and hyperventilation to convulsions. They were apparently made sick by a scene with extremely rapid flashes of red and blue. 

To find out whether the incident had any lasting effects, Dr. Akihisa Okumura and colleagues in Nagoya sent questionnaires to doctors who had treated 103 “Pokemon” patients in the prefecture, or state, of Aichi. They got back results for 91 patients.

Twenty-five had had at least one more convulsion in the five years since the “Pokemon” episode. They were divided almost evenly between those diagnosed with epilepsy and those who weren’t. However, electroencephalograms revealed that 10 of the 13 who had not been diagnosed with epilepsy did, in fact, have the disease.

His findings were published as a letter to the editor in Thursday’s New England Journal of Medicine.

“That’s very much what I would have expected,” said Dr. Donald M. Olson, director of pediatric epilepsy at Stanford University’s Lucille Packard Children’s Hospital.

“A lot of us may have a genetic predisposition to epilepsy but never have a seizure in their lives,” he said. “This is just one of those unusual occurrences where a specific trigger — this kind of flashing screen — provoked seizures in people who might not otherwise have had them.”

Olson said the risk of TVs, video games and computers triggering a seizure is extremely low for children who have not already had seizures.

The incident in Japan was by far the largest in which seizures have been traced to a TV broadcast.