July 4, 2008 -- It started with a migraine, not even five minutes after the fireworks show began. Damon Thorne tried to look away but the entire sky was lit up. "Even closing my eyes -- I could still see the fireworks through my eyelids," he says.
Then, his right hand began to quiver. Little points of light, much like the "stars" that compose a firework's bloom, panned across his field of view. This was Thorne's "aura," visible only to him, and a warning sign that a seizure was about to happen.
"Next thing I remember, I was waking up in the hospital," says Thorne, who has epilepsy. "Come to find out I had some massive grand mal seizure."
The incident at the St. Louis County Fair and Air Show in 2006 would become the first indication to Thorne that his epilepsy appeared to be sensitive to the barrage of light that accompanies a professional pyrotechnics display.
While it's an uncommon experience, there are reports like Thorne's of fireworks triggering seizures in susceptible people. And some neurologists think it's worth noting, especially for parents with children who might not have had their first seizure yet.
Seizures affect more than 3 million people in the United States, according to the Epilepsy Foundation of America. The seizures typically come about when groups of nerve cells in the brain fire abnormally, setting off a range of symptoms from behavior changes to muscle spasms and loss of consciousness. When someone has a pattern of repeated seizures, they are usually diagnosed with epilepsy.
In what's called reflex epilepsy, the seizures can be sparked by things patients see or hear, even sense in the environment around them. A small percentage of people with epilepsy -- somewhere between 3 and 5 percent -- are considered photosensitive, because light can trigger their seizures. The source could be a computer monitor, a television or even sunlight reflecting off water in a certain way.
Doctors often can determine whether patients are photosensitive by having them look at a strobe light to see if it sets off a seizure. This photostimulation exercise is routinely done during a common diagnostic test for epilepsy, in which technicians use an electroencephalogram, or EEG, to monitor patients' brain waves for unusual electrical activity.
"There are literally thousands of different triggers for seizures," says Dr. John Gibbs, a neurologist who now treats Damon Thorne in Greeneville, N.C. "[Fireworks] certainly can mimic photostimulation."
Diagnosing photosensitivity is important because it can guide the type of medication patients get and help them identify a potential trigger to avoid, helping prevent further seizures.
A Different Ballgame
"They've never pinpointed exactly what it is with him," says Cindy Mitchell, referring to her son, Robert, who had his first seizure at 2 1/2 years old. Doctors diagnosed him with idiopathic generalized epilepsy -- epilepsy with no apparent biological cause.
"His seizures are totally unpredictable," says Mitchell. "It definitely affects his quality of life, and it affects the whole family."
One study determined that children with idiopathic epilepsy have a more than 67 percent chance of becoming seizure-free by the time 20 years have passed since diagnosis. Robert Mitchell is now 20 years old; the seizures haven't stopped.
"He's got easily between seven and 10 tonic-clonic seizures per month," Mitchell says. Tonic-clonic, or grand mal, seizures describe the dramatic, convulsive type of seizure usually depicted in Hollywood films.
It wasn't until the Mitchells got season tickets to watch the Anaheim Angels professional baseball team that Cindy Mitchell noticed her son's potential sensitivity to fireworks. After each Friday home game, fans are treated to a pyrotechnics show above Anaheim Stadium.
"What he gets is a quick flip or a jerk of his wrist or his ankle ... and sometimes blinking or twitching of the eyes," says Mitchell. But the family still goes to the games, because the fireworks-triggered reactions are not as severe as the tonic-clonic seizures, explains Mitchell.
Frequency and Intensity
Despite Thorne's and Mitchell's stories, neurologists who treat patients with epilepsy think such reactions do not occur in a large number of people.
"You may well get some anecdotal reports of firework-provoked seizures ... but this would be a rarity, not by any means the norm," says Dr. James Grisolia, a neurologist at Scripps Memorial Hospital in San Diego, Calif.
Most light-induced seizures require a fixed frequency of light exposure. For example, photosensitive people might be bothered by the rapid shutter effect you see when looking at a sunlit picket fence from a moving car, explains Dr. Shlomo Shinnar, director of the Comprehensive Epilepsy Management Center at Montefiore Medical Center.
The intensity of the light is also a key factor in affecting the brain. "This is why we advise kids to sit away from [the] TV with room lights on if they are somewhat sensitive," says Shinnar. Fireworks, he says, are usually too far off in the sky and fail to erupt with a fixed frequency of bursts.
Other neurologists suspect the sounds generated by the explosions in the fireworks' lift charges and breaks might be to blame.
"I have, in the past, had one patient who had seizures provoked by fireworks, but it was due to the loud percussive sounds causing a startle rather than the lights," says Dr. Orrin Devinsky, director of the New York University Epilepsy Center.
But what about the fireworks finale? Dr. Giuseppe Erba thinks the climactic conclusion we've all come to expect in professional shows is the most fitting time for photosensitivity to kick in.
"I recommend caution at the end of the fireworks, when the whole sky lights up," says Erba, a professor of neurology and pediatrics at the University of Rochester. The blasts are "wider and they occupy most of the visual field," if you're up close to the display.
For most patients with epilepsy who are on the right medication, the pyrotechnic climax should not have an effect, says Erba. His concern is for those people, most likely children around school age, who "do not know they're photosensitive."
When you're watching the fireworks show, "be very observant of how your body responds," he says. "If you start getting some involuntary jerks, that may be the first signal that something is wrong."
Should that happen, Dr. Erba recommends covering one eye with the palm of your hand to block out the light. Cutting light input to the visual cortex by half should be enough to prevent a seizurelike cascade of electrical activity in the brain, explains Erba.
Cindy Mitchell incorporates an approach similar to Erba's eye-covering technique by having her son wear sunglasses during the fireworks shows.
"I think you have to go on living life and allowing your child to have the experiences that bring joy," says Mitchell.
Still, the family is missing the Angels' Fourth of July game due to a church function.
As for Damon Thorne, now 37, and his Fourth of July plans: "I am not going to see no fireworks now."