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.
"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.