June 19, 2008
FIREWORKS and EPILEPSY
With July fourth rapidly approaching and very little information regarding how fireworks may trigger seizures in those living with epilepsy, Epilepsy.com sought out one of the top experts on photosensitivity, Dr. Guiseppe Erba, Professor of Neurology and Pediatrics at the University of Rochester, Rochester, New York.
Dr. Erba, can you explain how fireworks can trigger a seizure?
Any strong light that flashes repeatedly straight into the eyes of an individual with photosensitive predisposition to seizures has the potential for causing a seizure. In addition to the intensity of the light (luminosity) and the flicker (frequency), there are other determining factors such as the color (red being more provocative than green and blue), the contrast between light stimulus and background, and the extent to which the light stimulus fills up the field of vision. Fireworks are no exception in terms of potential risks. However, visual effects vary greatly in the course of fireworks and the risk will change accordingly.
Typically, the first part of the fireworks program consists of single shots in two or three successive stages, generating trajectories of small multicolored lights that move at slow pace, leaving an evanescent trace that quickly vanishes. The overall effect is that of a slow moving, irregular linear pattern that does not flicker. It is unlikely that single fireworks of this type may have adverse effects even on photosensitive individuals.
The conditions change dramatically during the final display of the fireworks that typically consist of a sustained barrage of multiple explosions producing bright flashes in rapid successions all over a large area of the visual field. During the final seconds of fireworks spectators are exposed simultaneously to a multitude of intensely bright white lights that flicker rapidly like a powerful strobe against the dark sky. This is therefore potentially a dangerous type of stimulation because it could possibly trigger a seizure in whoever is photosensitive. Children, who are often part of the fireworks crowd, are at greater risk than grown ups. This is because the genetic predisposition toward photosensitivity has maximal expression in the young age group.
Are there certain precautions people with epilepsy can take before attending a July 4th firework display?
People with epilepsy should make sure they have taken their medication fully in the preceding 12 hours. If their doctor has prescribed additional medication ?when needed? such as lorazepam (Ativan), it may be reasonable to take a preventive dose half hour before the beginning of the fireworks. This would be particularly indicated if the patient had previous experience with seizures that may have been triggered by some type of photic stimulation.
It is not advisable to go to fireworks display alone. People with epilepsy should be accompanied by a competent adult with experience in seizure management.
Individuals who know they are photosensitive and still wish to watch the fireworks should be particularly careful. The same word of caution applies to all individuals who never had seizures but have close relatives with history of epilepsy, particularly PGE, irrespective of whether the relative has had seizures triggered by visual stimuli or not. They are at risk of carrying the photosensitive genes without knowing it. All individuals at risk are well advised not to get too close. Watching from a distance that reduces the view of the full fireworks display to approximately one quarter of the total field of vision is a recommended precaution. They should not stand in dark surroundings but rather choose to watch the display from a well lit place. Most importantly, they should cover one eye with the palm of one hand during the grand finale of strong multiple flashing lights. Cutting down half of the visual input by covering one eye is usually sufficient to prevent abnormal brain responses to most types of photic stimulation. Finally, they should be ready to also cover the other eye immediately in case they perceive involuntary jerking in their muscles, even if slight.
Covering both eyes will exclude any further stimulation and will prevent progression into a full seizure. It is important to know that simply ?closing? the eyes or looking away in another direction is not sufficient. In order to prevent the seizure it is essential to completely obliterate the visual input by tightly sealing the orbit with the palm of one hand.
|
