Blog #101: FLASHING LIGHTS AND EPILEPSY

 

            It’s been known for more than a century that flickering sunlight, as with driving under leafy trees, can trigger epileptic seizures in susceptible people. Currently, flashing and flickering lights in video games and television can do the same. Warnings about the potential for seizures have been added to these games. This is PHOTOSENSITIVE EPILEPSY. Some people, usually children, can convulse or have a brief staring spell (petit mal or absence seizure) with rhythmic jerky movements of the arms lasting 5-10 seconds or have an involuntary limb jerk or have eyelid movements by looking at a television screen, a computer screen, or an electronic screen game. It is estimated that 3-10 percent of all persons with new-onset epilepsy, especially in the age range 7-19 years, are found to be susceptible to visually-induced seizures; two-thirds of photosensitivity-associated-epilepsy patients are female. Photosensitive epilepsy is reported to be familial in eight percent of cases. ¹ Forty percent of siblings of photosensitive patients with epilepsy are photosensitive as well.²

            Physical exams and CT and MRI scan results are usually normal. The EEG, however, reveals epileptogenic changes (spike-and-wave and multiple-spike abnormalities) when the patient is exposed to flickering photic stimulation, usually at 9-, 10-, and 25 Hertz/second with the EEG’s own lights. During this exposure the patient will demonstrate altered consciousness as demonstrated by ceasing to count or talk accompanying the flickers with some jerks of the arms. This photo-paroxysmal response is diagnosed as Photosensitive Generalized Epilepsy. It is sensitive to the photic flicker frequency in the EEG lab. 

            The eyes may be open or closed during the test and the EEG will still demonstrate the epileptiform changes; the response does not occur if a light-occlusive patch covers one eye. A susceptible patient could cover one eye with a hand when near such light exposure to lessen chances of a seizure. Sensitivity to television stimuli can also be reduced by wearing blue eyeglasses or by not getting close to the screen, by watching under bright ambient lighting or having a table lamp on top of the TV set or computer screen. One hundred Hertz-TV screens are effective in reducing these seizures.³  Antiepileptic medications helpful for photosensitive epilepsy include valproic acid (Depakote), lamotrigine (Lamictal) and topiramate (Topamax).

            Normal individuals can develop a repetitive waveform on the EEG that is at the same flash rate of the flashing light over the patient in the EEG lab called photic following. These waves are not disorganized multi-spike complexes seen in photosensitive epilepsy. This is an EEG Photoparoxysmal Response, or “Photosensitivity,” and is not associated with physical seizure activity or loss of awareness.

 

1. Wilkins AJ, Darby CE, Binnie CD et. al. Television epilepsy—the role of pattern. Electroencepalogr Clin Neurophysiol. 1979;47:163-171.
2. Doose H, Gerken H. On the genetics of EEG-anomalies in childhood: IV. Photoconvulsive reaction. Neuropadiatrie. 1973;4:162-171.
3. Ricci S, Vigevano F, Manfredi M et.al. Epilepsy provoked by television and video games: Safety of 100-Hz screens. Neurology. 1998;50:790-793.

 
 
Lance Fogan, M.D. is Clinical Professor of Neurology at the David Geffen School of Medicine at UCLA. “DINGS” is his first novel. It is a mother’s dramatic story that teaches epilepsy, now available in eBook, audio book and soft cover editions.