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.
- Wilkins AJ, Darby CE, Binnie CD et. al. Television epilepsy—the role of pattern. Electroencepalogr Clin Neurophysiol. 1979;47:163-171.
- Doose H, Gerken H. On the genetics of EEG-anomalies in childhood: IV. Photoconvulsive reaction. Neuropadiatrie. 1973;4:162-171.
- 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.
