photosensitive epilepsy

October 19, 2007 7:19 AM

I do not have "regular" epilepsy, have never had a seizure of any kind but I am now wondering if I may have photosensitive epilepsy.

It happens when driving at dawn or dusk with sun flickering through a line of trees. When the sun reappears from behind a tree, it is a jolt like I've been hit in the head with baseball bat, (or cricket bat, if you prefer). Recovery is instant, no after effects.

This has happened all my life (I am 46 now). It is no better or worse than it has ever been. Looking on the web, I see that a P.E. seizure can be generated by various things (lights on a police car, disco lights video games, contrasting light and dark patterns) but these do not bother me. I am sensitive to bright lights (flashing or not), but this probably because I have light blue eyes. I find things like flashes on cameras and flashing text on websites annoying, but that's all, just annoying. I do not like watching the teevee in the dark, it gives me a headache.

Since I experience it only in the one certain circumstance and I don't have a seizure, does it just mean that I have a very mild case of it? or is it something else?

posted by allelopath to health & fitness (5 comments total)

My brother can trigger migraines by walking from a dim building out into bright sunlight. Maybe it's a mild form of that.
posted by olinerd at 7:21 AM on October 19, 2007

Driving past a line of trees that is interrupting a patient's view of the sun is one of the classic real-world ways to get a photic stimulus. (The other is to look at a strobe light in a discotheque.)

A person who has epilepsy has had more than one seizure. If a person has not had a seizure, that person does not have epilepsy.

What you described sounds like an isolated myoclonic jerk after photic stimulation. People who get this often have what's called a 'photoparoxysmal response' (PPR) on their EEG; when they are flashed at the right frequency their brain waves synchronize in an unusual way, and this can occasionally be correlated with a myoclonic jerk or the onset of a seizure. More commonly the photoparoxysmal response is seen only on the brain waves and has no correlate. The epidemiology is not very high quality on this but some studies estimate that 1% of people show a PPR. Most people, with or without epilepsy, do not have a PPR.

Despite many efforts over nearly 50 years, no one has ever been able to show that the presence of a photoparoxysmal response, with or without myoclonus, was a significant risk factor for developing future epileptic seizures. This leads most of us in the field to guess that it probably is not a significant risk factor, while acknowledging that there is no scientifically rigorous evidence to make that statement conclusively.

I can't comment on a person's individual case or give you medical advice. For that reason I must recommend you consult a physician for advice or information tailored to your particular case.
posted by ikkyu2 at 7:30 AM on October 19, 2007 [8 favorites]

uh yeah, what that guy said.

If it involves epilepsy, you can bet it is the right thing to do to follow ikkyu2's advice. He's a doctor who studies epilepsy.
posted by Ironmouth at 9:16 AM on October 19, 2007 [1 favorite]

i've often wondered the same thing - it happens to me with the sun and the trees. also happens with strobe lights, but to a lesser extent. i'm not particularly light-sensitive at any other time.
posted by sarelicar at 9:33 AM on October 19, 2007

ikkyu2, thanks for the response. I've never of a myoclonic jerk before, but that appears to be accurate.
posted by allelopath at 12:04 PM on October 19, 2007