Sign at a zoo advising guests not to use flash photography as the baboon has photosensitive epilepsy

Flashy Stuff Is Not For Everyone: The Science Of PSE (Photosensitive Epilepsy)

I would wager that if you are here on Coaching for Geeks, you probably dabble in gaming.

Yet for some of our incredible community this can come with some dangers, so today we are going to take a bit of a dive into photosensitive epilepsy (PSE). The histories, causes, triggers, management of PSE, and of course, try to look at the science and dispel any misunderstandings.

What is PSE?

Put simply it’s when there is abnormal electrical activity in the brain that is triggered by an external visual stimuli. Usually it is 1 of 2 factors, or a mixture of both:

 – The brain isn’t wired correctly. This can be in one or both hemispheres of the brain.

 – Imbalance of the chemical transmitters in the brain known as neurotransmitters.

Though there is still massive scope for research as there are still plenty of unknowns.

Everyone has something known as a seizure threshold and that is the minimum it would take for you, as an individual, to have a seizure. In Epileptics, this is much lower. Many things can cause seizures, from alcohol and stress, to brain tumours and stroke. But we are going to just stick with PSE today. Around 5% of epileptics have PSE with around 40 million known epileptics worldwide. It is more common in women and young children.

PSE women children more common

Types of seizure

40% of seizures get classified as non-conclusive, but that leaves us 60% of convulsive seizure to go into. 66% of convulsive seizures start in just one side of the brain and they are referred to as focal seizures but can become generalised seizures. Generalised seizures cover both hemispheres and 34% of convulsive seizures start that way. Then we get down a bit more into the nitty gritty bits. Generalised seizures then can, primarily, be broken down into 5 categories:

 

1 – Absence seizure – brief loss of consciousness

2 – Myoclonic – brief involuntary muscular twitching

3 – Clonic – a longer series of rhythmic involuntary muscular contractions

4 – Atonic – a brief partial or complete loss of muscle tone

5 – Tonic-clonic – ‘traditional’ epileptic seizure with loss of consciousness and rhythmic involuntary muscular contractions

 

History lesson

In the 1830’s a renowned physiologist, Marshall Hall published his idea of reflex epilepsy. Epilepsy has been known about since antiquity, but this was the first real attempt at explain epilepsy scientifically. Hall believed that it was effectively a reflex that started in the medulla in the brain and then the nerves of the stomach or intestines in a reflex arc. He later asserted that it was the closure of the Larynx (vocal cords) that lead to unconsciousness. For its time, it was the accepted description of epilepsy. This was later superseded by Neurologist John Hughlings Jackson whose work showed epilepsy as being a brain disorder and that it was an electrical excitation. We still use the Jacksonian March to help describe seizures today. Helping neurologist work out where in the brain the centre is by looking and tracking which side of the body seizes and the pattern it moves in.

 

Diagnosis Of PSE

This tends to come in the self-report form. Having seizures, reporting to medical professionals and seeing what the likely triggers are, and importantly if it happens again. Almost anyone can have a seizure, but it’s when they happen more than once that a potential diagnosis can be made.

An Electroencephalograph (EEG) can be done alongside a device that uses controlled stimulation to look for abnormalities in response.

A young by in a green t short wearing an electrocardiogram headset

 

Triggers For PSE

This is where we get into the danger zone. What sort of things can cause seizures in people with PSE. Well, gaming can be a big one, TVs and computers have a long established history of triggering seizures within people with PSE. This is because of the flashing images. Rhythmic flashing images tends to be the biggest trigger, but that also extends into repeating patterns, fast moving fans, flickering lights, and even sunlight as it makes patterns through blinds, reflecting off water or in the gaps of trees whilst viewed from a moving car.

Early cases of PSE that related to video games as the cause was in 1981, with first case being ‘space-invader epilepsy’ by Rushton. This helped bring in preventative measures such as a minimum safe distance from the screen of 2m. Sadly, it was brought into the public focus again in 1992 when a 14 year old boy died from a PSE seizure whilst playing a game.

Many games don’t pass the recommendations of safety for people with PSE, so please do be safe and if you do have PSE or have younger children (who are more prone to seizures, even without epilepsy) then check to see if they have passed the flashing and pattern analyser (HardingFPA). Most games will come with a warning though to save you the time.

TV is a little harder as most modern editing is getting faster there by upping the risk. One of the earliest and most famous examples of a TV show causing an epileptic fit was from the now banned Pokémon anime episode “Cyber Soldier Porygon” in late 1997. Hundreds of PSE sufferers where triggered during a segment of the episode and it was subsequently banned.

A screen shot from the Pokemon cartoon episode cyber soldier porygon which caused photosensitive epilepsy in a number of japanese children

Cyber Soldier Porygon

 

It is this flashing, pattern etc that the brain cannot process in people with PSE, and because it can’t the result is a potentially fatal seizure.

 

 

Helping Someone With PSE

What do you do if a person is having a fit? How can you help your fellow geek? Well it is dependent on the kind of fit they are having, if they are aware for example the best thing you can do is talk to them calmly and be reassuring. If they are near a road or dangerous situation, guide them away if possible. Once the seizure is over keep them calm and if you feel you need, call for medical help.

What if the person is unaware/unconscious though? This is the harder situation to deal with but stay calm, I’m here to help. The best thing to do is to support their head with a top or something soft. Cupped hands work as well. The idea here is to just protect their head from hitting the hard ground repeatedly causing damage. Ideally remove potential hazards from the local area, such as furniture, but if this is in a busy road you may need to move the person, but only if there is a danger to you and them. Remove glasses, loosen tight collars etc. If it’s possible, time the seizure. This is important information because if it’s longer than 5 minutes it becomes status epilepticus and needs urgent medical treatment.

Four big DO NOTS:

Do not try to restrain them, let the seizure run its natural course.

Do not put anything in their mouth.

Do not attempt mouth to mouth breathing.

Do not try to give them food or drink till fully recovered.

 

Once the shaking has stopped put them into the recovery position, if there is any labouring sounds with their breathing, even snoring, lift their chin slightly to open their airway. Pop a coat or blanket over them as this helps with the cold and covers any embarrassing areas if they have wet themselves. Lots of reassurance helps too.

 

 

People will be very tired after a seizure and may have injured themselves so don’t be afraid to call for professional help if it is needed.

 

Treatment Of PSE

We currently have no cure for PSE but there are some drugs that help reduce the sensitivity of PSE. Common anti-epileptic drugs include sodium valproate, carbamazepine and lamotrigine, but there are others and it varies between the types of epilepsy. Buccal midazolam or rectal diazepam are the most commonly used emergency drugs to help break a seizure, but should only ever be administered by a trained, qualified person.

 

Final thought

I hope this has been a fun and educational quick dip into the world of photosensitive epilepsy, history, how to help and epilepsy in general.

As always, take care of yourselves and happy geeking!

 


Robert House – Operating Department Practitioner and Coaching for Geeks health correspondent

Follow Robert on Twitter @Roberthouse1985


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