Study challenges reliability of EEG test for photosensitivity

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The EEG strobe test produced astonishingly unreliable results in a recent study.

If the results of a recent study at SUNY at Buffalo are any indication, there are an awful lot of people vulnerable to visually induced seizures who are being told they aren’t at risk. The study showed that testing for photosensitivity using EEG with photic stimulation provides unreliable information. In the wake of these findings, ruling out photosensitive epilepsy–and ignoring the seizure risk from video games–simply on the basis of intermittent photic stimulation results would seem very unwise.

This study–not yet published–by the Buffalo research team found that the test is poorly correlated with vulnerability to visually induced seizures in everyday life. Just 6.2 percent of patients with a history of visually provoked seizures tested positive for photosensitivity.

The standard test for photosensitivity is intermittent photic stimulation—a strobe light flashing at specified frequencies—while hooked up to EEG. Abnormal waves provoked by the photic stimulation are known as the photoparoxysmal response (PPR).  (To avoid triggering a seizure during the procedure, the flashing is halted as soon as any of these abnormal waves appear.)

Researchers have known for a long time that many people who test positive never actually experience photic seizures. The Buffalo study confirms this:  of 86 patients whose EEG yielded a PPR, just 13 (15.11 percent) reported having experienced visually triggered seizures. What’s new here is the finding that many people who test negative do actually experience these seizures.

The investigators, led by Novreen Shahdad, MD,  initiated their study after a patient with a clear history of seizures provoked by electronic screens did not test positive for photosensitivity. “With the increasing popularity of video games and parental concern of their predisposition for seizures,” the authors wrote, “there is a need to identify individuals at risk for PIS [photic induced seizures].”

Shahdad and her colleagues examined a Buffalo EEG database and found 129 patients between 1999 and 2013 who reported seizures triggered by TV, computer use, and video games. Of those patients, a total of 8 tested positive for photosensitivity. Thirty of the 129 patients had reported a history of video game seizures. Of those 30, only one showed a photosensitive response on EEG!

Photosensitivity is defined by researchers as the appearance on EEG, in response to photic stimulation, of certain spike and wave patterns characteristic of epilepspy. Note that the criterion for photosensitivity is not the occurrence of visually induced seizures in everyday life—it refers only to the strobe test.

The study concluded:

“In contrast to the general impression, our study did not find a significant association of a positive response to photic stimulation in patients with photic induced seizures (PIS). This association was seen only in 6.2% of patients with PIS. In addition, PPR on EEG was not associated with statistically significant increase of PIS. Hence we conclude that PPR cannot be used as an isolated predictor for PIS.”

I’ve previously raised questions about diagnosing vulnerability to visually induced seizures soleley on the basis of EEG response to photic stimulation. More study is certainly warranted.


Some doctors too reassuring about seizure risk

Howcast's video, "What Is Photosensitive Epilepsy (PSE)?"

The Howcast video, “What Is Photosensitive Epilepsy (PSE)?” is apparently designed to be upbeat and reassuring to families worried about video games.

You know how you’re not supposed to trust all the medical information on the Internet? Very true, and sometimes it’s actually the medical professionals who are placing material online that is oversimplified to the point of being misleading.

Trying to explain photosensitive epilepsy in a video of a minute and a half is pretty tough, and a Howcast clip that attempts to do that is just full of statements that make me very uncomfortable. It’s one of a series of videos on different aspects of epilepsy, but the presenters, despite their epilepsy expertise, aren’t necessarily experts in the specialty of photosensitivity. Photosensitive seizures are considered so out of the mainstream of epilepsy that few epilepsy specialists know a great deal about them.

The video in question, uploaded a year ago, features a pediatric epilepsy nurse and the Director of Pediatric Epilepsy at highly respected hospitals in New York City. My own qualifications for assessing the content of their video are found here.  I’m quite certain that I’ve read more of the research on photosensitive epilepsy and seizures triggered by video games than anyone on the planet who isn’t a photosensitive epilepsy specialist. There are very, very few photosensitivity experts in the US.

This video downplays the overall prevalence/likelihood of photosensitive seizures, and it doesn’t address photosensitivity in people with no other seizures. And it overstates the conclusiveness of EEG for identifying seizure activity. Epilepsy clinicians and advocacy groups tend to want to reassure young patients and their families that in the vast majority of cases, video games and other flash-filled leisure pursuits don’t pose a seizure risk. While it’s good to encourage patients to live lives that are as normal as possible, the oversimplified message promotes the view that photosensitive epilepsy is quite rare and that doctors can know for sure, based on EEG testing, whether an individual should worry about video games as a seizure risk.

If you want to watch the video, please come back here to read my responses to what’s in it! Here’s a transcript with my comments in blue.

————————————————————————————————————————————————————————————————————-Nurse: “You know, whenever anybody comes into the office, they always ask us first thing whether epilepsy can be triggered by strobe lights, and people often think back to when the first Pokemon movies came out and all those children in Japan seized during the movies. So photosensitive epilepsy is something people worry about all the time.”

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Two issues here:

1) Epilepsy is a condition that makes people vulnerable to seizures. It’s the seizures that are triggered; the epilepsy condition already exists. Why take issue with such a seemingly minor point? Being less than careful in how she worded things allowed a doctor in a WebMD video to incorrectly reassure viewers that video games cannot cause seizures!

2) The problem is much bigger than the population of epilepsy patients who come in to be evaluated by neurologists–people with no seizure history may develop photosensitive epilepsy (for example, the Navy pilot who can’t ever fly again after having a grand mal seizure while playing Oblivion: The Elder Scrolls IV). The general public, though–which presumably is the audience for this video–doesn’t worry enough about it. The epilepsy community should be doing more outreach to the general public to let them know they could be at risk.

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Doctor: “On all the video games there’s those warnings that say, you know, you shouldn’t play this game in case you have epilepsy. But only one specific type of epilepsy has photosensitivity to it, and that’s a generalized epilepsy, that’s when the whole brain turns on all at once–“

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This is what neurologists believed in the past.  But numerous studies in the last 20+ years show this is not the case. A 1994 paper that included a review of other studies concluded that about 30 percent of photosensitive seizures are partial seizures—which do not involve the whole brain. The doctor’s statement could lead viewers to think that only people with generalized (typically grand mal) seizures need to worry about photosensitivity.

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Nurse:…”lights up all at once, there’s a big burst of electricity through the whole brain. It’s one of the reflex epilepsies, so kids for the most part with epilepsy can play video games and can go under strobe lights unless they very specifically seize when they’re under strobe lights, and when we do the EEGs, we do the tests of their brain waves, we actually flash lights at them to see if it does create a seizure.”

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The intermittent photic stimulation procedure used during EEG measures the brain’s reaction to a strobe light. The effect of a strobe light on the brain is not equal to the effect of playing a fast-moving, flashing video game. Some people who don’t respond to the strobe light can have seizures in response to video games or other visual stimuli. Studies of video game seizures frequently include individuals who experience seizures from games but do not test positive for photosensitivity. Photosensitive epilepsy in the research literature describes epileptic discharges on EEG in response to a strobe light in a laboratory. Some studies discuss non-photosensitive video game seizures: people who have the seizures even though a strobe light doesn’t produce signs of epilepsy on an EEG.  

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Doctor: “So by doing the EEG and flashing the lights in the child’s eyes, and having the EEG run at the same time, we can conclusively tell families whether the children can play video games or not play video games, and that will make a child very happy, hopefully finding out that it’s perfectly safe to play the video games and that they don’t have photosensitive epilepsy.”

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EEG doesn’t conclusively rule out any type of seizure! It can confirm seizures but cannot rule them out since the technology does not detect all seizure activity. Some people who have seizures have normal EEGs. Oddly enough, in another video, What’s the Difference between Seizures and Epilepsy?” featuring the same clinicians in the same Howcast series, they contradict their statements in the first video, conceding that some seizures are too located too deep inside the brain to be detectable by EEG on the scalp.  

7/19/2014 update: See information on a study showing just 6.2 percent of patients with visually induced seizures tested positive for photosensitivity in the photic stimulation EEG procedure.

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Nurse: “As well as the teenagers and the young adults who will call or text and say, “Can I go–we’re going to a party and I know there’s going to be strobe lights. Is that OK?” So at least we have an answer for them after we’ve done the initial EEG.

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Photosensitive epilepsy is a genetic trait that is dormant until it becomes activated by a combination of factors. The most common time for the disorder to emerge is in adolescence. Thus a child who shows no signs of photosensitivity (again, based on testing with strobe lights, not video games) may later experience photosensitive seizures.

We need epilepsy clinicians and advocacy organizations to:

  • be more concerned about the many visual stimuli in our environment that can trigger seizures
  • think more broadly about who may be at risk–including members of the public who have no other seizures
  • convey their concern about hazardous visual stimuli to the public, the digital entertainment industry, and lawmakers
  • push for public policy changes that will rein in the stimuli and reduce the occurrence of visually triggered seizures.
  • question reliance on EEG and photic stimulation to diagnose vulnerability to visually induced seizures

It’s a big job. It’s a much bigger undertaking than I can even imagine, but it needs to be done.


Bread and video games

What do a loaf of bread and an action video game have in common? Both are man-made and widely consumed, yet hugely underrecognized as potentially serious health hazards. There are a lot more parallels.

Sensitivity to gluten, the primary protein in wheat, and to the bright flash and rapidly moving patterns game of screens, are both considerably more pervasive than the medical community and the general public had realized. Awareness of gluten sensitivity has grown tremendously in the past decade, though, because a portion of the medical community broadened its understanding of a disorder once defined by very rigid diagnostic criteria.

Consider this comparison:

Progress on the gluten front

For decades the only type of gluten sensitivity recognized by doctors was celiac disease, a severe condition that often, but not always, manifests with gastrointestinal problems. The only diagnostic testing required an intestinal biopsy that–turns out–is easily falsely negative. After a negative biopsy, would be told that celiac disease had been ruled out, and that therefore it was OK to eat wheat and other grains containing gluten. In actuality many of these patients either had celiac–but a misleading biopsy that didn’t collect tissue samples from the affected area of the intestine–or they had a different form of gluten sensitivity that causes damage only to other body organs, rather than the intestine.

Because doctors were taught in medical school that celiac disease is very rare, occurring in only one in several thousand individuals, there seemed to be little reason to consider the diagnosis in patients, order a biopsy, or question a negative biopsy result. Some researchers suggest that ten percent or more of the American public has a sensitivity to gluten, in most cases with no obvious symptoms or symptoms that don’t suggest a food sensitivity. Even without obvious symptoms gluten intolerance can be a very serious disorder that affects daily functioning and quality of life.

Growing numbers of consumers without an official diagnosis of gluten sensitivity are being more proactive by experimenting on their own with a gluten-free diet as a healthier way to eat. Many notice a range of improvements in their well-being from this change. A rapidly expanding market of prepared gluten-free foods makes a gluten-free lifestyle less burdensome. An increasing number of restaurants offer gluten-free menus, and new gluten-free foods are a booming market for food retailers. Celiac and gluten-free support groups provide practical and moral support. In addition to peer-reviewed research, there are now a lot of books for consumers and online resources. Probably most consumers are learning about gluten sensitivity from these sources rather than their clinicians, and some are helping educate their doctors about it.

The photosensitive epilepsy front

Because doctors were taught in medical school that photosensitive epilepsy is very rare, occurring in only one in several thousand individuals, there has seemed to be little reason to consider the diagnosis in patients, order an EEG with photic stimulation, or question a negative or inconclusive EEG. There is no practical, reliable way to know how prevalent photosensitive epilepsy is in the general population. Even without obvious symptoms of a seizure, people who experience subtle seizures can experience impairments that affect daily functioning and quality of life.

Without an official diagnosis of photosensitivity, consumers can experiment with a screen-reduced or screen-free lifestyle–should they have an inkling that subtle seizure activity caused by screen exposure is affecting their health. However, at this time there are few products or supports to help them cut back on recreational screen time. A limited number of mental health providers offer therapy for Internet or video game addiction. Most focus on treating the addiction itself rather than on overcoming the physical and mental health consequences of exposure to potentially seizure-causing screens. Consumers are still essentially on their own to figure out the connection between video games and seizure activity, and there is little for them to read on the subject. Little research is being carried out in the US on photosensitivity and today’s electronic entertainment.

Perhaps there is reason to be encouraged by the progress in educating the public and clinicians about gluten-related health problems. In the face of similar obstacles to wider awareness and prevention, it should be possible for seizures induced by visually overstimulating electronic media to become better known, understood, and prevented. In the interim, a great deal of work lies ahead to empower consumers with the information they deserve about screen-induced seizures. Please help spread the word.


A continuum of visual sensitivity

Even readings outside the red zone may indicate the need for caution.

If a neurologist tells you that you don’t need to worry about seizures from electronic screen exposure, because you’re not photosensitive, what does that really mean?

It means that when you were tested for your response to a white strobe light, an EEG didn’t detect a particular abnormal electrical pattern in your brain. (I’ve noted some limitations of this procedure elsewhere.) Epileptology looks for yes or no, typically relying on EEG to rule out epilepsy. If yes, possibly medicate; if no, it’s not a case the clinician will pursue.

It does not indicate that bright flashing and/or patterns from electronic screens don’t adversely affect your brain function.

Researchers have gradually come to consensus on exactly what the EEG must look like to indicate photosensitive epilepsy (the photoparoxysmal response): certain spike/wave patterns that appear in both brain hemispheres. In arriving at these criteria, researchers excluded three other types of EEG abnormalities that in prior research “qualified” as a photoparoxysmal response. Epilepsy researchers aren’t certain what the significance of these other abnormalities is, but because the other patterns cannot conclusively be associated with epileptic seizures, there’s little interest in further research.

So these other EEG abnormalities from photic stimulation don’t count, in current neurology practice, and nobody would even tell you about them if they were found in your EEG. You’d be told the EEG was normal, period. But what if these other abnormalities were a sign that neurological function is in fact disturbed by visual stimuli, but not to the point of a seizure?

Let’s say you had one of the three other EEG abnormalities (which you wouldn’t know about, because the EEG was deemed normal). Maybe these indicate that you’re vulnerable to symptoms of a visual-overload-not-to-the-point-of-seizures syndrome. Neurologists have been examining the overlap between epilepsy, photosensitive epilepsy, and migraines. More about this in a future post, but actually there are many overlapping symptoms and correct diagnosis can be difficult. So if video game exposure or photic stimulation produces headaches and visual disturbances, and an inconclusive EEG, it may be that the visual overload is triggering migraines. Or perhaps the exposure is triggering another form of hyperexcitability in the brain’s visual cortex, which has been termed visual stress. While research has been done on this, it’s not part of a conventional neurology practice.

What about patients with more subtle or mood-related symptoms of a visual-overload-not-to-the-point-of-seizures problem? Who is treating these patients? Could be psychiatrists and psychologists, who view altered behavior and cognitive function through the lens of their respective training. Because there’s such a dearth of research of the gray areas of brain dysfunction following exposure to electronic screens, mental health providers have no basis for treating these patients for anything but mental health disorders. It’s clear that more research is needed and that more effects on the brain will be uncovered. One intriguing paper explores the contribution of fluorescent lighting to agoraphobia. The SpongeBob study published last year showed diminished executive function in children who viewed the cartoon.

In her Psychology Today blog, psychiatrist Victoria Dunckley recently posted a compelling piece about the effects on her patients of electronic screen time. She recommends creating a diagnostic category called Electronic Screen Syndrome to identify a dysregulation of mood, attention, or arousal level due to overstimulation of the nervous system by electronic screen media. She has seen dramatic improvements in hundreds of patients’ mood, behavior, and cognition after they go on an “electronic fast.” (Some have underlying psychiatric diagnoses, some don’t.) Maybe these patients were having very subtle seizures from electronic screens. Maybe the effects on the nervous system weren’t quite what epileptology defines as seizures. Either way, many kids exposed to electronic screens are experiencing diminished quality of life (as are their families) for a problem that medicine has not yet acknowledged.


Would you know if you just had a seizure?

No, not necessarily. You might have no idea it happened, even. Multiple studies have shown that people often aren’t aware of their own seizures. When you consider that altered consciousness is characteristic of many seizures, it’s not so surprising. People who aren’t “all there” during the seizure may have no memory of it.

And if you have a seizure with subtle symptoms, anyone who’s with you may not realize it’s happening, either. This is a key reason many people haven’t heard much about video game seizures–many just go undetected.

The big seizures, of course, get noticed. Anyone nearby can clearly see a person who has fallen and is having convulsions. Individuals emerging from a grand mal seizure (what doctors now refer to as a tonic-clonic seizure) won’t remember the event itself, but will realize they’re not where they were before (perhaps finding themselves on the floor or in an ambulance), and may have bruises from uncontrolled movements.

Although studies show that photosensitive epilepsy can cause any type of seizure, a lot of clinicians still assume the condition produces only grand mal/tonic-clonic seizures. They may not know that partial and absence seizures are associated with photosensitivity, too. Click here for a list of some typical signs you may have had a seizure.

What are partial and absence seizures?

Partial and absence seizures can act like stealth attacks on the brain. They cause unusual behaviors and sensations, and may be followed by additional symptoms, but they often escape notice while the seizure is in progress.

Simple partial seizures produce temporary symptoms such as distorted vision or unexpected movement or tingling in one limb. Because they affect a small area of the brain, awareness and memory are not affected.

Complex partial seizures occur in 35 percent of people with seizures. Many types of behavior can take place during the seizure, depending on which parts of the brain are affected. Sometimes people may seem to continue whatever they had been doing, including talking with others. Sometimes during one of these events people are conscious enough to allow them to hear what’s going on around them–perhaps feeling everything  is happening far away–but they aren’t able to speak. Because consciousness is altered, it’s not uncommon to have either no memory of what happened during the seizure or just a vague idea. The event can be over in 30 seconds, or it may last for a few minutes.

The seizures are typically followed by headache, temporary confusion, memory loss, and/or other neurological dysfunction, as well as fatigue and “brain fog” that gradually dissipate over a period lasting up to a few days. Lingering after-effects of complex partials can easily be more of a disruption to everyday life than the seizures themselves.

Absence seizures, where a person briefly stares and “zones out,” may be very hard to notice and can be mistaken for attention problems. Learning, memory, and social interaction are often affected by the gaps resulting from interruptions in awareness, but absence seizures are not followed by after-effects.

Research shows people often don’t detect their own seizures 

In a study published in 2007 by Christian Hoppe and colleagues, 91 seizure patients were asked to record all of their seizures in a diary during the time they were being monitored on EEG. In instances where patients activated a reporting alarm just prior to or during a seizure, only two-thirds of the seizures were documented afterwards by the patients. The reliability of patient reporting was lowest when documenting complex partial seizures and seizures experienced during sleep. Of 150 complex partial seizures (verified on EEG) while subjects were awake, only 52.7 percent of the events were reported, even though subjects were periodically reminded to report all their seizures.

The study authors state, “Seizure-induced seizure unawareness is a frequent, but rather unrecognized, postictal [post-seizure] symptom particularly associated with seizures from sleeping and with CPS [complex partial seizures].”  Now consider, what are the chances that a person who has never had a seizure before, or whose seizures have never been identified, will remember after the event that something unusual happened?

In the 2004 review article “Visual Stimuli in Daily Life,” Kasteleijn-Nolst Trenité and colleagues note that during photic stimulation testing many patients do not notice brief seizures that are detected on the EEG but have no clinical signs. “The question must be raised,” they continue, “whether asymptomatic individuals might have unnoticed reflex seizures triggered by daily-life stimuli and become overtly symptomatic only when a critical age is reached (early adolescence), in combination with lifestyle-related factors.” In other words, after adolescence, photosensitive seizures that were already happening but nobody was aware of may become more visible, possibly when the nervous system is affected by additional circumstances (lack of sleep, alcohol consumption, etc.).

Need more data? In a 1996 study of 27 seizure patients by Blum and colleagues, patients were not aware of 61 percent of their seizures detected on EEG! Seven patients didn’t recall any of their seizures. Patients were questioned periodically throughout the day as to whether they’d had a seizure or if anything unusual had occurred, so the seizures would be expected to be fresh in their minds.

Can an EEG help determine whether you had a seizure? 

Let’s say something suddenly felt very weird yesterday, and you’re wondering if it was a seizure. An EEG conducted today can’t tell you if yesterday’s event was a seizure. That’s because EEGs can’t provide data on any period other than the time the electrodes are in place and recording brain activity. An initial EEG usually lasts for 20 to 30 minutes and can be thought of as an extended “snapshot” of brain wave patterns. If you have a seizure during an EEG, the EEG can confirm that it was a seizure–but only if electrodes pick up the brain waves that typically signify a seizure.

Usually at some point during the EEG you’re exposed to a strobe light to see if your brain has an abnormal response to flash. If that part of the EEG is abnormal, it can indicate that you have photosensitive epilepsy and should avoid flashing lights. The test is done in a way that doesn’t provoke an actual seizure, but it can show an abnormal “firing” of neurons that is consistent with seizures. Note that strobe lights may not create that EEG response even if a video game does–the flashing white light doesn’t make the same impact on the visual cortex that a colorful screen with lots of action. Some people don’t respond to the strobe but do have an abnormal EEG response to certain sharply defined patterns. Video games and TV may include some of these patterns, but little testing is done for pattern sensitivity in the US.

EEGs done with scalp electrodes miss a lot of seizure activity that involves a small area and/or lies deep inside the brain, far from electrodes on the surface. I’ve written about this before, but I can’t resist adding that this point was acknowledged in the above study by Blum et al. “…there are seizure types that often do not manifest on surface EEG. The most important of these is frontal lobe epilepsy, but this also occurs with complex partial seizures of temporal lobe origin.”

In fact, “it is crucial to recognize that a normal EEG does not exclude epilepsy, as around 10% of patients with epilepsy never show epileptiform discharges,” according to a 2005 paper in the Journal of Neurology, Neurosurgury & Psychiatry.

Seizures are more common and frequent than current technology and human memory can demonstrate.


When “slam dunk” EEG evidence is missing

My daughter played video games to deliberately provoke photosensitive seizures during extended, inpatient EEG monitoring. She had plenty of seizures, but they weren’t detected by the EEG sensors on her scalp. Although she was exhausted and cognitively slow from all the seizure events, the clinicians said–based entirely on the EEG data–that they saw no sign of seizures. We’ve tried this at several hospitals, always leaving with this frustrating result. Many patients with inconclusive EEGs are dismissed by neurologists and told there’s no evidence of seizures. This is probably even more frequently the case with visually induced seizures, since most neurologists know little about them. In their training they were taught that photosensitivity is extremely rare and that photosensitive seizures are big, generalized (grand mal) episodes. Typically, neurologists are very conservative about issuing a diagnosis of epileptic seizures (although this was not always the case). If there’s an unmistakable seizure pattern on the EEG, they feel comfortable stating that you have seizures. Without clear EEG evidence, many neurologists may not feel a seizure diagnosis is justified. If this has happened to you, you’re not alone. Although clinicians are supposed to diagnose epilepsy based on the patient’s history as well as EEG and other tests, most often EEG results are considered more indicative than all other data–even though EEG is extremely imprecise. The result is that it can take years before a patient is properly diagnosed. Here is a sampling from various reports we received on my daughter’s video game-induced seizures and the EEG recordings done during the events:

  • “It is interesting that they almost always occur when she is alone.” [when she can concentrate fully on the game and more easily lose contact with her surroundings]
  • “Most photosensitive seizures are primary generalized with bursts of spike waves, polyspike waves, or polyspikes. It is possible for some types of visual stimuli to bring on a partial seizure. These are more rare. Even in those instances, usually there is some sort of epileptic discharge.” [Oh.]
  • “It is true that with surface EEG, we could miss partial seizures. At the same time, there are also many clinical signs that make a seizure unlikely…MRI has been normal and our clinical suspicions are quite low.” [Don’t seek and you shall not find.]
  • “The EEGs have never shown epileptiform activity, nor has there been a photosensitive response.” [See my post on testing for photosensitivity using photic stimulation]
  • “Due to the normal EEG and the precipitation of events with only limited stimuli, we feel it is unlikely that these events represent seizures.” [In other words, if only video games precipitate seizures, these can’t really be seizures.]
  • “The patient was playing a video game and then stopped…There was no obvious change in the patient’s observed behavior in that she was sitting on a stool in front of a monitor playing a game…The EEG also did not show significant change…[She stopped playing the game—isn’t this a change in behavior?]
  • “The two…events that were recorded…failed to reveal an identified behavioral change that would appear to be convulsive in nature.” [Since when are all seizures convulsive?]
  • “The patient had a few jerks of her limbs during photic stimulation, but there was no electrographic correlate.” [Hmmmmm.]
  • “There is a generalized irregular slow wave burst…at which time the patient is swaying her head to and fro while watching a video. This activity is not epileptic and most likely related to movement.” [An unsupported guess with no effort to gather more evidence. Ask the family if swaying the head to and fro is typical behavior. Or ask the patient if she recalls swaying while playing.]

Sound familiar? Anyone else want to share similar results?


Autism’s high rate of photosensitivity

Young people with autism spectrum disorders (ASD) are far more likely than the rest of the population to be photosensitive–susceptible to visually triggered seizures from flashing light, video games, and other strong visual stimuli. Results from a new study made public last week at the American Epilepsy Society annual meeting showed that fully 25 percent of those age 15 and up with ASD are photosensitive. In contrast, the prevalence of photosensitivity among typical young people is said to be 1 in 4,000 (although I believe this is an underestimate).

For some time I’ve suspected that the rate among ASD young people is elevated, and I’ve been attempting to find funding for a study that would examine young people with ASD and their risk of seizures from video games. Here are some reasons why I believe video games pose a particularly acute seizure risk to young people with autism:

  • This population develops classic epilepsy at significantly higher rates than the general population
  • Children with ASD have very high rates of sensory processing disorders, including difficulties with visual processing
  • Children with ASD tend to spend their leisure time with electronic media, and they exhibit a preference for animated material, thus they are likely to be heavy users of video games

Not only are young people with ASD at higher risk of visually induced seizures, they are also less likely to have their seizures noticed and properly identified:

  • The unusual repetitive and nonresponsive behaviors that are common in individuals with ASD can be difficult for an observer to distinguish from seizures
  • In children with ASD, impaired executive function, energy, mood, attention, and cognitive ability resulting from seizures might be masked by pre-existing chronic deficits in these functions

My guess is that photosensitivity among young people with ADHD (attention deficit hyperactivity disorder) is probably higher than average, too, because of these same factors.

Here’s why this matters so much: Although it would be difficult to change game usage habits, parents of children with autism should exercise particular caution in allowing exposure to visually overstimulating images. Reducing or eliminating visually induced seizures could result in noticeable improvements in their children’s daily functioning. The last thing these vulnerable kids need is added interference, due to seizures, with cognitive and behavioral flexibility.

The study announced last week is the first to look at the photosensitivity rate in autism. It was performed at Children’s Hospital in Boston, where researchers investigated the EEG histories of children diagnosed with ASD. More research is certainly warranted, particularly since the photosensitivity assessments were done the usual way, using photic stimulation with a strobe light. Photic stimulation may show a person’s vulnerability to seizures from a strobe light, but a strobe does not recreate the experience of exposure to a video game screen. Some individuals who do not demonstrate an EEG response to the strobe may nevertheless experience seizures provoked by video games.

NOTE:  Read more on autism and seizures from sensory overload in this post from 2012. You may also want to read this post on ADHD in connection with and video games and seizures.


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