Would you know if you just had a seizure?Posted: 01/28/2012
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.