A small number of people have what is known as reflex epilepsy, in which seizures are set off by specific stimuli. These can include:
- flashing lights
- a flickering computer monitor
- sudden noises
- hot water
- reading or listening to music
- other forms of visual and/or tactile stimuli
What are other terms for reflex epilepsy?
Other terms for reflex epilepsy include:
- epilepsy with reflex seizures
- sensory precipitation epilepsy
- stimulus sensitive epilepsy
There are also many terms for specific types of reflex epilepsy.
What are the features of reflex epilepsy?
There are many different types of reflex epilepsy, depending on the area of the brain that is affected. Seizure stimuli may be very specific, or they may be broad categories. They can include the following.
- Flashing or flickering lights, including computer monitors or video games. This is called photosensitive epilepsy. It is the most common childhood form of reflex epilepsy, and the child may eventually outgrow it.
- the sight of a particular pattern; this is called visual pattern reflex epilepsy.
- Thinking about certain things.
- Performing certain tasks, such as typing, drawing or playing cards. This is called praxis-induced epilepsy.
- Reading.
- Language-related stimuli such as writing, listening to speech, singing or reciting.
- Certain passages of music; this is called musicogenic epilepsy.
- Certain sounds; this is called audiogenic epilepsy.
- Surprises or startles.
- Eating.
- Making certain movements or being in a certain position.
- Touching a particular “trigger zone” on the body.
- Immersion in hot water, such as a bath.
Visual sensitive epilepsy
Visual sensitive epilepsy can be caused by flickering light, television, blinking or specific patterns. Visual sensitive epilepsy is the most common form of reflex epilepsy.
Pure photosensitive epilepsy
About 40 per cent of people with seizures that are provoked by light have pure photosensitive epilepsy, the most common reflex epilepsy. In children with this syndrome, flickering light provokes generalized tonic-clonic seizures. This syndrome usually begins in adolescence and affects females more than males. Screens are the most common seizure stimulus, but any source of flickering light, such as light flickering through trees, can provoke a seizure. Flashing lights from televisions, computer screens, strobe lights and certain visual effects in movies or video games can trigger seizures in people with photosensitive epilepsy.
The colour of the flickering light is also a factor; one study found that rapidly alternating red and blue-green light could cause seizures even when the overall light level did not change. Flickering red light is more likely to cause seizures than light of other colours.
Photosensitive seizures and spontaneous seizures
Children with juvenile myoclonic epilepsy and other idiopathic epilepsy syndromes may also have photosensitive seizures and spontaneous seizures, meaning that they can have both unprovoked seizures and seizures triggered by light. This condition usually begins in childhood or adolescence.
Pattern-sensitive seizures
About 30 per cent of people with reflex epilepsy have pattern-sensitive seizures. In this syndrome, striped patterns may cause absence, myoclonic or tonic-clonic seizures. These patterns may be seen in many places, including curtains, wallpaper, clothing, escalator steps or in a television screen when it is seen up close. Because they are so common, the child and their parents may not make the association between the pattern and the seizures.
Self-induced seizures
About 40 per cent of people with photosensitive epilepsy can induce their own seizures. If they are sensitive to flicker, they may induce seizures by waving a hand in front of their eyes. The term Sunflower syndrome is often used to describe children with photosensitive epilepsy as they tend to gaze at the sun while waving fingers in front of their face to induce a seizure. Some people can induce seizures by slowly rolling their eyes up and fluttering their eyelids. Some people find that this feeling is pleasant and relieves stress; they often do not want to give up their seizures. Treating them can therefore be difficult.
Seizures induced by thinking
Seizures induced by thinking are rare. They begin when the child is 15 years old on average. Most people with this type of seizure are male. In this syndrome, activities that involve complex thought, such as card games, board games, mental arithmetic or making complex decisions can trigger seizures.
Praxis-induced seizures
Praxis-induced seizures are similar to seizures induced by thinking. However, they involve using a part of the body to perform a task. Typing is one example of a stimulus for this type of seizure. This syndrome causes myoclonic, absence or generalized tonic-clonic seizures.
Reading and language-induced epilepsy
Primary reading epilepsy
Primary reading epilepsy usually begins when the person is between 12 and 25 years old. In this condition, seizures are provoked only by reading, and people do not have seizures at other times. Usually, while reading, the person’s jaw clicks or jerks and, if they keep reading, they may have a generalized tonic-clonic seizure. Other seizure types may also occur. People with this syndrome often have a family history of epilepsy, and cases of reading epilepsy that run in families have been reported. Primary reading epilepsy may be a specific form of language-induced epilepsy (see below).
Secondary reading epilepsy
Secondary reading epilepsy is very similar to primary reading epilepsy, except that people with this condition may also have unprovoked seizures.
Language-induced epilepsy
In language-induced epilepsy, stimuli such as writing, typing, listening to speech, singing or reciting may trigger seizures. People with this syndrome have jaw jerks with abnormal EEG activity.
Some symptomatic epilepsies may also result in reading- or language-induced seizures.
Other forms of reflex epilepsy
Musicogenic epilepsy
In musicogenic epilepsy, the seizure stimulus is music. People with this syndrome often have very specific stimuli, so that their seizures are triggered by only one particular piece of music. However, researchers have not found any common features in the various pieces of music. Some people with this condition also have unprovoked seizures.
Startle epilepsy
In startle epilepsy (audiogenic), seizures may be provoked by loud noises or sudden surprises. Developmental delay and neurological problems are often seen with this syndrome. There may be an underlying brain abnormality.
Seizures in response to eating
Seizures in response to eating have been seen in young children as well as adults. They are usually related to focal epilepsy with an identified cause. It is unclear exactly what happens in this type of seizure.
Proprioceptive-induced seizures
Proprioceptive-induced seizures appear to be provoked by certain movements or by having the body or limbs in a particular position.
Seizures induced by touch
People who have damage in the sensory cortex of the brain may have focal seizures triggered by somatosensory stimulation (tapping or rubbing a particular “trigger zone” region of the body).
This syndrome is different than touch-evoked seizures, which are generalized seizures that usually occur in babies and toddlers without damage to the brain. These seizures may be part of an idiopathic myoclonic epilepsy syndrome.
Hot water epilepsy
Hot water epilepsy is common in India but rare in North and South America, Europe and Japan. In this syndrome, children (usually males) have focal impaired awareness or generalized tonic-clonic seizures when hot water is poured over their head or they are immersed in hot water, such as in the bath.
There are other reflex seizures that do not fall into a defined category, such as those provoked by looking at a specific object such as one’s own hand.
What causes reflex epilepsy?
The seizure stimulus is not the underlying cause of the epilepsy. Rather, it sends a particular message to a sensitive, seizure-prone area of the brain, excites the neurons there and causes a seizure. Because this sensitive area is different for each person, no two people’s seizure stimuli are exactly the same.
Different types of reflex epilepsy may be caused by different things. Photosensitive epilepsy has a genetic component, although a single gene for it has not been identified. However, reflex epilepsy may also be caused by focal brain abnormalities.
How many other children have reflex epilepsy?
About 4 per cent to 7 per cent of people with epilepsy have reflex seizures. They are more common in children than adults, and more common in females than in males.
How do you know that a child has reflex epilepsy?
Reflex epilepsy is defined as reliably having seizures in response to a particular stimulus. If you suspect that your child has reflex epilepsy, it can help your child’s health-care provider make a diagnosis if you keep a record of:
- what your child was doing when the seizure occurred
- whether seizures often seem to happen under the same circumstances
- suspected stimuli
Your child will probably have an EEG. During the EEG, they may be tested with the possible seizure stimulus. For example, if they may have photosensitive epilepsy, they will be shown flickering light or specific patterns to confirm whether they have seizures in response to them. Note, though, that it is possible to have an abnormal EEG in response to flickering light without actually having reflex epilepsy.
How is reflex epilepsy treated?
If your child’s seizure stimulus can easily be avoided, or if they are aware of subtle symptoms that may indicate they are about to have a seizure, they may not need to take anti-seizure medications. However, some seizure stimuli, such as visual patterns or thinking, can be hard to avoid in daily life. As well, some children with reflex epilepsy also have spontaneous seizures. In these cases, anti-seizure medications can help control the seizures.
The most important way to control reflex epilepsy is to avoid or modify the stimulus. Your child’s treatment team will help to develop a strategy for them to avoid their seizure stimuli.
If your child has photosensitive epilepsy, for example, they may try the following strategies:
- Avoid sources of flashing lights.
- Cover one eye and turn away from the flashing light if they notice any twitching or jerking in their face, eyelid or a body part.
- Wear sunglasses or polarizing eyeglasses.
- Watch a small television set in a well-lit room.
- Avoid looking at possible seizure stimuli with both eyes at once; cover one eye, changing eyes occasionally.
If your child has primary reading epilepsy, the following strategies may be helpful.
- Avoid reading for long periods.
- Take short breaks to think about something else.
- Use audio texts instead of reading.
- Mask part of the text if their seizures happen in response to patterns or eye movement.
If the child has self-induced seizures, they may be harder to treat. People with self-induced seizures may enjoy them and do not want to stop having them. If this is the case, they may need a formal psychological evaluation and counselling.
What is the outlook for a child with reflex epilepsy?
The outlook for a child with reflex epilepsy is quite variable, depending on the cause of seizures and whether the child also has spontaneous seizures. The outlook is good if the seizures are controlled fairly easily, either by avoiding seizure stimuli or with medication. About one-quarter of children with photosensitive epilepsy will eventually lose their photosensitivity, usually when they are in their twenties.
