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Seizures occur when there is excessive electrical activity in your brain. This can occur locally in one part of the brain (a focal seizure) or throughout (a generalized seizure). These disturbances typically last only a few minutes and are self-limiting. After the seizure, the brain usually reduces its activity as a way of recovering.
Seizures do not normally cause long-lasting damage unless severe and prolonged (over five minutes). Most harm is caused by the reduced level of consciousness and depends on the activity — for example, having a seizure when driving can cause an accident.
If you have recurrent unprovoked seizures, you may be diagnosed with epilepsy, a medical condition where individuals are prone to seizures. Epilepsy can be successfully managed with anti-epileptic medications. It is reported that seizures are prevented in 70%¹ of people with epilepsy using medication.
Atonic is derived from the Greek word atonos, which describes something with no tone. Hence, this type of seizure can be characterized by the temporary loss of muscle tone. A more formal definition² is ‘seizures with preserved consciousness and reduced muscle tone.’
Atonic seizures are more prominent in childhood and can disappear during adolescence and adulthood. However, they are rare. It is reported that only 1-3%³ of child seizures are atonic. Two conditions associated with this type of seizure are Dravet⁴ or Lennox-Gastaut⁵ syndrome.
Traditionally, atonic seizures have been classified as generalized seizures, but more recently, research has found that they can also occur exclusively as focal seizures.
The mechanism is not completely understood. One explanation is that there is an activation of areas in the brain that inhibit movement. Hence, over-activation would lead to reduced or incomplete muscle tone.
Most people will think of complete collapse when they think about atonic seizures, but that's not necessarily the case, as not all muscles have to be affected. Generalized seizures involve the entire body, whereas focal seizures can cause isolated muscle weakness.
Consequently, there is a spectrum of symptoms. They include:
Drooping of the eyelids
Slumping forward of the head
Inability to use any or all limbs
The duration is very brief, only lasting 1–2 seconds, and the individual typically recovers quickly after the event.
Many factors can trigger seizures. While these factors increase your likelihood of seizure, they do not necessarily cause epilepsy. There is limited evidence investigating certain triggers to atonic seizures, but there is extensive information regarding seizures in general.
Awareness of potential triggers is important for controlling seizures, and minimizing these factors (especially if they caused them in the past) is a great prevention strategy.
Triggers can be internal or external. Internal factors refer to things happening within the body (e.g., stress, fatigue), whereas external factors refer to things occurring outside (e.g., flashing lights).
It has been reported that some individuals with epilepsy can identify certain triggers that provoke their seizures. An article from the Epilepsia Journal reported that figure to be around 53-65%⁶. More astonishingly, studies have shown that between 70-90% report two or more triggers, suggesting a correlation.
The most common triggers reported are stress, fatigue, lack of sleep, and fever (in children).
Stress is the most commonly self-reported trigger of seizures in those with epilepsy. While part of everyday life, excessive amounts can result in poorer health outcomes.
Stress can arise psychologically or physically. For example, you might have recently experienced the loss of a loved one, lost your job, or been suffering from an acute illness.
Stress has multiple effects on the brain, but it is thought that several mechanisms lead the brain into a more excitable state, making it more vulnerable to seizure activity.
One simple study⁷ investigated the relationship between stress and seizures by asking participants to write in a diary for three months. The study found that seizures were more likely to occur on days that had been stressful for participants.
Other studies have produced similar results. For instance, it was found that seizures were more common in combative soldiers when compared to their administrative counterparts in one military study.
Another study investigated the prevalence of seizures in children from war-affected areas of Croatia in 1991–1992. The number of children with epilepsy in the war-torn areas (n=72) was almost double that of children not in those areas (n=39). This is supportive evidence that stress does increase your risk of a seizure.
Sleeping is very important for general health and well-being. There are several theories about why sleep is essential, e.g., recuperation theory and adaptation theory. We can understand its importance in sleep deprivation studies where participants will become very irritable, inattentive, drowsy, and, in extreme settings, experience hallucinations, and paranoia.
People with epilepsy are already at risk of poorer sleep patterns. Fatigue results from sleeping problems and has been reported to be a factor for 47.1%⁸ of adult participants with epilepsy. This is greater than the general population.
This is an important trigger (and cause) of seizures, particularly in children. It typically occurs when you are ill, and your body is trying to fight the infection or virus. This may produce febrile seizures⁹ and is important to look out for.
Photosensitivity refers to people who are vulnerable to abnormal responses in the brain from visual stimuli and therefore become prone to having a seizure.
One study investigated the relationship between light and seizure activity in 1,000 epileptic participants. They found that 6% had seizures directly caused by a stimulus; of that proportion, 5% were photosensitive.
This occurs when you breathe a lot over a relatively short period and can be the body’s natural response when it thinks it needs more oxygen, e.g., after an intense workout or an asthma attack. However, voluntary hyperventilation can also trigger seizures.
Hyperventilation increases your oxygen levels, but it also affects the carbon dioxide levels in your body, which is a waste product of metabolism. Carbon dioxide is also important in regulating the pH of your body because it is one of its main acidic compounds.
When carbon dioxide levels become low, we make our body more alkanoic. The exact mechanism is unknown, but research¹⁰ has found links between hyperventilation and seizure activity.
If your doctor has prescribed you anti-epileptic medication, you must take them. There are several types of anti-epileptic medications available that work in different ways. Overall, they are effective in reducing the excitability of the brain. Hence, not taking them will increase the chances of having a seizure.
If you have actively chosen not to take medications for any reason, such as due to their potential side effects, talking to your doctor is essential. They will be able to hear your concerns and work with you to come up with a solution that you are happy with.
Diagnosing atonic seizures is largely based on clinical findings. This is because the brain is normal most of the time unless having a seizure.
Your doctor will want to know what happened before, during, and after the event. Then, they will want to perform several examinations, such as neurological tests. The first step is to rule out other causes, e.g., fainting or other seizure types.
Atonic seizures cannot be cured but can be managed successfully with anti-epileptic drugs. If you are concerned that atonic seizures are happening to you or someone you know, please visit your doctor to discuss possible options.
Atonic seizures are primarily characterized by the loss of muscle tone, but not all muscles have to be affected. They can produce a range of symptoms, including drooping of the eyelids and drooping of the head.
Atonic seizures occur briefly, and people usually recover quickly unless other factors cause harm, e.g., from hitting your head. These types of seizures are relatively rare and frequently occur in children.
Triggers are factors that can increase your likelihood of having a seizure. They include stress, fatigue, and flashing lights. Awareness of triggers and staying away from them is one method to reduce their recurrence.
If you are concerned about yourself or someone you know, please visit your local doctor. They may prescribe anti-epileptic medication, which is generally very effective.
Atonic seizures | AboutKidsHealth
Dravet syndrome | Epilepsy Foundation
Lennox gastaut syndrome LGS | Epilepsy Foundation
Febrile seizures | NHS
Atonic seizures | Defeating Epilepsy
Lack of sleep and epilepsy | Epilepsy Foundation
Epilepsy imitators | International League Against Epilepsy