Types Of Seizures: Why Do They Occur And What Causes Them?

When we think about neurological disorders such as epilepsy, the first image that comes to mind for most people is that of a person suffering from seizures, sudden and violent contractions throughout the body that make them shake in a child’s bed. hospital or on the ground.

Indeed, Seizures are one of the most visible and important symptoms of epilepsy (in fact, its diagnosis is made, among other things, if the subject has had several crises). But not all seizures are the same, nor do they occur only in epilepsy. In this article we are going to visualize the different types of seizures.

Seizure: brief definition of the term

Convulsions are understood to be those spasmodic movements of the voluntary skeletal muscles that occur abruptly, rhythmically, repetitively and completely involuntarily, with violent contractions of one or more muscle groups.

Seizures are a symptom of the existence of a brain problem that can have various origins.. They are usually short in duration (generally up to two minutes), although longer episodes can be dangerous and are treated as an emergency. Its main cause is found in the existence of electrochemical imbalances in the brain, or hyperexcitability of specific neuronal groups.

Types of seizures

As indicated above, not all seizures are the same, but different types can be established depending on the brain area or areas affected, the level of muscle contraction or the causes of the seizure.

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1. Classification according to the brain areas affected

Depending on whether the seizures are due to the alteration in a specific brain area or at a general levelwe can consider the existence of two main groups of seizures.

1.1. Focal-onset seizures or partial seizures

These are seizures due to the alteration of one or several well-defined regions of the brain. The affected area will determine the type of symptoms that will be experienced. The seizure at the motor level occurs in a specific part of the body, or even in a hemibody (that is, on one side of the body).

They can be simple and complex, depending on whether alterations of consciousness occur (the latter being complex). There may be sensory alterations and perseveration of actions and gestures, and can even serve as a warning of the arrival of future generalized crises. It is also common for a focal seizure to become generalized, first activating some brain areas and subsequently expanding to the rest of the brain, these seizures being called secondary generalized seizures.

1.2. Generalized seizures

Generalized seizures are those in which it is all or a large part of the brain, with electrical alterations appearing in both hemispheres. They usually cause loss of consciousness and tonic-clonic seizures appear. They occur suddenly, although they may be preceded by an aura, and cause the patient to fall. It is common for there to be loss of sphincter control, tongue biting and even twisting. and muscle group injuries.

Within this subgroup we can find absence seizures (in which there may be slight contractions), myoclonic seizures, tonic-clonic seizures (these being the most representative) or even atonic seizures in which a seizure does not occur, but loss. of muscle tone after a contraction.

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2. Depending on the level of muscle contraction

Another classification could be made depending on the intensity level or the characteristics of the seizure itself. Among them the following stand out.

2.1. Tonic seizures

This is a type of seizure in which a powerful muscular contraction of one of the muscles or one or more muscle groups occurs. There is a high level of stiffness in the affected muscle or muscles.

2.2. Clonic seizures

Clonic seizures are those that occur repetitively every two or three seconds, of short intensity and power.

23. Myoclonic seizures

Like clonic spasms, these are small muscle spasms of minimal duration, but which result in involuntary movement of a part of the body.

2.4. Tonic-clonic seizures

Tonic-clonic seizures are the most prototypical types of seizures, with both tonic and clonic seizures appearing at the same time. This is the type of seizure that is part of a grand mal seizure.

2.5. Atonic seizures

In this type of crisis, true seizures do not occur, but rather the sudden disappearance of muscle tone. Sometimes this disappearance is preceded by a powerful muscle spasm.

3. Depending on the cause of the seizures

Seizures can be caused by many different causes.. It is important not to identify seizures with epilepsy because, although they are very common in this disorder, seizures can also occur due to other conditions. Some types are as follows.

3.1. Epileptic seizures

Epilepsy is one of the main disorders that appear linked to the presence of seizures.

3.2. Febrile seizures and infection

The presence of fevers higher than 39 degrees can cause convulsive episodes without previous neurological alterations that explain them. They can be simple if they do not repeat and last less than fifteen minutes, or complex if there is a recurrence of the episode in the first twenty-four hours (in which case they can also be called cluster or atypical seizures).

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3.3. Seizures due to organ failure

The presence of alterations in the liver or kidneys can also cause the onset of seizure episodes.

3.4. Seizures due to substance use

Both some medications and certain drugs can cause seizures, both as a side effect and during overdose, or during withdrawal syndromes.

3.5. Hysterical convulsions

Seizures do not only arise due to medical causes. Certain psychological disorders such as somatoform disorders cause the subject to suffer from them. These types of seizures have the peculiarity that they usually occur only in the presence of others and do not generate alterations in an electroencephalogram (although these are not fictitious symptoms, but psychologically generated ones).

3.6. Seizures due to anxiety

In some situations of very high anxiety, motor and somatic alterations may arise, and seizures may appear.