The 8 Types of Seizures

The different types of seizures that exist today have their own characteristics that allow them to be differentiated from each other. Fortunately, their identification is simple, which facilitates its treatment.
The 8 Types of Seizures

Last update: 17 December, 2022

Seizures are one of the most common neurological disorders worldwide. They can present in different ways according to the brain area where the seizure focus originates. Are you interested in learning about the 8 types of seizures? In the following article, we’ll tell you what you need to know.

The term seizure is used to describe an abnormal, sudden, excessive, and hypersynchronous electrical discharge from a group of neurons. Epilepsy is a chronic brain disease characterized by recurrent seizures that can affect part or all of the body.

Studies affirm that this disease occurs during childhood in most cases, with more than 50% of seizures before the age of 10. Seizures usually appear as abnormal, involuntary movements in any part of the body. However, they can also cause sensory, cognitive, and even emotional disorders.

Why do seizures occur?

Seizures are the result of an imbalance between the excitatory and inhibitory elements of the central nervous system. In order for them to occur, there must be a neuronal predisposition and a factor that stimulates the electrical discharge. The seizure focus may be isolated or distributed to the entire brain after its formation.

The overactivation of neurons promotes different symptoms according to the affected brain region. Involuntary jerking movements usually appear when the frontal lobe of the brain is stimulated.

Some of the most common causes of the various types of seizures are the following:

Types of seizures

Seizures are classified according to their clinical manifestations and the findings found during a study with an electroencephalogram. The International League Against Epilepsy (ILAE) proposed grouping the different types of seizures into generalized, focal, and of unknown origin.

Localized seizures are those limited to a specific brain region or within the same brain hemisphere. They can occur with or without altered consciousness and be of a motor or non-motor nature.

On the other hand, generalized seizures are those that initially affect the entire brain tissue. This group can present as motor or non-motor seizures, called absence seizures.

A woman lying on the ground during a seizure.
Epilepsy is a chronic disease that’s associated with seizures as a symptom.

1. Generalized tonic-clonic seizures

This type of seizure is one of the most common forms in people with epileptic seizures. It usually begins with a sudden loss of consciousness and falling to the ground while standing. Similarly, it’s characterized by a generalized and sustained muscle contraction of the body for 10 to 20 seconds.

The muscle contraction phase is followed by periods of muscle relaxation during the clonic phase. In this regard, people will manifest rhythmic movements of the head and all four limbs. Usually, there may be biting of the tongue and involuntary urination during the seizure episode.

Tonic-clonic seizures last approximately 1 minute. After the seizure episode, a progressive recovery phase will begin accompanied by confusion, headache, fatigue, and muscle aches that can last minutes or hours.

2. Generalized myoclonic seizures

Myoclonic seizures usually involve short, sudden jerks of part or all of the body. Involuntary movement is the result of the sudden contraction of a muscle group. In general, this type of seizure affects the hands and arms, causing objects to fall due to loss of support.

These crises are often associated with metabolic disorders, degenerative diseases, and brain injuries. In addition, myoclonic episodes are characteristic of juvenile myoclonic epilepsy, a type of generalized epilepsy common in adolescence.

3. Generalized atonic seizures

This type of seizure involves a sudden loss of muscle tone and posture with rapid recovery. Consciousness can be affected for a couple of seconds; however, post-episode confusion is rare. These seizures are responsible for injuries and fractures from falls.

Atonic seizures can present as a single isolated episode. However, they’re associated with other types of seizures.

4. Generalized absence seizures

Absence seizures are a form of generalized seizure also called a petit mal. They occur during school age or adolescence and are associated with poor academic performance. Typically, the person will manifest a transitory loss of contact with the surrounding environment, without loss of postural tone.

Affected people remain immobile, with a fixed gaze and loss at some point in the visual field. They may also show rapid blinking movements and tremors in the hands. The episodes only last a few seconds and the person recovers quickly and without any confusion.

At the same time, some patients may present atypical absence seizures. In this case, the episodes are longer, with a less abrupt onset and recovery. In addition, they can be accompanied by more obvious involuntary movements.

5. Focal seizures without altered consciousness

These types of seizures were previously called simple partial seizures. The affected person doesn’t lose contact with reality while the seizure occurs.

The clinical manifestations vary according to the area of the brain where the seizure focus occurs. The most common forms of focal seizures are:

  • Motor: Involves repetitive involuntary movements and paralysis of a body segment, as well as abnormal positions and postures. Usually, the seizure focus is located in the frontal prerolandic area of the brain.
  • Sensory: The person has an alteration in superficial or deep sensitivity. It manifests itself with sensations of tingling, cold, heat, or pain to the touch. The seizure originates in the parietal lobe of the brain. In addition, auditory and olfactory hallucinations are evident when the condition’s in the temporal region.
  • Autonomic: These types of seizures usually alter the involuntary functions regulated by the autonomic nervous system. For this reason, the person may manifest sudden changes in temperature, profuse sweating, excessive salivation, and pupillary dilation.
  • Cognitive: Episodes are associated with memory and thinking disturbances. In addition, the sensations of experiences already lived or déjà vu are frequent, as well as repetitive thinking.
  • Emotional: The patient usually suffers from intense emotions that aren’t related to the current psychological state or to situations that are being witnessed. Abnormal fear is the most common form of presentation.

6. Focal seizures with impaired consciousness

Seizures with impaired consciousness are often preceded by an aura, such as the feeling of fear and déjà vu. Initially, the patient will be immobile and staring blankly. The appearance of involuntary and repetitive chewing and swallowing movements, as well as senseless gestures, is typical.

After the seizure, a person’s full recovery can take up to 1 hour. This period is accompanied by confusion, amnesia, and moderate-intensity headaches.

A woman with a headache.
Seizures that precede auras have symptoms that herald the onset of the condition.

7. Focal seizures with progression to bilateral tonic-clonic

These types of seizures are the result of the extension of the epileptic focus from its primary site of origin to the entire surface of the brain. The abnormal neuronal discharge usually forms in the frontal lobe and the clinical manifestations are similar to a generalized tonic-clonic seizure.

8. Epileptic spasms

This type is about the sudden, brief, and sustained flexion or extension of the proximal muscles of the body, including those of the trunk. The episode usually lasts 1 to 5 seconds, and the patient’s head and neck may be severely affected. They’re common during the first year of life and rare from 2 years of age onward.

The different types of seizures shouldn’t be underestimated

There are different types of seizures that describe the origin and severity of the clinical picture of the affected person. Seizures can result from cerebrovascular events, trauma, febrile seizures, and even brain tumors. So, their appearance is usually a sign of alarm.

Similarly, seizures are associated with multiple complications that can progress to death in the short term. For this reason, it’s essential to seek medical attention as soon as possible before a seizure. A health specialist is the only one trained to evaluate the condition, detect the underlying cause, and offer the best therapeutic option.

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