Different Types Of Generalized Seizures

Seizures are caused by changes in electrical activity in the brain. Depending on the type of seizure, some symptoms are more noticeable than others, and you may wonder how they present themselves.

Within the category of generalized seizures, there are several different types. So here's a quick overview of what they are and their associated symptoms. 

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What is a generalized seizure?

A seizure is an uncontrollable electrical disturbance in the brain that occurs suddenly. It can alter your behavior, movement, or feelings and may cause a loss of consciousness or reduced awareness. 

There are different types of seizures; one of the main categories is generalized seizures. Other categories include focal seizures or unknown seizures. Unknown seizures have an unknown onset. 

Within the generalized seizure category, seizures can be further defined as being: 

  • Absent 

  • Atonic 

  • Myoclonic

  • Tonic

  • Clonic

  • Tonic-clonic 

Regardless of the type, a typical seizure can last up to two minutes. However, seizures that last longer than five minutes are considered a medical emergency and require urgent help. 

What sets generalized seizures apart from others is that they occur in both halves (hemispheres) of the brain. Hence, the right and left sides of the brain are affected by a seizure at the same time. In contrast, other seizures, such as focal seizures, only affect one side of the brain while they are happening. 

Additionally, certain generalized seizures can be regarded as motor or non-motor, meaning some generalized seizures affect movement while others do not. 

What causes generalized seizures?

As with most seizure types, a range of factors can trigger a seizure. These include:

  • Serious head injuries 

  • Brain tumors 

  • Strokes

  • Brain infections, such as encephalitis or meningitis 

  • Oxygen loss at birth 

  • Alzheimer's disease 

If someone has experienced any of the above, they will have a higher risk of experiencing seizures. However, if someone experiences reoccurring or unprovoked seizures, their doctor may diagnose them with epilepsy

Absent seizures

Absent seizures, sometimes called "petit mal" seizures, involve no motor symptoms and are characterized by staring spells. 

These seizures are easily mistaken for daydreaming because the person experiencing them stares in one direction for a prolonged period. They are most common in children between the ages of 4–12.

Typical absent seizures last up to 30 seconds. During this time, the patient is unresponsive and may experience a loss of awareness. 

The symptoms or signs of absence seizures include:

  • A blank stare

  • Loss of awareness

  • Stopped or reduced activity 

  • Eyelid fluttering

  • Oral automatisms, such as lip smacking, chewing or swallowing 

  • Pallor (pale appearance) 

Most absent seizures will not have a warning or aura (an unusual sensation) before they start. 

Atonic seizures

Atonic seizures also called drop attacks, are characterized by a sudden decrease in muscle tone. As a result, the body, or part of the body, suddenly goes limp and collapses. This may cause an injury depending on what the person was doing before the seizure suddenly started. 

Symptoms of atonic seizures include:

  • A sudden fall or going limp without apparent warning 

  • Loss of tone in the body 

  • A brief loss of consciousness

  • Drooping eyelids

  • Slight jerking motions

These seizures are also unpredictable, and an individual may have no warning or aura before the episode starts.

Myoclonic seizures

Myoclonic seizures are characterized by sudden movements, such as repetitive jolting motions. It may appear as though the person has been suddenly shocked by electricity. 

Symptoms include:

  • Uncontrollable muscle jerks

  • Uncontrollable repetitive movements

  • Shock-like contractions

These seizures occur suddenly and are unlikely to have a warning or aura beforehand. 

Infantile spasms

Infantile spasms are a subtype of myoclonic seizures. They have similar symptoms, except they occur in infants. In most cases, they arise in infants before the age of one. 

Tonic and clonic seizures 

Tonic seizures

Tonic seizures are characterized by stiffened muscles and a loss of consciousness. During these seizures, the eyes may also roll back, and the contracting muscles in the chest, arms, and legs may cause the back to arch. 

Symptoms of tonic seizures include:

  • Impaired awareness

  • Possible loss of consciousness

  • Stiff muscles 

Clonic seizures

Clonic seizures predominantly affect the elbows, legs, and neck. This is because the muscles in these areas flex and then relax with jerking motions. These movements are also like spasms or cramps. 

Symptoms include: 

  • Twitching or jerking

  • Muscle spasms and cramps

  • Possible loss of consciousness or awareness 

Tonic-clonic seizures 

Tonic-clonic seizures are also known as "grand mal" seizures. Essentially, they are a combination of tonic and clonic seizures, so tonic and clonic-like movements occur at the same time. In some cases, there might be a tonic phase, followed by a clonic phase. 

The lowdown

There are four types of generalized seizures: absent, atonic, myoclonic, and tonic-clonic. Each has varying symptoms, but they are all linked to seizures that originate in both sides of the brain simultaneously.

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