A seizure is a sudden surge of electrical activity in the brain that causes involuntary movements or a loss of consciousness.

Seizures may occur due to medication or trauma that damages the brain. Epilepsy is a condition where people have recurring seizures.

This article looks at the different types of seizures, signs to look out for, treatments, and how to help someone having a seizure.

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A seizure is a sudden surge of abnormal electrical activity in the brain. The brain usually creates tiny electrical impulses in a regular pattern, which travel through nerve cells to communicate with the rest of the body.

A burst of abnormal electrical activity creates a change in behavior or sensation and may cause a loss of awareness or consciousness.

Medications or trauma to the brain may cause seizures. A person with recurring seizures has a medical condition called epilepsy.

Seizures and epilepsy are related but distinct terms.

A seizure is a sudden, uncontrolled electrical disturbance in the brain. This creates a change in behavior or sensation and may cause a loss of awareness or consciousness. Having a seizure by itself does not mean a person has epilepsy. Rather, they can occur as a one-off event or as part of another condition.

Meanwhile, epilepsy is a neurological disorder that involves recurring seizures. It is sometimes known as seizure disorder. Seizures associated with epilepsy can vary in type and severity, and it is a long-term condition that requires ongoing management. It is usually diagnosed after a person has two or more unprovoked seizures.

There are many types of seizures, and they fall into two categories. Focal or partial seizures start in one area of the brain, whereas generalized seizures occur in both sides of the brain.

Focal onset seizures

In a focal onset seizure, abnormal electrical activity occurs in one sensory area of the brain. Also known as partial seizures, they may cause twitching or a change in taste or smell.

Focal onset seizures may occur due to trauma, stroke, or meningitis, which can scar the brain.

A focal onset seizure can cause minor symptoms, which people call an “aura.” They may experience:

  • a feeling that something is about to happen
  • sensations in the stomach, which may feel similar to riding a rollercoaster
  • other unusual sensations or movements

Focal onset seizures can be split into two types: focal onset aware seizure and focal onset awareness-impaired seizure.

Focal onset aware seizure

A seizure that starts on one side of the brain and does not cause a person confusion or loss of awareness is called a focal onset aware seizure. This was previously known as a simple partial seizure.

Focal onset awareness-impaired seizure

A seizure that starts on one side of the brain and causes a person confusion, or a change in awareness during some or all of it, is called a focal onset awareness-impaired seizure. This was previously known as a complex partial seizure.

If a person has a complex partial seizure, they may:

  • be dazed or confused
  • stare blankly into space
  • be unable to respond to instructions or questions
  • make repetitive movements or sounds, such as lip-smacking, chewing, grunting, or shouting
  • shaking or stiffening of muscles

Generalized seizures

Generalized seizures include the following types:

  • Absence: Absence seizures can cause people to stare into space or blink rapidly.
  • Tonic: Tonic seizures can cause a sudden stiffening of the arms and body, which may result in falls or injuries. Lennox Gastaut syndrome can cause tonic seizures.
  • Atonic: Atonic seizures can cause a sudden loss in body tone, which causes people to collapse and may lead to injuries.
  • Clonic: Clonic seizures affect the muscles and cause jerking movements in the arms and legs. They can affect one or both sides of the body. People may or may not have awareness or consciousness.
  • Myoclonic: Myoclonic seizures cause sudden, jerky movements of the arms, head, or neck. These spasms affect both sides of the body and commonly occur in the morning.
  • Tonic-clonic: A focal or generalized seizure can cause tonic-clonic seizures. People may cry out, lose consciousness, or have muscle spasms.

Febrile seizures

Fever in young children can cause febrile seizures and is not a sign of epilepsy or other seizure disorders.

A child may lose consciousness, roll their eyes, shake, or develop rigid limbs. A febrile seizure does not cause any long-term health issues.

Infantile spasms

Infantile spasms are a symptom of West Syndrome, a form of epilepsy affecting infants. Symptoms of this type of seizure include a sudden bending forward of the body, arching the back, and stiffening of the limbs.

Symptoms can vary depending on the type of seizure a person has but may include:

  • staring into space
  • a dazed or confused state
  • rapid blinking
  • crying out
  • falling to the ground
  • shaking
  • twitching
  • jerky movements or muscle spasms
  • a change in sensation, such as altered smell or taste
  • loss of response or awareness of what is going on around them
  • loss of consciousness

Some common causes of seizures include the following:

  • epilepsy
  • head injury
  • stroke
  • infection
  • high fever
  • brain tumor
  • lack of sleep
  • alcohol or drug withdrawal

Seizures generally have three stages, though not all stages include every stage:

  1. Beginning stage (prodrome and aura): Some people sense a seizure coming hours or days in advance, which is known as the prodrome phase. Others may experience an aura, which is marked by symptoms such as déjà vu, odd smells, sounds, or tastes, nausea, and fear, which may or may not lead to a full seizure.
  2. Middle ictal stage: This is the seizure itself, marked by intense brain activity. Common signs include loss of awareness, memory lapses, confusion, and loss of muscle control.
  3. Ending postictal stage: This is the recovery stage, when any physical after effects of the seizure are felt. These may include exhaustion, headache, thirst, and embarrassment.

To diagnose a seizure, doctors may assess physical symptoms and carry out tests such as:

  • Electroencephalogram (EEG): An EEG shows electrical activity in the brain, and doctors use this to look at brain wave patterns and determine which type of seizure a person has.
  • MRI scan: An MRI scan can show any structural damage to areas of the brain.
  • Positron emission tomography (PET) scan: A PET scan can show changes in brain chemistry.
  • Single photon emission computed tomography (SPECT): A SPECT scan can show changes such as blood flow and brain cell activity when a seizure occurs.

Treatment for seizures may involve a combination of methods, which may include:

A seizure is a sudden surge of abnormal electrical activity in the brain, which may occur as a result of epilepsy or damage to the brain.

There are various types of seizures, and they have similar symptoms with some differences. Doctors use imaging tests to determine the cause of a seizure.

If people have a seizure for the first time, they must contact a doctor as soon as possible.

Treatment for seizures includes medication and surgery. It is possible to reduce the risk of seizures by adopting healthy lifestyle habits.