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.

Learn more about epilepsy here.

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.

Simple focal seizures

Simple focal seizures affect a small area of the brain. Simple focal seizures may cause twitching or a change in taste or smell.

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

A simple focal 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

In a simple focal seizure, abnormal electrical activity occurs in one sensory area of the brain.

People may also refer to a simple focal seizure as a simple partial seizure or a focal aware seizure. People keep their awareness during this type of seizure and will not lose consciousness.

Learn more about focal seizures here.

Complex partial seizures

A simple focal seizure may spread into other areas of the brain, becoming a complex partial seizure. As abnormal electrical activity affects a larger section of the brain, symptoms can become more severe.

People may also refer to a complex partial seizure as a complex focal seizure or a focal unaware seizure. These seizures affect a person’s awareness.

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

Learn more about complex partial seizures here.

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.
  • Tonic-atonic: A tonic-atonic seizure occurs when an atonic seizure follows a tonic seizure.

Febrile seizures

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

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

Learn more about the signs and symptoms of seizures here.

The Centers for Disease Control and Prevention (CDC) advise the following first-aid to help someone having any type of seizure:

  • remain with the person while they are having a seizure, and stay with them until the seizure stops and they become fully awake or alert again
  • time the seizure from when it starts to when it ends
  • help the person sit down in a safe, comfortable space
  • comfort and calm the other person, and calmly explain what has happened
  • check if the person has any emergency medical information on them, such as a medical bracelet
  • offer to call a taxi or someone they know to pick them up and make sure they get home safely
  • call 911 if a seizure lasts for longer than 5 minutes or if the person has an injury

Other important tips include storing sharp or dangerous objects safely and keeping the person from falling into water, such as a bathtub or pool.

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:

  • medication
  • diet changes
  • surgery
  • electrical stimulation

Read about medication and other treatments for seizures here.

People can try to identify any triggers and avoid them where possible. People who are prone to seizures may find the following factors increase the risk of seizures:

Seizures can affect people differently, impacting some lives more than others. Seizures can be a one-off event. Many people with epilepsy can live normal and active lives.

Around 70–80% of people can effectively manage their seizures with treatments such as medication or surgery.

Working alongside healthcare professionals and taking medication as a doctor prescribes may help people manage the condition.

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. People who have a seizure for longer than 5 minutes require immediate medical attention.

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