What is a Seizure?

A seizure is an abnormal release of electrical activity in the brain that causes temporary changes in how a person moves, feels, or thinks.

  • Seizures can take many different forms, including whole-body convulsions/shaking or changes in awareness or behavior.
  • Where the seizure occurs in the brain determines what the seizure looks like.
  • Seizures can last from a few seconds to several minutes.
  • One in 10 people will have a seizure in their lifetime.

Seizures are classified as either focal or generalized onset. Focal seizures begin in one area in the brain, while generalized seizures affect multiple areas or the entire brain.

Depending on which areas of the brain are involved, seizures may cause a variety of symptoms, including altered awareness, uncontrolled physical movements, sensory
impairment, intense emotional reactions, convulsions, and loss of consciousness. It is possible for someone to have more than one type of seizure.

Seizure Locations

The two primary seizure classifications are generalized, which occur in multiple areas or throughout the entire brain, and partial, which are confined to just one area of the brain. The brain lobes affected by the abnormal electrical activity determines what the seizure looks like and how it affects the person having one:

  • Frontal Lobe – Motor skills, problem-solving, memory, language skills
  • Parietal Lobe – Sensation, perception, sensory communication
  • Occipital Lobe – Visual processing
  • Temporal Lobe – Hearing, emotions, mood, memory

Sometimes seizures can cause a person to have convulsions and lose consciousness, but that’s not always the case. Other common signs someone is having a seizure includes altered awareness, uncontrolled physical movements, sensory impairments, and intense emotional reactions. People can also have more than one type of seizure.

Common causes of epilepsy include brain tumor, stroke, head trauma, infections, and maternal injuries, but in 70% of cases the cause of a person’s epilepsy is unknown.

Thriving with Epilepsy

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Common Seizure Types

Generalized Onset – Tonic Clonic (formerly known as Grand Mal)

These begin with a sudden loud sound caused by air being forced out of the diaphragm, followed by stiffening of the body (tonic phase), and convulsions (clonic phase). May be accompanied by drooling, biting of the tongue, vomiting, or possible loss of bowel or bladder control. These seizures typically last one to three minutes, includes a loss of consciousness, and is followed by a period of confusion.

Generalized Onset – Absence (formerly known as Petit Mal)

These look like a staring spell that lasts a few seconds, sometimes perceived as daydreaming. May be accompanied by blinking or chewing movements and includes a loss of consciousness.

Focal Onset – Impaired Awareness (Complex Partial)

The individual remains conscious but lacks awareness of surroundings. They may display random repetitive movements like picking at clothing, chewing, or lip-smacking. Often includes staring or dazed facial expressions and the person may be unable to speak coherently. Lasts one to three minutes, followed by a period of confusion.

Focal Onset – Aware (Simple Partial)

The individual remains conscious and aware during the seizure. Depending on where in the brain the seizure occurs, they may display jerking of one or more body parts, have visual or auditory hallucinations, or experience unusual smells or tastes. These sensory perceptions may not be obvious to observers.

Atonic (Drop Attack)

Part or all of the person’s body becomes limp, and if standing they’ll likely fall to the ground. These typically last 15 seconds.


Sudden, brief, shock-like muscle spasms involving all or part of the body. These are short seizures that can easily be overlooked and mistaken for tics, tremors, or clumsiness.

Epilepsy Syndromes

Epilepsy Syndromes may be diagnosed when a group of features occur together, or “cluster.” “Features” include signs and symptoms like:

  • Type of seizure
  • Genetic information
  • Causes of the seizures
  • Age at which the seizures began
  • Part of the brain involved
  • Triggers that provoke a seizure
  • Severity and frequency of seizures
  • A pattern of seizure activity by time of day
  • Certain patterns found on the EEG (electroencephalogram)
  • Brain image findings through an MRI or CT scan
  • Other disorders in addition to seizures
  • The prospects for recovery or worsening

To learn more, talk with your doctor for further testing on syndromes.

Learn basic seizure first aid

One in 10 people will have a seizure in their lifetime; do you know what to do? Learn how to safely respond to someone having a seizure.

Learn seizure first aid