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What is a Seizure?

A seizure occurs when there is a sudden electrical disturbance in the brain. Depending on the type of a seizure, a person may temporarily have involuntary muscle movements and lose awareness or consciousness. The type of seizure a person experiences depends on where the seizure begins in the brain.

Generally, a person is diagnosed with epilepsy after two or more unprovoked seizures, or after a high risk of having another seizure is identified after an initial seizure. Provoked seizures—also known as acute symptomatic seizures—have a clear, immediate cause, such as a stroke or brain injury. 

pediatrician using stethoscope on patient

Symptoms of Seizures

Different types of seizures present with different symptoms. Seizures can be broadly divided into generalized (involving the whole brain) and focal (involving one small part of the brain).

Generalized Seizures

  • Absence seizures cause a very brief (a few seconds) loss of consciousness. They begin with little or no warning and may occur several times per day. They are more common in children.
  • Myoclonic seizures cause rapid jerks or twitches, which usually affect both sides of the body. These jerks and twitches are often described as being like an electrical shock.
  • Clonic seizures cause repetitive, rhythmic jerks and involuntary body movements.
  • Tonic seizures cause stiffening of the muscles, which results in the body becoming inflexible or rigid.
  • Atonic seizures cause unexpected loss of muscle tone, usually in the arms and legs. This can sometimes result in falls and other accidents.
  • Tonic-clonic seizures (formerly known as grand mal seizures) cause loss of consciousness, 30-60 seconds of stiffening of the body (including the arms and legs), followed by 30-60 seconds of involuntary muscle jerking of the arms and legs. After the seizure, most people fall into a deep sleep and may wake up after several minutes disoriented or confused.

Focal Seizures

  • Focal aware seizures cause a variety of symptoms depending on where they originate in the brain. Some symptoms include a funny feeling in the stomach, anxiety, déjà vu, of involuntary movements of the body. They do not involve a loss of consciousness.
  • Focal seizures with impaired awareness cause a loss of consciousness or awareness. Though a person’s eyes usually remain open, the person seems “out of it” and may stare into the distance. They also may perform repetitive actions, like lip smacking and hand waving.
  • Sometimes focal seizures evolve into tonic-clonic seizures.

Please seek the help of a licensed medical professional if you are concerned about your health, and call 911 if you are experiencing an emergency.

senior woman with her hand on her chest in pain

Treatments for Seizures

Not everyone who has a seizure will have a second one, so treatment is not always necessary. Your doctor will order testing to determine your risk of additional seizures and recommend medications if your risk is high. For some causes of seizures, like brain tumors, treating the underlying condition can prevent future seizures.

Learn about Epilepsy Treatment

Additional Information

How common are seizures?

Seizures are common, occurring in approximately 10% of people over a lifetime. Most of these are provoked seizures. About 1 in 100 people in the United States has been diagnosed with epilepsy.  If you have had more than one seizure, please see the epilepsy page.

Who gets seizures?

Because provoked seizures have numerous causes, they can affect anyone. However, they are more common in young children and older adults.

The following are possible causes of acute symptomatic seizures:

  • Brain infection (such as meningitis or encephalitis)
  • Brain tumor
  • Fever (especially in young children)
  • Heat illness
  • Hyponatremia (low salt levels)
  • Illicit drug use
  • Stroke
  • Traumatic brain injury
  • Venomous bites and stings
  • Withdrawal from drugs or alcohol

Additional Information and Resources

Epilepsy Foundation
National Association of Epilepsy Centers
Epilepsy Learning Healthcare System

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  People
About 1 in 100 people in the United States has had a single unprovoked seizure or has been diagnosed with epilepsy.

Request an Appointment with a Seizures Specialist