About Seizures

A seizure is a change that happens to a person’s body or behavior because of unusual electrical activity in the brain.

How a doctor may diagnose epilepsy

A doctor may diagnose a person with epilepsy when he or she has any of the following:

  • Two or more seizures that happen on their own more than 24 hours apart
  • A seizure that happens on its own with a strong chance of another seizure occurring
  • A diagnosis of an epilepsy syndrome
Seizure disorders affect more than two million Americans of all ages.

Understanding seizure disorders

Seizure disorder is a term that may be used in place of the term epilepsy. A seizure disorder is a condition where recurring seizures are a symptom. A person with a seizure disorder may feel just as healthy as everyone else most of the time, but sometimes he or she has a seizure. When a person’s seizure disorder has certain features, he or she may have a specific epilepsy syndrome.

An example of an epilepsy syndrome is Lennox-Gastaut (LEN-uks gas-TOW) syndrome (LGS). LGS is a rare and severe epilepsy syndrome. Seizures typically begin in childhood and can be difficult to treat. People living with LGS may experience many different types of seizures.

Types of seizures

Partial seizures, also called partial-onset or focal seizures, occur in a specific area in the brain. They are the most common type of seizure.

  • Simple partial seizure—a type of seizure in which the unusual electrical activity is limited to a specific area in the brain, and the person remains conscious or aware during the seizure
  • Complex partial seizure—a type of seizure in which the unusual electrical activity is limited to a specific area in the brain, and the person loses or has impaired consciousness

Generalized seizures, such as tonic-clonic seizures, affect both sides of the brain from the beginning of the seizure.

  • Secondarily generalized seizure—a seizure that begins as a partial seizure, in a specific area of the brain, but then spreads throughout the brain.
  • Tonic-clonic (formerly called grand mal)—the most common type of generalized seizure. In the tonic phase, the limbs stiffen. During the clonic phase, the limbs and face make jerking movements.