OHSU

Types of Seizures

What is a seizure?

The brain is the center that controls your body’s responses. It is made up of nerve cells that communicate with each other through electrical activity. When your brain receives a burst of electrical signals that temporarily stops its normal electrical activity, you might have a seizure.

At the OHSU Comprehensive Epilepsy Center, your doctor will spend time talking with you about your seizures to understand what type you have. This is important because certain types of seizures may respond best to particular medications or treatments. This information also may be important in searching for a cause of your seizures and having other tests or treatments.

What are the different types of seizures?

Different types of epilepsy cause different symptoms. Depending on the type of epilepsy you have, you might have:

Partial seizures

Partial seizures (also called focal seizures) start in one area of the brain. A partial seizure may be caused by a brain  tumor, stroke, head injury or other problem. Sometimes the cause is unknown even with the most detailed tests.

Simple partial seizure

Only a small part of your brain is affected. You do not lose consciousness (awareness of what is going on around you). Your symptoms may depend on which area of the brain is involved. A simple partial seizure can affect your movements, vision or other senses. You may also sweat or become pale or nauseated.

Complex partial seizure

A larger area of your brain that controls emotion and memory is affected. You are not aware of what is going on around you. You may smack your lips, scream, cry, laugh or run. Afterward, you may feel tired or sleepy.

Secondarily generalized tonic-clonic seizure

This type of seizure starts as a partial seizure. It spreads to your entire brain, becoming “generalized.” This type used to be called a “grand mal” seizure.


Generalized seizures

A generalized seizure affects both halves of your brain. Often these seizures begin in childhood. They might be caused by a genetic (inherited) tendency to have seizures. There are several types of generalized seizures:

  • Generalized tonic-clonic seizures (used to be called “grand mal” seizures) have different phases. You may first lose consciousness (awareness of your surroundings). Your body, arms and legs may then stiffen (called the “tonic” phase). Next, your body might shake very hard (“clonic” phase). After this, you may be very tired or sleepy, have problems seeing or talking or have a bad headache or body aches.
  • Absence seizures (used to be called “petit mal” seizures) cause you to lose consciousness for a short time or stare. You usually stay upright. Your face may move or your eyes may blink. After your seizure, you may not remember what happened. You might be able to continue your activities. You can have absence seizures several times a day. Absence seizures are sometimes mistaken for learning or behavior problems. They almost always start between ages 4 and 12.
  • Atonic seizures (also called “drop attacks”) cause you to suddenly lose muscle tone (muscle strength and resistance). You may fall from a standing position or suddenly drop your head.  During the seizure you are limp and unable to respond.
  • Myoclonic seizures cause quick movements or sudden jerking of a group of muscles. They may happen several times a day or for several days in a row.
  • Infantile spasms affect babies 6 months old or younger. The neck, body or legs can move for a few seconds. It often happens when the baby is waking up or trying to go to sleep. Infants may have hundreds of these seizures a day. This is a rare and serious condition.
  • Febrile seizures are caused by fever, usually in children from 6 months to 5 years old. They may run in families. Seizures that last less than 15 minutes are called "simple." They usually don’t cause health problems. If a febrile seizure lasts longer than 15 minutes (“complex”) may cause health problems in the child.