2017 Revised Classification of Seizures

The International League against Epilepsy (ILAE) is the world's main scientific body devoted to the study of epilepsy, and it has recently revised its classification of seizures. The changes will help make diagnosing and classifying seizures more accurate and easier. In this article, you'll find the new general outline and basic seizure classification. In the coming weeks, epilepsy.com will be updated to reflect the new classification to help users searching for both the older and newer terms.

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  • In a tonic seizure, the body arms or legs make sudden stiffening movements. 
  • Usually no first aid is needed, unless an injury has occured. 
  • These seizures can occur in anyone but is often seen in people with Lennox-Gastuat Syndrome. 

What is a tonic seizure?

Muscle "tone" is the muscle's normal tension at rest. In a "tonic" seizure, the tone is greatly increased and the body, arms, or legs make sudden stiffening movements. Consciousness is usually preserved. Tonic seizures most often occur during sleep and usually involve all or most of the brain, affecting both sides of the body. If the person is standing when the seizure starts, he or she often will fall. These seizures usually last less than 20 seconds.

Tonic seizures in Lennox-Gastaut syndrome may become more difficult to control over time. Some patients do achieve a good outcome.

Who is at risk for tonic seizures?

They are particularly common in people who have the epilepsy syndrome called Lennox-Gastaut syndrome, but they can occur in anyone.

What is it like to have a tonic seizure and how can I tell if someone is having one?

Tonic seizures may involve the arms or legs and one or both sides of the body. The arms or legs suddenly stiffens forcefully. Children with other neurological problems sometimes make movements that could be mistaken for tonic seizures. The EEG should be able to tell the difference.

What happens after a tonic seizure?

When a tonic seizure ends, the person may or may not be sleepy or confused. Typically no first aid is needed unless an injury has occurred as a result of the seizures.

If someone has tonic seizures, how often will they happen?

It depends and varies between people. Some people may have just one seizure and others may have back to back seizures.

How are tonic seizures diagnosed?

The EEG can clearly show these seizures.

How are tonic seizures treated?

There are medicines that can help prevent tonic seizures.

What should I do if I think my child or loved one may have tonic seizures?

If you think that you or your loved one may be having tonic seizures, talk to your child’s or loved one’s doctor as soon as possible for immediate diagnosis and treatment.

Authored by: Orrin Devinsky, MD | Joseph Sirven, MD on 7/2013
Reviewed by: Joseph I. Sirven, MD | Patricia O. Shafer, RN, MN on 3/2014
What It Looks Like...

Here's a typical story:

"When Jeff has an episode, he just stiffens up. Both arms are raised over his head and his face has a grimace, as if someone is pulling on his cheeks. If he's standing, he may lose his balance and fall. These seizures don't knock him out like the tonic-clonic seizures, but if he has a few close together, he is often tired."