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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  • The tonic-clonic seizure is what most people think of when they think of a convulsive seizure. 
  • A person loses consciousness, muscles stiffen, and jerking movements are seen.
  • These types of seizures usually last 1 to 3 minutes and take much longer for a person to recover. 
  • A tonic-clonic seizure lasting more than 5 minutes is a medical emergency. 

What is a tonic-clonic seizure?

This type is what most people think of when they hear the word "seizure." An older term for them is "grand mal." As implied by the name, they combine the characteristics of tonic seizures and clonic seizures. 

  • The tonic phase comes first: All the muscles stiffen. Air being forced past the vocal cords causes a cry or groan. The person loses consciousness and falls to the floor. The tongue or cheek may be bitten, so bloody saliva may come from the mouth. The person may turn a bit blue in the face.
  • After the tonic phase comes the clonic phase: The arms and usually the legs begin to jerk rapidly and rhythmically, bending and relaxing at the elbows, hips, and knees. After a few minutes, the jerking slows and stops. Bladder or bowel control sometimes is lost as the body relaxes. Consciousness returns slowly, and the person may be drowsy, confused, agitated, or depressed.
  • These seizures generally last 1 to 3 minutes.
  • A tonic-clonic seizure that lasts longer than 5 minutes needs medical help. A seizure that lasts more than 10 minutes, or three seizures without a normal period in between, indicates a dangerous condition called convulsive status epilepticus. This requires emergency treatment.

Who is at risk for tonic-clonic seizures?

They affect both children and adults. For children who have had a single tonic-clonic seizure, the risk that they will have more seizures depends on many factors.

Some children will outgrow their epilepsy. Others who are seizure-free for a year or two while taking seizure medicine will stay seizure-free if the medicine is gradually stopped.

The risk that an individual will have more seizures depends on factors such as whether his or her EEG shows any epilepsy waves, or whether the doctor finds any abnormalities on a neurological exam. Among children with no epilepsy waves and a normal exam, about 70% of those who have had tonic-clonic seizures will stay seizure-free without medication. The comparable number is less than 30% for children with epilepsy waves and an abnormal exam. All these figures are more favorable than those for partial seizures.

What’s it like to have a tonic-clonic seizure?

When people have tonic-clonic seizures, they are not aware of what’s going on around them. These seizures may require first aid including making certain that the person is breathing and there are no injuries. After the seizure has occurred, the person may be sleepy or confused for several minutes or longer. They may have lost bowel or bladder function. They also may have bitten their tongue.

How can I tell if someone is having a tonic-clonic seizure?

Some nonepileptic (psychogenic) seizures resemble tonic-clonic seizures. The surest way to tell the difference is with video-EEG monitoring. In some cases, the same person may have both tonic-clonic and nonepileptic seizures.

People who faint sometimes develop tonic or clonic movements. These movements are rarely as intense or prolonged as a tonic-clonic seizure.

How are tonic-clonic seizures diagnosed?

The typical appearance of a tonic-clonic seizure is usually easy to recognize. The doctor will want a detailed description of the seizures. An EEG and other tests may help to confirm the diagnosis or suggest a cause.

How are tonic-clonic seizures treated?

There are many medicines that can be used to prevent tonic-clonic seizures. Moreover, there are special medicines used only in the setting of emergencies that can help stop further tonic-clonic seizures from occurring after it is taken. There is also a device (vagus nerve stimulation) that can help to prevent seizures as well if the person is diagnosed with epilepsy.

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

If you think that your child, loved one or yourself, may be having tonic-clonic seizures, please talk to your doctor or your child or loved one’s doctor as soon as possible. Tonic-clonic seizures can lead to injury and in some rare cases death. Getting these diagnosed and treated is essential.

Authored by: Orrin Devinsky, MD | Joseph I. 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 from a parent's view: "These seizures frighten me. They only last a minute or two but it seems like an eternity. I can often tell Heather's going to have one because she acts cranky and out of sorts. It begins with an unnatural shriek. Then she falls, and every muscle seems to be activated. Her teeth clench. She's pale, and later she turns slightly bluish. Shortly after she falls, her arms and upper body start to jerk, while her legs remain more or less stiff. This is the longest part of the seizure. Finally it stops and she falls into a deep sleep."

generalized tonic-clonic seizure
Generalized Tonic Clonic Seizure

Here the whole brain is affected from the beginning. In (a) there is a cry and loss of consciousness, arms flex up then extend in (b) and remain rigid (the tonic phase) for a few seconds. A series of jerking movements take place (the clonic phase) as muscles contract and relax together. In (c) the jerking is slowing down and will eventually stop. In (d) the man has been placed on his side to aid breathing and to keep the airway clear.