What is a tonic–clonic seizure?

The tonic-clonic seizure

There are many different types of epileptic seizures. The tonic-clonic cramp is well known, and the one people tend to think of when imagining an epileptic seizure. It has been known as a ”grand mal” but that term is fading out of use.

The tonic-clonic seizure comes in two phases. The seizure starts with a sudden rigidity in the body called the tonic phase. One may feel air being pushed out of the lungs, and it becomes impossible to move. Hereafter one loses conscience, fully or partly, and falls to the ground.

Then the clonic phase starts with contractions and cramps in the muscles. During the seizure it is difficult to breathe and one's lips become blue due to anoxia – (lack of oxygen). It is normal that one during a seizure bites their own tongue, experience involuntary urination and froths from the mouth. After a seizure one is often disorientated and exhausted.

Please notice: Danish Care Technology cannot give advice on epileptic disorder. If you have any questions please contact your doctor or association. 

Are tonic-clonic seizures dangerous?

A general tonic-clonic seizure is mostly not dangerous, even though a person can bite themselves or get hurt from falling.

In rare cases the tonic-clonic seizure lasts very long, and that can be dangerous. Long lasting seizures can lead to durable and lasting damage due to the restricted breathing. In the worst cases it can be life-threatening or cause brain-damage.

If a seizure is longer than 4-5 minutes it is necessary to stop it medically. Those kinds of seizures are dangerous during sleep, or other situations where the one with epilepsy is alone.

Our alarms Epi-Care freeEpi-Care mobile og Epi-Care 3000 can secure that the dangerous seizures will be detected and stopped in time.

It will also notify a parent/guardian/kin or caregiver who can be by the persons side during and after the seizure.

A tonic-clonic seizure is easy to recognise

A tonic-clonic seizure is easy to recognise. First the sudden rigidity and later the cramps. The Epi-Care alarms can monitor epileptic person's movement and alert when it discovers the cramps.

All Epi-Care alarms consists of a sensor that can measure movement. The sensor is the size of a watch, and is placed on the wrist (or on the bed with Epi-Care 3000).

Data from the sensor is constantly monitored, and if the alarm detects movement-patterns corresponding to a tonic-clonic seizure it will automatically alert. A clinical test has proven Epi-Care free to detect 89 percent of all seizures. You can read an article in the scientific journal Epilepsia about Epi-Care free here:

As stated there are a variety of types of seizures where the body reacts differently than a a tonic-clonic seizure. Those seizures cannot be detected by our alarms.

This is a generalized tonic-clonic attack - Seen through the "eyes" of the Epi-Care system

This is a generalized tonic-clonic attack - Seen through the "eyes" of the Epi-Care system

Read more about the different types of epileptic seizures

Epilepsy society

Epileptic Seizures

Seizure Types


Epilepsy Action

Epileptic seizures explained

Tonic-clonic seizures

Jens Jørgen