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Tonic-Clonic Seizures Explained

Posted on July 20, 2022
Medically reviewed by
Evelyn O. Berman, M.D.
Article written by
Brooke Dulka, Ph.D.

When people think of epilepsy, they often envision jerking limbs and a loss of consciousness. These symptoms describe a type of seizure called tonic-clonic seizures. Generalized tonic-clonic seizures were previously called grand mal seizures.

Here’s what to know about these seizures, including symptoms, causes, diagnosis, and treatment options, as well as what you can do if you witness someone having a tonic-clonic seizure.

Symptoms of Tonic-Clonic Seizures

The term “tonic-clonic” describes what happens during the two phases of these seizures.

“Tonic” refers to the stiffening, or sustained contraction, of muscles. During the tonic phase, which generally lasts less than 30 seconds, a person experiencing typical symptoms of epilepsy may also:

  • Let out a cry or groan as air pushes past the vocal cords
  • Lose consciousness
  • Fall down
  • Bite their tongue
  • Foam at the mouth

“Clonic” refers to rhythmic jerking, usually of the face, arms, and legs. This phase can be brief or last a few minutes. If the jerky movements continue for more than 5 minutes, the seizure becomes a neurological emergency called status epilepticus.

After the clonic phase ends, the person’s body will begin to relax. This relaxation sometimes includes the muscles of the bladder or bowels, causing accidental urination or a bowel movement. As the person then slowly regains consciousness, they may be confused, irritated, tired, or depressed. These symptoms are all normal for a person coming out of a tonic-clonic seizure.

What Causes Tonic-Clonic Seizures?

Tonic-clonic seizures are caused by abnormal electrical activity in the brain. When this electrical activity occurs on both sides of the brain at once, the seizures are called generalized tonic-clonic seizures. If the activity starts on one side and progresses to both sides, the seizures are called focal to bilateral tonic-clonic seizures (formerly called secondarily generalized seizures).

Abnormal electrical activity in the brain has been associated with several risk factors. Some of these risk factors are genetic, as tonic-clonic seizures tend to run in families. Tonic-clonic seizures also can be related to:

  • Brain injury or structural damage
  • Infection
  • Substance misuse, including alcohol misuse

Diagnosing Tonic-Clonic Seizures

Some people have one tonic-clonic seizure and never have another. Other people have many tonic-clonic seizures, which may help doctors make an epilepsy diagnosis. Reaching a diagnosis of an epileptic disorder can be time-consuming and frustrating. You may need to go to several doctors and neurology specialists before your health care team can make a conclusion.

The most important diagnostic tool a neurologist might use to diagnose epilepsy is an electroencephalogram (EEG), which measures brain waves. EEG testing may reveal abnormal brain activity in between seizures to help establish a diagnosis. MRI scans, which visualize the brain, may also help your doctor determine if there is a structural cause of seizure activity.

How Are Tonic-Clonic Seizures Treated?

Tonic-clonic seizures are typically treated with antiepileptic or anti-seizure medications. One study found that three drugs, (Tegretol), phenytoin (Phenytek), and valproate (Depakote), completely stopped seizures in roughly 50 percent of participants.

Lamotrigine (Lamictal) has also proved to be a successful treatment option for tonic-clonic epilepsy.

In other cases, such as for status epilepticus, a class of antianxiety medications called benzodiazepines is recommended to end the seizure.

Not all medications work for everyone, and your doctor may prescribe several different drugs before finding the one that works best for you.

Staying Safe During a Seizure

Watching someone have a seizure can be scary. By understanding what to do and what not to do, you will be better prepared to deal with the situation. If someone is having a tonic-clonic seizure, here are some safety tips to keep in mind:

  • Stay calm.
  • Remain with the person.
  • Roll the person onto their side immediately if they have food or water in their mouth.
  • Place something soft under their head.
  • Try to protect the person from injury.
  • Time the seizure.

It’s also important to know these tips on what not to do:

  • Don’t try to put something in the person’s mouth. It is not true that someone having a seizure can swallow their tongue.
  • Don’t restrain the person.
  • Don’t offer food or drink, which could cause choking.

Talk With Others Who Understand

MyEpilepsyTeam is the social network for people with epilepsy and their loved ones. On MyEpilepsyTeam, members come together to ask questions, give advice, and share their stories with others who understand life with epilepsy.

Do you or a loved one have tonic-clonic seizures? Do you have any tips for being prepared to deal with these situations? Share your experience in the comments below, or start a conversation by posting on your Activities page.

All updates must be accompanied by text or a picture.
Evelyn O. Berman, M.D. is a neurology and pediatric specialist and treats disorders of the brain in children. Review provided by VeriMed Healthcare Network. Learn more about her here.
Brooke Dulka, Ph.D. is a freelance science writer and editor. She received her doctoral training in biological psychology at the University of Tennessee. Learn more about her here.

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