Epilepsy: What is a Tonic-Clonic Seizure?

The kind of seizure most people associate with epilepsy is the tonic-clonic, or grand mal, seizure. This is a generalized seizure that affects the whole brain. The seizure is named for its two main phases: the tonic phase, in which the muscles tense up; and, the clonic phase in which the body jerks rhythmically. The clonic phase is the part of the seizure commonly identified as a convulsion.

Like many seizures, the tonic-clonic seizure is sometimes preceded by a sort of warning phase called the aura. During aura the person experiences some sort of a sensory disturbance like paresthesia ("pins and needles") or alterations in hearing or vision. These changes include a wide variety of effects, such as a humming or buzzing in the ear, the zigzag lines in the accompanying illustration, or even hallucinations.

A short film about the famous neurologist Wilder Penfield portrays a woman with epilepsy whose aura involved the smell of burnt toast. Some people may also experience feelings of anxiety, weakness or nausea during the aura, or may lose the ability to either speak or understand what is being said to them.

After the clonic phase of a tonic-clonic seizure there is a further period in which the individual returns to normal. The postictal phase, as it is called, generally lasts from 5 to 30 minutes. During this time the person may have difficulty thinking clearly or speaking; they may also experience fatigue, nausea or headache, or may have laboured breathing. For some people the postictal phase can last many hours, or even days, and may lead to postictal bliss (PB) or postictal psychosis (PP.) Finally, tonic-clonic seizures are frequently associated with memory loss around the events of the seizure.

First Aid for Seizures

A tonic-clonic seizure is difficult to witness. Friends and loved ones can become distressed, as there is little to do but let the seizure run its course. This is clearly evident in a video taken for diagnostic purposes, by the parents of a young boy who was experiencing a variety of seizure types including tonic-clonic seizures (graphic depiction of a seizure, with some off-colour language.)

The most important thing you can do to help a person having a tonic-clonic seizure is to remain calm. Remove hazards from the vicinity, and try to make note of when the seizure started so you can time its length. Do not try to move the person or hold them down, nor to put anything into their mouth: this can result in an injury. If you are able to remove glasses or to place something soft under the person's head, do so. It is unlikely you will be able to loosen tight clothing until after the convulsions stop, but you may be able to turn the person on their side.

During the seizure, the person may stop breathing or turn blue. This is normal, but not easy to watch. Do not attempt to initiate CPR. Breathing should start again during the clonic phase of the seizure, although it will be shallow. During the postictal phase there may be strange sounding, laboured breathing. Normal breathing should resume on its own as part of the recovery process.

Once the clonic phase is complete be sure the person remains on their side for a while, in order to open the airway and allow for safe drainage of any fluids from the mouth (saliva, vomit.) If there is blood coming from the mouth, do not be distressed. It is not uncommon for an epileptic person to bite their tongue, inner cheek or lip during a seizure.

Stay with the person and offer them reassurance. If the seizure has drawn a crowd, clear the area. A person recovering consciousness after a seizure doesn't want an audience. They will need understanding and reassurance. If they have lost bladder or bowel control, or have soiled their clothing with vomit or saliva, they will likely appreciate having a trusted person close by to help them get cleaned up. Do not be concerned if the person seems out of sorts or unable to speak for a brief period after they regain consciousness. If they are frightened or disoriented, stay with them and keep them away from hazards until they are back to normal.

The person may have a headache or generalized muscle pain after they return to consciousness. They may also be nauseous. The person should wait until they are fully alert before attempting to eat, drink or take any medication.

Call for medical assistance if this is the person's first convulsive seizure, if the seizure lasts more than five minutes, or if another seizure begins before the person has fully recovered. Also seek help if there is evidence of a head injury, any other serious injury or severe pain; if the seizure occurred in water or during pregnancy it is also important to see a doctor.

Disclaimer: The writer of this article is not a doctor. Data presented is gathered from research and personal experience, and is intended for information purposes only. Individuals with epilepsy, or parents who suspect their child might have photosensitive epilepsy, should seek advice from a neurologist or other competent medical practitioner.

Sources:

"First aid for seizures" Epilepsy Ontario

"Tonic, clonic, and tonic-clonic seizures" About Kids Health (Toronto Hospital for Sick Children)