Tonic-clonic convulsions

Tonic-clonic convulsions

Description, Causes and Risk Factors:

A convulsions is a short episode of symptoms caused by a burst of abnormal electrical activity in the brain. Typically, a convulsions lasts from a few seconds to a few minutes.

The brain contains millions of nerve cells (neurons). Normally, the nerve cells are constantly sending tiny electrical messages down nerves to all parts of the body. Different parts of the brain control different parts and functions of the body. Therefore, the symptoms that occur during a tonic-clonic convulsions depend on where the abnormal burst of electrical activity occurs.

There are different types of convulsions but they are broadly divided into two main types - generalised and partial: A tonic-clonic convulsions is the most common type of generalised convulsions. Your body becomes rigid due to strong muscular contractions (the tonic part). You lose consciousness and fall. Your chest muscles contract and force air out of your mouth, often with a grunt. Your jaw muscles contract and you may bite your tongue. Saliva may escape from your mouth. Your bladder may contract and you may pass urine. This stiff or tonic phase soon passes into the clonic (shaking or convulsive) phase. This is when the muscles repeatedly contract and relax. Your whole body appears to shake. This may last from a few seconds to a few minutes.

When the convulsions has stopped, you gradually regain consciousness, but you may be confused and dazed for a while. The time taken to recover varies. You may have some soreness due to the muscular contractions. You may have a headache and want to sleep after a convulsions.

Tonic-clonic convulsions occur when the electrical activity over the whole surface of the brain becomes abnormally synchronized. In general, convulsions are caused by abnormal, rhythmic nerve cell (neuron) activity in the brain. The brain's nerve cells normally communicate with each other by sending electrical and chemical signals across the synapses that connect the cells. In people who have convulsions, the brain's usual electrical activity is altered.

Exactly what causes the changes to occur remains unknown in about half the cases. However, tonic-clonic convulsions are sometimes caused by underlying health problems, such as:

    Very low blood levels of glucose, sodium, calcium or magnesium.

  • Traumatic head injuries.

  • Using or withdrawing from drugs, including alcohol.

  • Brain tumors.

  • Strokes.

  • Infections, such as encephalitis or meningitis, or history of such infection.

  • Injury due to a previous lack of oxygen.

  • Blood vessel malformations in the brain.

  • Genetic syndromes.

Risk factors for tonic-clonic convulsions include:

    A family history of seizure disorders.

  • Any injury to the brain from trauma, stroke, previous infection and other causes.

  • Sleep deprivation.

  • Medical problems that affect electrolyte balance.

  • Illicit drug use.

  • Heavy alcohol use.


The following signs and symptoms occur in some but not all people with tonic-clonic convulsions:

    Aura. Some people experience a warning feeling (aura) before a Tonic-clonic convulsions. This warning varies from person to person, but may include feeling a sense of unexplained dread, a strange smell or a feeling of numbness.

  • A scream. Some people may cry out at the beginning of a seizure because the muscles around the vocal cords seize, forcing air out.

  • Unresponsiveness after convulsions. Unconsciousness may persist for several minutes after the convulsion has ended.

  • Loss of bowel and bladder control. This may happen during or following a seizure.

  • Confusion. A period of disorientation often follows a tonic-clonic convulsion. This is referred to as postictal confusion.

  • Fatigue. Sleepiness is common after a grand mal seizure.

  • Severe headache. Headaches are common but not universal after grand mal seizures.


You should see a doctor if you have had a possible tonic-clonic convulsions or similar event. Sometimes it is difficult for a doctor to confirm that you have had a tonic-clonic convulsion. The most important part of confirming the diagnosis is the description of what happened. Other conditions can look like tonic-clonic convulsions - for example, faints, panic attacks, collapses due to heart problems, breath-holding attacks in children, and some other problems.

Therefore, it is important that a doctor should have a clear description of what happened during the event. Preferably this is from the person affected, and also from an eyewitness. The description may be typical of a tonic-clonic convulsion. However, sometimes it is difficult for a doctor to confirm the diagnosis definitely.

Tests may include:

    A brain scan - usually a magnetic resonance imaging (MRI) or computed tomography (CT) scan - can show the structure of different parts of the brain. A brain scan is not always necessary.

  • EEG (electroencephalogram). This test records the electrical activity of the brain. Special stickers are placed on various parts of the scalp. They are connected to the EEG machine. This amplifies the tiny electrical messages given off by the brain, and records their pattern on paper or computer. The test is painless. Some types of seizure produce typical EEG patterns. However, a normal recording does not rule out epilepsy, and not all EEG abnormalities are related to epilepsy.

  • Blood tests and other tests may be advised to check on your general well-being. They may also look for other possible causes of the event.


Not everyone who has one seizure will have another one, and because a seizure can be an isolated incident, your doctor may decide to not start treatment until you have had more than one. Treatment usually involves the use of anti-seizure medications. Finding the right medication and dosage can be challenging. Your doctor likely will first prescribe a single drug at a relatively low dosage, and then increase the dosage gradually until your seizures are well controlled. Many people with epilepsy are able to prevent seizures by taking only one drug, but others require more than one. To achieve the best seizure control possible, take medications exactly as prescribed. Always call your doctor before adding other prescription medications, over-the-counter drugs or herbal remedies. And never stop taking your medication without talking to your doctor.

NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.


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