Tonic Clonic Seizure Symptoms, Causes, and Diagnosis

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A tonic clonic seizure often referred to as a grand mal seizure, is a type of seizure that involves uncontrolled jerking and stiffness of the arms, legs, or body. It generally lasts for a few seconds and often involves loss of consciousness or unawareness of the event.


If you or someone you know experiences a tonic clonic seizure, it can be recognized by the jerking movements. A seizure that is characterized by stiffening and jerking of the arms or legs is described as tonic-clonic.

Symptoms of tonic clonic seizures can include any combination of the following:

  • An unusual sensation prior to the seizure often described as an aura
  • Jerking and stiffening of one or more extremities
  • Drooling
  • Urinary or fecal incontinence
  • Tongue biting
  • Falling down
  • Screams, grunts or sounds
  • Eye movements or eye jerking
  • After a seizure, you may experience confusion, sleepiness, and inability to recall the event

You may not be aware if you are having a tonic clonic seizure if you also have impairment of consciousness along with the physical movements. A tonic clonic seizure can be described as a partial seizure or a generalized seizure.

Partial Seizure

You may be completely alert during a partial seizure, although usually, a partial seizure is characterized by a decrease in the level of consciousness or awareness.

Generalized Seizure

A generalized seizure always causes a loss of consciousness, which means a lack of alertness and awareness. During a generalized seizure, a person is typically unable to respond or maintain control. Sometimes a generalized seizure can cause someone to fall to the ground. And often, a person who has had a generalized seizure cannot recall all or some details of the event.


There are a number of medical problems can cause a person to experience tonic clonic seizures.

Causes of tonic clonic seizures:

  • Epilepsy: The most common cause is epilepsy, a medical condition characterized by recurrent seizures. A person may be born with epilepsy, or it may develop later in life as a result of brain damage.
  • Brain injury: Other medical problems that can cause a tonic clonic seizure to include head trauma, brain injury, strokes, aneurysms, brain tumors, and brain infections. The seizures triggered by these conditions can be temporary, or these problems can cause long term epilepsy.
  • Medical reactions: Certain medications, severe illnesses, electrolyte abnormalities, organ failure, high fevers, and severe infections can cause tonic clonic seizures. Generally, the seizures should improve once the illness resolves.
  • Drugs: Drug or alcohol overdose, or withdrawal can cause disturbances in brain activity that cause tonic clonic seizures.

Why Tonic Clonic Seizures Happen

When the brain is injured, the electrical activity that normally controls brain function may become disturbed or erratic, and may 'fire' when it shouldn't, resulting in unwanted physical actions, which often manifest as a tonic clonic seizure. Generally, a tonic clonic seizure causes jerking and stiffness in the region of the body that is controlled by the injured area of the brain.

If the abnormal brain activity involves a small region of the brain, this can manifest as a partial seizure, while abnormal electrical activity involving the whole brain manifests as a generalized seizure.


A tonic clonic seizure is often diagnosed based on the clinical manifestations. Diagnostic testing such as electroencephalogram (EEG) and brain imaging may also help in the diagnosis and treatment plan.

Seizure diagnosis is based on:

  • Description: If you have had a tonic clonic seizure, you may recall how you felt immediately prior to the seizure, and you may recall some parts of the seizure itself. If anyone else was around, a description of the event is helpful.
  • EEG: An EEG is a test that detects brain waves. If you have had a seizure or if you are prone to seizures, your EEG may show an area or several areas of erratic electrical brain activity. An EEG is particularly helpful if you have a seizure during your EEG which correlates with the electrical abnormality.
  • Sleep deprived EEG: Sometimes, an EEG does not show electrical abnormalities when you are well rested, and you may need a sleep deprived EEG. Sleep deprived EEG is done when you have been awake for a prolonged period of time, which induces a metabolic state that can trigger a seizure and makes your EEG more likely to show electrical abnormalities.
  • Brain imaging: A brain CT or MRI does not show seizures, but it can identify abnormalities that can cause tonic clonic seizures, such as a brain tumor, a stroke, an abscess, or an abnormal blood vessel in the brain.

    Treatment and Prevention

    Tonic clonic seizure treatment is primarily focused on prevention, and it is rare that a tonic clonic seizure needs to be treated while it is occurring.

    Status Epilepticus

    If you have a prolonged tonic clonic seizure lasting for five minutes or longer, this is diagnosed as status epilepticus, a medical emergency that can cause brain damage or even death. The treatment of status epilepticus typically includes injection of powerful and fast acting anti-seizure medications to stop the seizure. Medications used for treatment of status epilepticus include IV lorazepam, IV diazepam, and IV midazolam.

    Avoiding Triggers

    There are a variety of ways to effectively prevent seizures. If you have a certain trigger, such as alcohol, drugs, or medications, then controlling the use of that substance is by far the safest way to prevent a seizure.


    Most people who are prone to recurrent tonic clonic seizures could experience a seizure due to a fever, infection, sleepiness or even without any known trigger. Anti-seizure medications also referred to as anticonvulsants, are often recommended to prevent or reduce recurrent seizures.

    Common anti-seizure medications used for treatment of tonic clonic seizures include:

    • Tegretol, Carbatrol (carbamazepine)
    • Keppra (levetiracetam)
    • Dilantin (phenytoin)
    • Depakote (valproic acid)
    • Neurontin (gabapentin)
    • Phenobarbital
    • Topamax (topiramate)
    • Gabitril (tiagabine)
    • Fycompa (perampanel)

    A Word From Verywell

    If you or a loved one has experienced a tonic clonic seizure, there is a high likelihood that you will achieve reduced seizures once the cause is found and anticonvulsant medication is started. Most people who have epilepsy can achieve the optimal outcome and a good quality of life.

    However, living with tonic clonic seizures can be stressful. It is helpful to learn as much as you can about your condition and to try to learn what your triggers are and to learn to recognize whether you experience a pre-seizure aura.

    Tonic clonic seizures may also cause embarrassment or problems at school or work. If you can learn how to explain your illness to people who are important in your life, this can help prevent fear and misunderstandings and can provide you with support from friends.

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