An Overview of Convulsions

How Convulsions, Seizures, and Epilepsy Differ

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A convulsion is a medical condition characterized by erratic movements in which muscles involuntarily contract and spasm. A convulsion can be caused by any number of medical conditions, including epilepsy, a head injury, severe fever, an inflammatory brain infection, and certain medications.

Although the words convulsion and seizure are often used interchangeably, a seizure refers to an electrical disturbance in the brain, while a convulsion simply describes the violent jerks and contractions that a person cannot control

it is possible, for example, to have an epileptic seizure without convulsions. It is also possible to have convulsions in the absence of epilepsy. A convulsive episode should not inherently suggest that epilepsy is the cause.

If you or someone you know experiences a convulsion, it is important to seek a diagnosis from an appropriate specialist (which may include a neurologist, pharmacologist, or infectious disease specialist). The treatment of convulsions is based on the underlying cause.


Convulsions are generally quite noticeable. They may involve the whole body or be limited to a certain part, such as an arm or a leg. Convulsions may be brief in duration, lasting for only a few seconds, or continue for a long period of time, increasing the risk injury or trauma.

Convulsions can vary by the underlying cause and the part of the brain being affected. Among some of the possible features of a convulsion are:

  • Involuntary spasms or jerking
  • Sudden shaking of the entire body
  • Whole-body rigidity
  • A clenched jaw
  • Impairment of consciousness
  • Confusion
  • Drooling
  • Loss of bowel or bladder control
  • Gagging or gaps in breathing
  • A brief blackout

A convulsion should not be confused with tremors in which there is uncontrollable trembling caused by everything from Parkinson's disease to drinking too much caffeine.

Tonic-Clonic Seizures

The most common type of convulsion is a tonic-clonic seizure (sometimes referred to as a generalized convulsion). Unlike some forms of convulsion, a tonic-clonic seizure is characterized by the loss of consciousness leading to physical collapse. Body rigidity, jerking, and the loss of bladder control are common features.

A tonic-clonic seizure can occur as a feature of epilepsy but is not synonymous with epilepsy. By definition, a seizure is a single event, while epilepsy is a neurological condition characterized by two or more seizures.

There are some forms of epilepsy that cause only minor twitches or changes in sensation or consciousness, including absence seizures and simple focal seizures.


Although the possible causes of convulsions are extensive and varied, they are ultimately characterized by the misfiring of nerve cells (neurons) in the brain.

A convulsion occurs when there is a sudden and severe imbalance between the excitatory and inhibitory forces in the brain that either speed or slow the transmission of electrical signals between nerve cells.

If, for any reason. the excitatory forces are abnormally amplified or the inhibitory forces are impeded, the nerve signals can fire chaotically and cause convulsions. Where the misfiring of signals occurs in the brain will ultimately determine how extensive or severe the convulsion will be.

The causes of convulsion are many, some of which are related to a genetic abnormality and other of which are acquired. Neurotoxic substances, including those produced in response to disease and certain drugs, can also cause convulsions.

Among some of the possible causes of an isolated convulsion are:


The first steps in the diagnosis of convulsion are a review of your medical history and symptoms followed by a physical exam. Given that convulsions are the result of abnormal brain activity, the diagnostic focus will be placed on the neurological causes or conditions that can trigger abnormal brain activity.

Neurological Exam

As part of the diagnostic workup, your doctor will perform a neurological exam. This is a series of in-office tests to assess your mental status, motor function, balance, coordination, reflexes, and sensory responses.

A neurological exam does not cause any pain and only involves instruments like a penlight or reflex hammer. Based on your responses, your doctor will have a better idea if the cause is neurologic (related to the central nervous system).

Electroencephalogram (EEG)

If a neurologic disorder is suspected, the doctor will likely order a painless, non-invasive procedure known as an electroencephalogram (EEG). This involves the connection of electrodes to the head to measure electrical brain activity. In some cases, an EEG may require an overnight stay in order to "catch" a convulsive episode when it occurs.

Certain abnormal brain patterns may be highly suggestive of epilepsy, a brain injury, brain tumor, or other neurologic disorders. These insights can help the doctor decide which tests are needed to confirm the suspicions.

Blood and Lab Tests

Blood tests may be ordered to check for signs of infection, electrolyte imbalances, and generalized markers of inflammation. A drug toxicology report may also be ordered.

If epilepsy is suspected, the doctor will order a blood test that measures the amount of the hormone prolactin in the blood. This can help determine whether the convulsive episodes were caused by epilepsy or another disorder.

In meningitis is suspected, the doctor may order a lumbar puncture in which a needle is inserted into the lower spine to extract a sample of fluid. An evaluation of the fluid in the lab can detect if there an infection is involved.

Imaging Studies

Imaging studies may be ordered to check for evidence of brain lesions or tumors as well as signs of bleeding, clots, or subdural effusion (an abnormal accumulation of fluid in the skull). The choice of study depends on the suspected cause and may include:

Differential Diagnoses

In addition to exploring the possible causes of convulsions, the doctor may also want to exclude causes in which convulsion are not inherently linked to neurological dysfunction. This is especially important if it is a first convulsive episode. Examples include:


The treatment of a convulsive episode is based on the underlying cause. If the convulsion is an isolated event⁠—such as that caused by an infection, head injury, or a diabetic crisis—the appropriate treatment would be dispensed based on the findings. Hospitalization may be required. In some cases, the problem can be resolved during a single visit; others may require ongoing and extensive care.

If medications are to blame, a change of treatment or adjustment of dose may be enough to prevent future episodes. Substance abusers would typically require substance abuse treatment.

Epilepsy is typically treated with anti-epileptic drugs (AEDs) such as Topamax (topiramate), Tegretol (carbamazepine), and Lamictal (lamotrigine). A ketogenic diet, responsive neurostimulation (involving an electrical implant in the brain), and surgery (such as a subpial transection) may be also be involved.

Because the causes of a convulsion are so varied, the treatment will initially be focused on stabilizing the individual even before the cause of the convulsion is identified. It only after the person has been stabilized that the process of diagnosis and treatment can begin.

What to Do in an Emergency

If you witness a seizure, the first thing to do is ensure the person is not in harm's way. Call 911, and try to keep others from crowding around the fallen individual. If there are any sharp or hard objects around, remove them to prevent injury.

Do not place anything in the person's mouth or try to hold them down if they are having a seizure. Instead, turn them gently on the side to keep the airways clear and avoid suffocation if there is vomiting.

If possible, try to keep track of the time so that you can tell the emergency medical team how long the seizure lasted. The more information you can provide⁠—including drugs that may have been taken or symptoms that occurred beforehand⁠—the sooner the medical team will find the cause and deliver the appropriate treatment.

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