What Is a Convulsion?
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Medically reviewed by Diana Apetauerova, MD
A convulsion is a medical event in which nerve cell activity in the brain is disrupted, causing muscles to involuntarily contract and spasm. This results in sudden, violent, and irregular movements of the body. A convulsion is not the same thing as a seizure, but it can be a symptom of different types of seizures.
Convulsion may be associated with any number of medical conditions, including epilepsy, a head injury, severe fever, an inflammatory brain infection, exposure to toxins, and certain medications. It often requires a doctor such as a neurologist or infectious disease specialist to determine the reason it has occurred. Once a cause has been diagnosed, the appropriate treatment can follow.
This article discusses the different types of convulsions, their symptoms, and their causes. It also explores how convulsions are diagnosed and treated.
Seizures That Cause Convulsions
A convulsion is a general term used to describe uncontrollable muscle contractions. Though the possible causes of convulsions are extensive, they ultimately are characterized by the misfiring of nerve cells (neurons) in the brain.
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.
Convulsions are a major symptom of some types of seizures. Neurotoxic substances, including those produced in response to disease and certain drugs, also can cause convulsions.
Epileptic Seizure
Epileptic seizures are characterized by electrical disturbances in the brain. Not all are associated with convulsions; those that are include:
Generalized tonic-clonic seizures: Also known as grand mal seizures, characterized by stiffening during the tonic phase and violent jerking during the clonic phase
Myoclonic seizures: Characterized by sporadic and brief jerking, typically on both sides of the body
Tonic seizures: Only involve stiffening
Clonic seizures: Only involve jerking and spasms
Atonic seizures: Often start with a myoclonic disease before muscle control is abruptly lost
Simple partial seizures: Can sometimes cause jerking, stiffening, muscle rigidity, spasms, and head-turning
Partial seizures with secondary generalization: Often are accompanied by tonic-clonic seizures
Related: Guide to Anti-Epileptic Drugs
Febrile Seizure
Febrile seizures are brought on by a high fever. They're most common in children between 6 months and 5 years, tend to occur on the first day of fever, and last for only a few minutes. Symptoms include severe shaking, stiffening, and, on occasion, sudden loss of consciousness.
Takeaway
Although frightening, a febrile seizure usually is harmless. However, emergency care should be sought if a febrile seizure lasts for longer than 10 minutes or occurs repeatedly.
Related: Why Febrile Seizures Occur
Non-Epileptic Seizure
Non-epileptic seizures belong to a broad category of conditions that are not caused by electrical disturbances in the brain. Some may be psychogenic (meaning they have psychological origins).
Others may occur as a result of an infection that causes the swelling in the brain and the release of toxins that disrupt electrical signals. Brain injuries can also disrupt electrical activity and not be considered epilepsy if there is only one event.
Among causes of non-epileptic seizures are:
Brain trauma
Encephalitis (inflammation of the brain)
Meningitis (inflammation of the membrane surrounding the brain and spinal cord)
Sepsis (the body’s extreme response to an infection)
Brain tumor
Stroke
Diabetic ketoacidosis
Heatstroke
Severe electrolyte imbalance (often seen in people with kidney disease)
Acute kidney failure
Pediatric celiac disease
Related: Overview of Pseudoseizures
Medication-Induced
Seizures may be induced by drugs that cause a sudden rise in chemicals that overstimulate the brain or a sudden drop in chemicals meant to regulate electrical brain activity.
Antidepressants such as Wellbutrin (bupropion) and Remeron (mirtazapine), stimulants (cocaine, methamphetamine), Benadryl (diphenhydramine), tramadol (a painkiller sold under the brand name ConZip and others), and isoniazid (an antibiotic) account for most medication-induced convulsions.
Drug overdose, alcohol poisoning, and drug withdrawal from barbiturates, benzodiazepines, alcohol, or glucocorticoids also can cause convulsions and seizures, sometimes severe.
Related: Causes and Prevention of Seizures
Symptoms
It usually is obvious when someone is experiencing a convulsion. An episode may involve the whole body or be limited to a certain part, such as an arm or a leg. It may be brief, lasting for only a few seconds, or continue for a long period of time, increasing the risk injury.
That said, what a convulsion looks like typically depends on what is causing it and and the part of the brain affected. Among the possible features of a convulsion are:
Involuntary spasms or jerking
Sudden shaking of the entire body
Whole-body rigidity
A clenched jaw
Confusion
Drooling
Loss of bowel or bladder control
Gagging or gaps in breathing
Near or total loss of consciousness or a brief blackout
Takeaway
Convulsions should not be confused with tremors, which are defined as uncontrollable trembling that may be caused by anything from drinking too much caffeine to Parkinson's disease.
Seizure vs. Convulsion
The words convulsion and seizure often are used interchangeably, but physiologically they are different events. A seizure occurs due to an electrical disturbance in the brain, while a convulsion describes the involuntary action of jerking and contraction.
It is possible, for example, to have an epileptic seizure without convulsions. It also is possible to have convulsions in the absence of epilepsy. In other words, a convulsive episode is not a definitive indication of epilepsy.
Related: Epilepsy Symptoms and Complications
Diagnosis
To diagnose the cause of a convulsion, a doctor will first take a medical history and consider any other symptoms a person has, followed by a physical examination. This likely will be followed by a focus on potential neurological causes or conditions that can trigger abnormal brain activity.
Neurological Exam
A neurological examination is a series of in-office tests to assess mental status, motor function, balance, coordination, reflexes, and sensory responses. It typically involves instruments like a penlight or reflex hammer and is not painful.
A neurological workup can help a doctor determine if a convulsion occurred because of an issue with the central nervous system.
Electroencephalogram (EEG)
If a neurologic disorder is suspected, the doctor will likely order an electroencephalogram (EEG), a non-invasive test in which electrodes attached to the head measure electrical brain activity.
In some cases, an EEG may require an overnight hospital stay in order to "catch" a convulsive episode when it occurs. Certain abnormal brain patterns may be suggestive of epilepsy, a brain injury, brain tumor, or other neurologic disorders.
Related: What Is an EEG Used For?
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.
Takeaway
If epilepsy is suspected, the doctor will order a blood test that measures the amount of the hormone prolactin. This can help determine whether the convulsive episodes were caused by epilepsy or another disorder.
If 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 can 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:
Computerized tomography (CT): Uses X-ray to obtain cross-sectional images of the brain.
Magnetic resonance imaging (MRI): Uses powerful magnets and radio waves to create a detailed image of the brain.
Positron emission tomography (PET): Low-dose radioactive materials are injected into a vein to detect metabolic abnormalities suggestive of cancer.
Differential Diagnoses
A doctor may also want to exclude causes in which convulsion is not inherently linked to neurological dysfunction, especially important if it is a first convulsive episode. Examples include:
Tourette's syndrome
Myoclonic jerks (a sudden muscle jerk not related to disease)
Migraine
Panic attack
Psychotic episodes
Restless leg syndrome
Early-onset Alzheimer's disease
Acute dystonic reactions (a drug side effect related to certain antipsychotic drugs)
Aging-related dementia
Treatment
Initial treatment of a convulsion typically will focus on stabilizing the individual even before the cause of the convulsion is identified. After that they can be diagnosed and treated accordingly, based on the underlying cause.
If that turns out to be an infection, head injury, or a diabetic crisis, for example, the appropriate treatment would be dispensed based on that finding. 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. If a person has a convulsion in response to illicit drug use, they'll likely benefit from substance abuse treatment.
Epilepsy typically is treated with anti-epileptic drugs (AEDs) such as Topamax (topiramate), Tegretol (carbamazepine), Lamictal (lamotrigine), or Dilantin (phenytoin). A ketogenic diet, responsive neurostimulation (involving an electrical implant in the brain), and surgery (such as a subpial transection) may also be part of the protocol.
Related: Risks and Complications of Seizures
What to Do if Someone Has a Convulsion
Most seizures are not emergencies. If you witness a seizure, first make sure the person is not in harm's way. If there are sharp or hard objects around, for example, remove them. Keep other people from crowding around.
You can help support the person having a seizure by remaining calm and staying with them until they regain consciousness.
Afterwards, help get them to a safe place and explain what happened. Make sure the person has a safe way to get home.
Takeaway
Do not place anything in the mouth of a person having a seizure or try to hold them down. Instead, turn them gently on one side to keep the airways clear and avoid suffocation if there is vomiting.
Related: First Aid for Epilepsy Seizures
When Is it an Emergency?
Call 911 if:
This is the person's first seizure
The seizure lasts longer than 5 minutes
The person has a second seizure after recovering from the first
The person injures themselves during the seizure
The person is in water when they have the seizure
The person has a medical condition such as diabetes or is pregnant
The person has trouble breathing
The person won't wake up after the seizure has ended
If possible, keep track of the time so that you can tell the emergency medical team how long the seizure lasted. The more details you can provide, such as drugs that may have been taken or symptoms that occurred beforehand, can help the medical team figure out the cause of a convulsive episode and determine how to treat it.
Summary
As alarming as a convulsion is, it can ultimately be caused by any number of things, some of which may not be serious. As a symptom of a condition (rather than a condition until itself), convulsions often resolve once the underlying cause is identified and treated. This is why you should never ignore a convulsion, even if it is relatively mild.
In some cases, a convulsion may be the sign of an as-of-yet undiagnosed condition or caused by a drug treatment that can be adjusted or stopped. If epilepsy is involved, early diagnosis can ensure you get the appropriate treatment to better prevent future episodes.
