Definition

What is myoclonus?

Myoclonus describes a symptom and not a diagnosis of a disease. It refers to sudden, involuntary jerking of a muscle or group of muscles. Myoclonic twitches or jerks usually are caused by sudden muscle contractions, called positive myoclonus, or by muscle relaxation, called negative myoclonus. Myoclonic jerks may occur alone or in sequence, in a pattern or without pattern. They may occur infrequently or many times each minute. Myoclonus sometimes occurs in response to an external event or when a person attempts to make a movement. The twitching cannot be controlled by the person experiencing it.

In its simplest form, myoclonus consists of a muscle twitch followed by relaxation. A hiccup is an example of this type of myoclonus. Other familiar examples of myoclonus are the jerks or “sleep starts” that some people experience while drifting off to sleep. These simple forms of myoclonus occur in normal, healthy persons and cause no difficulties. When more widespread, myoclonus may involve persistent, shock-like contractions in a group of muscles. In some cases, myoclonus begins in one region of the body and spreads to muscles in other areas. More severe cases of myoclonus can distort movement and severely limit a person’s ability to eat, talk, or walk. These types of myoclonus may indicate an underlying disorder in the brain or nerves.

How common is myoclonus?

Please discuss with your doctor for further information.

Symptoms

What are the symptoms of myoclonus?

People with myoclonus often describe their signs and symptoms as jerks, shakes or spasms that are:

  • Sudden
  • Brief
  • Involuntary
  • Shock-like
  • Variable in intensity and frequency
  • Localized to one part of the body or all over the body
  • Sometimes severe enough to interfere with eating, speaking or walking

There may be some symptoms not listed above. If you have any concerns about a symptom, please consult your doctor.

When should I see my doctor?

If your myoclonus symptoms become frequent and persistent, talk to your doctor for further evaluation and proper diagnosis and treatment.

Causes

What causes myoclonus?

Myoclonus may develop in response to infection, head or spinal cord injury, stroke, brain tumors, kidney or liver failure, lipid storage disease, chemical or drug poisoning, or other disorders. Prolonged oxygen deprivation to the brain, called hypoxia, may result in posthypoxic myoclonus. Myoclonus can occur by itself, but most often it is one of several symptoms associated with a wide variety of nervous system disorders. For example, myoclonic jerking may develop in patients with multiple sclerosis, Parkinson’s disease, Alzheimer’s disease, or Creutzfeldt-Jakob disease. Myoclonic jerks commonly occur in persons with epilepsy, a disorder in which the electrical activity in the brain becomes disordered leading to seizures.

Risk factors

What increases my risk for myoclonus?

Please discuss with your doctor for further information.

Diagnosis & treatment

The information provided is not a substitute for any medical advice. ALWAYS consult with your doctor for more information.

How is myoclonus diagnosed?

To diagnose myoclonus, your doctor will review your medical history and symptoms and conduct a physical examination.

To determine the cause of myoclonus and rule out other potential causes of your condition, your doctor may recommend several tests, including:

Electroencephalography (EEG)

This procedure records the electrical activity of your brain and may help determine where in your brain the myoclonus originates. In this procedure, doctors attach small electrodes to your scalp. You may be asked to breathe deeply and steadily and look at bright lights or listen to sounds, as these actions may uncover abnormal electrical activity.

Electromyography (EMG)

This test measures the electrical discharges produced in muscles and helps establish the pattern of myoclonus. In this procedure, doctors put EMG surface electrodes on multiple muscles, especially on those muscles that are involved in the jerking.

An instrument records the electrical activity from your muscle at rest and as you contract the muscle, such as by bending your arm. These signals help to determine the pattern and origin of the myoclonus.

Magnetic resonance imaging (MRI)

An MRI scan may be used to check for structural problems or tumors inside your brain or spinal cord, which may cause your myoclonus symptoms. An MRI scan uses a magnetic field and radio waves to produce detailed images of your brain, spinal cord and other areas of your body.

Laboratory tests

Your doctor may suggest genetic testing to help identify possible causes of myoclonus. He or she may also test your blood or urine to check for:

  • Metabolic disorders
  • Autoimmune disease
  • Diabetes
  • Kidney or liver disease
  • Drugs or toxins

How is myoclonus treated?

Treatment of myoclonus focuses on medications that may help reduce symptoms. The drug of first choice to treat myoclonus, especially certain types of action myoclonus, is clonazepam, a type of tranquilizer. Dosages of clonazepam usually are increased gradually until the individual improves or side effects become harmful. Drowsiness and loss of coordination are common side effects. The beneficial effects of clonazepam may diminish over time if the individual develops a tolerance for the drug.

Many of the drugs used for myoclonus, such as barbiturates, levetiracetam,phenytoin, and primidone, are also used to treat epilepsy. Barbiturates slow down the central nervous system and cause tranquilizing or antiseizure effects. Phenytoin, levetiracetam, and primidone are effective antiepileptic drugs, although phenytoin can cause liver failure or have other harmful long-term effects in individuals with PME. Sodium valproate is an alternative therapy for myoclonus and can be used either alone or in combination with clonazepam. Although clonazepam and/or sodium valproate are effective in the majority of people with myoclonus, some people have adverse reactions to these drugs.

Some studies have shown that doses of 5-hydroxytryptophan (5-HTP), a building block of serotonin, leads to improvement in people with some types of action myoclonus and PME. However, other studies indicate that 5-HTP therapy is not effective in all people with myoclonus, and, in fact, may worsen the condition in some individuals. These differences in the effect of 5-HTP on individuals with myoclonus have not yet been explained, but they may offer important clues to underlying abnormalities in serotonin receptors.

The complex origins of myoclonus may require the use of multiple drugs for effective treatment. Although some drugs have a limited effect when used individually, they may have a greater effect when used with drugs that act on different pathways or mechanisms in the brain. By combining several of these drugs, scientists hope to achieve greater control of myoclonic symptoms. Some drugs currently being studied in different combinations include clonazepam, sodium valproate, levetiracetam, and primidone. Hormonal therapy also may improve responses to antimyoclonic drugs in some people.

Lifestyle changes & home remedies

What are some lifestyle changes or home remedies that can help me manage myoclonus?

Please discuss with your doctor for further information.

If you have any questions, please consult with your doctor to better understand the best solution for you.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Review Date: November 24, 2017 | Last Modified: November 24, 2017

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