Diagnosis

To diagnose myoclonus, your healthcare professional reviews your medical history and symptoms and gives you a physical exam.

You may have tests to look for the cause of your symptoms. Imaging tests or nerve tests also may be needed.

  • Laboratory tests. Blood or urine tests can check for metabolic conditions, autoimmune diseases, diabetes, and kidney or liver disease. They also can look for signs that toxins or medicines are the cause of your symptoms. Your healthcare professional also may recommend genetic testing.

  • Electroencephalography (EEG). This procedure records the electrical activity of the brain. It may help determine where in the brain your symptoms begin. Small metal discs called electrodes are attached to the scalp. You then may be asked to breathe deeply and steadily and look at bright lights or listen to sounds. These actions may help your healthcare professional find irregular electrical activity.
  • Electromyography (EMG). In this procedure, electrodes are placed on multiple muscles, especially muscles involved in the jerking movements. An instrument records the electrical activity from the muscles when they are at rest and when they are contracted, such as when you bend your arm. These signals help determine the pattern and origin of the myoclonus.
  • Evoked potential studies. These tests measure the electrical activity of the brain, brainstem and spinal cord that is triggered by touch, sound, sight and other stimuli.
  • Magnetic resonance imaging (MRI). An MRI scan may be used to check for structural changes or tumors inside the brain or spinal cord, which may cause myoclonus symptoms. An MRI scan uses a magnetic field and radio waves to produce detailed images of the brain, spinal cord and other areas of the body.

Treatment

Treatment of myoclonus works best if you can address the cause. For example, treatment may focus on another condition, a medicine or a toxin that is causing symptoms.

Most of the time, the cause can't be cured or eliminated. Treatment is aimed at reducing symptoms, especially when they're disabling. There are no medicines designed to treat myoclonus, but treatments for other diseases may help relieve your symptoms. More than one medicine may be needed.

Medicines

Medicines that healthcare professionals commonly prescribe for myoclonus include

  • Tranquilizers. Clonazepam (Klonopin) is the most common drug used to treat myoclonus symptoms. Clonazepam may cause side effects such as loss of coordination and drowsiness.

  • Antiseizure medicines. These medicines can help reduce myoclonus symptoms. The most common antiseizure medicines used are levetiracetam (Keppra, Spritam), valproic acid, zonisamide (Zonegran, Zonisade) and primidone (Mysoline). Piracetam is another medicine that's been found to be effective, but it's not available in the United States.

    Valproic acid may cause side effects such as nausea. Levetiracetam may cause fatigue and dizziness. Side effects from primidone may include sedation and nausea.

Therapies

OnabotulinumtoxinA (Botox) injections may help treat various forms of myoclonus, especially if only a single area is affected. This treatment blocks the release of a chemical messenger that triggers muscle contractions.

Surgery

If myoclonus symptoms are caused by a tumor in the brain or spinal cord, surgery may be an option. People with myoclonus affecting parts of the face or ear also may benefit from surgery.

Deep brain stimulation has been tried in some people with myoclonus and other movement disorders. Electrodes are implanted within certain areas of the brain. They produce electrical signals to block the irregular impulses that can cause myoclonus. Researchers continue to study deep brain stimulation for myoclonus.

Preparing for your appointment

You're likely to see your healthcare professional. Your health professional might then refer you to a specialist trained in nervous system conditions, called a neurologist.

Here's some information to help you get ready for your appointment and to know what to expect.

What you can do

  • Be aware of any pre-appointment restrictions, and ask if there's anything you need to do in advance.
  • Write down a list of your symptoms, noting if there's anything that seems to trigger them or make them better.
  • Make a list of all your medicines, including any vitamins or supplements, and doses.
  • Write down questions to ask your healthcare professional, including questions about possible causes and treatments.

Your time with your healthcare professional is limited, so preparing a list of questions ahead of time may help you make the most of your time together. For myoclonus, some basic questions to ask include:

  • What's the most likely cause of my symptoms? Are there other possible causes?
  • What kinds of tests do I need?
  • Is my condition likely short term or long lasting?
  • What is the best course of action?
  • What are the alternatives to the primary approach that you're suggesting?
  • I have other health conditions. How can I best manage them together?
  • Are there any restrictions that I need to follow?
  • Are there any brochures or other printed material that I can take home with me? What websites do you recommend visiting?

In addition to the questions that you've prepared, don't hesitate to ask questions during your appointment at any time that you don't understand something.

What to expect from your doctor

Your healthcare professional is likely to ask you a number of questions. You might be asked:

  • When did you first start having symptoms?
  • Do you have a history of seizures or other nervous system conditions?
  • What medicines do you take?
  • Have you taken illegal drugs or been exposed to chemicals?
  • Do you have a family history of myoclonus or epilepsy?
  • Have your symptoms been constant or do they come and go?
  • How bad are your symptoms?
  • Does anything improve your symptoms?
  • What, if anything, appears to worsen your symptoms?
By Mayo Clinic Staff