MYOCLONUS

Symptoms, Causes, Tests & Diagnosis and Treatment & Drugs

Definition

Myoclonus refers to a quick, involuntary muscle jerk. For example, hiccups are a form of myoclonus. So are the sudden jerks, or "sleep starts," you may experience just before falling asleep. These forms of myoclonus occur in healthy people and rarely present a problem.

More severe types of myoclonus can be triggered by an underlying medical condition, such as a head injury or a reaction to a medication.

For effective treatment, you need to discover what's causing your myoclonus symptoms. If the cause of your myoclonus is chronic or unexplained, then treatment focuses on reducing the effects of myoclonus on your quality of life.

Symptoms

The muscle jerks associated with myoclonus are:

• Sudden
  
• Involuntary
  
• Shock-like
  
• Variable in intensity and frequency
  
• Often limited to one muscle, or initially limited to a group of muscles before spreading to other areas
  
• Sometimes severe enough to interfere with eating, talking or walking

When to see a doctor

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

Causes

Myoclonus may be caused by a variety of problems, including:

• Head or spinal cord injury or infections
  
• Strokes
  
• Brain tumors
  
• Kidney or liver failure
  
• Chemical or drug poisoning
  
• Prolonged oxygen deprivation
  
• Multiple sclerosis
  
• Epilepsy
  
• Parkinson's disease
  
• Alzheimer's disease
  
• Metabolic problems

Preparing for your appointment

You'll probably first discuss your concerns with your family doctor, who may decide to refer you to a neurologist. Because appointments can be brief, it's a good idea to come prepared to make the best use of the time allotted.

What you can do

• Write down a list of your symptoms, noting if there's anything that seems to trigger them or make them better.
  
• Take a list of all your medications, including any vitamins or supplements.
  
• Compile a list of questions for your doctor, asking about possible causes, treatments and prognosis.

What to expect from your doctor

Your doctor will ask you to describe your myoclonus symptoms in detail. He or she may also ask if you have a history of:

• Seizures
  
• Any other neurological problems
  
• Drug or chemical exposure
  
• Other medical problems
  
• Family members with a similar problem or epilepsy

Your doctor may try to provoke your myoclonus symptoms, so he or she can see how many muscle groups are involved and if there are any other neurological abnormalities that occur at the same time.

Tests and diagnosis

Determining the cause of myoclonus usually is a process of elimination. To rule out potential causes, your doctor may recommend the following types of tests:

Electroencephalogra phy (EEG)

This procedure records the electrical activity of your brain and may help determine from which part of the brain the myoclonus appears to originate. EEGs are painless and take less than an hour. Small electrodes are attached to your scalp with paste or an elastic cap. You may be asked to breathe deeply and steadily for several minutes or to stare at a patterned board. At times a light may be flashed in your eyes.

Electromyography (EMG)

This test measures the electrical discharges produced in muscles. Very fine wire electrodes are inserted into the muscles your doctor wants to study. This may be uncomfortable, but most people are able to complete the test. 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 determine if there's damage to the muscle or to the nerves leading to the muscle. The test takes at least an hour to complete.

MRI

This scan may be used to check for such things as structural problems or tumors inside your skull, which may be causing your myoclonus symptoms. MRIs use radio waves and a powerful magnet to produce detailed images of internal organs. The scan itself is noisy but painless, although some people experience claustrophobic feelings.

Laboratory tests

Your doctor may want to test your blood or urine for evidence of:

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

Treatments and drugs

Treatment of myoclonus is most effective when a reversible underlying cause can be found — such as a medication or toxin that can be discontinued or "flushed out" of your body. There are no drugs specifically designed to treat myoclonus, but doctors have borrowed from other disease treatment arsenals to relieve myoclonic symptoms.

Medications

Medications that doctors commonly prescribe for myoclonus include:

• Tranquilizers. Clonazepam (Klonopin) is the most common drug used to combat myoclonus symptoms.
  
• Anticonvulsants. Drugs used to control epileptic seizures have also proved helpful in reducing myoclonus symptoms. The most common anticonvulsants used for myoclonus are divalproex sodium (Depakote), primidone (Mysoline) and levetiracetam (Keppra).




• Immunosuppressants. These may be used to treat specialized forms of myoclonus that occur only in children. They may include adrenocorticotropic hormone (ACTH), azathioprine (Imuran), corticosteroids or immunoglobulin therapy (IVIg).

Therapies

Botulinum toxin type A (Botox) injections may be helpful in treating various forms of myoclonus, particularly if only a single area is affected. Botulinum toxins block the release of a chemical messenger that triggers muscle contractions.

Surgery

If your myoclonus symptoms are caused by a tumor or lesion in your brain or spinal cord, surgery may be an option.