Symptoms

People with myoclonus often describe the 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, 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 underlying problems. Doctors often separate the types of myoclonus based on their causes, which helps determine treatment. Types of myoclonus include the following categories.

Physiological myoclonus
This is the type that occurs in normal, healthy people and rarely needs treatment. Examples include:

• Hiccups
• Sleep starts
• Infant muscle twitching during sleep or after a feeding

Essential myoclonus
Essential myoclonus occurs on its own, typically without other symptoms and without being related to any underlying illness. The cause of essential myoclonus is often unexplained (idiopathic) or, in some cases, hereditary.

Epileptic myoclonus
This type of myoclonus occurs as part of an epileptic disorder. Muscle jerks may be the only symptom or one of many.

Symptomatic (secondary) myoclonus
This is a common form of myoclonus. Muscle jerks occur as a result of an underlying medical problem, such as:

• Head or spinal cord injury or infection
• Stroke
• Brain tumor
• Kidney or liver failure
• Chemical or drug poisoning
• Prolonged oxygen deprivation
• Medication reaction
• Huntington's disease
• Alzheimer's disease
• Parkinson'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, including what seems to trigger your symptoms and when or how they go away. 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:

Electroencephalography (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 and helps establish the pattern of myoclonus. 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.

Magnetic resonance imaging (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

Treatment 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. Most of the time, however, the underlying cause can't be cured or eliminated, so treatment is aimed at easing myoclonus symptoms, especially when they're disabling. 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 levetiracetam (Keppra), valproic acid (Depakene) and primidone (Mysoline).

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.

Deep brain stimulation has also been tried in some people with inherited disorders that are hard to treat.