Myoclonus

Definition

Myoclonus is a brief and rapid twitching of a muscle or group of muscles. The twitching happens quickly. It can’t be stopped or controlled.

There are many types of myoclonus. Some are normal, like the hiccups or moving while falling asleep. Other types are not normal. They are classified based on the:

  • Cause
  • Pattern of movement
  • Origin within the body

Causes    TOP

An unusual electrical signal in the nervous system causes the movements. The electrical discharge may start in the:

  • Brain
  • Spinal cord
  • Nerves in the body

The signal travels along the nerves to the muscle. There it causes a contraction of the muscles.

The Nervous System Pathways

CNS and PNS
Copyright © Nucleus Medical Media, Inc.

There are many different issues that may cause the unusual signal. It is often a symptom of a nervous system or metabolic problem. Possible causes are:

  • A lack of oxygen or nutrients
  • Certain medicines or toxins
  • Problems of the nervous system
  • Metabolic disorders
  • Damage to the brain or spinal column

Risk Factors    TOP

You have an increased risk if you have family members who have had myoclonus.

You may also be at increased risk if you have:

Symptoms    TOP

Symptoms can vary from person to person. Movements are often described as jerking, twitching, or spasm that:

  • Range from mild to severe
  • Occur every once in a while or often
  • Affect one area of the body or the entire body
  • Occur at rest or during other movements

Mild forms may be a twitch followed by release. Hiccups are one example of mild myoclonus. Moderate forms may cause shock-like spasm in muscle groups. Severe forms can then make it hard to eat, speak, or walk.

Diagnosis    TOP

You will be asked about your symptoms and health history. A physical exam will be done. Myoclonus is a symptom not a disease. The doctor can identify it with your description and an exam.

Tests may be done to look for a cause. Tests that may be done include:

Treatment    TOP

Treatment will focus on the cause. The cause may not be clear or may not be curable. In this case, steps may be taken to better manage symptoms.

Medicine may be needed to reduce twitching. Options include::

  • Sedatives
  • Anticonvulsants
  • Dietary supplements
  • Adrenocorticotropic hormone (ACTH)

You may need more than one type of medicine. They can have serious side effects. Work with your doctor to find the best balance of risks and benefits.

Some medicine can cause myoclonus. In this case your doctor will change the dose or stop the medicine. Talk to your doctor before stopping a medicine.

Prevention    TOP

Prevention will depend on the cause.

RESOURCES:

National Institute of Neurological Disorders and Stroke
http://www.ninds.nih.gov

CANADIAN RESOURCES:

Canadian Association of Neuroscience Nurses
http://cann.ca

References:

Dalmau J, Rosenfeld MR. Paraneoplastic syndromes of the CNS. Lancet Neurology. 2008;7:327-340.
Eberhardt O, Topka H. Myoclonic disorders. Brain Sci. 2017;7(8):E103.
Michaeil-Demo Y, Gavvala JR, Bellinski IL, et al. Clinical classification of post anoxic myoclonic status. Resuscitation. 2017;119:76-80.
Myoclonus and its disorders. Neurologic Clinics. August 2001.
Last reviewed June 2018 by EBSCO Medical Review Board Rimas Lukas, MD
Last Updated: 7/25/2018

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