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:
- Pattern of movement
- Origin within the body
An unusual electrical signal in the nervous system causes the movements. The electrical discharge may start in the:
- 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|
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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
You have an increased risk if you have family members who have had myoclonus.
You may also be at increased risk if you have:
Injuries or illness of the brain and spinal cord such as:
- Head or spinal cord trauma or injury
- Tumors of the brain or spinal cord
- Multiple sclerosis
- Parkinson disease
- Alzheimer disease
- Creutzfeldt-Jakob disease and other prion diseases
- Huntington disease
- Paraneoplastic syndromes—problems that happen in people with certain types of cancer
- Metabolic disorders, such as:
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.
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 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::
- 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.
National Institute of Neurological Disorders and Stroke http://www.ninds.nih.gov
WE MOVE http://www.wemove.org
Canadian Association of Neuroscience Nurses http://cann.ca
Health Canada https://www.canada.ca
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.
- Reviewer: EBSCO Medical Review Board Rimas Lukas, MD
- Review Date: 05/2018
- Update Date: 07/25/2018