Patient education: Myoclonus (The Basics)

What is myoclonus? — Myoclonus is the medical term for short, jerking movements that a person cannot control. When people have myoclonus, their muscles jerk, twitch, spasm, or shake.

Myoclonus can affect different parts of the body. It can affect the whole body at once, or just 1 part, such as a leg or arm.

What causes myoclonus? — Some myoclonus is normal in healthy people. For example, many people have a sudden muscle twitch or jerk when they are falling asleep. This is more common when the person hasn't gotten enough sleep recently. Sometimes, the whole body jerks. Movements or twitches that happen during sleep can also be myoclonus.

Myoclonus can be caused by:

●A disease that damages the brain and nervous system, often one that starts in childhood or runs in families

●An injury or condition that kept the brain from getting enough oxygen for too long

●Epilepsy

●Diseases that affect certain organs or glands in the body – These include liver failure, kidney failure, and overactive thyroid.

●A bad reaction to medicines or chemicals

●A condition called "essential myoclonus" – In this condition, myoclonus is the most obvious symptom or the only symptom.

Should I see a doctor or nurse? — Yes. See a doctor or nurse if you start having muscle spasms or twitches you cannot control.

If you have epilepsy and your seizures change or get worse, see your doctor or nurse.

Will I need tests? — Maybe. Your doctor or nurse will talk with you and do an exam. They will decide which tests you should have based on your age, other symptoms, and situation. There are lots of tests, but you might not need any.

The most common tests for myoclonus are:

●Blood and urine tests

●EEG – This test measures electrical activity in the brain and records brain wave patterns.

●Brain or spine imaging tests – These tests create pictures of the inside of the body. These tests include CT scans and MRIs.

●Lumbar puncture (also called a "spinal tap") – For this test, a doctor puts a thin needle in the lower back and removes a small amount of spinal fluid. Spinal fluid is the fluid around the brain and spinal cord. Another doctor will do lab tests on the spinal fluid.

●EMG – This test measures electrical activity in the muscles. It shows whether the muscles are responding the right way to electrical signals.

How is myoclonus treated? — Treatment depends on what is causing the myoclonus. If it is caused by a condition doctors can cure, such as a disease or tumor, doctors will treat that condition. This can make myoclonus get better or go away.

But myoclonus is often caused by conditions that doctors cannot cure. This can make it very hard or impossible to get rid of myoclonus.

Doctors can try different treatments. These help some people feel better. In general, these treatments work by blocking or calming the nerve signals that make the muscles jerk or twitch. Treatments include medicines normally used to control seizures and shots of a medicine called "botulinum toxin."

What if my child gets myoclonus? — If your baby or child starts having muscle twitches or spasms, take them to see a doctor or nurse. If your child has epilepsy and the seizures get worse or change, talk to their doctor.

Some children get a type of myoclonus that can run in families. It is not usually serious. Children with this condition just have myoclonus, not another problem that is causing myoclonus. For them, the muscle jerks and spasms usually start around age 4 to 8 years, but the symptoms can start later.

More on this topic

Patient education: Seizures (The Basics)
Patient education: Epilepsy in adults (The Basics)
Patient education: Tremor (The Basics)

Patient education: Seizures in adults (Beyond the Basics)
Patient education: Seizures in children (Beyond the Basics)
Patient education: Tremor (Beyond the Basics)