Myoclonus

Medically Reviewed by Gabriela Pichardo, MD on May 11, 2022
Written by Stephanie Booth
4 min read

Myoclonus is sudden muscle spasms that you can’t control. They can be normal -- a hiccup or a "sleep start" when you’re falling asleep, for example -- or they may be a sign of a serious health condition such as multiple sclerosis, dementia, or Parkinson's disease. 

Myoclonus might include sudden jerking, quivering, or twitching. You can have one episode or many in a row. And they can last up to a few minutes.

The types of myoclonus include:

  • Action. It’s triggered by movement. It can affect your arms, legs, face, and voice.
  • Physiological. This type happens in people with no underlying health problems. It causes hiccups, twitches when you’re startled, and spasms when you’re just falling asleep or waking up.
  • Essential. The twitches or jerks are the only sign. It may become more severe over time. Sometimes, it runs in families.
  • Symptomatic (secondary). This is caused by another health condition, such as an infection, a stroke, a brain tumor, a lack of oxygen, or contact with a chemical or drug.
  • Stimulus-sensitive. This is triggered by things in the world around you like lights, noise, or movement.
  • Brainstem. A sudden noise or something you see might cause a grimace. Your elbows, knees, neck, and other parts of your body may flex.
  • Cortical reflex. Doctors think this is a kind of epilepsy. People who have it are prone to sudden jerk-like movements in their upper limbs and face.
  • Palatal. This is a tremor in the roof or soft palate of your mouth. It may involve your face, tongue, diaphragm, and throat. These muscle twitches come fast. You could have as many as 150 in a minute. Bursts of movement might happen while you sleep.
  • Reticular reflex. Twitching or jerking throughout your whole body can happen with this kind of myoclonus. Triggers include movements or something you see or hear.
  • Sleep. Your muscles spasm while you sleep. It mainly affects your lips, eyes, fingers, and toes.
  • Epileptic. This happens in people who have seizure disorders (epilepsy).
  • Progressive myoclonus epilepsy (PME). A kind of epileptic myoclonus, this is a group of diseases that usually start in children and teens. They tend to get worse over time.

Myoclonus spasms are:

  • Sudden
  • Brief
  • Uncontrolled
  • Shock-like
  • Varied in strength and time
  • In one part of your body or all over
  • Sometimes severe enough to get in the way of eating, speaking, or walking

Myoclonus happens because your nervous system isn't working the way it should. Something makes your nerve cells misfire and send the wrong signal to your muscles.

Doctors think several parts of your brain may be involved. But they aren't sure what causes this glitch in your nervous system. Sometimes, there’s no cause.

If you have multiple sclerosis (MS), it could result from lesions, or injuries, on your brain or spinal cord.

Other nervous system conditions that can cause myoclonus include:

Sometimes, the cause is a medical condition, such as:

  • Head or spinal cord injury
  • Infection
  • Kidney or liver failure
  • Opioid reaction
  • Stroke or heart attack that keeps your brain from getting oxygen
  • Metabolic disorders like high or low blood sugar or low levels of calcium or sodium

 

Your doctor will do an exam and note which parts of your body have spasms. They may recommend tests such as:

  • Electroencephalogram (EEG). This tracks and records the patterns of electrical activity in your brain to figure out where the myoclonus starts. The doctor will put small discs (called electrodes) on your scalp. They’ll connect them to wires that send signals to a computer.
  • Electromyography (EMG). This test checks the health of your muscles and the nerve cells that control them. It uses electrodes to sense and record the signals your nerves send to your muscles.
  • MRI. Your doctor will use this test to take detailed pictures of your brain, spinal cord, and other body parts that might be involved.

They may also check your blood for signs of other causes.

 

If another health condition is causing the spasms, your doctor will treat it.

Myoclonus itself can be hard to treat. Depending on your case, you may need to take several medicines at the same time. They act on different parts of your brain.

Treatment may include:

  • Benzodiazepines. Clonazepam (Klonopin) is often the first drug doctors use. It relaxes your muscles to keep them from twitching. Common side effects include feeling sleepy and being a bit clumsy. Because of that, your doctor will probably start with a very small dose. They’ll get bigger until your symptoms go away.
  • Anti-seizure drugs. Medicines like levetiracetam (Keppra), valproic acid (Valproic), and primidone (Mysoline) prevent seizures in people with epilepsy. But they can also help with myoclonus. Side effects include nausea, fatigue, and feeling dizzy.
  • 5-hydroxytryptophan (5-HTP). This is a building block of serotonin. Some studies have found that it helps people with certain forms of myoclonus.
  • Botox injections. The botulinum toxin "freezes" your muscles and keeps them from twitching. This may work best if myoclonus affects only one area of your body.
  • Surgery. You might need it to remove the brain or spinal cord lesion that's causing your symptoms.
  • Deep brain stimulation (DBS). In this surgical procedure, your doctor puts electrodes into your brain and uses wire to connect them with a device implanted in your chest. The device sends out signals that block the ones causing your myoclonus. DBS can lower the number of muscle twitches, but as with all surgeries, there are risks. Doctors are researching its use for MS. Right now, it’s mostly used as a treatment for Parkinson’s disease.

If you don’t have an underlying condition, myoclonus probably won’t be a problem in your daily life. More severe cases can cause trouble with movement, such as eating, talking, or walking. Your doctor will work with you to ease the spasms.

There’s no way to prevent myoclonus. But medical specialists might help you avoid injury from severe spasms.

Your doctor may recommend that you see a neuropsychiatrist. They can help you spot triggers and learn to manage movement problems.

Working with a physical therapist can improve your balance, strength, and coordination.