What Is Myoclonus?
Myoclonus (pronounced "my-OCK-lo-nus") is a sudden muscle spasm that you can’t control. It can be a natural reflex – like jumping when something scares you or getting the hiccups from laughing too hard. But sometimes, it can be a sign of a nervous system condition such as multiple sclerosis, dementia, or Parkinson's disease.
Myoclonus can include sudden jerking, quivering, or twitching. You can have one episode or many in a row. And it can be over in seconds or last up to a few minutes.
Types of Myoclonus
The different kinds of myoclonus include:
Physiological myoclonus
This type happens in people with no other health problems. Hiccups are one example. Another are twitches when you’re startled.
Sleep myoclonus
As you fall asleep, your muscles, especially in your legs, can twitch. You might also feel like you're falling and trying to catch yourself. Also known as hypnic jerks, these are considered a normal type of myoclonus. They're usually not a cause for concern as long as they don't happen often or interfere with your sleep.
You might notice that hypnic jerks happen more often when you're feeling stressed.
Essential myoclonus
If you have this kind, twitches or jerks are the only sign. They usually don't become more severe over time. Sometimes, essential myoclonus runs in families.
Symptomatic (secondary) myoclonus
Sometimes, myoclonus is caused by another health condition, such as an infection, a stroke, or a brain tumor. It can also be caused because of a prescription drug or other substance, like alcohol or cocaine, that's in your system.
Stimulus-sensitive myoclonus
Sometimes, sudden muscle spasms can be triggered by things in the world around you like lights, noise, or movement. Feeling surprised might make this type of myoclonus more likely.
Cortical reflex myoclonus
Doctors think this is a kind of epilepsy. If you have it, you're prone to sudden jerk-like movements in your upper limbs and face.
Palatal myoclonus
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 can happen while you sleep. You might hear a clicking sound in your ear when they do.
Reticular reflex myoclonus
Experts know that this type of myoclonus starts in your brainstem, the part of your brain that controls functions like breathing and your heart rate. Twitching or jerking throughout your whole body is common, but only part of your body could also be affected. Reticular reflex myoclonus is very rare but can interfere with your quality of life.
Brainstem myoclonus
This is a broad term that includes both reticular myoclonus and the natural startle response, which puts your body in a defense position when you're surprised. When you're startled, you might not even realize that you're making a face, flexing your knees, or pulling back your arms, but this is a common human reaction. A main feature of brainstem myoclonus is that you're very sensitive to sound.
Epileptic myoclonus
If you live with a seizure disorder, muscle spasms can be one symptom or the only symptom you have during a seizure. There are different types of myoclonic seizures. For instance, juvenile myoclonic epilepsy (JME) usually affects your neck, shoulders, or upper arms.
Progressive myoclonus epilepsy (PME)
A kind of epileptic myoclonus, this is a group of rare disorders that usually start in kids and teens. The symptoms tend to get more intense over time.
Action myoclonus
One of the most severe types of myoclonus, it can affect your arms, legs, and the muscles in your face. Action myoclonus is triggered by movement and could become more severe at times, especially when you're trying to move very precisely and carefully.
Myoclonus Symptoms
Myoclonus spasms aren't easy to define because they vary so much from one person to another. Generally speaking, they:
- Happen without warning
- Don't last long
- Aren't movements that you're able to control
- May feel like little electric shocks
- Can be mild or intense
- Can happen very often or every once in a while
- Can affect one small part of your body or all over
- Are sometimes severe enough to get in the way of daily functions like eating, speaking, or walking
Your muscles can flex or tighten, which is called positive myoclonus.
Or they can relax and go limp, which is known as negative myoclonus.
Many people have both positive and negative myoclonus.
Myoclonus Causes
Myoclonus often happens because your nervous system isn't working the way it should. Various things, such as neurological disorders, genetic conditions, brain injuries, and exposure to toxins, can cause your nerve cells to misfire and send wrong signals to some of your muscles.
Doctors are aware that several parts of your brain are involved. But more research needs to be done to pinpoint what happens, or doesn't happen, to cause myoclonus. An imbalance of brain chemicals may make the regions of your brain that control movement more active than they need to be. But other times, there's no clear cause.
If you have multiple sclerosis (MS), myoclonus could be due to lesions on your brain or spinal cord.
Other nervous system conditions that can cause myoclonus include:
- Stroke
- Brain tumor
- Alzheimer’s disease
- Parkinson’s disease
- Lewy body dementia
- Creutzfeldt-Jakob disease (CJD)
Sometimes, the cause is a medical condition, such as:
- Autoimmune conditions
- Vitamin or mineral deficiency
- High or low blood sugar
- Genetic disorder you inherited from your parents
- Head or spinal cord injury
- Viral or bacterial infection, like Lyme disease
- Kidney or liver issues
- Stroke or heart attack that keeps your brain from getting oxygen
Both prescribed and recreational drugs can also cause myoclonus. Among the kinds known to do this are:
- Blood pressure medications
- Antibiotics
- Antidepressants
- Anti-seizure drugs
- Surgical anesthetics
- Opioids
- Alcohol
- Cocaine
- Ecstasy
- Heroin
- Amphetamines
Myoclonus Diagnosis
A muscle spasm or twitch every now and then usually isn't a cause for concern. But if your symptoms are frequent or making it a challenge to do things you need or like to do, it's important to see your doctor.
To try to figure out the cause, they'll ask you questions about your health history and which parts of your body have spasms. You might write down some information ahead of time and bring it to your appointment. For instance, it can be helpful for your doctor to know:
- When you first started having spasms
- How often you have them
- How severe your symptoms are
- If you've noticed anything that makes the spasms better or worse
To get more information, your doctor may suggest tests like:
- Urine and blood tests. Lab work will provide a general view of your health and can check for conditions like diabetes, kidney disease, or autoimmune disorders.
- Electroencephalogram (EEG). This painlessly 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.
- Magnetic resonance imaging (MRI). Your doctor can use this test to get detailed pictures of your brain, spinal cord, and other body parts that might be involved.
Myoclonus Treatment
If another health condition is causing your spasms, your doctor will try to treat it. If it can't be cured, then your doctor will work on lessening your symptoms.
Because so many conditions can cause myoclonus, the treatments vary. Depending on your case, you may need to take several medicines at the same time. They may act on different parts of your brain.
There are no specific myoclonus drugs. But many types of medicines have been found to reduce how often you have spasms and how severe they are. They 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 can increase the amount as needed until your symptoms go away.
- Anti-seizure drugs. Medicines like levetiracetam (Keppra), primidone (Mysoline), and valproic acid (Valproic) help 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, an important neurotransmitter. Some studies have found that 5-HTP helps people with certain forms of myoclonus.
- Botox shots. Botulinum toxin "freezes" your muscles and keeps them from twitching. These shots can be helpful if you have frequent spasms on one side of your face.
- Surgery. If a brain or spinal cord lesion is causing your symptoms, your doctor may suggest a procedure to remove it.
- Deep brain stimulation (DBS). In this surgery, 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 multiple sclerosis. Right now, it’s mostly used as a treatment for Parkinson’s disease.
Experts continue to look for new ways to treat myoclonus. Clinical trials are large research studies that rely on volunteers to understand if new treatments work well enough to be available to the general public. If you're interested in being part of one, talk to your doctor about how to apply.
Myoclonus Outlook
Ideally, your doctor will be able to treat the condition that's causing your symptoms. But if not, they can work with you to ease your spasms. Because myoclonus is so complex, it's not uncommon to try more than one treatment or need to see different types of doctors.
Myoclonus Injury Prevention
There’s no way to prevent myoclonus. But you can try to reduce your chances of getting hurt when a severe spasm happens. To do that:
Get specialized support. For instance, a neuropsychiatrist can help you spot triggers and learn to manage movement issues. Working with a physical therapist can improve your balance, strength, and coordination.
Protect yourself. Wear protective gear so you don't risk further damage to your nervous system or brain. For instance, always wear a seat belt when you're in a car. And wear a helmet to protect your head when you're riding a bike or playing contact sports.
Follow your doctor's advice. If you live with another health issue, do your best to manage it. Take any medication as prescribed and see your doctor regularly.
Takeaways
Myoclonus is a twitch or spasm that you can't control. Sometimes, it's a sign of another health issue. Your doctor can help you figure out the cause and how to either stop, or better manage, these muscle jerks.
Myoclonus FAQ
Is myoclonus a symptom of anxiety?
Psychogenic myoclonus is a type of movement disorder that's caused by stress or another mental health condition. It can be difficult to tell it apart from other kinds of myoclonus, but there are a few differences. For instance, the symptoms usually stop if you're able to distract yourself.
This kind of myoclonus isn't due to damage to your central nervous system. It's because of how your body naturally reacts to stress. Because of that, working with a mental health expert will be an important part of your treatment.
