Myoclonus is a brief, sudden, involuntary jerk of a muscle or group of muscles. It can be caused by a sudden muscle contraction (positive myoclonus) or a sudden loss of muscle tone (negative myoclonus) (1). These movements can’t be consciously controlled. Myoclonus is usually considered a symptom rather than a disease, and it can have hundreds of different underlying causes. It often affects the hands and face. In severe cases, it can make balance and stability difficult and interfere with everyday activities like eating, talking and getting dressed.
How Common Is Myoclonus?
Some forms of myoclonus are more common than others, but overall it is not common. Myoclonus affects about 8.6 people per 100,000, and it becomes more common after age 50 (2). In about a quarter of cases, myoclonus is temporary and usually caused by a medication. It affects men and women equally.
What Are the Signs of Myoclonus?
The main sign of myoclonus is a fast, involuntary muscle jerk. Each jerk starts suddenly, and jerks may happen one at a time or repeatedly. They can occur at rest, during movement, or in response to touch or other triggers. The movements are often described as shock-like and can vary in strength. Sometimes they are strong enough to interfere with daily activities like eating, dressing and walking (3).
Because myoclonus can be a sign of a serious underlying condition, new or worsening myoclonus should be evaluated by a physician. If myoclonus comes with confusion, a seizure or a sudden change in alertness, seek medical care right away.
What Causes Myoclonus?
Myoclonus can result from an injury or other problem anywhere along the nervous system, including the peripheral nerves, spinal cord, brainstem and cerebral cortex. Problems in the cortex can cause myoclonus in one area or an entire limb. Based on where the movements occur and how much of the body is involved, a provider can often narrow down which part of the nervous system is involved.
Some myoclonus is harmless and happens in healthy people. Examples include hiccups and the sudden jerks some people feel as they fall asleep. This is called physiologic myoclonus. Other causes include infections, traumatic brain injury, Parkinson’s disease, multiple sclerosis, epilepsy, Alzheimer’s disease and Creutzfeldt-Jakob disease. Myoclonus can also occur with brain tumors, kidney or liver failure, drug or chemical toxicity, and other metabolic problems. These are called pathologic myoclonus (4).
What Happens in the Brain With Myoclonus?
Myoclonus happens when motor nerve cells suddenly and abruptly send signals to a muscle, often from the areas of the brain’s cortex that control that muscle. The brainstem, which controls the startle reflex, can also be involved. Less often, the problem lies in the peripheral nerve that supplies the muscle. Myoclonus can result from damage to the areas generating the jerks, or to the pathways that normally keep this kind of activity in check (5).
How Is Myoclonus Diagnosed?
Myoclonus is diagnosed by a physician, usually a neurologist. It can look like other movement disorders, so a detailed history is important, including when it started, how often it happens, where it occurs and how quickly each jerk begins.
A physician may order tests to confirm myoclonus and look for its cause (4). These can include electromyography (EMG), which measures the electrical activity of muscles; electroencephalography (EEG), which uses electrodes on the scalp to measure brain activity that may be triggering the jerks; evoked potential studies, which measure the brain’s and spinal cord’s responses to touch, sound or visual stimuli; blood and urine tests to look for underlying causes; and MRI of the brain and spinal cord.
How Is Myoclonus Usually Treated?
Treatment focuses on the underlying cause when possible. Medications are the main treatment for the myoclonus itself, and most work by calming overactive nerve signals. All medications can have side effects, so it’s important to work closely with your doctor to find the right medication and dose (6).
Botulinum toxin (Botox) injections may also be used to temporarily weaken the affected muscles. Because the effects wear off, repeat treatments are needed (3, 2).
Deep brain stimulation of certain deep brain structures, such as the globus pallidus or the thalamus, has shown benefit for some people with myoclonus (7).
How the NeuroRescue Program Can Help
We generally cannot cure the conditions that cause myoclonus. Our goal is to help improve the function of the systems involved, with a focus on movement control, balance, daily function and quality of life. Our care works alongside your neurologist and other providers, never in place of them. Please don’t change any medication without talking with your prescriber.
Eye movements. Myoclonus is often related to overactivity in specific parts of the brain. Vision is our most developed sense, and the many types of eye movements we make depend on large parts of the cortex, deeper brain structures and brainstem. Changes in these areas can show up as changes in eye movements (8). We use targeted eye movement exercises with the goal of improving the function of the brain areas, basal ganglia and cerebellar regions involved, and of the systems that help regulate myoclonus.
To move through the world, your brain first needs to know where things are. Saccades, the quick jumps the eyes make from one object to another, help take in your surroundings quickly. They need to be fast, accurate and quick to start. Because saccades depend on many of the same brain regions involved in myoclonus, they can be affected as well (9). We use targeted saccade exercises with the goal of improving the function of these brain regions and reducing the impact of myoclonus.
Other therapies. Depending on your needs, your program may include visual and vestibular rehabilitation; optokinetic visual stimulation, which has been studied for movement control and posture in Parkinson’s disease and related conditions (10, 11); various forms of electrical stimulation, applied through the skin, which have been studied for supporting eye movements, balance and other sensory and motor functions (12); and virtual reality exercises, which have been studied for improving daily function and reducing fall risk (13).
Transcranial magnetic stimulation. TMS has been studied for improving movement control and emotional regulation (14). At our clinic, TMS is provided by our psychiatric mental health nurse practitioner, who will evaluate whether it’s appropriate for you.
Every NeuroRescue Program is different, with therapies chosen based on your testing and your specific situation.
How the NeuroRescue Program Works
Your NeuroRescue Program begins with your Discovery Day. We start with a detailed history of your condition and your life on a timeline, including your health before the myoclonus began, family history and other related conditions. This helps us understand the factors that may have contributed to where you are now, and identify related conditions that may be making it harder to move forward.
We measure how your visual, vestibular and balance systems are working through computerized analysis of your eye movements, inner ear reflexes and balance under different conditions. Our testing includes videonystagmography and saccadometry to measure several types of eye movements, the video head impulse test to measure inner ear reflexes, and CAPS computerized posturography to assess your balance under different sensory conditions. We also use NeuroSensoryMotor Integration testing to evaluate hand-eye coordination and cognition, and Virtualis testing to assess dynamic eye tracking and your perception of vertical in a virtual reality environment.
We combine this with a thorough physical and neurological exam of your sensory, motor, autonomic and cognitive systems. We also review any relevant lab work, imaging and prior testing, and integrate it with our findings.
Together, this helps us understand which parts of your nervous system are working well, which are struggling, and how quickly they tire. We use that information to design your personal NeuroRescue Program, aimed at improving function and endurance in the systems that need support. Our testing also helps us decide when to push and when to let you rest.
Our goal is to help you move with more control and confidence, improve your balance and daily function, and enjoy more of your life.
Your Next Step
Living with myoclonus is challenging. While we cannot cure the conditions that cause it, many symptoms can be managed, and function and quality of life can often improve. To find out if the NeuroRescue Program is right for you, contact one of our patient care coordinators to schedule your Discovery Day.
