Myoclonus is the medical term for brief, involuntary muscle twitching or jerking. Myoclonus comes on suddenly. It’s not a disease but a sign of another condition.
People who experience myoclonic twitches or jerks have muscles that unexpectedly tighten or contract (positive myoclonus) or relax (negative myoclonus). Muscle twitches may occur in one hand, arm or leg, or the face. Sometimes, myoclonus involves many muscles at the same time.
How common is myoclonus (muscle twitch)?
Everyone has involuntary muscle twitches. If you’ve ever had the hiccups, jumped from being startled, or felt your body jerk as you drifted off to sleep, you’ve experienced myoclonus.
What are the types of myoclonus (muscle twitch)?
Experts classify myoclonus by the underlying cause. Types include:
Action: Moving or just thinking about moving brings on muscle twitches. Action myoclonus is the most disabling type. Muscle spasms can affect a person’s face, arms, and legs.
Epileptic: People with epilepsy are more prone to muscle twitches and jerks.
Essential: Healthcare providers don’t know what causes essential myoclonus. It sometimes occurs in families but can also happen randomly. Essential myoclonus tends to progress slowly.
Sleep: Muscle twitches happen as you’re falling asleep. These muscle twitches may be a sign of restless legs syndrome.
Stimulus-sensitive: Outside stimuli, such as lights, noise, or activity, trigger muscle twitching.
Symptomatic: People with these muscle twitches have an underlying medical cause, such as ataxia or Parkinson’s disease. Providers may call this type secondary myoclonus.
What causes myoclonus (muscle twitch)?
A disturbance to the central nervous system (brain and spinal cord) most likely causes these involuntary muscle twitches. For unknown reasons, the central nervous system sends an electrical impulse to muscles. Rarely, myoclonus occurs after an injury to the peripheral nerves outside the central nervous system.
What conditions are associated with myoclonus (muscle twitch)?
People with certain conditions are more prone to myoclonus. These conditions include:
Autoimmune diseases, such as multiple sclerosis.
Head or spinal cord injuries, including traumatic brain injuries and cerebral hypoxia (lack of oxygen to the brain).
Kidney failure, liver failure, or other organ failures.
Neurological disorders, such as Alzheimer’s disease, Creutzfeldt-Jakob disease, or Parkinson’s disease.
Seizure disorders like epilepsy.
Should I be worried?
Everyone has occasional involuntary muscle twitches or myoclonus. But for some people, muscle spasms become disruptive and even dangerous. You should call your healthcare provider if you experience frequent or severe muscle twitches that affect your ability to work, sleep or enjoy life. Your healthcare provider can determine the cause of myoclonus. Medications can reduce the severity and frequency of myoclonic twitches and jerks.