Almost all of us will have experienced a fasciculation at one time or another. A fasciculation is simply a small, involuntarymuscle twitchthat occurs spontaneously on any body part. Thetwitchcan be large enough to be felt but generally not large enough to cause a muscle jerk.
Although some people will notice a fasciculation when it happens—such as when aneyelid twitches—many of the events will go unnoticed. However, in a condition called benign fasciculation syndrome, these twitches are frequent and widespread.
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What Causes Fasciculations?
In neurologic terms, fasciculations are the spontaneous firing of a motor unit—a group of nerve and muscle cells that work together to contract a muscle. With fasciculation, one or a few of these units will fire unprompted.
Fasciculations are generally benign (not harmful) and are more of an annoyance. In fact, benign fasciculations are relatively common, affecting around 70% of otherwise healthy people at one time or another.
Common Causes of Fasciculations
Benign fasciculations can often happen after drinking too much caffeine or smoking (due to the stimulant effect ofnicotine). Other stimulant and non-stimulant drugs are also associated with the condition, including:
At other times, having too little of a certainelectrolyte, such as magnesium or calcium, can cause a spontaneous twitch.
Benign fasciculations can also occur at times of stress or illness and even during exercise. Exercise is, in fact, one of the more common causes. The twitches typically occur after a person has completed a workout and is at home resting.
Uncommon Causes of Fasciculations
Less commonly, fasciculations may be a sign of something more serious. These include illnesses or conditions that affect the central nervous system, either directly or indirectly.
Among some of the more concerning causes are:
Within this context, the treatment of fasciculation is focused on resolving or managing the underlying condition.
Difference Between Twitches, Spasms, and Jerks
Benign Fasciculation Syndrome
In addition to known causes, there is a condition called benign fasciculation syndrome (BFS), in which the cause of persistent muscle twitching is idiopathic (meaning of unknown origin). With BFS, the twitching is often described as relentless, occurring either continuously or in random episodes in areas like theeyelids, hands, and legs.
The term “benign” is not meant to downplay the disruption the BFS can cause. The relentlessness of the condition can diminish a person’s quality of life and sense of well-being, leading to severeanxiety and depression.
Treatmentfor Fasciculations
Although some control of severe fasciculations can be achieved withbeta-blockersandanti-seizure medications, no drug has ever been shown to alleviate the symptom consistently.
One of the most effective means of controlling BFS is relaxation andanxietymanagement. Anxiety has a cause-and-effect relationship with fasciculation; it can trigger an episode and aggravate its severity once it starts.
If anxiety is severe, it is best to seek help from a psychologist or psychiatrist who can providestress-reduction trainingor prescribe anti-anxiety drugs if needed. Stimulants like caffeine should also be avoided.
Diagnosing Benign Fasciculation Syndrome
Benign Fasciculation Syndrome vs ALS
ALS is a disease that negatively affects motor nerves—the nerves that controlvoluntary muscleslike the biceps, hamstrings, and abdominals. With ALS, motor nerve cells degenerate, causing a loss of muscle function, which leads to the weakening of muscles due to inactivity. Symptoms of ALS can include:
ALS can also cause breathing problems like shortness of breath and respiratory failure as the muscles involved in breathing, such as the diaphragm, are affected.
The direct cause of ALS is unknown, but experts believe that mutations in certain genes, environmental pollutants, infectious agents, and physical trauma may play roles.
Since BFS or ALS can both lead to muscle twitching, some people may worry that these conditions are related or that BFS may develop into ALS. However, these two disorders are not linked to each other and are different. Although the exact causes for these disorders are unknown, BFS is much more common and doesn’t lead to muscle wasting like ALS.
How Amyotrophic Lateral Sclerosis (ALS) Is Diagnosed
A Word From Verywell
As per its name, benign fasciculation syndrome is not serious and usually resolves on its own without treatment. However, if it persists, or if the twitching causes you undue stress or aggravation, ask your healthcare provider to investigate the possible causes and help you find relief.
In some cases, a change of medication may be all that is needed. At other times, you may be referred to aneurologistfor testing. If no cause is found, some medications and stress-management techniques may help reduce the twitching.
What Involuntary Twitching During Sleep Means
Frequently Asked Questions
Fasciculations and muscle twitches essentially mean the same thing and are often used interchangeably.
Learn MoreWhat Are Tremors?
11 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Filippakis A, Jara J, Ventura N, et al.A prospective study of benign fasciculation syndrome and anxiety.Muscle Nerve. 2018;58(6):852-854. doi:10.1002/mus.26193
Simon NG, Kiernan MC.Fasciculation anxiety syndrome in clinicians.J Neurol. 2013;260(7):1743-7. doi:10.1007/s00415-013-6856-8
Blackman G, Cherfi Y, Morrin H, et al.The association between benign fasciculations and health anxiety: A report of two cases and a systematic review of the literature.Psychosomatics. 2019;60(5):499-507. doi:10.1016/j.psym.2019.04.001
National Center for Advancing Translational Sciences.Cramp-fasciculation syndrome.
National Institute of Neurological Disorders and Stroke.Amyotrophic lateral sclerosis (ALS) fact sheet.
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