What Are Benign Fasciculations?

Almost all of us will have experienced a fasciculation at one time or another. A fasciculation is simply a small, involuntary muscle twitch on any part of the body spontaneously. The twitch can be large enough to be felt but not generally not large enough to cause a muscle jerk.

Although some people will notice a fasciculation when it happens—such as when an eyelid twitches—many of the events will go unnoticed.

Man holding leg
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Causes

Benign fasciculations are generally more annoying than serious. They are relatively common, affecting around 70% of otherwise healthy people at one time or another.

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.

Common Causes

Benign fasciculations can often develop after drinking too much caffeine or smoking (due to the stimulant effect of nicotine). Other stimulant and non-stimulant drugs are also associated with the condition, including:

At other times, having too little of a certain electrolyte, such as magnesium and 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, typically occurring after a person has completed a workout and is at home resting.

Fasciculations caused by these conditions should be considered worrisome or in need of medical attention.

Uncommon Causes

Less commonly, fasciculations may be the 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 cause are:

Within this context, the treatment of fasciculation is focused on resolving or managing the underlying condition.

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 being relentless, occurring either continuously or in random episodes.

The term "benign" is not mean to downplay the disruption the BFS can reap. The relentlessness of the condition can diminish a person's quality of life and sense of well-being, leading to severe anxiety and depression.

Because BFS is idiopathic, the diagnosis needs to be made by exclusion, using a battery of tests and investigations to rule out all other possible causes. These not only include the abovelisted known causes but conditions that can often manifest with twitching, such as:

When accompanied by cramps or pain, the condition is often referred to as cramp-fasciculation syndrome (CSF).

Treatment

Although some control of severe fasciculations can be achieved with beta-blockers and anti-seizure medications, no drug has ever been shown to consistently alleviate the symptom.

One of the most effective means of controlling BFS is relaxation and the management of anxiety. Anxiety has both a cause-and-effect relationship with fasciculation; it can both 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 provide stress-reduction training or prescribe anti-anxiety drugs if needed. Stimulants like caffeine should also be avoided.

A Word From Verywell

Benign fasciculation is, as per its name, usually benign and usually resolves on its own without treatment. If it does not, or the twitching causes you undue stress or aggravation, ask your doctor to investigate the possible causes.

In some cases, a change of medication may be all that is needed. At other times, you may be referred to a neurologist who specializes in disorders of the central nervous system. If no cause is found, efforts may be made to reduce stress or treat underlying anxieties that may be fueling the fasciculations.

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  1. Leite MA, Orsini M, de Freitas MR, et al. Another perspective on fasciculations: when is it not caused by the classic form of amyotrophic lateral sclerosis or progressive spinal atrophy?Neurol Int. 2014;6(3):5208. doi:10.4081/ni.2014.5208

  2. Filippakas A, et al. A prospective study of benign fasciculation syndrome (S45.007). Neurology. 2017;88(16 Supp):852-4. doi:10.1002/mus.26193

  3. Walter TR. Benign fasciculation syndrome. J Pain Palliat Care Pharmacother. 2015;29(1):54-5. doi:10.3109/15360288.2014.997856

  4. Fermont J, Arts IM, Overeem S, Kleine BU, Schelhaas HJ, Zwarts MJ. Prevalence and distribution of fasciculations in healthy adults: Effect of age, caffeine consumption and exercise. Amyotroph Lateral Scler. 2010;11(1-2):181-6. doi:10.3109/17482960903062137

  5. 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

  6. National Center for Advancing Translational Sciences. Cramp-fasciculation syndrome. Updated September 19, 2016.

  7. Simon NG, Kiernan MC. Fasciculation anxiety syndrome in clinicians. J Neurol. 2013;260(7):1743-7. doi:10.1007/s00415-013-6856-8