Benign Fasciculation Syndrome: Causes and Treatment

Almost all of us will have experienced a fasciculation at one time or another. A fasciculation is simply a small, involuntary muscle twitch that occurs spontaneously on any body part. The twitch can 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 an eyelid twitches—many of the events will go unnoticed. However, in a condition called benign fasciculation syndrome, these twitches are frequent and widespread.

This article will explain why fasciculations happen, and discuss the causes and symptoms of benign fasciculation syndrome.

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 of nicotine). Other stimulant and non-stimulant drugs are also associated with the condition, including:

• Benadryl (diphenhydramine)
• Dramamine (dimenhydrinate)
• Sudafed (pseudoephedrine)
• Ritalin (methylphenidate)

At other times, having too little of a certain electrolyte, 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.

Fasciculations caused by these conditions should not be considered worrisome or in need of medical attention.

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:

• Amyotrophic lateral sclerosis (also known as ALS or Lou Gehrig's disease) and other motor neuron diseases
• Moersch-Woltmann syndrome (also referred to as "stiff person syndrome")
• Paraneoplastic syndrome, a cancer-related nerve disorder
• Peripheral neuropathy, damage to nerves outside the central nervous system
• Rabies, caused by a virus that travels along nerves to the brain
• Schwartz-Jampel syndrome, a rare genetic disorder of the nervous system
• Spinal cord injury, including spinal concussion
• Spinal muscle atrophy, a genetic disorder of motor neurons in the spine and brainstem

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 relentless, occurring either continuously or in random episodes in areas like the eyelids, hands, and legs.

Treatment for Fasciculations

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

One of the most effective means of controlling BFS is relaxation and anxiety management. 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 provide stress-reduction training or prescribe anti-anxiety drugs if needed. Stimulants like caffeine should also be avoided.

Diagnosing Benign Fasciculation Syndrome

Because BFS is idiopathic, the diagnosis needs to be made by exclusion, using a battery of tests and investigations, typically a neurological examination and electromyography (EMG), to rule out all other possible causes. These not only include the known causes discussed above, but also conditions that can often manifest with twitching, such as:

• Chronic fatigue
• Fibromyalgia
• Paresthesias
• Myoclonic jerks
• Hyperreflexia (overactive reflexes)

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

Benign Fasciculation Syndrome vs ALS

ALS is a disease that negatively affects motor nerves—the nerves that control voluntary muscles like 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:

• Muscle twitches, usually starting in one arm, leg, shoulder, or the tongue
• Muscle tightness
• Muscle cramping
• Slurred speech
• Difficulty chewing or swallowing

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.

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 a neurologist for testing. If no cause is found, some medications and stress-management techniques may help reduce the twitching.