Benign fasciculation syndrome is persistent twitching in one or more muscles. A person may also experience tingling or numbness.

Benign fasciculation syndrome (BFS) is rare and can be confused with amyotrophic lateral sclerosis (ALS), which is also known as Lou Gehrig’s disease. Because of this possible confusion, it is imperative that doctors perform a thorough diagnosis.

Treatment focuses on managing symptoms and reducing stress levels to help people maintain a high standard of living.

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A fasciculation is commonly known as a muscle twitch. Muscle twitches are normal, and the majority of people will experience one at some point. Typical examples include an eyelid twitch or a leg spasm.

The twitch is usually strong enough for a person to feel. However, it will not cause a sudden jerk or full contraction in the muscle.

Muscles contain motor units, which are a group of muscle and nerve fibers that work together to contract a muscle. When the body needs them to move, they can do so instantaneously.

Fasciculations occur when one or more motor units “fire off” on their own. This activity is out of the brain’s control, and the resulting movement can be unexpected.

People with BFS experience a persistent twitch, and may have associated tingling, or numbness in one or more of their muscles.

BFS causes chronic muscle twitching, which can last for extended periods of time or come back regularly. Twitches may appear in random muscles and may get better or worse with time.

Twitching often happens in the leg, but can happen almost anywhere in the body. Fasciculations may appear randomly or may stay in one muscle for an extended period.

The twitch will be most noticeable when the body is at rest. After some time, a person may also experience pain in the affected muscle. The muscle may not respond well to exercise, and many people report feeling weakness as well.

According to an article in the journal Neurology, more than 70% of healthy people experience benign fasciculations, which are rarely associated with a serious neuromuscular disorder. These people may also experience numbness and cramps in the affected muscles.

Symptoms of BFS also appear to be a cause of stress and anxiety for people who have the condition. Authors of a 2019 study suggest that some people with BFS can go on to develop health anxiety surrounding the development of motor neuron disease.

It is unclear if this stress and anxiety make symptoms worse. However, the authors suggest that anxiety symptoms may play a causal role in the development of benign fasciculations.

If stress does exacerbate the symptoms, then some people could find themselves in a cycle of BFS symptoms and anxiety.

BFS is rare, and the exact cause is still unknown. A 2019 article notes that a person will receive a diagnosis of BFS if they experience persistent fasciculations but there is no clear cause.

Physical exercise, stress, fatigue, and caffeine may exacerbate symptoms of BFS.

Causes of muscle twitches

Fasciculations themselves can have a range of causes, including the use of certain substances or medications. These twitches will usually subside when the person stops taking the medication and do not cause BFS.

Muscle twitches may also be due to trauma and injury or may be symptoms of anxiety. They can sometimes be linked to other stress-related symptoms such as headache.

Fasciculations may also be linked to other routine factors such as:

  • strenuous exercise
  • drinking alcohol
  • smoking cigarettes
  • fatigue
  • caffeine intake

When diagnosing BFS, doctors may test a person’s tendon reflexes and ask about their medical history, personal background, and stress levels. The doctor may also carry out strength and resistance tests.

Much of the diagnosis focuses on ruling out other more serious disorders, such as multiple sclerosis (MS) or ALS.

If a doctor thinks a person may have a more serious condition, they may also do neurological testing, blood work, and electromyography to rule out nerve damage. BFS is not associated with nerve damage, so finding any nerve damage would be a sign of a different disorder.

Doctors may prescribe medications to treat tremors or cramps. Examples include anti-seizure medications, such as gabapentin, carbamazepine, and phenytoin.

Some anti-inflammatory drugs or muscle relaxers may help people with pain, fatigue, and inflammation. If blood work identifies any mineral deficiency, the person may use supplements.

Because of the link that BFS may have to stress and anxiety, people diagnosed with the condition may find it helpful to try to reduce their daily stress and anxiety.

A person can help reduce anxiety by:

Benign fasciculations may be challenging to treat. However, people may find they can manage their symptoms with lifestyle changes.

If symptoms persist, get worse, or interfere with a person’s quality of life, they should see a doctor to discuss treatment options.

BFS and amyotrophic lateral sclerosis, also known as Lou Gehrig’s disease, may display some similar symptoms. However, they are different disorders.

A key sign of ALS is what is known as muscle wasting. The affected muscles will atrophy or get smaller over time. This also means that a person with ALS will begin to feel weaker as the condition progresses. Muscle wasting does not usually occur with BFS.

While both conditions create muscle fasciculations, fasciculations appear to be more widespread in BFS. The twitching also affects the muscle while it is resting. However, it will typically stop when the person starts using the muscle.

In ALS, twitching can start in one place. However, it will often spread to the areas near that starting point rather than appearing in random places. ALS will also have other symptoms, such as difficulty with breathing, swallowing, or speech.

People with BFS may fear that it can turn into ALS. However, the two disorders are different and do not seem to have any significant link to each other.

Anyone who is uncertain of their symptoms should return to their doctor for a diagnosis.

BFS has no known cause or permanent treatment, and symptoms can disrupt everyday life. There are some lifestyle changes that can help make a difference in some people.

If a person is experiencing persistent muscle twitches and has not yet been diagnosed, they should speak with a doctor. The doctor may need to rule out any other possible causes or underlying conditions.

By working directly with a doctor to diagnose BFS and develop a treatment plan, many people find they can manage their symptoms well.

BFS refers to persistent muscle twitching with no known or clear cause. It is not associated with a serious neuromuscular condition.

People with symptoms of BFS may have concerns that their symptoms are a result of ALS, or Lou Gehrig’s disease. If a person develops persistent twitching, weakness, or numbness in their muscles, they should speak with a doctor.