What is benign fasiculation syndrome?
Benign fasciculation syndrome is a mild neurological disorder that is characterized by involuntary twitching of skeletal muscles at rest. The involuntary twitching can occur in any skeletal muscle group in the body. However, the muscles in the eyelids, arms, legs and feet are the most commonly affected. It can affect both males and females in any age group. The muscle twitching can be either occasional or continuous.
Neurological disorders encompass a group of diverse conditions that primarily affect the nervous system.
Activities of both central (brain and spinal cord) and peripheral nervous systems (peripheral nerves) can be disrupted. Common symptoms of neurological disorders include dizziness, twitching of muscles, cramps, tremors, and pain.The severity of neurological diseases varies considerably. It can range from very mild or debilitating. Some of these diseases can also be life-threatening. The twitching of skeletal muscles in benign fasciculation syndrome can be a cause for concern because this is also a feature of serious neurological conditions such as multiple sclerosis, amyotrophic multiple sclerosis (ALS), and spinal injury.
Signs and Symptoms
The following are some of the main signs and symptoms of benign fasciculation syndrome:
Involuntary muscle twitching (or fasciculation) is the main symptom of benign fasciculation syndrome. The twitching can occur in any skeletal muscle of the body, and is usually present when the muscle is at rest. When voluntary muscle movements are initiated, twitching is inhibited. The twitching resumes when the muscle returns to a resting state.
Skeletal muscle twitches also occur in normal people. However, those normal twitches are short-lived, whereas the twitches in benign fascicular syndrome persist over a longer period of time. The muscle twitches in benign fasciculation syndrome may occur at the same locus. However, it also frequently migrates to different muscle locations at different times. The twitching also becomes more severe at night time, and increases with stress, exertion and infections.
Another feature of the muscle twitch in benign fasciculation syndrome is its intermittent nature and spontaneous resolution. There might be alternating periods of twitching and normal muscle tone. The length of the symptom-free period varies.
Read more on lip twitching.
A correlation has been observed between anxiety and benign fasciculation syndrome. Anxiety precedes symptoms of benign fasciculation syndrome in many patients. In others, both conditions may also coexist.
Occasional muscle twitching that can affect any person is usually a painless experience. However, pain may accompany some episodes of muscle twitching in benign fasciculation syndrome. Muscle cramps may also result from frequent contractions. It is important to note that twitching and spasm (cramps) are two different entities.
Unlike normal muscle twitching, benign fasciculation syndrome can produce fatigue in the affected muscles. In fact, it is a common symptom in this disorder and reduces exercise tolerance in the affected persons. This fatigue is often mistaken for muscular weakness that characterizes other serious neurological disorders, such as amyotrophic lateral sclerosis (ALS). However, the perceived weakness in benign fasciculation syndrome is not clinical verifiable, unlike the weakness caused by loss of muscle tissue in ALS. Overall ALS is a rare condition, whereas benign fasciculation syndrome is a common occurrence.
- Numbness and tingling sensations may also be associated with benign fasciculation syndrome.
- Muscle stiffness may also be present in the affected individuals. Stiff muscles feel tight rather than relaxed. The stiffness is caused by contraction of muscles.
Causes of Benign Fasciculation Syndrome
The cause of benign fasciculation syndrome is not known. Muscle twitching, which is the main feature of this condition, can be caused by dysfunctions at any of the following three locations:
- Skeletal muscle cells.
- Nerves that innervate the skeletal muscle.
- Neuromuscular junction that mediates communication between nerve and muscle cells.
However, it is not known if benign fasciculation syndrome is caused by dysfunction of the nerve cells (neurons), skeletal muscles, or neuromuscular junctions. Despite the uncertainty, there are some theories about the cause of benign fasciculation syndrome, based on observations of certain conditions that are associated with its occurrence. Some of these potential causes are as follows:
- Anxiety and stress are thought to be putative causative factors. Alternatively, anxiety may also be caused by worrying about the symptoms of benign fasciculation syndrome.
- Long-term use of certain drugs such as anti-cholinergics (for example, dimenhydrinate) and opiates (for example, morphine).
- Deficiency of certain micronutrients, such as magnesium and vitamin D.
- Hypocalcemia can result in muscle twitching.
- Paresthesias with small fiber neuropathy may be a possible cause of muscle twitches.
- Long-term exposure to certain insecticides.
- It is also thought that benign fasciculation syndrome could be a manifestation of an autoimmune response to a viral infection.
Read more on muscle cramps.
Diagnosis of Benign Fasciculation Syndrome
Due to muscle twitching being a feature of many mild and severe neurological disorders, a diagnosis of benign fasciculation syndrome is made by ruling out other neurological causes such as Lyme disease, amyotrophic lateral sclerosis (ALS), and multiple sclerosis. Patients with benign fasciculation syndrome typically show a worsening of muscle twitches with anxiety or exertion. No nerve damage is apparent in these patients, and the electromyograph (EMG) is typically normal. Hyperreflexia, or brisk reflexes, become apparent in a detailed neurological examination.
Treatment for Benign Fasciculation Syndrome
The term benign means that the condition is not serious. However, it can cause significant discomfort and affect life. There is no specific treatment for benign fasciculation syndrome. Medication may be helpful in controlling some of the potential causes of muscle twitches.
- Anti-anxiety medications are often the most effective treatments for controlling muscle twitches in benign fasciculation syndrome. Other measures to reduce anxiety include practicing relaxation techniques (like meditation), reducing intake of stimulants (like caffeine, cola and nicotine), and general stress management measures (like proper exercise and sleep routines).
- Beta-blockers and anti-convulsion drugs like carbamazepine can also have some marginal effects on muscle twitches.
- Dietary supplementation with magnesium may also help.
- If muscle ache is also present, over-the-counter pain medications (such as ibuprofen and acetaminophen) may be used.
Despite the cause and treatments for benign fasciculation syndrome being uncertain, the prognosis is generally good. No long-term physical damage occurs as a result of this condition. In time, the duration of twitch-free intervals increase, and the muscle twitches become less intense.