Benign Fasciculation Syndrome (BFS) Constant Muscle Twitching

Neurological disorders are a diverse group of diseases affecting the brain, spinal cord and nerves. Many neurological symptoms are part of occasional experiences in normal healthy individuals and is not linked to any disease – like pain, dizziness, numbness, muscle twitches, cramps or even tremors. Some neurological disorders can be very mild, causing minimal discomfort, while some can be very serious, life-threatening or debilitating disorders. Benign fasciculation syndrome (BFS) is a less severe but annoying type of neurological disorder. It is sometimes referred as ‘muscle twitching syndrome’ or ‘fasciculation syndrome’ and involves the rapid contraction and relaxation of the muscles.

What is benign fasciculation syndrome (BFS)?

Benign fasciculation syndrome is characterized by occasional or nearly continuous twitching of various skeletal (voluntary) muscles in the body. This type of muscle twitching can also be seen in association with serious disorders like spinal injury, multiple sclerosis (MS) or amyotrophic lateral sclerosis (ALS). This can sometimes make benign fasciculation syndrome patients extremely anxious about the twitching due to the similarity of symptoms.

Symptoms of Benign Fasciculation Syndrome

Benign fasciculation syndrome can affect individuals of any sex and any age. In some patients it has been found to develop following viral infections. It is characterized primarily by twitching (fasciculation) of various muscles of the body. These involuntary movements can affect any group of muscles including the muscles of arms, fingers, back muscles, legs or eyelids. Occasionally it can even affect muscles of the tongue.

Muscle Twitching in BFS

The twitches resemble those which can happen occasionally in healthy individuals, except that in benign fasciculation syndrome the twitch persists for long periods. The twitches usually develop when the muscle is at rest. These twitches disappear when the muscle is moved voluntarily. It may affect the same area again or more commonly it can migrate from one muscle to another.

Twitching is slightly more severe at night and exacerbates during periods of stress, exertion or infection. The symptoms may spontaneously improve in a few months or persist for several months to years. There can be periods of intense symptoms interspersed with periods of milder symptoms or symptom-free periods. With time the muscle twitching may get less intense and the duration of symptom-free period may increase.

Other Symptoms

  • Anxiety. Most patients with benign fasciculation syndrome are also seen to suffer from anxiety. There may be a history of anxiety even before BFS develops.
  • Pain. Some benign fasciculation syndrome patients can have pain during the muscle twitching. This may include muscle cramping due to repeated contractions.
  • Fatigue is common in benign fasciculation syndrome patients and can reduce the ability to undertake physical activity (reduced exercise tolerance). This is often mistaken for weakness associated with neurological disorders like ALS. Weakness is not present in BFS and if present, further investigation is required to exclude the possibility of other neurological disorders.
  • Other symptoms may include :
    • numbness
    • tingling or ‘pins and needles’ sensation
    • muscle stiffness

Amyotrophic lateral sclerosis (ALS) vs benign fasciculation syndrome (BFS)

  • ALS is a rare disease while benign fasciculation syndrome is more common.
  • ALS patients suffer primarily with weakness and also show fasciculations. Benign fasciculation syndrome patients primarily suffer from fasciculations and may suffer from fatigue.
  • The weakness in ALS is due to loss of muscle tissue and can be assessed clinically. The weakness in benign fasciculation syndrome is perceived weakness and cannot be clinically verified.
  • The twitch in benign fasciculation syndrome starts in one spot and usually migrates to other spots. In ALS the twitch starts at one spot to progress throughout the body with time.
  • The twitches in benign fasciculation syndrome occur in healthy muscle tissues while in ALS twitches are caused by dying muscle tissue. This can be differentiated with an EMG. In benign fasciculation syndrome the EMG remains normal. The EMG is abnormal in ALS.

Causes of Benign Fasciculation Syndrome

The exact cause of benign fasciculation syndrome is unknown. A muscle twitch can result from disease of the muscle, the nerve supplying the muscle or a problem at the junction where the nerve supplies the muscle cells (neuromuscular junction). In benign fasciculation syndrome, the exact site of the disease is not clear.

Anxiety, stress and physical exertion are significantly related to the severity of symptoms but are not the cause of BFS. It is believed that benign fasciculation syndrome is an autoimmune reaction to a viral infection. There may also be a link to :

  • use of certain drugs like anticholinergics like dimenhydrinate
  • withdrawal of opioids like morphine
  • chronic exposure to certain insecticides
  • deficiency of magnesium and certain micronutrients

Diagnosing Benign Fasciculation Syndrome

Patients typically whave a history of twitching that is worsened by anxiety or overexertion. Diagnosis of benign fasciculation syndrome is made by excluding other possible causes for muscle twitching like Lyme disease neuropathy, ALS, multiple sclerosis.

A detailed neurological examination in benign fasciculation syndrome can reveal brisk reflexes (hyperreflexia). Electromyography (EMG) is an important diagnostic tool. Since benign fasciculation syndrome is not associated with any real nerve damage, the EMG appears normal or a fairly normal. BFS should only be diagnosed once other neurological disorders have been excluded. A change in the symptoms, including development or progression of weakness should prompt repeat investigations including EMG to rule out ALS.

Treatment for BFS

There is no satisfactory definitive treatment for benign fasciculation syndrome. Some medication and measures that may be considered include :

  • anti-anxiety medication
  • reducing the use of stimulants – caffeine and nicotine
  • stress management
  • relaxation techniques including meditation

Several drugs and dietary supplements have been used with marginal benefits. This includes :

  • anti-epileptic drugs like carbamazepine or phenytoin
  • dietary supplements like magnesium
  • quinine
  • propranolol
  • verapamil