Fasciculation

A fasciculation (or "muscle twitch") is a small, local, involuntary muscle contraction (twitching) visible under the skin arising from the spontaneous discharge of a bundle of skeletal muscle fibers. Fasciculations have a variety of causes, the majority of which are benign, but can also be due to disease of the motor neurons.

Causes and risk factors

Conditions

• The origin of most cases is at present unknown and has therefore been given the title benign fasciculation syndrome.
• Lower motor neuron lesions
• Werdnig-Hoffman disease
• Amyotrophic lateral sclerosis (rare)
• Kennedy disease
• Organophosphate poisoning
• Benzodiazepine withdrawal
• Magnesium deficiency (which can be caused by stress)
• Multiple sclerosis
• Myalgic Encephalomyelitis
• Dehydration
• Fatigue
• Lyme Disease

Medications

Other risk factors may include the use of anticholinergic drugs over long periods, in particular ethanolamines such as Benadryl, used as an antihistamine and sleep aid, and Dramamine for nausea and motion sickness. Persons with benign fasciculation syndrome (BFS) may experience paraesthesia shortly after taking such medication; hours later as it wears off (especially upon awaking), fasciculation episodes begin.

Stimulants can cause fasciculations directly. These include caffeine, pseudoephedrine (Sudafed), amphetamines, and the asthma bronchodilators albuterol/salbutamol (e.g. Proventil, Combivent, Ventolin). Medications used to treat attention deficit disorder often contain stimulants as well, and are common causes of benign fasciculations.

Treatment

Inadequate magnesium intake can cause fasciculations, especially after a magnesium loss due to severe diarrhea. Over-exertion is another risk factor for magnesium loss. As much as 80% of the population does not get the recommended daily amount of magnesium, this may be a common cause. Treatment is with supplements or increased intake of foods rich in magnesium, especially almonds & other nuts, and bananas. Ironically, magnesium supplements may result in diarrhea and more magnesium loss, so dosage and timing (i.e. with meals) are important.

Fasciculation also often occurs during a rest period after sustained stress, such as that brought on by unconsciously tense muscles. Reducing stress and anxiety is therefore another useful treatment.

Atropine sulfate can be used with Suxamethonium chloride to decrease fasciculations during rapid sequence intubation (RSI).

References

External links

• Fasciculations - additional details and underlying conditions