Fasciculation

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

Conditions

 * The origin of most cases is at present unknown and usually inconclusive, has therefore been given the title benign fasciculation syndrome.
 * Neuromyotonia, also known as Isaacs' syndrome
 * Lower motor neuron lesion
 * Werdnig-Hoffman disease
 * Amyotrophic lateral sclerosis
 * Kennedy disease
 * Organophosphate poisoning
 * Benzodiazepine withdrawal
 * Magnesium deficiency
 * Myalgic Encephalomyelitis
 * Dehydration
 * Fatigue
 * Lyme Disease
 * Myasthenia Gravis
 * Rabies
 * Fibromyalgia

The most effective way to detect fasciculations may be surface electromyography (EMG). Surface EMG is more sensitive than needle electromyography and clinical observation in the detection of fasciculation in people with ALS.

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; fasciculation episodes begin as the medication wears off.

Stimulants can cause fasciculations directly. These include caffeine, pseudoephedrine (Sudafed), amphetamines, and the asthma bronchodilators 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.

The depolarizing neuromuscular blocker, succinylcholine, causes fasciculations. It is a normal side effect of the drug's administration, and can be prevented with a small dose of a nondepolarizing neuromuscular blocker prior to the administration of succinylcholine, often 10% of a nondepolarizing NMB's induction dose.

Fasciculations can happen in any muscle in the body.

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 70-80% of the adult population does not consume the recommended daily amount of magnesium, inadequate intake may also be a common cause. Treatment consists of increased intake of magnesium, such as nuts (especially almonds) and bananas. Magnesium supplements may also be taken, however too much magnesium may cause diarrhea, causing dehydration and nutrient loss (including magnesium).

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.

There is no proven treatment for fasciculations in people with ALS. Among patients with ALS, fasciculation frequency is not associated with the duration of ALS and is independent of the degree of limb weakness and limb atrophy. No prediction of ALS disease duration can be made based on fasciculation frequency alone.