Benign fasciculation syndrome
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Benign fasciculation syndrome (BFS) is a disorder characterized by fasciculation (localized, uncoordinated twitching) of various voluntary muscles in the body. The twitching can occur in any voluntary muscle group but is most common in the eyelids, arms, legs, and feet. The twitching may be occasional or may go on nearly continuously. Any intentional movement of the involved muscle causes the fasciculations to cease immediately, but may restart once the muscle is at rest again. Pain, paraesthesia, generalized fatigue, exercise intolerance and muscle cramping may or may not accompany the twitching.
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Common features
Another common feature of the disorder is an dramatic increase in the patient's level of anxiety, especially health-related anxiety. It's not uncommon for the patient to fixate on ALS, vCJD, or some other similarly fatal disorder, refusing to believe the BFS diagnosis.
Causes
Though twitching is sometimes a symptom of various serious diseases (spinal injury, muscular dystrophy, ALS, etc), it is much more often due to more benign causes (BFS, over-exertion, etc), and virtually everyone will experience some episodes of benign fasciculation during their lifetime.
The precise cause of BFS is unknown, though very frequently anxiety is a major contributing factor. Another factor that seems to be common in many cases is a history of regular strenuous exercise. Attention deficit disorder or a related disorder may be a contributing factor. In addition, there are likely genetic and environmental factors that make the patient more susceptible to BFS.
Other risk factors may include using anticholinergic drugs over long periods--in particular, the ethanolamines (the most sedating of the over-the-counter medications). These include diphenhydramine (Benadryl®) for allergies, but also labeled as a sleep aid such as Unisom®, and dimenhydrinate (Dramamine®) for nausea and motion sickness. Typically in persons with BFS, they will experience paraesthesia shortly after taking such medication, then hours later as it wears off (especially upon awaking), fasciculation episodes begin.
Stimulants can cause fasciculations directly. These include caffeine (coffee, tea, cola), pseudoephedrine (Sudafed®), and albuterol/salbutamol (Proventil®, Combivent®, Ventolin®). WARNING: DO NOT DISCONTINUE OR REDUCE ALBUTEROL (SALBUTAMOL) USE FOR ASTHMA EXCEPT ON THE ADVICE OF YOUR PHYSICIAN. Asthma can be deadly, while fasciculations are benign. Some medications used to treat attention deficit disorder may contain stimulants. Ask your doctor or pharmacist.
Inadequate magnesium intake can cause fasciculations, especially after a magnesium loss due to severe diarrhea (diarrhoea). Over-exertion is another risk factor. Up to 80% of people do not get the recommended amount, even when otherwise healthy. Foods rich in magnesium include green vegetables such as spinach, nuts (especially almonds), and to a lesser extent bananas. Magnesium mineral supplements are widely available where vitamins are sold. However, care must be taken not to overdose resulting in diarrhea (and more magnesium loss, as it's a laxative). Supplements containing 300-350 mg will cause diarrhea in many people (particually at first when their body is not accustomed to it). Diet and smaller supplements (or multi-vitamin/mineral tablets) at about 100-133 mg are usually much better options. Many people prefer the more expensive (and harder to find) "chelated" magnesium which is somewhat less likely to cause diarrhea. Blood tests are available, but of questionable value, since most magnesium is not found in the blood. Furthermore, only the ionized form has any effect on the body's nervous system. Very few laboratories in the world can test for ionized magnesium, and for a relatively benign condition such as BFS, would probably not be cost justified.
Frequency
Diagnosis
Treatment
Outlook
BFS is not life-threatening and generally not disabling, but it may be persistent enough to create some degree of disability, especially if pain is also present. In many cases, however, the accompanying anxiety is more disabling than the disease itself.
Outlook is mixed. The vast majority of cases clear up spontaneously in a few days or weeks (and in fact are never presented for diagnosis), but some may continue for years. Some degree of control of the fasciculations may be achieved with the same drugs used to treat essential tremor -- beta-blockers and anti-seizure drugs. However, often the most effective approach to treatment is to treat any accompanying anxiety.
Note: Wikipedia does not give medical advice.