Restless Legs Syndrome Physiology
Restless legs syndrome (RLS) is a neurological disorder that causes unusual sensations in the limbs, especially the legs. These sensations are generally at their worst when the sufferer is at rest or is overly tired; they are usually relieved by movement. Because each patient's experience of RLS is unique, the ailment is poorly understood.
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Defining RLS
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Some RLS sufferers describe the sensations as a feeling of bugs creeping inside the muscles of the legs; others experience itching, burning or even pain. Still others feel a shortness of breath that can only be relieved by incessant movement.
According to the National Institutes of Health, criteria for diagnosing RLS include an urge to move the limbs with or without sensations, improvement with activity, worsening of symptoms when at rest and worsening of symptons in the evening or at night.
Types of RLS
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RLS is categorized as either primary or secondary or sometimes as early onset or late onset.
Primary RLS exists without any known causative factor. It is sometimes called early onset RLS because it can appear in young people who display no other health problems.
Secondary RLS is the result of another medical condition or external factor. Chronic kidney problems, diabetes, varicose veins, thyroid disease and Parkinson's disease are some of the conditions that can produce RLS. Some drugs can also produce secondary RLS or trigger episodes in those who already have symptoms.
Pregnant women frequently experience temporary RLS.
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Causes and Contributing Factors
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While the cause of primary RLS remains unknown, certain factors seem to be present in most or all cases. At least half of primary RLS sufferers have a family history of the illness. RLS is likely to be related to the dopamine and iron levels in the body.
Most patients with either type of RLS present with some level of anemia or reduced levels of iron. In some cases, correcting this deficiency is all that is necessary. For others, treating the iron deficiency can lessen, but not eliminate, the symptoms.
Research
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Functional brain imaging has been used to explore the connection between dopamine and iron-related markers in the brain fluid of individuals with RLS. The results have been confirmed by brain autopsies of RLS sufferers.
There has been extensive research into the genetic component of the syndrome, as well.
Treatment
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Lifestyle changes, including altering exercise habits and reducing or eliminating caffeine, alcohol and tobacco, are the first course of action recommended for RLS sufferers.
RLS is often treated with a class of medicines known as dopamine agonists, the same medications used to treat Parkinson's disease. These include pramipexole, carbidopa/levodopa and ropinerole. The RLS foundation recommends ruling out all possible secondary causes of RLS before considering drug treatment, as these medications frequently have side effects. One of these, augmentation, can actually cause symtpoms to worsen at times. Research has also shown that dopamine agonists can cause compulsive gambling.
Opioids and benzodiazepines are prescribed for patients who have a hard time sleeping because of RLS, and those who experience pain with RLS are sometimes given anticonvulsant medications.
There are some alternative solutions on the market, but none of these have been proven effective.
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