Restless legs syndrome (RLS) is a neurologic disorder characterized by a crawling, aching, or otherwise uncomfortable sensation in the legs, accompanied by the urge to move the lower extremities. Ten percent of adults in America and Europe are affected. One third of those afflicted have symptoms that are severe enough to require medical therapy.
RLS can be a particularly troublesome condition, causing sleep disruption, daytime fatigue, and even difficulties with bed partners.
Causes
The specific causes of RLS are not well understood. While RLS is often a primary disorder (and primary RLS probably has a genetic component) the condition may be secondary to or aggravated by the following:
- Iron deficiency: Studies have shown abnormal iron and dopamine levels in the central nervous systems of individuals with RLS (iron is a cofactor in the conversion of the amino acid tyrosine to dopamine). Low serum iron stores, measured by serum ferritin, have been correlated with the severity of RLS symptoms.
- Kidney failure: When kidney disease interferes with the normal production of erythropoietin, anemia and iron deficiency result. Up to 40% of patients with end-stage renal disease suffer from RLS.
- Pregnancy: In general, women are more prone to RLS than men, and many women develop symptoms late in pregnancy. Studies have revealed a correlation between low hemoglobin levels (anemia) and symptoms of RLS in pregnant women.
- Medications: Since RLS is a central nervous system disorder, medications that affect neurologic function can exacerbate symptoms (antihistamines, SSRI and tricyclic antidepressants, anti-emetics, lithium, etc).
- Alcohol, caffeine, and tobacco: All of these substances have been implicated in worsening RLS symptoms.
- Spinal cord injury.
Diagnosis
The diagnosis of RLS is based upon a patient’s history and physical examination. While laboratory analysis is not necessary to make the diagnosis, a battery of focused tests (metabolic panel and ferritin level) can help exclude secondary causes.
Criteria for diagnosing RLS include:
- The urge to move one’s legs, usually accompanied by discomfort or unpleasant sensations (the arms or other body parts may be involved)
- Symptoms that begin or worsen during periods of inactivity or rest
- Symptoms that are partially or completely alleviated by movement
- Symptoms that are worse in the evening or at night, or are only present at night (in severe cases, symptoms may occur during the day, but a careful history almost always reveals that complaints originally began in the evening or at night)
Treatment
Not all people who are affected by RLS require medication. In fact, two-thirds of patients can be managed non-pharmacologically. Physicians use the following algorithmic approach to treat RLS, based on the frequency and severity of the patient’s symptoms (algorithms are guidelines, and doctors may offer therapies that lie outside these recommendations):
Intermittent or Mild RLS
- Administer iron supplementation for iron-deficient patients
- Discontinue or reduce dosages of potentially offending medications whenever possible
- Suggest abstinence from caffeine, alcohol, and tobacco
- Consider lifestyle changes such as “alerting” activities (reading, puzzles, journal writing), lower-extremity resistance training or aerobic exercise
Daily RLS
- In addition to the above, consider dopamine agonists (the most commonly used drug class for RLS) such as Mirapex or Requip
- Other potentially effective drugs: Carbidopa/levodopa (Sinemet), gabapentin (Neurontin), benzodiazepines (Valium, Xanax, Klonopin, etc), or low-dose, low-potency opioids (narcotics)
Refractory or Severe RLS
- If the patient doesn’t respond to the above measures, increase pharmacologic therapy as tolerated, utilizing different drugs of the same class, higher doses of the same drugs, or combinations of medications until symptoms are reduced or relieved
- Consider referral to a specialist (neurologist)
If restless legs syndrome is caused by an underlying disorder, most individuals will improve when that condition is treated. For others, medications and lifestyle changes will at least make the symptoms of RLS more tolerable.
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