Restless legs syndrome: Diagnostic time-savers, Tx tips

Restless legs syndrome (RLS) has become increasingly familiar to Americans in recent years, as the medical literature, consumer ads, and lay press have focused on new findings and treatments. Yet much about this movement disorder remains a mystery.

Both the number of people with RLS and the proportion of RLS patients whose symptoms are frequent or severe are among the unknowns. Estimates of prevalence range from approximately 2% of the general population to 15% of adults.^1-6

Diagnosing RLS remains complicated. Although 4 key features, or “essential criteria,” have been identified, there is no definitive clinical finding or laboratory test for this syndrome. And, because the symptoms of a number of other movement disorders resemble those of RLS, you need to be alert to other clinical features and distinguishing characteristics to confirm an RLS diagnosis.

The pathophysiology of RLS is certainly not clear-cut, either. Possible mechanisms involve overexcitation of the spinal cord by the brain stem, decreased dopamine signaling, and low iron levels.^5-8 Low serum iron levels, and especially low central nervous system ferritin levels, have been closely correlated with the severity of RLS symptoms.^5,9,10 Genetic links to RLS are also being studied, but have not yet been clearly established.^2,7,10,11

What we do know is that the prevalence of RLS increases with age. In a National Sleep Foundation poll, nearly 25% of people older than 65 reported symptoms of RLS.¹² In a more recent study of the elderly conducted under the auspices of the World Health Organization, 9.8% of participants met the criteria for RLS.¹³

An aging population means you’re likely to see an increasing number of patients with symptoms of RLS, which can range in severity from occasional discomfort to daily leg pain. This update will help you hone your diagnostic skills and provide the best possible care to patients who are affected.

Start with the URGE mnemonic

Initial diagnostic criteria for RLS were developed by the National Institutes of Health (NIH) in 2002 and revised by the International Restless Legs Syndrome Study Group (IRLSSG) in 2005.⁹ They begin with 4 essential criteria ( TABLE 1 ), easily remembered with this simple mnemonic:

• Urge to move the legs
  Rest induced
  Gets better with activity
  Evening and night accentuation.

Here’s what to keep in mind about each.

Urge. Patients with RLS experience a powerful urge to move their legs, and often their arms or other body parts, as well. Some patients also experience discomfort in their legs,^14,15 which arises from deep within the legs rather than from the surface—a characteristic that helps differentiate RLS from other movement disorders.^3,6,16

Rest induced. Numerous studies have shown that RLS symptoms worsen during periods of physical and mental inactivity, and when patients are in a seated or lying position.^3,5,15,16 The longer the rest period, the more severe the symptoms become. Mentally stimulating activities, such as playing video games or reading, are often enough to prevent the onset of symptoms, at least in the early stage of the disorder.^3,5,15,16

Gets better with activity. While inactivity exacerbates RLS symptoms, activity typically brings complete or partial relief. Symptom relief can be the result of physical movement, a mentally stimulating activity, or even a change in temperature. Touching and rubbing the legs often helps, too, although this effect diminishes as RLS progresses.^3,6,15,16

Evening accentuation. The severity of RLS symptoms tends to follow the same circadian pattern as body temperature—increasing in the evening and peaking between the hours of 11 PM and 3 AM, and making it difficult, if not impossible, for patients to experience hours of uninterrupted sleep.

TABLE 1
Diagnosing restless legs syndrome^2,17,26,33