Assessment and Diagnosis of Restless Leg Syndrome (RLS)
Restless Legs Syndrome (RLS) is diagnosed by interviewing the individual about the presence or absence of the following five criteria:43
- An urge to move the limbs, usually (but not always) accompanied by, or felt to be caused by, uncomfortable and unpleasant feelings in the legs;
- These sensations begin or worsens during periods of rest and/or inactivity;
- These sensations are partially or completely relieved by movement (such as walking around or stretching), for as long as the movement continues;
- These sensations occur predominantly during the evening or night; and
- These sensations are not symptoms of another medical or behavioral condition.
As noted in #5, above, all patients should be screened for symptoms that mimic RLS but are actually related to other conditions. The most important of these “mimics” are leg cramps, positional discomfort, arthritis, myalgias, leg edema, peripheral neuropathy, radiculopathy, and habitual foot tapping.
Polysomnographic evaluation to assess the frequency of periodic limb movements during sleep (PLMS), which often accompany RLS, is not necessary for the diagnosis, but can be useful in some cases. Polysomnography should be performed in all patients with symptoms suggestive of a second sleep disorder (such as sleep apnea), which might aggravate RLS. Where possible the PLMS should be evaluated over several nights not on just one night in the sleep lab.44
Supportive clinical features include a family history of RLS and a positive response to dopaminergic medication.45
Assessment for secondary RLS includes lab tests for serum ferritin levels. In some patients, lab tests for kidney disease (uremia) may also be required.
43 International Restless Legs Syndrome Study Group, 2012 Revised IRLSSG Diagnostic Criteria for RLS, Rochester MN: IRLSSG, 2012. Available online at: http://irlssg.org/diagnostic-criteria.
44 Trotti LM, Bliwise DL, Greer SA, et al. Correlates of PLMs variability over multiple nights and impact upon RLS diagnosis. Sleep Med 2009;10:668-71.
45 Montplasir J, Allen RP, Walters A, Ferini-Strambi L, “Restless Legs Syndrome and Period Limb Movements During Sleep,” in Kryger M, Roth T, Dement W (ed.), Principles and Practice of Sleep Medicine (5th Edition), St. Louis: Elsevier Saunders, 2011, page 1028.