Restless Legs Syndrome
One of the most common sleep movement disorders explained. By Catherine Friederich Murray, MNLM
R
estless legs syndrome (RLS) is a sensorimotor neurologic disorder with a profound impact on sleep. The difficult-to-describe sensations (sensory) and urge to move (motor) occur most often during rest or inactivity, primarily in the evening and at night, and are relieved by movement. Once thought to be rare, RLS is now understood to be fairly common, affecting almost 3% of adults with moderate to severe symptoms at least 2 nights a week.
TERMS USED TO DESCRIBE THE SENSATIONS OF RLS ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○
Aching Ants crawling under the skin Coca-Cola running through the veins Crazy legs Creepy-crawly Electric current Elvis legs Fidgets Grabbing Heebie-jeebies Itching Jittery Pain Pins and needles Pulling Shock-like Throbbing
10 | Winter 2022 | Restless Legs Syndrome
RLS can be primary, meaning that it has no known cause other than perhaps a genetic predisposition, or it can be secondary. Secondary RLS, sometimes called comorbid RLS, is associated with another condition, most commonly with iron deficiency, end-stage kidney disease, or pregnancy. Cardiovascular disease and Parkinson disease may also be comorbid conditions, but the science behind those is a little less clear. AGE OF ONSET OF RLS RLS has a bimodal distribution of onset, meaning that there are two peak times when most people develop RLS—one peak is about age 20 and the other is in the mid-40s. In younger people, the likelihood is greater that they will have another family member with RLS, as compared with people older than 30. This has led researchers to speculate that heredity (genetics) might play a role in people with RLS who have a younger age at symptom onset. DIAGNOSIS OF RLS There is no specific blood or imaging test to diagnose RLS. Instead, the gold standard is a clinical interview. Without that interview to rule out RLS mimics, many other conditions fulfill the four original diagnostic criteria for RLS, which led to an overestimation in epidemiologic studies of the number of people who actually have RLS. However, when knowledgeable clinicians ask appropriate questions to tease out the presence of those RLS mimics, a more accurate diagnosis can be made; therefore, the fifth criterion was added to the diagnostic criteria in 2014. When the diagnosis is not clear through the interview, clinicians may order laboratory or imaging tests to rule out other conditions.
