Restless Legs Syndrome

Restless legs syndrome (RLS), also called Willis-Ekbom disease, is a neurologic sensorimotor disorder recognized by a very specific pattern rather than by a single laboratory result. The patient experiences an urge to move the legs, usually with unpleasant sensations such as crawling, pulling, tingling, aching, or an internal “electric” feeling. Symptoms begin or worsen during rest, improve at least temporarily with movement, and are worse in the evening or at night. The symptoms must not be better explained by another condition or behavior. All five International Restless Legs Study Group criteria must be present. Missing one criterion should prompt a search for a mimic rather than a confident RLS diagnosis. The problem is not simply restless muscles. Regional brain iron deficiency, particularly involving the substantia nigra and thalamus, disrupts basal ganglia dopaminergic signaling. Iron supports tyrosine hydroxylase, an enzyme involved in dopamine synthesis. Brain iron can therefore be insufficient even when the peripheral hemoglobin is normal. That is why iron studies matter more than a hemoglobin value alone. Patients commonly describe difficulty sitting through a movie, remaining in bed, or...