Prevalence and clinical characteristics of patients with restless legs syndrome with painful symptoms

Background: The complaint of pain has largely been ignored in the diagnostic criteria for restless legs syndrome (RLS). The purpose of this study was to investigate the prevalence of painful symptoms in RLS, and to compare sleep-related characteristics between the patients who experienced the painful symptoms and those who did not. Methods: The patients with RLS were retrospectively screened from July 2011 to December 2013 at a tertiary-care sleep center. For classifying those with pain and those without pain, more than three specialists separately observed the patients' reports and complaints of symptoms, and the final decision was made through consensus. The demographics and clinical characteristics, including sleep, psychiatric-related scales, and polysomnographic data were reviewed for the study. Results: One hundred and sixty patients with RLS were selected, and 23.8% of them reported painful symptoms of RLS. Patients with RLS who experienced painful sensations were found to have lower ferritin levels, more severe RLS symptoms, anxiety and depressive symptoms, and a lower quality of life. The polysomnography data found that patients with RLS who experienced painful sensations had a longer latency to sleep onset and a lower periodic limb movement index (PLMI) (p <0.05). Conclusions: Patients who experienced painful sensations had more severe RLS symptoms and a trend toward lower PLMI during sleep. According to these results, an inference can be made that painful sensations may be one important point in determining the severity of RLS.