title: Alterations in pain responses in treated and untreated patients with restless legs syndrome: associations with sleep disruption.
abstract: OBJECTIVE
  There has been recent interest in characterizing potential abnormalities of pain processing in patients with sleep disorders such as Restless Legs Syndrome (RLS). The aim of this study was to evaluate psychophysical responses to noxious heat and pressure stimuli in both treated and untreated RLS patients, compared to matched controls.
  
  
  METHODS
  This study is a cross-sectional group comparison of RLS patients with matched controls. A total of 31 patients (15 treated, 16 untreated) with a confirmed diagnosis of RLS were compared to 18 controls with no history of RLS or related sleep disorders.
  
  
  RESULTS
  RLS patients (both treated and untreated) demonstrated reduced pain thresholds and reported greater clinical pain relative to controls. Moreover, RLS patients demonstrated enhanced temporal summation of heat pain (p<.05), which may reflect aberrant central nervous system facilitation of pain transmission. Both treated and untreated RLS patients reported disrupted sleep relative to controls, and mediation analyses suggested that the reduced pain thresholds in RLS were attributable to sleep disturbance. However, the effect of RLS on the magnitude of temporal summation of heat pain was independent of sleep disturbance.
  
  
  CONCLUSIONS
  These findings suggest that central nervous system pain processing may be amplified in RLS, perhaps partially as a consequence of sleep disruption. RLS patients, even those whose symptoms are managed pharmacologically, may be at elevated long-term risk for the development or maintenance of persistent pain conditions. Further studies in larger samples could help to improve the prospects for pain management in RLS patients.
authors.affiliation: Department of Anesthesiology, Perioperative and Pain Medicine, Harvard Medical School, Brigham & Women's Hospital, Chesnut Hill, MA 02467, USA. RREdwards@partners.org
authors.forename: Robert R
authors.initials: RR
authors.lastname: Edwards
authors.forename: Phillip J
authors.initials: PJ
authors.lastname: Quartana
authors.forename: Richard P
authors.initials: RP
authors.lastname: Allen
authors.forename: Seth
authors.initials: S
authors.lastname: Greenbaum
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Earley
authors.forename: Michael T
authors.initials: MT
authors.lastname: Smith
mesh_terms: D000368:Aged; D052160:Benzothiazoles / Q000627:therapeutic use*; D003080:Cold Temperature; D003430:Cross-Sectional Studies; D003863:Depression / Q000503:physiopathology; D018491:Dopamine Agonists / Q000627:therapeutic use*; D005260:Female; D006358:Hot Temperature; D006801:Humans; D008297:Male; D008875:Middle Aged; D017288:Pain Threshold / Q000502:physiology*; D000077487:Pramipexole; D011312:Pressure; D011601:Psychophysics; D012148:Restless Legs Syndrome / Q000188:drug therapy* / Q000503:physiopathology*; D012893:Sleep Wake Disorders / Q000503:physiopathology*; D011795:Surveys and Questionnaires
chemical_list: D052160:Benzothiazoles; D018491:Dopamine Agonists; D000077487:Pramipexole