title: F-Wave Duration as a Specific and Sensitive Tool for the Diagnosis of Restless Legs Syndrome/Willis-Ekbom Disease.
abstract: OBJECTIVE
  Restless legs syndrome, also known as Willis-Ekbom disease (RLS/WED), is a frequent condition, though its pathophysiology is not completely understood. The diagnosis of RLS/WED relies on clinical criteria, and the only instrumental tool, the suggested immobilization test, may lead to equivocal results. Recently, neurophysiological parameters related to F-wave duration have been proposed as a diagnostic aid. The aim of this study is to assess and compare the diagnostic values of these parameters in diagnosis of RLS/WED.
  
  
  METHODS
  Fifteen women affected by primary RLS/WED and 17 age- and sex- matched healthy subjects. A complete electroneurographic evaluation, including nerve conduction studies (NCS), cutaneous silent period (CSP), and F-wave parameters, namely amplitude, F-wave duration (FWD), and the ratio between FWD and duration of the corresponding compound muscle action potential (FWD/CMAPD).
  
  
  RESULTS
  No subject showed alterations of the NCS. However, FWD and FWD/CMAPD of both upper and lower limbs were significantly longer in patients than controls. Tibial FWD/CMAPD best discriminated RLS/WED patients from controls. A cutoff of 2.06 yielded a sensitivity of 69.2%, a specificity of 94.1%, a positive predictive power of 90%, and a negative predictive power of 80% (area under the curve = 0.817; 95% confidence interval = 0.674-0.959). The combination of ulnar or tibial FWD/CMAPD increases the sensitivity (85.7%) while slightly decreasing the specificity (87.5%, positive predictive value: 85.7%, negative predictive value: 87.5%).
  
  
  CONCLUSIONS
  Lower limb FWD/CMAPD ratio may represent a supportive diagnostic tool, especially in cases of evening lower leg discomfort of unclear interpretation.
authors.affiliation: Sleep Disorders Center, University of Cagliari, Italy.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Congiu
authors.affiliation: Neurology Department, CHU Clermont-Ferrand, University of Auvergne, France.
authors.forename: Maria Livia
authors.initials: ML
authors.lastname: Fantini
authors.affiliation: Sleep Disorders Center, University of Parma, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Milioli
authors.affiliation: Neurology UOC, University of Cagliari, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Tacconi
authors.affiliation: Sleep Disorders Center, University of Cagliari, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Figorilli
authors.affiliation: Sleep Disorders Center, University of Cagliari, Italy.
authors.forename: Gioia
authors.initials: G
authors.lastname: Gioi
authors.affiliation: Biostatistics Unit (DRCI), CHU Clermont-Ferrand, France.
authors.forename: Bruno
authors.initials: B
authors.lastname: Pereira
authors.affiliation: Neurology UOC, University of Cagliari, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Marrosu
authors.affiliation: Sleep Disorders Center, University of Parma, Italy.
authors.forename: Liborio
authors.initials: L
authors.lastname: Parrino
authors.affiliation: Sleep Disorders Center, University of Cagliari, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Puligheddu
mesh_terms: D000328:Adult; D000368:Aged; D004576:Electromyography / Q000379:methods*; D005260:Female; D006801:Humans; D007866:Leg / Q000294:innervation* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology*; D012148:Restless Legs Syndrome / Q000175:diagnosis* / Q000503:physiopathology*; D012680:Sensitivity and Specificity
keywords: F waves; diagnostic tool; restless legs syndrome/Willis-Ekbom disease