title: Low sensitivity of F-wave in the electrodiagnosis of carpal tunnel syndrome.
abstract: OBJECTIVE
  Previous studies showed "F-wave inversion" (F-INV) as a sensitive method in the electrodiagnosis of early stage of carpal tunnel syndrome (CTS). This study aimed at evaluating the sensitivity and specificity of F-wave and nerve conduction velocity (NCV) testing in CTS.
  
  
  METHODS
  We consecutively enrolled 244 cases and 108 controls. F-waves analysis included: Fwave minimum and mean latencies, F-wave persistence and chronodispersion, mean-F/CMAP amplitude ratio, F-INV. Specificity and sensitivity of F-waves parameters were calculated in the whole sample of CTS patients and by grouping the patients according to CTS severity. Multivariate logistic regression was also performed using F-INV as a dependent variable.
  
  
  RESULTS
  In the whole sample the sensitivity of F-mean-INV and of median-ulnar NCV comparative testing was 50.8% and 93.7%, respectively. F-INV sensitivity dropped to 8% in CTS early stage. F-INV could be predicted only by distal motor latency of the median nerve. The sensitivity of all F-wave parameters increased only in the most severe stages of CTS.
  
  
  CONCLUSIONS
  This study does not confirm the electrodiagnostic usefulness of F-INV in early stage of CTS. All F-wave parameters, including F-INV, are much less sensitive than conventional NCV in CTS electrodiagnosis. F-wave does not add further useful information specifically related to CTS.
authors.affiliation: EMG Service, Local Health Unit 7, Siena, Italy. Electronic address: m.mondelli@usl7.toscana.it.
authors.forename: Mauro
authors.initials: M
authors.lastname: Mondelli
authors.affiliation: EMG Service, Local Health Unit 7, Siena, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Aretini
mesh_terms: D000328:Adult; D000368:Aged; D002349:Carpal Tunnel Syndrome / Q000175:diagnosis* / Q000503:physiopathology*; D004568:Electrodiagnosis / Q000379:methods* / Q000592:standards*; D005260:Female; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000502:physiology; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology; D009431:Neural Conduction / Q000502:physiology; D011446:Prospective Studies
keywords: Carpal tunnel syndrome; Electromyography; F-inversion; F-wave; Median nerve; Nerve conduction velocity