title: Ultrasound for diagnosis of carpal tunnel syndrome: comparison of different methods to determine median nerve volume and value of power Doppler sonography.
abstract: OBJECTIVE
  To compare ultrasound measurement of median nerve cross-sectional area (CSA) at different anatomical landmarks and to assess the value of power Doppler signals within the median nerve for diagnosis of carpal tunnel syndrome (CTS).
  
  
  METHODS
  A prospective study of 135 consecutive patients with suspected CTS undergoing two visits within 3 months. A final diagnosis of CTS was established by clinical and electrophysiological findings. CSA was sonographically measured at five different levels at forearm and wrist; and CSA wrist to forearm ratios or differences were calculated. Intraneural power Doppler signals were semiquantitatively graded. Diagnostic values of different ultrasound methods were compared by receiver operating characteristic curves using SPSS.
  
  
  RESULTS
  CTS was diagnosed in 111 (45.5%) wrists; 84 (34.4%) had no CTS and 49 (20.1%) were possible CTS cases. Diagnostic values were comparable for all sonographic methods to determine median nerve swelling, with area under the curves ranging from 0.75 to 0.85. Thresholds of 9.8 and 13.8 mm(2) for the largest CSA of the median nerve yielded a sensitivity of 92% and a specificity of 92%. A power Doppler score of 2 or greater had a specificity of 90% for the diagnosis of CTS. Sonographic median nerve volumetry revealed a good reliability with an intraclass correlation coefficient of 0.90 (95% CI 0.79 to 0.95).
  
  
  CONCLUSIONS
  Sonographic assessment of median nerve swelling and vascularity allows for a reliable diagnosis of CTS. Determination of CSA at its maximal shape offers an easily reproducible tool for CTS classification in daily clinical practice.
authors.affiliation: Department of Rheumatology and Immunology, Medical University Graz, , Graz, Austria.
authors.forename: Christian
authors.initials: C
authors.lastname: Dejaco
authors.forename: Martin
authors.initials: M
authors.lastname: Stradner
authors.forename: Dorothea
authors.initials: D
authors.lastname: Zauner
authors.forename: Werner
authors.initials: W
authors.lastname: Seel
authors.forename: Nicole Elisabeth
authors.initials: NE
authors.lastname: Simmet
authors.forename: Alexander
authors.initials: A
authors.lastname: Klammer
authors.forename: Petra
authors.initials: P
authors.lastname: Heitzer
authors.forename: Kerstin
authors.initials: K
authors.lastname: Brickmann
authors.forename: Judith
authors.initials: J
authors.lastname: Gretler
authors.forename: Florentine C
authors.initials: FC
authors.lastname: Fürst-Moazedi
authors.forename: Rene
authors.initials: R
authors.lastname: Thonhofer
authors.forename: Rusmir
authors.initials: R
authors.lastname: Husic
authors.forename: Josef
authors.initials: J
authors.lastname: Hermann
authors.forename: Winfried B
authors.initials: WB
authors.lastname: Graninger
authors.forename: Stefan
authors.initials: S
authors.lastname: Quasthoff
mesh_terms: D000328:Adult; D000368:Aged; D002349:Carpal Tunnel Syndrome / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D016022:Case-Control Studies; D005260:Female; D005542:Forearm / Q000000981:diagnostic imaging / Q000294:innervation; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D008875:Middle Aged; D009431:Neural Conduction; D011446:Prospective Studies; D012039:Regional Blood Flow; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D018608:Ultrasonography, Doppler / Q000379:methods; D014953:Wrist / Q000000981:diagnostic imaging / Q000294:innervation