title: Sonography in carpal tunnel syndrome.
abstract: BACKGROUND
  Our objective in this study was to assess the diagnostic utility of the median nerve cross-sectional area (CSA) at the wrist, the wrist-forearm ratio, and the wrist-forearm difference in patients with and without carpal tunnel syndrome (CTS).
  
  
  METHODS
  Individuals with electrodiagnostically proven CTS and asymptomatic control subjects were recruited prospectively from among patients referred to our electrodiagnostic laboratory. Blinded measurements of CSA were made from transverse sonographic images of the median nerve at the wrist (pisiform) and mid-forearm.
  
  
  RESULTS
  Fifty-five cases and 49 controls were recruited. Wrist median nerve CSA (15 vs. 9 mm²; P < 0.0001), wrist-forearm ratio (3.09 vs. 1.90 mm²; P < 0.0001), and wrist-forearm difference (10 vs. 4 mm²; P < 0.0001) were all significantly larger in CTS cases (areas under the curve = 0.89, 0.82, and 0.88, respectively).
  
  
  CONCLUSIONS
  Median nerve CSA at the carpal tunnel inlet and wrist-forearm difference provides the best discrimination between patients with CTS and controls according to receiver operator characteristic (ROC) analysis. Age, gender, height, weight, and wrist size have no effect on CSA.
authors.affiliation: Department of Neurology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA.
authors.forename: Andrea N Leep
authors.initials: AN
authors.lastname: Hunderfund
authors.forename: Andrea J
authors.initials: AJ
authors.lastname: Boon
authors.forename: Jayawant N
authors.initials: JN
authors.lastname: Mandrekar
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Sorenson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D002349:Carpal Tunnel Syndrome / Q000000981:diagnostic imaging* / Q000473:pathology; D004568:Electrodiagnosis / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000000981:diagnostic imaging; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D012680:Sensitivity and Specificity; D013018:Sound Spectrography; D014463:Ultrasonography; D055815:Young Adult