title: Sonographic cross-sectional area measurement in carpal tunnel syndrome patients: can delta and ratio calculations predict severity compared to nerve conduction studies?
abstract: OBJECTIVE
  To evaluate the accuracy of two different sonographic median nerve measurement calculations in predicting carpal tunnel syndrome (CTS) severity in a study population with clinically and electrophysiologically confirmed CTS.
  
  
  METHODS
  643 wrists of 427 patients (325 females and 102 males, age range: 17-90 years, mean ± SD: 57.9 ± 14.7) were included with CTS diagnosis based on clinical and nerve conduction studies (NCS). Cross-sectional area (CSA) measurement of the median nerve was performed at the carpal tunnel level (CSAc) and at the pronator quadratus muscle level (CSAp). Two parameters were calculated: delta (∆-CSA), which is the difference between proximal and distal measurements, and ratio (R-CSA), calculated by dividing distal over proximal measurements.
  
  
  RESULTS
  Patients were classified into mild, moderate and severe CTS based upon NCS. The mean ∆-CSA (4.2 ± 2.6, 6.95 ± 2.2 and 10.7 ± 4.9 mm(2)) and mean R-CSA (1.5 ± 0.4, 1.95 ± 0.4 and 2.4 ± 0.7) values were significantly different between all groups (p < 0.001). Optimal cut-off values for ∆-CSA and R-CSA were 6 mm(2) and 1.7, respectively, to distinguish mild from moderate disease, and 9 mm(2) and 2.2, respectively, to distinguish moderate from severe disease.
  
  
  CONCLUSIONS
  Threshold values for the calculated sonographic parameters ∆-CSA and R-CSA are useful in predicting CTS severity compared to NCS.
  
  
  CONCLUSIONS
  • Two proposed parameters were calculated (∆-CSA, R-CSA) and compared to NCS. • A defined sonoanatomical proximal landmark was used for the calculation. • Both parameters showed ability to detect CTS severity comparable to NCS. • Cut-off values could be determined for both parameters.
authors: Department of Diagnostic Radiology, Medical University Innsbruck, Anichstrasse 35, 6020, Innsbruck, Austria.
authors: Andrea S
authors: AS
authors: Klauser
authors: Mohamed M H
authors: MM
authors: Abd Ellah
authors: Ethan J
authors: EJ
authors: Halpern
authors: Christian
authors: C
authors: Siedentopf
authors: Thomas
authors: T
authors: Auer
authors: Gernot
authors: G
authors: Eberle
authors: Rosa
authors: R
authors: Bellmann-Weiler
authors: Christian
authors: C
authors: Kremser
authors: Martin
authors: M
authors: Sojer
authors: Wolfgang N
authors: WN
authors: Löscher
authors: Markus F
authors: MF
authors: Gabl
authors: Gudrun M
authors: GM
authors: Feuchtner
authors: Werner R
authors: WR
authors: Jaschke
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002349:Carpal Tunnel Syndrome / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000000981:diagnostic imaging* / Q000502:physiology; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology*; D009460:Neurologic Examination / Q000379:methods; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D014463:Ultrasonography; D014953:Wrist / Q000000981:diagnostic imaging; D055815:Young Adult