title: Strain and Morphological Changes of Median Nerve After Carpal Tunnel Release.
abstract: OBJECTIVE
  Characterization of the changes of ultrasound parameters after carpal tunnel release may be useful for clarifying the effectiveness or the recovery process of the carpal tunnel syndrome treatment. We evaluated strain and morphological changes of the median nerve before and after carpal tunnel release in carpal tunnel syndrome patients.
  
  
  METHODS
  Twenty-two wrists of 20 idiopathic carpal tunnel syndrome patients who underwent open carpal tunnel release were evaluated by ultrasound. Cross-sectional images of the median nerve were obtained at the proximal carpal tunnel. The cross-sectional area, perimeter, aspect ratio of the minimum enclosing rectangle, and strain of the median nerve were measured and compared before and after carpal tunnel release. According to the patient's recovery, the areas under the receiver operating characteristic curves (AUCs) were compared among the parameters.
  
  
  RESULTS
  After carpal tunnel release, the area and perimeter significantly decreased, and the strain significantly increased compared with before carpal tunnel release. There were no significant changes in the aspect ratio after carpal tunnel release. The AUCs were 0.663, 0.643, 0.543, and 0.731 for the area, perimeter, aspect ratio, and strain, respectively.
  
  
  CONCLUSIONS
  Significant decreases in median nerve area and perimeter as well as significant increases in median nerve strain were observed after carpal tunnel release. The results of this study may be useful when considering how the median nerve recovers after carpal tunnel release.
authors.affiliation: Department of Orthopedic Surgery, Tokyo Medical University Ibaraki Medical Center, Ami, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Yoshii
authors.affiliation: Department of Occupational Therapy, Ibaraki Prefectural University of Health Sciences, Ami, Japan.
authors.forename: Wen-Lin
authors.initials: WL
authors.lastname: Tung
authors.affiliation: Department of Orthopedic Surgery, Tokyo Medical University Ibaraki Medical Center, Ami, Japan.
authors.forename: Tomoo
authors.initials: T
authors.lastname: Ishii
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002349:Carpal Tunnel Syndrome / Q000473:pathology* / Q000503:physiopathology* / Q000601:surgery; D019299:Decompression, Surgical / Q000379:methods*; D055119:Elastic Modulus; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000473:pathology* / Q000503:physiopathology* / Q000601:surgery; D008875:Middle Aged; D020127:Recovery of Function / Q000502:physiology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013314:Stress, Mechanical; D016896:Treatment Outcome
keywords: carpal tunnel syndrome; elastography; median nerve; ultrasonography