title: Comparison of proximal and distal cross-sectional areas of the median nerve, carpal tunnel, and nerve/tunnel index in subjects with carpal tunnel syndrome.
abstract: OBJECTIVE
  To provide a quantitative analysis of ultrasonographic measurements and possible pathophysiology of carpal tunnel syndrome by comparing cross-sectional areas of the median nerve, carpal tunnel, and nerve/tunnel index and the difference in ultrasonographic findings between affected and nonaffected hands and between sexes.
  
  
  METHODS
  Blinded comparison study.
  
  
  METHODS
  Secondary referral and training hospital of institutional practice.
  
  
  METHODS
  Patients (N=51; 42 women, 9 men) with suspected carpal tunnel syndrome who underwent sonography within 1 week after the electrodiagnostic study.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  Electrodiagnostic and ultrasonographic studies were conducted on both upper extremities. Cross-sectional areas of the median nerve and carpal tunnel were measured at 2 separate levels; proximal and distal cross-sectional areas of the carpal tunnel were each measured at the scaphoid-pisiform and trapezium-hamate levels, respectively.
  
  
  RESULTS
  Comparison between normative (n=24) and abnormal hands (n=78) revealed the following: the mean proximal cross-sectional areas of the median nerve, carpal tunnel, and nerve/tunnel index of electrodiagnostically normative hands were 10.941mm(2), 192.43mm(2), and 5.635%, respectively, whereas those of abnormal hands were 13.74mm(2), 208.87mm(2), and 6.693%, respectively, showing statistically significant differences for all (P<.05). Distal measurements of the cross-sectional area of the median nerve, carpal tunnel, and nerve/tunnel index were 10.088mm(2), 150.4mm(2), and 6.762%, respectively, in normative hands, and 11.178mm(2), 149.6mm(2), and 7.493%, respectively, in abnormal hands, showing no statistically significant differences (P>.05). In women, proximal cross-sectional areas of the median nerve and nerve/tunnel index of abnormal hands showed statistically significant differences, but no ultrasonographic measurement with a statistically significant difference was observed in men.
  
  
  CONCLUSIONS
  Compared with nonaffected hands, the proximal cross-sectional areas of the median nerve and carpal tunnel were greater, but the distal ultrasonographic measurements were not in affected hands. Ultrasonographic findings of carpal tunnel syndrome were different according to sex.
authors.affiliation: Department of Rehabilitation Medicine, National Health Insurance Corporation Ilsan Hospital, Gyeonggi-do, Republic of Korea.
authors.forename: Hyoung Seop
authors.initials: HS
authors.lastname: Kim
authors.forename: Seung Ho
authors.initials: SH
authors.lastname: Joo
authors.forename: Hyong Keun
authors.initials: HK
authors.lastname: Cho
authors.forename: Yong Wook
authors.initials: YW
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002349:Carpal Tunnel Syndrome / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000000981:diagnostic imaging* / Q000473:pathology; D008875:Middle Aged; D014463:Ultrasonography
keywords: BMI; CSA; CTS; Carpal tunnel syndrome; EMG; Median nerve; Rehabilitation; US; Ultrasonography; body mass index; carpal tunnel syndrome; cross-sectional area; electromyography; ultrasonography