title: Ultrasonographic reference sizes of the median and ulnar nerves and the cervical nerve roots in healthy Japanese adults.
abstract: The objective of this study was to identify, for practical use, ultrasonographic reference values for nerve sizes at multiple sites, including entrapment and non-entrapment sites along the median and ulnar nerves and among the cervical nerve roots. We verified reliable sites and site-based differences between the reference values. In addition, we found associations between the reference nerve sizes and several physical characteristics (gender, dominant hand, age, height, weight, body mass index [BMI] and wrist circumference). Nerves were measured bilaterally at 26 sites or levels in 60 healthy Japanese adults (29 males; age, 35.4 ± 9.7 y; BMI, 22.3 ± 3.6 kg/m(2); wrist circumference, 16.0 ± 1.3 cm on the right side and 15.9 ± 1.2 cm on the left side). The mean reference nerve sizes were 5.6-9.1 mm(2) along the median nerve, 4.1-6.7 mm(2) along the ulnar nerve and 2.14-3.39 mm among the cervical nerve roots. Multifactorial regression analyses revealed that the physical characteristics most strongly associated with nerve size were age, BMI and wrist circumference at the entrapment sites (F = 7.6, p < 0.01, at the pisiform bone level of the carpal tunnel; F = 15.1, p < 0.001, at the level of Guyon's canal), as well as wrist circumference and gender at the non-entrapment sites (F = 70.6, p < 0.001, along the median nerve; F = 24.7, p < 0.001, along the ulnar nerve). Our results suggest that the factors with the greatest influence on nerve size differed between entrapment and non-entrapment sites. Site-based differences in nerve size were determined using one-way analyses of variance (p < 0.001). Intra- and inter-observer reliability was highest for the median nerve, at both the distal wrist crease and mid-humerus; at the arterial split along the ulnar nerve; and at the fifth cervical nerve root level. No systematic error was indicated by Bland-Altman analysis; the coefficients of variation were 5.5%-9.2% for intra-observer reliability and 7.1%-8.7% for inter-observer reliability.
authors.affiliation: Department of Clinical Neuroscience and Therapeutics, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan. sugitkmc@hiroshima-u.ac.jp
authors.forename: Takamichi
authors.initials: T
authors.lastname: Sugimoto
authors.forename: Kazuhide
authors.initials: K
authors.lastname: Ochi
authors.forename: Naohisa
authors.initials: N
authors.lastname: Hosomi
authors.forename: Tomoya
authors.initials: T
authors.lastname: Mukai
authors.forename: Hiroki
authors.initials: H
authors.lastname: Ueno
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Takahashi
authors.forename: Toshiho
authors.initials: T
authors.lastname: Ohtsuki
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Kohriyama
authors.forename: Masayasu
authors.initials: M
authors.lastname: Matsumoto
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008475:Median Nerve / Q000000981:diagnostic imaging*; D008875:Middle Aged; D009333:Neck / Q000000981:diagnostic imaging / Q000294:innervation; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013126:Spinal Nerve Roots / Q000000981:diagnostic imaging*; D014459:Ulnar Nerve / Q000000981:diagnostic imaging*; D014463:Ultrasonography / Q000592:standards* / Q000706:statistics & numerical data*; D055815:Young Adult
keywords: Cervical nerve root; Median nerve; Reliability; Ulnar nerve; Ultrasonography