title: Interexaminer variance of median nerve compound muscle action potential measurements in hand position with and without fixation in plaster.
abstract: OBJECTIVE
  We examined how hand fixation affects interexaminer variance in measuring compound muscle action potential (CMAP) during nerve conduction studies of the median nerve.
  
  
  METHODS
  Subjects comprised 6 experienced examiners [1 woman and 5 men; mean (SD) age, 38.3 +/- 8.5 years; range, 28-46 years]. The standardized median nerve motor conduction setting was used for electromyography. The mean of 5 serial stimulations was taken as 1 examination for each subject. Distal latency, conduction velocity, and peak-to-peak amplitude of CMAP were measured as parameters. Subjects were examined without hand fixation and with hands fixed in prepared plaster molds.
  
  
  RESULTS
  Fixation yielded significantly decreased coefficient of variance for CMAP amplitude (5.0% +/- 3.4%) compared with measurement without fixation (8.4% +/- 3.7%; P = 0.028). No differences in distal latencies or conduction velocities were evident between fixation and nonfixation.
  
  
  CONCLUSIONS
  This study provides quantitative evidence for empirical observations that hand fixation might decrease CMAP variability in median nerve studies.
authors.affiliation: Clinical Neurophysiology Unit, Matsusaka Chuo Hospital, Matsusaka, Mie, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Higuchi
authors.forename: Yugo
authors.initials: Y
authors.lastname: Narita
authors.forename: Shigeki
authors.initials: S
authors.lastname: Kuzuhara
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000328:Adult; D002370:Casts, Surgical; D004558:Electric Stimulation; D004576:Electromyography; D005260:Female; D006225:Hand / Q000294:innervation* / Q000502:physiology; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000502:physiology*; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000294:innervation* / Q000502:physiology; D009431:Neural Conduction / Q000502:physiology*; D015588:Observer Variation; D011187:Posture / Q000502:physiology; D011237:Predictive Value of Tests; D016059:Range of Motion, Articular / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D015203:Reproducibility of Results; D012149:Restraint, Physical; D014955:Wrist Joint / Q000502:physiology