title: A comparison of the accuracy of ulnar versus median nerve stimulation for neuromuscular monitoring.
abstract: BACKGROUND
  Inexperienced anesthesiologists are frequently unclear as to whether to stimulate the ulnar or median nerve to monitor the adductor pollicis. The primary purpose of this study was to determine whether monitoring the adductor pollicis by positioning the stimulating electrodes over the median nerve is an acceptable alternative to applying electrodes over the ulnar nerve.
  
  
  METHODS
  In 20 patients anesthetized with propofol and remifentanil, one pair of stimulating electrodes was positioned over the ulnar nerve. A second pair was placed over the median nerve on the other hand. The acceleromyographic response was monitored on both hands. Rocuronium 0.6 mg/kg was administered. Single twitch (ST) and train-of-four (TOF) stimulations were applied alternatively to both sites.
  
  
  RESULTS
  None of the patients showed a twitch response at either site after injection of rocuronium. There were no differences in the mean supramaximal threshold, mean initial TOF ratio, or mean initial ST ratio between the two sites. Bland-Altman analysis revealed a bias (limit of agreement) in the TOF and ST ratios over the median nerve of 7% (± 31%) and 26% (± 73%), respectively, as compared with the ulnar nerve. The median nerve TOF ratio was overestimated by 16.2%, as compared with that of the ulnar nerve value, and the median nerve ST ratio was overestimated by 72.9%, as compared to that of the ulnar nerve.
  
  
  CONCLUSIONS
  The ulnar and median nerves cannot be used interchangeably for accurate neuromuscular monitoring.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Hanyang University Hospital, Seoul, Korea.
authors.forename: Hee Jong
authors.initials: HJ
authors.lastname: Lee
authors.forename: Kyo Sang
authors.initials: KS
authors.lastname: Kim
authors.forename: Jae Chul
authors.initials: JC
authors.lastname: Shim
authors.forename: Sung Wook
authors.initials: SW
authors.lastname: Yoon