title: Reproducibility of current perception threshold with the Neurometer(®) vs the Stimpod NMS450 peripheral nerve stimulator in healthy volunteers: an observational study.
abstract: OBJECTIVE
  Current methods of assessing nerve blocks, such as loss of perception to cold sensation, are subjective at best. Transcutaneous nerve stimulation is an alternative method that has previously been used to measure the current perception threshold (CPT) in individuals with neuropathic conditions, and various devices to measure CPT are commercially available. Nevertheless, the device must provide reproducible results to be used as an objective tool for assessing nerve blocks.
  
  
  METHODS
  We recruited ten healthy volunteers to examine CPT reproducibility using the Neurometer(®) and the Stimpod NMS450 peripheral nerve stimulator. Each subject's CPT was determined for the median (second digit) and ulnar (fifth digit) nerve sensory distributions on both hands - with the Neurometer at 5 Hz, 250 Hz, and 2000 Hz and with the Stimpod at pulse widths of 0.1 msec, 0.3 msec, 0.5 msec, and 1.0 msec, both at 5 Hz and 2 Hz. Intraclass correlation coefficients (ICC) were also calculated to assess reproducibility; acceptable ICCs were defined as ≥ 0.4.
  
  
  RESULTS
  The ICC values for the Stimpod ranged from 0.425-0.79, depending on pulse width, digit, and stimulation; ICCs for the Neurometer were 0.615 and 0.735 at 250 and 2,000 Hz, respectively. These values were considered acceptable; however, the Neurometer performed less efficiently at 5 Hz (ICCs for the second and fifth digits were 0.292 and 0.318, respectively).
  
  
  CONCLUSIONS
  Overall, the Stimpod device displayed good to excellent reproducibility in measuring CPT in healthy volunteers. The Neurometer displayed poor reproducibility at low frequency (5 Hz). These results suggest that peripheral nerve stimulators may be potential devices for measuring CPT to assess nerve blocks.
authors.affiliation: Department of Anesthesiology and Pain Medicine, University of Alberta, 8-120 Clinical Sciences Building, Edmonton, AB, T6G 2G3, Canada. btsui@ualberta.ca
authors.forename: Ban C H
authors.initials: BC
authors.lastname: Tsui
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Shakespeare
authors.forename: Danika H
authors.initials: DH
authors.lastname: Leung
authors.forename: Jeremy H
authors.initials: JH
authors.lastname: Tsui
authors.forename: Gareth N
authors.initials: GN
authors.lastname: Corry
mesh_terms: D000293:Adolescent; D000328:Adult; D004056:Differential Threshold / Q000502:physiology; D004558:Electric Stimulation / Q000295:instrumentation*; D004568:Electrodiagnosis / Q000295:instrumentation*; D005260:Female; D005385:Fingers / Q000294:innervation; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000502:physiology*; D008875:Middle Aged; D010865:Pilot Projects; D015203:Reproducibility of Results; D012677:Sensation / Q000502:physiology; D011984:Sensory Receptor Cells / Q000502:physiology; D012684:Sensory Thresholds / Q000502:physiology*; D014459:Ulnar Nerve / Q000502:physiology*; D055815:Young Adult