A Calibrated Paper Clip Is a Reliable Measure of Two‐point Discrimination

• Published in: Academic emergency medicine Vol. 11; no. 6; pp. 710 - 714
• Main Authors: Finnell, John T., Knopp, Robert, Johnson, Phelps, Holland, Patrick C., Schubert, Warren
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-06-2004
• Subjects: emergency medicine; hand injuries/physiopathology; hand/innervation; reproducibility of results; sensation disorders; sensory thresholds
• ISSN: 1069-6563; 1553-2712
• DOI: 10.1197/j.aem.2003.11.022

Objectives: The primary objective of this study was to compare two different instruments for assessing digital nerve function; a secondary aim was to determine interobserver agreement among emergency physicians by using static two‐point testing of digital nerve function. Methods:This was a prospective, blinded, observational study of static two‐point discrimination involving healthy volunteers aged 18–59 years. The authors compared two instruments (paper clip set or Disk‐Criminator) to assess two‐point discrimination of the index and long fingers of the dominant hand. For each subject, the initial investigator and initial testing instrument were randomized. Two‐point testing was conducted at 4, 5, and 6 mm by using six randomly selected stimuli (1 or 2 points) for each distal phalanx tested. The study was designed to detect a 25% difference in mean two‐point distance with a power of 80%. Results: Seventy‐five subjects were entered into the study, of which two were excluded. Interinstrument agreement for a given investigator ranged from 77% to 84% for absolute agreement and 98% to 100% within 2 mm. Weighted kappa values for interobserver differences of 2 mm or less was 0.79 to 1.00. There was no statistically significant difference between instruments. Conclusions: Using a clinically relevant threshold of 2 mm, the authors found that a properly calibrated set of paper clips performed as well as the Disk‐Criminator.