Better palpation of pain: Reliability and validity of a new pressure pain protocol in TMD

The purpose of this research was to employ a double-blind placebo control d esign of iontophoretically administered lidocaine to assess the test-retest reliability and validity of a magnitude matching procedure using a pressur e algometer. In studies in the literature on assessment of pain in temporom andibular disorders (TMD), the pressure algometer has been found to be a re liable means of measuring pressure-pain threshold and a sensitive measure o f treatment-response in the laboratory. However, previous research with thi s apparatus has not employed more sophisticated psychophysics. This study e mploys a magnitude matching psychophysical protocol to obtain a multidimens ional pain report. Test-retest reliability over two occasions, 3-8 days apa rt, was found to be moderate for discriminability ((r) under bar = .71, (p) under bar < .01) but poor for response bias (r = .44). The validity study used iontophoresis as an anesthetic in a double-blind placebo and no-treatm ent control design. Although it was hypothesized that subjects in the anest hesia group would demonstrate reduced discriminability as compared with the control groups, no differences were found among the three groups on this m easure. However, differences in response bias were found, with both the pla cebo control and no-treatment control groups differing from the experimenta l group but not from each other. Possible explanations and the implications of these findings are discussed.