Experimental pain can elevate vibrotactile threshold, a phenomenon attributed in the literature to the operation of a ‘touch gate.’ It is not known, however, whether clinical pain produces similar effects. To explore this possibility, we measured vibrotactile threshold in patients with temporomandibular disorders (TMD) whose pain had a prominent myalgic component. Two-interval forced-choice tracking was used to determine threshold for a 25-Hz vibratory stimulus presented on the cheek. Threshold was found to be significantly elevated in the TMD group, compared to an age- and gender-matched control group of pain-free individuals. Within the TMD group, those with a supra-median level of muscle tenderness (corrected for background levels of spontaneous pain) had significantly higher threshold than those with lower levels of palpation pain. These findings are consistent with the idea of a touch gate, and suggest the usefulness of further research in this area with clinical pain populations. The effects of an adapting stimulus (25 Hz, 20 dB SL) were also studied, and found to produce parallel elevations in vibrotactile threshold in the TMD and pain-free groups. This result indicates that at least some adaptation occurs at a higher (subsequent) level of somatosensory information processing than does the touch gating implied by the unadapted thresholds.
*Corresponding author: Dr Mark Hollins, Department of Psychology, C.B. #3270, Davie Hall, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. Tel.: (919) 962-2441; Fax: (919) 962-2537.
1Present address: Department of Psychology, Bennett College, Greensboro, NC 27401, USA.
Submitted August 16, 1995; revised January 26, 1996; accepted January 30, 1996.
© Lippincott-Raven Publishers.