Many studies report that people with temporomandibular disorders (TMD) are more sensitive to experimental pain stimuli than TMD-free controls. Such differences in sensitivity are observed in remote body sites as well as in the orofacial region, suggesting a generalized upregulation of nociceptive processing in TMD cases. This large case-control study of 185 adults with TMD and 1,633 TMD-free controls measured sensitivity to painful pressure, mechanical cutaneous, and heat stimuli, using multiple testing protocols. Based on an unprecedented 36 experimental pain measures, 28 showed statistically significantly greater pain sensitivity in TMD cases than controls. The largest effects were seen for pressure pain thresholds at multiple body sites and cutaneous mechanical pain threshold. The other mechanical cutaneous pain measures and many of the heat pain measures showed significant differences, but with lesser effect sizes. Principal component analysis (PCA) of the pain measures derived from 1,633 controls identified 5 components labeled: 1) heat pain ratings; 2) heat pain aftersensations and tolerance; 3) mechanical cutaneous pain sensitivity; 4) pressure pain thresholds; and 5) heat pain temporal summation. These results demonstrate that compared to TMD-free controls, chronic TMD cases are more sensitive to many experimental noxious stimuli at extracranial body sites, and provide for the first time the ability to directly compare the case-control effect sizes of a wide range of pain sensitivity measures.
This article describes experimental pain sensitivity differences between a large sample of people with chronic TMD and non-TMD controls, using multiple stimulus modalities and measures. Variability in the magnitude and consistency of case-control differences highlight the need to consider multiple testing measures to adequately assess pain processing alterations in chronic pain conditions.
Key words : QST, chronic facial pain, heat pain, pressure pain, mechanical pain
| Supported by NIH grant U01DE017018. This material was also supported by the North Florida/South Georgia Veterans Health System, Gainesville, FL. The OPPERA program also acknowledges resources specifically provided for this project by the respective host universities: University at Buffalo, University of Florida, University of Maryland-Baltimore, and University of North Carolina-Chapel Hill.
| Roger Fillingim and Gary Slade are consultants and equity stock holders, and William Maixner is a cofounder and equity stock holder in Algynomics, Inc., a company providing research services in personalized pain medication and diagnostics. Richard Ohrbach, Joel Greenspan, Charles Knott, Ronald Dubner, Eric Bair, Flora Mulkey and Rebecca Rothwell declare that they have no conflicts of interest. Portions of these data were presented at the 2010 Annual Scientific Meeting of the American Pain Society in Baltimore, MD.
| Supplementary data accompanying this article are available online at jpain.org and sciencedirect.com.