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Association Between Pain Sensitivity and Endogenous Supraspinal Pain Modulation in Patients with Orofacial Pain.

Address correspondence to: Dr. Carla S. Enriquez, Physical Therapy Program, Stockton University School of Health Sciences, 101 Vera King Farris Drive, Galloway, NJ 08205-9441, USA. Tel 609-626-3508, fax 609-652-4858. carla.enriquez@stockton.edu.


PURPOSE
To investigate the association between pain sensitivity and endogenous supraspinal pain modulation activity using quantitative sensory tests (QST) in patients with orofacial pain.


METHODS
Temporal summation (TS) testing and conditioned pain modulation (CPM) are QSTs used to quantify individual pain processing mechanisms. TS testing was used to assess pain sensitivity which correlates to central sensitization and CPM for endogenous pain modulation. These tests were administered to a convenience sample of patients with orofacial pain (n=40) seen for initial examination in an orofacial pain clinic. Bivariate correlation analyses were conducted on TS and CPM scores, including age and gender.


RESULTS
A strong linear correlation was found between pain sensitivity and endogenous pain modulation (r=0.69, p<0.001). QST outcomes suggest that inefficient endogenous pain modulation is positively correlated with the magnitude of pain sensitivity among individuals who seek treatment for orofacial pain. A weak linear correlation was also found between TS and age (r=0.37, p=0.02).


CONCLUSION
QSTs demonstrated a strong association between heightened pain sensitivity and inefficient endogenous pain modulation revealed from higher pain report on TS and CPM testing in patients with orofacial pain. Our findings provide supporting evidence on the impairments in pain-processing mechanisms that require consideration when evaluating orofacial pain etiology, where increased pain sensitivity and aberrant pain modulation appear to significantly contribute in prolonged and persistent pain experience.