Association Between Anxiety and Descending Pain Modulation of Thermal Stimuli in Patients with Burning Mouth Syndrome: A Cross-Sectional Study

Aims: To investigate the predictive power of depression and anxiety for conditioned pain modulation (CPM) and to examine the relationships of CPM at 40 degrees C and CPM at 47 degrees C with age, disease-related pain, pain duration, and psychosocial factors in burning mouth syndrome (BMS). Methods: A total of 22 patients with BMS and 22 healthy female controls participated in this study. Temporal summation was used as the test stimulus for CPM, and subsequent exposure either to a nonpainful (40 degrees C) or a painful (47 degrees C) Peltier thermode was used as the conditioning stimulus. CPM was calculated as the difference in pain perception following the conditioning stimulus. Psychosocial factors were examined using the Profile of Mood States (POMS) and the State-Trait Anxiety Inventory (STAI). Results: State anxiety and tension-anxiety scores were significantly higher for patients with BMS than for control participants. Multiple regression analyses showed that CPM47 degrees C was affected by vigor, fatigue, confusion, and trait anxiety (adjusted R-2 = 0.685, F = 5.147, P = .098). The corresponding analysis for CPM40 degrees C showed that the model was not predictive for the following variables: disease-related pain, pain duration, or components of the POMS or STAI. A significant positive correlation was found between CPM47 degrees C and trait anxiety, suggesting that trait anxiety negatively affected the endogenous pain modulation system. Conclusion: Increases in trait anxiety reduced the CPM effect. These findings suggest that CPM impairments and increases in trait anxiety are involved in the development of BMS.