Time of day influences psychophysical measures in women with burning mouth syndrome

Abstract

Burning mouth syndrome (BMS) is a chronic orofacial pain condition that mainly affects postmenopausal women. BMS type I patients report little to no spontaneous pain in the morning and increases in pain through the day, peaking in the afternoon. Quantitative sensory testing (QST) findings from BMS type 1 patients are inconsistent as they fail to capture this temporal variation. We examined how QST in BMS type 1 compared to healthy participants was affected by time of day. QST of the face and forearm included warmth detection threshold (WDT), cold detection threshold (CDT), and heat pain thresholds (HPT), ratings of suprathreshold heat, and pressure pain thresholds (PPT), and was performed twice: once in the morning and once in the afternoon. BMS patients reported: no differences in morning and afternoon comparisons of the orofacial region between groups and no differences in PPTs in either orofacial or arm regions between groups; lower within group PPTs of the masseter in the afternoon; higher WDTs, and lower CDTs of the forearm in the morning compared to healthy participants; lower CDTs and higher pain intensity ratings to heat stimuli at low temperatures on the forearm in the afternoon compared to healthy participants. The findings indicate that compared to healthy participants, BMS Type I patients had altered thermal sensitivity, which depended on body area tested (forearm vs orofacial region), and higher pain sensitivity, which was slightly more pronounced in the afternoon plausibly due to a hypervigilance.