Cyclic Effects on Experimental Pain Response in Women with Temporomandibular Disorders

Aims: Since cyclic effects on experimental pain response in women with temporomandibular disorders (TMD) have not been adequately studied, the aim of this study was to assess variations in experimental pain response at 4 phases of the menstrual cycle. Methods: Eighteen normally cycling women with TMD, 25 women with TMD and taking oral contraceptives (OC), 25 normally cycling pain-free controls, and 26 pain-free controls taking OC underwent 3 experimental pain procedures at 4 phases during each of 3 menstrual cycles. These procedures included algometer palpations at fixed amounts of pressure and pressure pain thresholds at several body sites, and an ischemic arm pain task. Repeated measures analysis of variance was used to compare cycle phase, TMD group, and OC status differences in experimental pain response. Results: Significant phase-related differences were seen for palpation intensity measures (P values , .05). Normally cycling women with TMD showed higher palpation pain intensity at menses and midluteal phases, while women with TMD taking OC showed stable palpation pain intensity ratings at menses, ovulatory, and midluteal phases, with increased intensity at the late luteal phase. TMD subjects had greater palpation pain and ischemic pain intensity and lower pressure pain thresholds compared to controls. Conclusion: Phase-related differences in experimental pain response were not strong and were more often found for experimental stimuli with greater clinical relevance (ie, palpation pain) compared with an ischemic pain task. Keywords: experimental pain, menstrual cycle, temporomandibular disorders