Cardiovascular responses to and modulation of pressure pain sensitivity in normotensive, pain-free women

Background and purposeThe psychophysiological responses to and modulation of pressure pain stimulation are relatively new areas of investigation. The aims of the present study were to characterize subjective and cardiovascular (CV) responses to pressure pain stimulation, and to examine the relationship between CV responding and pain pressure pain sensitivity.MethodsThirty-nine pain-free, normotensive women were included in the study and tested during the follicular phase of their menstrual cycles. Pain threshold and tolerance were recorded at the right masseter muscle and the sternum, and visual analogue scales (VAS) were used to rate both pain intensity (the sensory dimension) and discomfort (the affective dimension). Mean arterial pressure (MAP), heart rate (HR), and facial and digital skin blood flux (SBF) were registered continuously.ResultsThe pain threshold and tolerance were significantly higher at the sternum compared with the masseter, but the level of affective distress was higher at the masseter tolerance point. No associations emerged between pressure pain threshold and tolerance stimulation levels, and the corresponding VAS ratings. Pressure pain stimulation of the masseter induced significant increases in MAP, HR, and a decrease in digital SBF. During sternum pressure stimulation a significant change in HR and digital SBF was observed. There were no significant correlations between CV responding and pressure pain sensitivity.ConclusionHealthy women seem to display higher pressure pain sensitivity at the masseter region relative to the sternum. Pressure pain stimulation was associated with significant changes in MAP, HR, and SBF, but was not modulated by CV responses. The validity of these findings is strengthened by our control for menstrual cycle events, weekend-related changes in physiology, and CV changes during pain stimulation.ImplicationsThis study extends previous reports of SBF sensitivity to electrocutaneous pain into the field of pressure stimulation. Moreover, this study suggests that the often demonstrated association between high BP and low pain sensitivity may not apply to pressure pain specifically. Alternatively, this finding adds to the literature of gender differences in the relationship between CV responding and acute pain sensitivity in general.

► Pressure pain sensitivity was higher over the masseter than over the sternum region.
► There were no relationship between pain sensitivity and subjective response.
► Orofacial pressure pain generated increased mean arterial pressure and heart rate and decreased digital skin blood flux (SBF).
► Sternum pressure pain generated increased HR and decreased digital SBF.
► No relationship was found between blood pressure increases and pain sensitivity.