Psychological stress affects chronic myofascial pain syndrome in the craniofacial region

Abstract

Purpose: To define the response of the sympathetic nerve activity that caused by psychological or physical stress in myofascial pain syndrome (MPS) patients.
Methods: This study examined 10 Japanese MPS patients suffering from chronic pain for over 6 months (MPS group) and 10 adult volunteers who served as the controls. In separate sessions conducted over one-week interval, subjects were exposed to psychological stress, visual stress, which was produced by the International Affective Picture System, or physical stress, which consisted of the active standing test. Changes of the sympathetic nerve activity were estimated by a spectral analysis of the heartbeat fluctuation using the Relax Meijin computer software (Crosswell Inc., Tokyo). The spectral components analyzed included low frequency power (L: power between 0.04 and 0.15 Hz), high frequency power (H: power between 0.15 and 0.4 Hz) and L/H, which is a tool that is used to assess autonomic cardiovascular regulation.
Results: In both groups, L/H during physical stress loading was significantly higher compared with baseline (P < 0.05). There were no differences between the control and MPS groups. During psychological stress loading, the L/H was significantly higher in the MPS versus the control group (P < 0.05).
Conclusions: There found psychological stress increases the sympathetic nerve activity responsible for the manifestation and continuation of MPS.