Pain modulation and gender differences

Abstract

The thesis Pain modulation and gender differences consist of two parts; first, an introduction to the study which provides detailed theoretical information on the topic in a larger context, and second, the article Inhibition of electrically induced Tibialis anterior pain is inhibited by painful and non painful conditioning which give an thorough presentation of methodology and results. The thesis describes an experimental pain study, conducted at the National institute of Occupational health in Oslo. The experiment was designed to test the pain inhibitory system in men and women, focusing on the following questions: - Is electrically induced muscle pain inhibited by a conditioning heat pain stimulus? - Do women show signs of reduced inhibition compared to men? A conditioned pain modulation (CPM) model was used in the experiment, where the experimental setup included both a painful and a non painful session. A total of 40 healthy volunteers (50% women) participated. Electrical muscle pain was induced in Tibialis anterior and heat pain was induced on the opposite forearm. The inhibitory effect was measured from the participants' subjective responses using a visual analogue scale (VAS). Statistical analyses were performed in SPSS by the use of independent samples t-test and RM ANOVA respectively. The analyses showed no CPM effect, but revealed that painful and non-painful conditioning reduced the pain experience among both women and men. The thesis discusses several methodological concerns related to the results and what consequences this might have had for gender differences in previous CPM studies. Finally, the conclusion emphasize the importance of attention in CPM studies and the significance of considering sex hormones when studying gender differences in pain.