Long-term fluctuations of pressure pain thresholds in healthy men, normally menstruating women and oral contraceptive users

The aim of this investigation was to evaluate whether the pressure pain thr eshold (PPT) in masticatory muscles of symptom-free subjects was influenced by fluctuations of the sex hormones. The PPT was measured with an electron ic algometer for at least 10 consecutive menstrual cycles in 10 women using oral contraceptives and 10 women not using oral contraceptives, with a reg ular menstrual cycle (26-31 days). In addition, 10 men were measured in a r egular pattern over a period of I year. All subjects were symptom-free with an age range between 18 and 39 years. Measurement sessions were held durin g three different cycle phases (follicular, luteal, perimenstrual) and each session consisted of four consecutive PPT measurements. By means of a line ar mixed model (SAS), the PPTs of the masster, temporalis and thumb muscles were compared between: (1) groups, (2) sex-hormonal phases, (3) the Four c onsecutive measurements of each muscle per session and (4) time. The PPTs o f the masseter (p=0.8419) and temporalis muscles (p=0.2786) did not change significantly over time. There was no significant difference in variance fo r the masseter (p=0.6250), temporalis (p=0.9705) and thumb (p=0.7446) betwe en the three groups. The PPTs of all muscles were significantly lower durin g the perimenstrual phases in the two female groups. The present data showe d similar patterns of PPTs for the three muscle groups. Moreover, the resul ts have shown a very good consistency of the PPTs over a long time period, both in males and females. (C) 2001 European Federation of Chapters of the International Association for the Study of Pain.