Masticatory muscle pain: a review of clinical features, research findings and possible mechanisms.
A review of chronic muscle pain is presented. The clinical features of various chronic muscle pain problems in the jaw region are discussed. Additionally, some of the objective findings of experimental studies which have utilized an acute experimental pain model (isometric contraction) in the jaw system are discussed. Some theories elucidated to explain chronic muscle pain are reviewed with emphasis on the possible role of the sympathetic nervous system which controls intramuscular blood flow. Blood flow studies are one way to evaluate post-contraction recovery of muscle to see if differences exist in subjects with or without chronic muscle pain. Methods to evaluate intramuscular blood flow during muscle contractions and some recent work looking at this issue are discussed. At present, a satisfactory model for evaluating chronic muscle pain has not been developed.