Tender points: evolution of concepts of the fibrositis/fibromyalgia syndrome.

The association of chronic pain, exhaustion, and multiple somatic complaints with apparent physical good health and long survival has a long history. The syndrome was called by many names including neuresthenia, rheumatism, and invalidism. When skeletal pain and stiffness were prominent, many observers recorded the existence of sites of tenderness and sometimes of areas of induration. The work of Lewis and Kellgren provided an experimentally reproducible method of study of the phenomena of referred pain and referred tenderness, which led to hypotheses about the nature of many of these syndromes, which were unfortunately too numerous and often contradictory. More recently, it has been learned that the sites of tenderness are precisely predictable in location and, under some circumstances, experimentally inducible. They are unknown to the patient and, therefore, due to mechanisms other than distortions of interpretation. The association with a variety of forms of sleep disturbance was discovered. These events have permitted the rapid evolution of controlled, numerical studies of these associations, which are reviewed briefly in this article.