Chronic pain syndromes.

Chronic pain has traditionally been defined as pain lasting more than three to six months. Many conditions in rheumatology can produce chronic pain. These include diseases such as rheumatoid arthritis and osteoarthritis. Pain in these conditions can usually be attributed to specific pathological mechanisms such as inflammatory synovitis or joint destruction. Effective treatment modalities are available to relieve some, if not most, of the pain in these situations. Over the past two decades or so, more attention has been given to previously existing conditions, now redefined as syndromes, that produce chronic musculoskeletal pain but in which the underlying pathophysiological mechanisms responsible for the pain have not been elucidated. These conditions have been arbitrarily divided into those causing diffuse versus regional pain. Fibromyalgia is by far the most common chronic diffuse musculoskeletal pain syndrome seen by rheumatologists. Myofascial pain syndromes (MPS) and repetitive strain syndromes (RSS) represent examples of chronic regional pain syndromes. These diffuse and regional pain syndromes have many features in common including the absence of an identifiable organic cause, behavioural maladaptations to pain, and much overlap in symptoms and signs (table). The purpose of this article is to review some of the recent concepts and controversies related to these three syndromes.