Current Understanding of Fibromyalgia: Diagnosis, Treatment, and Theories About Causes

Abstract

Fibromyalgia (FM) is a challenge to clinicians and patients because of its constellation of symptoms that are frequently shared with other chronic pain conditions, and the lack of a definitive diagnostic test or known cause. This article reviews the epidemiology, diagnostic issues and criteria, conventional and complementary and alternative medicine (CAM) therapies used to treat FM, the evidence base for CAM therapies, and theories of the causes of this complex disorder that affects the health-related quality of life (HRQoL) of millions of patients. Historical Background and EpidemiologyDerived from the Latin term for fibrous tissue (fibro) plus the Greek terms for muscle (myo) and pain (algia), FM is a disorder of unknown etiology characterized by chronic widespread pain and fatigue. 1 Symptoms may also include sleep disturbances, morning stiffness, cognitive problems, and depression. Although FM is often considered a rheumatic condition like arthritis, FM does not cause inflammation of-or damage to-the joints, muscles, or other tissues. The syndrome was called "fibrositis" prior to the mid-1970s. 2 The first controlled clinical study validating the symptoms of FM was published in 1981. The idea that FM was interconnected with similar conditions was also proposed in the 1980s. The American College of Rheumatology (ACR) published its first diagnostic criteria for FM in 1990, which were later revised.Recent estimates put the prevalence of FM in the United States as ranging from 2% to 8% of the population, second only to osteoarthritis (OA) as the most common "rheumatic" disorder. 3 The prevalence is similar in many other countries. The majority of patients affected are women, although FM can also affect men and children. Diagnostic Issues and CriteriaThere is currently no diagnostic test specifically for FM. In addition, many patients experience symptoms that also characterize other chronic pain disorders, including chronic fatigue syndrome, irritable bowel syndrome (IBS), temporomandibular disorders, and migraine. American College of Rheumatology CriteriaThe ACR developed criteria for classifying FM in 1990; this classification focused on tenderness upon pressure in at least 11 of 18 tender-point sites, in conjunction with widespread pain-defined as pain in 3 of the 4 quadrants of the body. No distinction was found between the diagnoses of primary and secondary FM, so the use of these terms was abandoned. 4 The ACR criteria accelerated research on FM, but were revised in 2010 in response to issues raised regarding the necessity of a tender-point-examination, lack of consideration of nonpain symptoms, and the observation that FM might represent the extreme end of a pain spectrum. 5 Daniel J. Clauw, MD-a professor of anesthesiology, medicine (rheumatology), and psychiatry at the University of Michigan in Ann Arbor, and director of the university's Chronic Pain and Fatigue Research Center-is among researchers who questioned the clinical utility of the ACR's emphasis on tender points in diagnosing FM. 6 Dr. Clauw com...