Fibromyalgia and myofascial pain (MP) are among the most common musculoskeletal disorders from which older adults suffer. These disorders represent opposite ends of the pain spectrum with the discrete character of MP at one extreme and the widespread symptoms of fibromyalgia at the other. MP may be acute or chronic, and is associated with taut muscle bands and hypersensitive areas called trigger points. Fibromyalgia syndrome includes symptoms of sleep disruption, fatigue, and psychological distress in addition to widespread pain. Both fibromyalgia and MP syndromes may result in significant functional impairment and cause suffering and disability comparable to that of rheumatoid arthritis and osteoarthritis. Diagnosis of these disorders is grounded in appropriately targeted history and physical examination; these are the tools required to avoid unnecessary ordering of “diagnostic” tests and foster implementation of appropriate management strategies.
Definition and Epidemiology
While a number of fibromyalgia classification criteria have been proposed, the criteria developed by the American College of Rheumatology are used most commonly. These criteria, which are 81% sensitive and 88% specific, allow fibromyalgia patients to be distinguished from patients with widespread pain caused by other rheumatological disorders (e.g., systemic lupus erythematosus, rheumatoid arthritis). They include a history of generalized body pain (i.e., pain in at least three of four body quadrants) for at least 3 months duration and at least 11 out of 18 specific tender points on physical examination. Although initially developed for classification of fibromyalgia, practitioners tend to regard them as required for diagnosis, although this is not accurate. Older adults who present with widespread pain and other supportive clinical features (see below) should be considered to have fibromyalgia even if they do not precisely fulfill the ACR criteria. These criteria are best used as a general guide and to allow for study enrollment, not for strict use in the office setting.
The incidence of fibromyalgia syndrome (the proportion of new cases or first ever episodes) is difficult to measure in part because symptoms seem to ebb and flow over time. According to five large population studies, approximately 10% of the population has widespread pain. Of those with widespread body pain, approximately 2% meet ACR diagnostic criteria for fibromyalgia. Women are four to seven times as likely to have fibromyalgia compared to men, with the greatest prevalence in those 60 to 79 years of age. Patients with fibromyalgia also have been estimated to have a two- to sevenfold greater risk of suffering from depression, anxiety, headache, irritable bowel syndrome, chronic fatigue syndrome, systemic lupus erythematosus, and rheumatoid arthritis compared to healthy individuals.
While recent studies have added to our understanding of the pathogenesis of fibromyalgia, the exact cause is still unknown. Most studies suggest that abnormal central nervous system pain processing, known as central sensitization, plays a key role in fibromyalgia pathogenesis. Abnormal peripheral pain processing, peripheral sensitization, also contributes to fibromyalgia pathogenesis. The cause of sensitization is ...