Musculoskeletal pain is the one of the most common reasons for medical consultations in the community. Nonarticular rheumatic pain syndromes (eg, tendinitis, bursitis, enthesitis, or muscular tear) constitute a major proportion of these consultations. In most cases, these conditions are self-limited and respond to treatment.
Diffuse pain may be caused by inflammatory and noninflammatory conditions. Polymyalgia rheumatica (see Chapter 30), rheumatoid arthritis (see Chapter 15), and systemic lupus erythematosus (see Chapter 21) are common causes of diffuse inflammatory pain, while fibromyalgia and primary generalized osteoarthritis (see Chapter 43) are common causes of noninflammatory diffuse pain. Both inflammatory and noninflammatory diffuse pain conditions sometimes occur in the same patient, causing confusion in diagnosis and treatment. Because inflammatory conditions are covered elsewhere in this book, fibromyalgia is the main focus of this chapter.
Although some experts argue that fibromyalgia is not a distinct disease entity and that labeling patients with the diagnosis encourages chronic illness behavior and increases healthcare consumption, data from the General Practice Research Database has shown this premise to be false. The General Practice Research Database has collected information from over 750 practices, with more than 3 million patients and 35 million patient years of data. Based on this data, a 2006 study showed that healthcare utilization among fibromyalgia patients was already very high in the 8 years preceding the diagnosis. Furthermore, healthcare utilization decreased after diagnosis, indicating that the diagnosis could be used constructively to reassure and educate patients.
- Diffuse pain for longer than 3 months. Pain is defined as above and below the waist bilaterally; axial skeletal pain must also be present.
- Increased tenderness to light pressure (allodynia).
- Fatigue and nonrestorative sleep.
- Depression and anxiety disorders are common, but mood disorder is not universal and response to antidepressants is independent of any change in mood.
Fibromyalgia is one of the most common causes of chronic diffuse pain. It is associated with increased tenderness to light pressure (allodynia). Although the term fibromyalgia has only been used in the last 2 decades, it is not a new disease. In 1850, Froriep described hard places in the muscles of patients with “rheumatism” that were painful to light touch. Gowers used the term fibrositis to describe patients who complained of tenderness with light pressure in the absence of any signs of local or systemic inflammation. Subsequently, fibrositis was found to be a common cause of muscular pain, although many clinicians considered it as “psychogenic rheumatism.”
Patients with fibromyalgia have altered pain processing compared to normal individuals. This includes greater subjective pain, decreased pain threshold, increased pain ratings, and a steeper rise of response to repeated stimulation. These abnormalities have been attributed to an underlying central sensitization. Central sensitization is a term denoting a state of enhanced, or amplified, neural processing within the central nervous system. The normal physiologic role of central sensitization ...