Fibromyalgia is a syndrome defined by chronic widespread pain of at least 3 months’ duration. It is a multisystem illness associated with neuropsychological symptoms including fatigue, stiffness, unrefreshing sleep, cognitive dysfunction, anxiety, and depression. The majority of patients are women, for whom fibromyalgia is six times more common than in men [1]. The prevalence of the condition increases with age and is greater than 7% in women older than 60 years [2].

A discrete etiology of fibromyalgia has not been identified. Available evidence implicates sensitization of the central and peripheral nervous systems as key in maintaining pain and other core symptoms of fibromyalgia [3–6]. There may be a role for genetics, as individuals with certain genotypes are more likely to develop chronic pain and an overall increased sensitivity to pain during their lifetimes. These genes include catecholamine methyltransferase, sodium and potassium channels, and a number of others. Environmental factors, such as physical or emotional trauma, and infection (e.g., Epstein-Barr virus, Lyme disease, parvovirus), may interact with genetic factors to facilitate the development of fibromyalgia [6].

According to the 2010 American College of Rheumatology preliminary diagnostic criteria for fibromyalgia and measurement of symptom severity, a patient must have a widespread pain index score of at least 7 and a symptom severity scale score of at least 5 or a widespread pain index score of at least 3 and a symptom severity scale score of at least 9. The scoring is based on number and severity of somatic symptoms. In addition, symptoms must be present at a similar level for at least 3 months, and the patient must not have another disorder that would otherwise explain the pain (Table 101.1). These criteria do not include a tender point examination, as previously described by the 1990 American College of Rheumatology diagnostic criteria [7].

Table 101.1

Widespread Pain Index and Symptom Severity Scale Scores

Widespread Pain Index (score 0-19, 1 point for each location)
Has the patient had pain in any of the following areas in the last week?
Shoulder girdle (left)	Neck	Upper arm (left)	Upper leg (left)	Hip (left)
Shoulder girdle (right)	Upper back	Upper arm (right)	Upper leg (right)	Hip (right)
Jaw (left)	Chest	Lower arm (left)	Lower leg (left)	Lower back
Jaw (right)	Abdomen	Lower arm (right)	Lower leg (right)
Symptom Severity Scale (score 0-12, total of specific symptoms plus general severity)
Specific symptoms: How severe have the following symptoms been during the last week?
(0 = no problem, 1 = slight/mild/intermittent, 2 = moderate/frequent, 3 = severe/pervasive/continuous) • Fatigue • Waking unrefreshed • Cognitive symptoms

Number of general somatic symptoms (0 = none, 1 = few, 2 = moderate, 3 = many)

t0010

Data from Wolfe F, Clauw DJ, Fitzcharles M, et al. The American College of Rheumatology preliminary diagnostic criteria for fibromyalgia and measurement of symptom severity. Arthritis Care Res 2010;62:600-610.

A patient must have a widespread pain index score of at least 7 and a symptom severity scale score of at least 5 or a widespread pain index score of at least 3 and a symptom severity scale score of at least 9.

Symptoms

Fibromyalgia is characterized by widespread and long-lasting pain (> 3 months) located above and below the waist, on both sides of the body. A series of other symptoms are frequently reported by patients. These include marked fatigue, stiffness, sleep disorders, cognitive disturbances (e.g., decreased comprehension, memory problems), anxiety, depression, temporomandibular joint syndrome, paresthesias, headache, genitourinary manifestations (e.g., pelvic or bladder pain), irritable bowel syndrome, and orthostatic intolerance [4].

Physical Examination

The findings of the general medical examination, including thorough joint inspection, should be normal. Blood pressure recording for orthostatic hypotension is performed. Mood and affect are noted.

The neurologic examination findings should also be largely normal but may demonstrate slight sensory or motor abnormalities [8]. By conducting a comprehensive neurologic and musculoskeletal examination, one may rule out superimposed pain generators, such as bursitis, tendinitis, radiculopathy, and myofascial trigger points.

Functional Limitations

Patients are limited in their daily activities and exercise tolerance by both pain and fatigue. Patients also report cognitive dysfunction with difficulty in concentration, organization, and motivation. This has been termed “fibro fog.” Approximately 25% of patients with fibromyalgia report themselves disabled and are collecting some form of disability payment. Individuals are more likely to become disabled if they report higher pain scores, work at a job that requires heavy physical labor, have poor coping strategies and feel helpless, or are involved in litigation [9–11].