ESSENTIALS OF DIAGNOSIS
Most frequent in women aged 20–50.
Chronic widespread musculoskeletal pain syndrome with multiple tender points.
Fatigue, headaches, numbness common.
Objective signs of inflammation absent; laboratory studies normal.
Fibromyalgia is a common syndrome, affecting 3–10% of the general population. It shares many features with myalgic encephalomyelitis/chronic fatigue syndrome, namely, an increased frequency among women aged 20–50, absence of objective findings, and absence of diagnostic laboratory test results. While many of the clinical features of the two conditions overlap, musculoskeletal pain predominates in fibromyalgia whereas lassitude dominates myalgic encephalomyelitis/chronic fatigue syndrome.
The cause is unknown, but aberrant perception of painful stimuli, sleep disorders, depression, and viral infections have all been proposed. Fibromyalgia can be a complication of hypothyroidism, rheumatoid arthritis, or, in men, sleep apnea.
The patient complains of chronic aching pain and stiffness, frequently involving the entire body but with prominence of pain around the neck, shoulders, low back, and hips. Fatigue, sleep disorders, subjective numbness, chronic headaches, and irritable bowel symptoms are common. Even minor exertion aggravates pain and increases fatigue. Physical examination is normal except for “trigger points” of pain produced by palpation of various areas such as the trapezius, the medial fat pad of the knee, and the lateral epicondyle of the elbow.
Fibromyalgia is a diagnosis of exclusion. A detailed history and repeated physical examination can obviate the need for extensive laboratory testing. Rheumatoid arthritis and SLE present with objective physical findings or abnormalities on routine testing. Thyroid function tests are useful, since hypothyroidism can produce a secondary fibromyalgia syndrome. Polymyositis produces weakness rather than pain. The diagnosis of fibromyalgia should be made hesitantly in a patient over age 50 and should never be invoked to explain fever, weight loss, or any other objective signs. Polymyalgia rheumatica produces shoulder and pelvic girdle pain, is associated with anemia and an elevated ESR, and occurs after age 50. Hypophosphatemic states, such as oncogenic osteomalacia, can cause musculoskeletal pain unassociated with physical findings. In contrast to fibromyalgia, oncogenic osteomalacia usually produces pain in only a few areas and is associated with a low serum phosphate level.
A multidisciplinary approach is most effective. Patient education is essential. Patients can be comforted that they have a diagnosable syndrome treatable by specific though imperfect therapies and that the course is not progressive. Cognitive behavioral therapy, including programs that emphasize mindfulness meditation, is often helpful. Exercise programs are also beneficial, particularly tai chi and yoga. The following medications have shown modest efficacy: amitriptyline, fluoxetine, duloxetine, milnacipran, cyclobenzaprine, pregabalin, gabapentin, or low-dose naltrexone. Tramadol and acetaminophen combinations have ameliorated symptoms modestly in short-term trials. Less than 50% of the patients experience a sustained improvement. NSAIDs are generally ineffective. Opioids and corticosteroids are ineffective and should not be used to treat fibromyalgia.