Fibromyalgia (FM) is a common cause of chronic musculoskeletal pain. It is one of a group of soft tissue pain disorders that affect muscles and soft tissues such as tendons and ligaments. None of these conditions is associated with tissue inflammation and the etiology of the pain is not known.Fibromyalgia, like other functional somatic syndromes, has been a controversial illness. Patients look well, there are no obvious abnormalities on physical examination, and laboratory and radiologic studies are normal. Thus, the role of organic illness has been questioned, and fibromyalgia has often been considered to be psychogenic or psychosomatic. Current pathophysiologic concepts focus on alterations in central nervous system pain processing.
Fibromyalgia (FM), was initially termed fibrositis; FM is now considered to be the most common cause of generalized, musculoskeletal pain in women between ages of 20 and 55 years; in the United States and in other countries, the prevalence is approximately 2 percent and increases with age. Fibromyalgia is six times more common in females in reports from specialty clinics, although the female predominance is not as striking in the community.
FM is characterized by widespread musculoskeletal pain and fatigue, and often by cognitive and mood disturbances. Physical examination reveals tenderness in multiple specific anatomic locations. Laboratory testing is normal in the absence of other illnesses. The cardinal manifestation of fibromyalgia is widespread musculoskeletal pain, involving both sides of the body and above and below the waist. However, the pain may initially be localized, often in the neck and shoulders. Common patient descriptions include "I feel as if I hurt all over", or "it feels as if I always have the flu." Patients typically describe pain predominantly throughout the muscles, but often state that their joints hurt, and sometimes describe joint swelling, although synovitis is not present on examination.
Patients also often report paresthesias, including numbness, tingling, burning, or creeping or crawling sensations, especially in both arms and both legs. However, unless a concurrent neurologic disorder, such as carpal tunnel syndrome or a cervical radiculopathy, is present, a detailed neurologic evaluation or formal testing is usually unremarkable.
The other universal symptom of FM is fatigue. This is especially notable when arising from sleep, but is also marked in the mid-afternoon. Seemingly minor activities aggravate the pain and fatigue, although prolonged inactivity also heightens symptoms. Patients are stiff in the morning and feel unrefreshed, even if they have slept 8 to 10 hours. Patients with FM characteristically sleep "lightly", waking frequently during the early morning and have difficulty getting back to sleep. A common quote is "No matter how much sleep I get, it feels like a truck ran me over in the morning". Cognitive and mood disturbances are present in the majority of patients. The cognitive disturbances are often referred to as "fibro fog". Patients typically describe problems with attention and difficulty doing tasks that require rapid thought changes. Neuropsychological testing reveals abnormalities that are somewhat different than those found in mood disturbances. Depression and/or anxiety are present in 30 to 50 percent of patients at the time of diagnosis. Headaches are present in more than 50 percent and include migraine and muscular (tension) types.
Patients also may have a variety of poorly understood pain symptoms, including abdominal and chest wall pain and symptoms suggestive of irritable bowel syndrome, pelvic pain and bladder symptoms of frequency and urgency suggestive of the interstitial cystitis/painful bladder syndrome, formerly female urethral syndrome. Other common complaints include ocular dryness, multiple chemical sensitivity and "allergic" symptoms, palpitations, dyspnea, vulvodynia, dysmenorrhea, sexual dysfunction, weight fluctuations, night sweats, dysphagia, dysgeusia, and orthostatic intolerance. In patients with fibromyalgia, the only reproducible finding on physical examination is tenderness in specific anatomic locations. The tender point examination requires that the examiner knows where to palpate and how much pressure to apply. In an attempt to provide some homogeneity in patient populations in clinical studies, various classification criteria for fibromyalgia have been developed and tested. The final 1990 ACR FM classification criteria included:
- Symptoms of widespread pain, both above and below the waist, and affecting both the right and left sides of the body.
- Physical findings of at least 11 of 18 tender points.
These simple criteria had greater than 85 percent sensitivity and specificity for differentiating patients with fibromyalgia from those with other rheumatic diseases. We diagnose fibromyalgia even if fewer than 11 of 18 tender points are present, provided the history is consistent with FM and the major differential diagnoses have been excluded. The tender points represent heightened pain perception rather than sites of inflammation or tissue pathology. Thus, they are proxies for pain, and the exact number necessary to diagnose fibromyalgia clinically is somewhat arbitrary. It is important to recognize that the classification criteria were validated for large patient populations and should be used primarily in clinical research and epidemiologic studies of fibromyalgia. FM does not cause any abnormalities in laboratory testing or imaging. Thus, any testing is done primarily to exclude an associated disease or another illness that may mimic FM.
Patients with fibromyalgia generally respond best to a multidisciplinary, individualized treatment program that incorporates physician as well as non-physician providers. This includes a team of physical medicine, rehabilitation, and mental health specialists.
The myofascial pain syndrome may be a localized form of fibromyalgia. Patients with this disorder complain of pain in one anatomic region, such as the right side of the neck and shoulder, and tenderness is confined to that area. There also appears to be a close relationship between the chronic fatigue syndrome and fibromyalgia. Diagnostic criteria for the classification of chronic fatigue syndrome (CFS) are similar to those for fibromyalgia, and the majority of patients with CFS meet tender point criteria for fibromyalgia.
Physical or emotional stress may precipitate or aggravate fibromyalgia. Approximately 30 percent of patients with fibromyalgia have major depression at the time of diagnosis; the lifetime prevalence of depression is 74 percent and that of an anxiety disorder is 60 percent. Those receiving the educational intervention had significantly more improvement than the controls, and beneficial effects lasted from three to 12 months after the sessions ended. The medications that have been most consistently effective in the treatment of fibromyalgia are antidepressants. From 2008 to 2009, two antidepressants, duloxetine and milnacipran, and one anti-seizure medication, pregabalin, were approved for the treatment of fibromyalgia by the FDA in the United States.
We use the following general guidelines for pharmacologic management: In general, drugs should be started at low doses and built up slowly (see discussion of each medication and class below). A low dose of a tricyclic medication at nighttime should be considered as initial therapy, especially since it is far less costly than some of the newer agents. The dose may be limited by adverse side effects, especially in the elderly. In patients with more problems with sleep, as an alternative to amitriptyline, we start with pregabalin at night. Gabapentin is an acceptable alternative that may cost less for some patients. Some patients do better with polypharmacy, such as a low dose of an SNRI in the morning with a low dose of an anticonvulsant in the evening, although there are no published studies using combinations of the newer agents.