Approach to the Patient with Fibromyalgia

Patients with diffuse, chronic musculoskeletal pain but no evidence of arthritis or myositis account for a large number of office visits. Some of them have mild rheumatoid disease; in other cases, their symptoms are caused by bony pathology, neuropathy, or myopathy. When no source stands out, clinicians start wondering about somatization despite protests from the patient that the problem is “not in my head.”

Over the past two decades, a syndrome of diffuse, chronic musculoskeletal pain, stiffness, focal tenderness, disordered sleep, and fatigue has become increasingly recognized as an important clinical entity, designated by the term fibromyalgia. Accumulating evidence points to a possibly hereditary, central pain-processing pathophysiology, sharing features with irritable bowel syndrome, chronic idiopathic low back pain, and temporomandibular joint dysfunction

Using the research diagnostic criteria of ≥3 months of persisting widespread pain and 11 of 18 tender points on digital palpation, it is estimated that the condition affects as much as 2% to 4% of the US population, with prevalence as high as 5% among adult women, who account for 80% to 90% of cases. After osteoarthritis, fibromyalgia accounts for the most visits to rheumatologists. Recent advances in understanding the pathophysiology of fibromyalgia have led to identification of pharmacologic and nonpharmacologic therapies capable of lessening pain, improving sleep, reducing fatigue, and improving quality of life for a significant number of persons who suffer from this condition.

When encountering a patient with diffuse, chronic musculoskeletal pain, the primary care physician needs to consider fibromyalgia in the differential diagnosis, address other possible causes (see Chapter 146), and, if present, fashion a comprehensive program of evidence-based care. While psychosocial distress can exacerbate fibromyalgia symptoms and effect response to therapy, it is no longer appropriate to view fibromyalgia as a purely psychosocial phenomenon.

PATHOPHYSIOLOGY, CLINICAL PRESENTATION, AND COURSE (1, 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11)

Pathogenesis

As noted, fibromyalgia is emerging as a condition of abnormal central processing of pain rather than a somatic manifestation of anxiety, depression, or other traditional psychiatric disorder. Although the symptoms suggest somatization, careful psychological studies reveal no etiologic relationship between symptoms and psychological status. Only an increased frequency of life stress has been found. Most patients are not depressed, and any onset of depression does not correlate with the level of pain. One of the most consistent findings is augmented central pain and sensory processing leading to amplification of pain perception. Significant alterations in central nervous system neurotransmitter metabolism and function have been found manifested by abnormal levels of such key neurotransmitters as serotonin, norepinephrine, glutamate, and substance P. Disturbances of stage 4 (non-rapid eye movement) sleep are characteristic and correlate with symptoms. Functional neuroimaging reveals consistently abnormal patterns of brain activity and metabolism. These findings point to a pathophysiologic common denominator that can account for the condition’s hallmark symptoms of pain, sleep disturbance, and fatigue. Abnormal nociception is emerging as an important element of the explanatory model (similar to its suspected role in irritable bowel syndrome—see Chapter 74). Patients are more sensitive to pressure and show less neuronal inhibitory control in response to noxious stimuli. However, the so-called opioidergic activity is normal. There appears to be a genetic component to the condition; first-degree relatives manifest an eightfold increase in risk of developing the condition. Neuroendocrine changes have also been observed but are not sufficient to be considered etiologic. Muscle biopsy findings and electromyographic data demonstrate no consistent or unique changes. Some increased cytokine activity has been noted, but mostly involving those related to neural functioning rather than inflammation.

Although not believed to be the primary mechanism of disease, behavioral and psychosocial factors can certainly exert an effect on the clinical presentation, and the condition can exacerbate underlying psychosocial distress. Concurrent psychosocial comorbidity has been found in 30% to 60% of persons with active disease.

Clinical Presentation

The hallmarks of fibromyalgia syndrome are chronic and diffuse musculoskeletal pain, disordered sleep, and fatigue. The pain tends to be constant, aching, and concentrated in axial regions (neck, shoulders, back, pelvis). “Stiffness” is the term often used to describe the discomfort, which is characteristically worse in the morning and exacerbated by changes in the weather, cold, humidity, sleeplessness, and stress and helped by warmth, rest, and mild exercise. Points of focal tenderness may be reported in the upper and lower extremities. Patients awake from sleep feeling tired and unrefreshed. Persistent fatigue rounds out the clinical picture. The typical patient is a woman between the ages of 30 and 50 years.

Anxiety and/or depression often accompanies fibromyalgia symptoms, exacerbating them and potentially affecting the clinical course and response to treatment. At times, there is concurrent inflammatory or degenerative joint disease, which may complicate the musculoskeletal presentation.

Physical examination findings are normal except for the presence of tender points—multiple, reproducible points of exaggerated tenderness to palpation. The tender points tend to be symmetric and located in the occiput, neck, shoulder, ribs, elbows, buttocks, and knees. Eighteen characteristic locations have been identified (Fig. 159-1).

Clinical Course

Fibromyalgia is a chronic but nonprogressive disorder that waxes and wanes, often in conjunction with changes in the weather, degree of situational stress, and amount of rest. The number and location of tender points tend to be stable over time. In some patients, the condition may become disabling, at least temporarily, but the clinical course overall is one of nonprogressive disease, with some patients experiencing spontaneous remission and many reporting some improvement with time.

The degree of disability can be considerable; up to one fourth of patients receive disability payments at some time during their illness. Unresolved psychosocial distress and lack of social support are important determinants of disability, health care utilization, a poor prognosis. Responsiveness to initial therapy portends a favorable clinical course.

Figure 159-1 Tender points in fibromyalgia syndrome.

DIAGNOSIS AND DIFFERENTIAL DIAGNOSIS (5,12,13)

Diagnosis

In the absence of a definitively confirmed pathophysiology and correspondingly objective measures of the disorder, the diagnosis of fibromyalgia syndrome remains a clinical one. The clinical diagnosis has been facilitated by use of standardized case definitions, initially using the research diagnostic criteria established by the American College of Rheumatology (ACR) in 1990:

Widespread pain (three of four quadrants including axial pain) for at least 3 months
Pain in at least 11 of 18 possible tender point sites (Fig. 159-1)

Shortcomings of this case definition include its focus on pain, which ignores other important components of the syndrome such as disordered sleep and fatigue. In addition, the dependence upon tender-point determination makes for inconsistency and error in evaluation—an estimated 25% of referred cases are found to be mislabeled. Finally, the definition fosters the impression that fibromyalgia as a purely peripheral musculoskeletal disease rather than a disorder involving central pain processing.

In 2010, the ACR proposed new diagnostic criteria (see Tables 159-1 and 159-2), which put more emphasis on the condition’s systemic somatic symptoms (fatigue, disordered sleep, cognitive impairment), downplayed peripheral complaints, and removed physical examination findings as diagnostic criteria. The aim was to facilitate accurate diagnosis in the primary care setting. The new criteria are comparable to the original physical exam-based criteria in correctly classifying about 85% of patients but also provide an assessment of severity. Though designed for application in everyday nonspecialty practice, the new criteria have yet to be prospectively validated for use in primary care. Concerns about these criteria include their de-emphasis of the physical examination, which could result in failure to elicit important findings indicative of an alternative diagnosis (see Physical Examination).

TABLE 159-1 The American College of Rheumatology 1990 Criteria for the Classification of Fibromyalgia

History of Widespread Pain
	Definition. Pain is considered widespread when all of the following are present: pain in the left side of the body, pain in the right side of the body, pain above the waist, and pain below the waist. In addition, axial skeletal pain (cervical spine or anterior chest or thoracic spine or low back) must be present. In this definition, shoulder and buttock pain is considered as pain for each involved side. “Low back” pain is considered lower segment pain.
Pain in 11 of 18 Tender Point Sites on Digital Palpation (Fig. 159-1)
	Definition. Pain, on digital palpation, must be present in at least 11 of the following 18 tender point sites:
	Occiput: bilateral, at the suboccipital muscle insertions
	Low cervical: bilateral, at the anterior aspects of the intertransverse spaces at C1-C7
	Trapezius: bilateral, at the midpoint of the upper border
	Supraspinatus: bilateral, at origins, above the scapula spine near the medial border
	Second rib: bilateral, at the second costochondral junctions, just lateral to the junctions on upper surfaces
	Lateral epicondyle: bilateral, 2 cm distal to the epicondyles
	Gluteal: bilateral, in upper outer quadrants of buttocks in anterior fold of muscle
	Greater trochanter: bilateral, posterior to the trochanteric prominence
	Knee: bilateral, at the medial fat pad proximal to the joint line
	Digital palpation should be performed with an approximate force of 4 kg.
For a tender point to be considered “positive,” the subject must state that the palpation was painful. “Tender” is not be considered “painful.” For classification purposes, patients are said to have fibromyalgia if both criteria are satisfied. Widespread pain must have been present for at least 3 months. The presence of a second clinical disorder does not exclude the diagnosis of fibromyalgia. From Wolfe F, Smyth HA, Yunus MB, et al. The American College of Rheumatology 1990 criteria for the classification of fibromyalgia. Report of the Multicenter Criteria Committee. Arthritis Rheum 1990;33:160, with permission. Copyright © 1990 American College of Rheumatology. With permission of John Wiley & Sons, Inc.

The new ACR criteria have been proposed as an alternative pathway to diagnosis of fibromyalgia syndrome rather than as a replacement for the initial criteria. Importantly, they still include the requirement to rule out other important, often treatable disorders that could account for the patient’s pain and associated symptoms.

Differential Diagnosis

As noted, the diagnosis of fibromyalgia must not be considered established until a host of similarly presenting conditions have been ruled out, conditions that may be mistakenly labeled as fibromyalgia. Complicating the diagnostic task is the concurrent presence of such conditions, a not uncommon situation.

Myofascial syndromes resulting from overuse may be confused with fibromyalgia, in that tender points are characteristic of both. Unlike those of fibromyalgia, the tender points of myofascial syndrome are clustered about just one area and trigger referred pain on compression (hence the term trigger points). Moreover, symptoms are focal rather than diffuse. A history of onset after excessive activity or muscle strain is typical. No fatigue or sleep disorder is associated with myofascial syndrome.

TABLE 159-2 American College of Rheumatology 2010 Diagnostic Criteria for Fibromyalgia Syndrome

Criteria (Three conditions must be met):
	1.	Score of ≥7 in the widespread pain index (WPI) and ≥5 in the symptom severity (SS) scale or WPI 3-6 and SS ≥9
	2.	Symptoms present at these levels for ≥3 mo
	3.	Other causes ruled out
Widespread Pain Index
	▪	Number of areas the patient has had pain in the past week (0-19)
	▪	Areas of importance:
		•	Left and right shoulder girdle
		•	Left and right hip (buttock trochanter)
		•	Left and right jaw
		•	Upper and lower back
		•	Left and right upper arm
		•	Left and right lower arm
		•	Left and right upper leg
		•	Left and right lower leg
		•	Neck
		•	Chest
		•	Abdomen
Symptom severity scale (total score 0-12, sum of level of severity and extent)
	▪	Level of severity over the past week for the following symptoms:
		•	Fatigue
		•	Waking unrefreshed
		•	Cognitive symptoms
		Levels
			0. No problem
			1. Slight or mild (often intermittent)
			2. Moderate (considerable, often present)
			3. Severe (pervasive continuous, life disturbing)
	▪	Extent of somatic symptoms
		0 None
		1 Few
		2 Many
Among somatic symptoms: muscle pain, irritable bowel syndrome, fatigue/tiredness, thinking or remembering problem, muscle weakness, headache, pain/cramps in the abdomen, numbness/tingling, dizziness, insomnia, depression, constipation, pain in the upper abdomen.
Based on Wolfe F, Clauw DJ, Fitzcharles MA, et al. The American College of Rheumatology preliminary diagnostic criteria for fibromyalgia and measurement of symptom severity. Arthritis Care Res 2010;62:600. Copyright © 2010 by the American College of Rheumatology. With permission of John Wiley & Sons, Inc.

Rheumatoid disease in its early or mild forms may cause diffuse musculoskeletal discomfort, morning stiffness, fatigue, and focal tenderness on physical examination. However, the tenderness appears to be less exaggerated, and results of serologic studies are abnormal. Polymyalgia rheumatica superficially resembles fibromyalgia, but the onset is at a much later age, symptoms are confined to the hip and shoulder girdles, few tender points are present, and the sedimentation rate is markedly elevated.

Ankylosing spondylitis and other spondyloarthropathies produce axial discomfort, fatigue, and focal tenderness; however, most patients with axial symptoms are men, and sacroiliitis is a defining manifestation of ankylosing spondylitis (see Chapter 146). Spondyloarthropathy in women can easily be mistaken for fibromyalgia because the likely symptoms are diffuse and may include chronic axial discomfort, focal spinal pain in multiple sites, and disordered sleep. Because it is more common in men, spondyloarthropathy is not commonly considered in women, and neck pain may be more prominent than lower back pain, further confusing the picture. Clinical findings suggestive of spondyloarthropathy include a positive family history, psoriasis, inflammatory bowel disease, risk factors for Reiter syndrome, relief of pain with exercise, sacroiliitis, and pain or tenderness at the site of insertion of a tendon or at the Achilles tendon or plantar fascia.

Chronic fatigue syndrome has been found to share many of the clinical features of fibromyalgia, including chronic, diffuse musculoskeletal pain and tender points, so that differentiation is difficult at times because both conditions are diagnosed clinically and may coexist. Pain tends to be less prominent in chronic fatigue syndrome, and not all patients have tender points. Sometimes, distinguishing between chronic fatigue syndrome and fibromyalgia is impossible because of so much clinical overlap, which is not critical functionally because the approach to management is very similar for both (see Chapter 8).

Lyme disease also enters into the differential diagnosis but is readily recognized by a history of deer tick exposure, residence in an endemic area, characteristic rash, polyarthritis, and neurologic deficits (see Chapter 160). Some patients may have a transient syndrome that temporarily resembles fibromyalgia. Other deer tick-borne illnesses, such as babesiosis and anaplasmosis, can also cause arthralgias and marked somatic symptoms, though fever is often a distinguishing feature, especially for anaplasmosis (see Chapter 160).

Hypothyroidism may be accompanied by diffuse myalgias and fatigue that simulate fibromyalgia (see Chapter 104). Differentiating features include cold intolerance, unexplained weight gain, characteristic skin changes, goiter, muscle weakness and soreness, and an elevated thyrotropin (TSH) level. Similarly, polymyositis may produce diffuse muscle achiness, but muscles are weak and diffusely sore, and the sedimentation rate and muscle enzyme levels are markedly elevated.

Depression and somatization disorder can cause chronic musculoskeletal pain and fatigue, but no reproducible tender points are found, and these conditions are accompanied by definite manifestations of underlying psychopathology (see Chapters 227 and 230).

The pain of hypertrophic osteoarthropathy may be diffuse, but tender points are minimal, and clubbing provides a unique hallmark.

WORKUP (5,12, 13, 14, 15, 16, 17, 18 and 19)

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