Fibromyalgia: Specific Diagnosis of Fibromyalgia

Fig. 1: Fibromyalgia tender points
(larger view)

"The hallmark of the examination of a fibrositis patient is the lack of objective findings in relation to the plethora of symptoms. The only abnormal finding is the presence of numerous tender points".
Robert Bennett, 1988

In 1990, the American College of Rheumatology published their criteria for classification of fibromyalgia. The classification was based on a blinded, multi-center study of 558 age and sex matched consecutive patients 9. Eleven symptom variables (such as sleep disturbance, frequent headaches) and modulating factors (such as stress, weather changes) were studied.

Two critical findings resulted from this study: 9

  1. "Widespread pain" was present in 98% of fibromyalgia patients, compared with 69% of the control group. Widespread pain is defined as pain in the left and right side of the body, above and below the waist, as well as axial skeletal pain (such as in the neck, front or back chest, low back).

  2. Pain in 11 of 18 tender points was reported on digital palpation ("tender" is not considered "painful"). 88.4% of fibromyalgia patients had widespread pain (described above) in combination with pain in 11 of 18 tender points as described.

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The findings of morning stiffness (76%), fatigue (78%), and unrefreshing sleep (76%) is certainly suggestive of fibromyalgia syndrome. Yet these symptoms are common and non-specific. Moreover, only 56% of patients have all three 9.

Instead, the diagnosis of fibromyalgia relies on the history of widespread pain (98%) and finding of discreet "tender points" on physical examination. Tender points are discreet areas of tenderness in the muscular and tendonous issue of fibromyalgia patients.

The patient is typically not aware of these points and is often quite surprised at how a knowledgeable physician can readily pinpoint them 4. The tender points may be found by firm palpation with the thumb or first and second fingers. While the precise location of tender points is highly predictable and uniform, they are often not regionally related to the patient’s feeling of pain.

Tender points are found at very uniform and consistent sites in fibromyalgia patients. Over 40 paired sites have been identified. The nine most sensitive and specific paired sites are shown in Figure 1.

The tenderness is detected by palpating these areas with a steady force using the fingers. Control sites are tested for comparison. Patients with fibromyalgia have localized tenderness at the uniform sites but are not diffusely sensitive to palpation elsewhere.

Laboratory or radiographic tests are not used to help establish a diagnosis of fibromyalgia. However, since fibromyalgia can occur simultaneous with other disorders, or its symptoms can be mimicked by a variety of conditions, certain blood tests may be in order. These tests will help rule out conditions such as inflammatory rheumatic disease, hypothyroidism, anemia or endocrinopathies 4, 10.

Invasive testing is seldom indicated, but a test to measure response to nerve stimulation (electromyography) or even muscle biopsy may at times be obtained if a patient has demonstrable weakness or if a disease of the muscle is suspected 4.