Official Diagnostic Criteria
Fibromyalgia has had a long, if rather obscure, history as an illness. Masquerading behind numerous medical aliases, FM has existed throughout history and throughout the world. It was only in 1990 that official diagnostic criteria for FM were established by the American College of Rheumatology (ACR). They include:
(1) A History of Widespread Pain: Chronic, widespread, musculoskeletal pain lasting longer than three months in all four quadrants of the body. ("Widespread pain" is defined as pain above and below the waist and on both sides of the body.) In addition, axial skeletal pain (in the cervical spine, anterior chest, thoracic spine, or low back) must be present.
(2) Pain in 11 of 18 Tender Point Sites on Digital Palpation: There are 18 tender points that doctors look for in making a fibromyalgia diagnosis (see Figure 1). According to the ACR requirements, a patient must have 11 of the 18 to be diagnosed with fibromyalgia. Approximately four kilograms of pressure (or about 9 lbs.) must be applied to a tender point, and the patient must indicate that the tender point locations are painful
(1 & 2) Occiput: bilateral, at the sub-occipital muscle insertions.
(3 & 4) Low Cervical: bilateral, at the anterior aspects of the inter-transverse spaces at C5-C7.
(5 & 6) Trapezius: bilateral, at the midpoint of the upper border.
(7 & 8) Supraspinatus: bilateral, at origins, above the scapula spine near the medial border.
(9 & 10) Second Rib: bilateral, at the second costochondral junctions, just lateral to the junctions on upper surfaces.
(11 & 12) Lateral Epicondyle: bilateral, 2 cm distal to the epicondyles.
(13 & 14) Gluteal: bilateral, in upper outer quadrants of buttocks in anterior fold of muscle.
(15 & 16) Greater Trochanter: bilateral, posterior to the trochanteric prominence.
(17 & 18) Knee: bilateral, at the medial fat pad proximal to the joint line.
(Source: Frederick Wolfe, M.D., et al., "The American College of Rheumatology 1990 Criteria for the Classification of Fibromyalgia: Report of a Multicenter Criteria Committee," Arthritis & Rheumatism, Vol. 33, No. 2, February 1990, pp. 160-172.)
As the ACR criteria suggest, a fibromyalgia diagnosis requires the "hands-on" evaluation of a patient by a skilled medical professional, typically a rheumatologist, though other medical specialists are becoming very knowledgeable in this area. As patients are not usually aware of the specific anatomical origins of pain in their bodies, self-diagnosis is not advised. Because routine laboratory and x-ray testing is usually normal in fibromyalgia patients, a complete medical history and physical exam are crucial for a correct diagnosis. Since FM symptoms mimic several other diseases (for example, systemic lupus, polymyalgia rheumatica, myositis/polymyositis, thyroid disease, rheumatoid arthritis, multiple sclerosis, and others), it is necessary to rule out those conditions before a FM diagnosis is made. While a diagnosis of fibromyalgia does not preclude the co-existence of another condition, it is important to ensure that no other condition is mistaken for fibromyalgia so that appropriate treatment may be initiated.
Limitations of the ACR Diagnostic Criteria
In the absence of diagnostic laboratory tests or x-rays, the ACR diagnostic criteria were a milestone in the recognition and study of fibromyalgia. For the first time, researchers around the world could identify and study FM patients using standardized measures. Patients who had fallen through the cracks of medical science could finally be diagnosed. Nevertheless, the criteria were not without their drawbacks.9
First, the tender point paradigm suggested that FM patients only experience pain in anatomically specific sites on the body. However, later studies, such as those reported by Granges and Littlejohn in 1993,10 began suggesting that individuals with FM are sensitive to painful stimuli throughout the body, not merely at the ACR-identified locations. Today, extensive body pain is commonly associated with FM.
Secondly, it quickly became evident that patient tenderness varied day-by-day and month-by-month. As a result, tender point counts on some days could be below the required 11 while on other days they might surpass it. Furthermore, patients did not always manifest pain in all four body quadrants. Some had unilateral pain; others had pain solely in the upper or lower halves of the body.
Thirdly, the tender point exams conducted by medical professionals are subject to human error. When performed incorrectly (at the wrong anatomical point or with an incorrect amount of digital palpation), they yield erroneous results. Unfortunately, the tender points of fibromyalgia are also sometimes confused with the trigger points of myofascial pain syndrome. Not uncommonly, FM is mistaken for MPS and vice versa. The search continues for a foolproof laboratory marker for FM. Meanwhile, the ACR criteria are still the most widely used diagnostic tool for fibromyalgia.
