Fibromyalgia Diagnosis
Fibromyalgia diagnosis is best performed by an expert. While the American College of Rheumatology has released specific criteria for diagnosis, most physicians use a more general clinical approach. The rigorous criteria, while good for clinical trials, are likely to miss fibromyalgia in up to 50% of patients.
There are two approaches to fibromyalgia diagnosis, but both require that a physician rule out other possible conditions during the process. The reason it is necessary to rule out other conditions is because fibromyalgia is somewhat difficult to define and can be mimicked by a variety of other diseases. So when asking “how is fibromyalgia diagnosed,” it is important to remember that at least part of the process is ensuring no other disease is the cause of the symptoms.
American College of Rheumatology (ACR) Criteria for Fibromyalgia Diagnosis
As a recognized clinical entity, fibromyalgia is relatively new. As a result, the first and only criteria officially used for diagnosis were developed in 1990. To make a diagnosis under the ACR criteria a patient must first have a chronic, widespread pain that involves all four quadrants of the body. He or she must also demonstrate the presence of 11 of 18 “tender points” on physical exam. The tender points are in pairs (one on each half of the body) in the following locations:
- The base of the skull on the rear of the neck
- The inner edge of the shoulder blade
- The top of the shoulders
- Either side of the tailbone
- The backs the hips just below the buttocks
- The ends of the collarbone where they meet the breastbone
- The pectoral muscles
- The inner elbow
- The inner aspect of the kneecap
These criteria are still used by a number of doctors, particularly primary care doctors who do not have specialized training in rheumatology and musculoskeletal disorders. However, it wasn’t long after these criteria were put forth that experts recognized that the criteria were deficient. As a result, many specialists in fibromyalgia prefer to use a broader set of diagnostic criteria.
Clinical Criteria for Fibromyalgia Diagnosis
One of the problems with the American College of Rheumatology criteria is that they were never intended to be applied to individual patients. Rather they were designed for use in clinical trials in order to ensure consistency and diagnosis. Most studies have found that at least half of individuals who have the clinical diagnosis of fibromyalgia will not fulfill the ACR criteria. As a result, most physicians use more general clinical criteria.
The clinical criteria are similar to the ACR in that they require widespread pain that involves all four quadrants of the body. The clinical criteria do not require that any of the tender points be met and only require that the pain has been present for at least three months. Many physicians will use tender point criteria to bolster the diagnosis, but do not consider it essential.
Ruling Out Other Diseases
When most people ask “how is fibromyalgia diagnosed,” they are expecting a specific test to be given or an x-ray to show some findings. Unfortunately, no such test exists for fibromyalgia and x-rays and other types of imaging will appear normal. As a result of this fact and the fact that fibromyalgia can mimic many other diseases, it is important to rule out a serious disorders before making an official fibromyalgia diagnosis.
Diseases that are commonly mimicked by fibromyalgia include hypothyroidism, polymyalgia rheumatica, hepatitis C, sleep apnea, parvovirus infection, and cervical stenosis. Most of these disorders can be ruled out based on history alone. If there is a moderate to high suspicion that any of these diseases may be playing a role in a patient’s symptoms, laboratory testing or imaging will be ordered.
There are a few diseases which fibromyalgia may mimic less commonly. They include autoimmune disorders like lupus, endocrine disorders like Cushing’s disease, Lyme disease, corticosteroid withdrawal, and cancer. Again, history can be used to rule out most if not all of these conditions.
For many patients, receiving a fibromyalgia diagnosis can take months or even years. This is usually occurs because many physicians are not familiar with the revised criteria for diagnosis or do not feel that fibromyalgia is a legitimate condition. For patients who suspect that they may have fibromyalgia, it is important to seek consultation with the specialist. Individuals familiar with fibromyalgia will be able to recognize the symptoms, and short but nothing else is contributing, and begin effective treatment. In the right hands, patients suffering from fibromyalgia should receive a fibromyalgia diagnosis within 6 to 8 weeks.
