A diagnosis of fibromyalgia is based mostly on subjective reports of pain by patients themselves. In May 2010, the American College of Rheumatology (ACR) proposed new diagnostic criteria for fibromyalgia (originally established by the ACR in 1990). The new process replaces the well-known "tender points test" with a widespread pain index (WPI). Other symptoms not related to pain (fatigue, cognitive problems, etc.) are rated on a severity scale from 0 to 3. Blood tests, X-rays, CT scans, and similar tests cannot detect fibromyalgia, but they may be used to rule out other possible causes of the symptoms.
Widespread Pain Index
The WPI is a checklist of 19 areas of the body. If the paitent has felt pain in the specific area on the list within the past seven days, a check is added and given a score of 1 point. After the checklist is completed, the score is tallied and will fall between 0 and 19 points.
Symptom Severity Score
One of the biggest complaints about the diagnostic process established in 1990 is that it only considered pain as a criteria for fibromyalgia diagnosis. It did not take into consideration other symptoms such as fatigue and cognitive issues ("fibro fog"). The symptom severity score (SS) addresses this issue by asking the patient to rate the severity or prevalence of the following symptoms:
- waking unrefreshed
- cognitive symptoms (diffculty concentrating or remembering things)
- somatic symptoms (headache, dizziness, bowel problems, numbness/tingling, etc.)
Each of these categories is rated in severity from 0 to 3 for a maximum score of 12.
Tender Points Examination
While tender points are still considered charateristic of fibromyalgia, the ACR update in May 2010 decreased their significance in diagnosing the condition. However, your doctor still might examine the 18 tender points associated with the disorder. In a tender points exam, your doctor will press on each point in turn with his or her fingertip, using just enough pressure to whiten the nail bed, and ask if you feel any pain.
Ruling Out Other Diseases
Many conditions other than fibromyalgia can cause similar symptoms (see Fibromyalgia Diagnosis section), and these must be ruled out to be certain of a fibromyalgia diagnosis. Blood tests are used for HIV, hypothyroidism, rheumatoid arthritis, and Lyme disease. X-rays, CT scans, and MRIs are used for degenerative spinal diseases and many kinds of cancer. Biopsies are also used to test for cancer. Other tests that may be used to rule out other conditions include sleep studies and psychological exams.