Definition

Fibromyalgia is a syndrome defined by chronic widespread pain of at least 3 months’ duration. It is a multisystem illness associated with neuropsychological symptoms including fatigue, stiffness, unrefreshing sleep, cognitive dysfunction, anxiety, and depression. The majority of patients are women, for whom fibromyalgia is estimated to be three times more common than in men. The prevalence generally increases with age, with a peak prevalence rate in the fifth decade of life.

A discrete etiology of fibromyalgia has not been identified. Available evidence implicates sensitization of the central and peripheral nervous systems as key in maintaining pain and other core symptoms of fibromyalgia. There may be a role for genetics, as individuals with certain genotypes are more likely to develop chronic pain and an overall increased sensitivity to pain during their lifetimes. These genes include catecholamine methyltransferase, sodium and potassium channels, and a number of others. Environmental factors, such as physical or emotional trauma, and infection (e.g., Epstein-Barr virus, Lyme disease, parvovirus), may interact with genetic factors to facilitate the development of fibromyalgia.

Criteria for diagnosing fibromyalgia was first standardized by a multi-center study in 1990, which resulted in the American College of Rheumatology (ACR) 1990 classification criteria for fibromyalgia based on a tender point examination. This classification was later replaced by the 2010 ACR diagnostic criteria for fibromyalgia, which include the following:

• 1.
  

  Widespread pain index (WPI) score of at least 7 and a symptom severity scale (SSS) score of at least 5, or a WPI score of at least 3 and an SSS score of at least 9.

  
  
• 2.
  

  Symptoms present at a similar level for at least 3 months.

  
  
• 3.
  

  The patient must not have another disorder that would otherwise explain the pain.

The 2010 criteria were modified in 2011, allowing the diagnosis to be made by patient self-report for the purpose of research, and most recently, a 2016 revision to the 2010/2011 criteria has been proposed by Wolfe et al. ( Table 102.1 ), which combines the physician and patient questionnaire, minimizes misclassification of regional pain disorders, and eliminates the recommendation regarding diagnostic exclusions. The 2016 criteria include:

• 1.
  

  WPI score of at least 7 and SSS score of at least 5 or WPI of 4–6 and SSS score of at least 9.

  
  
• 2.
  

  Generalized pain, defined as pain in at least 4 of 5 regions, must be present. Jaw, chest, and abdominal pain are not included in the generalized pain definition.

  
  
• 3.
  

  Symptoms have been generally present for at least 3 months.

  
  
• 4.
  

  A diagnosis of fibromyalgia is valid irrespective of other diagnoses. A diagnosis of fibromyalgia does not exclude the presence of other clinically important illnesses.

Also developed with the 2016 revisions is the fibromyalgia severity scale, which is the sum of the WPI and SSS, ranging from 0 (no symptoms) to 31 (most severe symptoms). This score can help monitor improvement.

Symptoms

Fibromyalgia is characterized by widespread and long-lasting pain (>3 months) located above and below the waist, on both sides of the body. A series of other symptoms are frequently reported by patients. These include marked fatigue, stiffness, sleep disorders, cognitive disturbances (e.g., concentration difficulties, forgetfulness, decreased comprehension), anxiety, depression, temporomandibular joint syndrome, paresthesias, headaches, genitourinary manifestations (e.g., interstitial cystitis, chronic prostatitis, vulvodynia), irritable bowel syndrome, and orthostatic intolerance.

Physical Examination

Even though the general medical examination of a patient with fibromyalgia should be normal, a thorough physical examination remains vital. One study found that of patients referred to a rheumatologist for suspected fibromyalgia, a diagnosis of inflammatory or degenerative arthritis or soft tissue rheumatism was missed by the referring physician in 45% of cases. Blood pressure recording for orthostatic hypotension should be performed, as patients with fibromyalgia show an increased prevalence of neurally mediated hypotension during tilt table testing. Evaluation of mood and affect is important since patients with fibromyalgia have a lifetime prevalence of mood disorders, mostly major depression, ranging between 20% and 86%.

As mentioned earlier, a tender point exam is no longer a part of the diagnostic criteria; however, patients with fibromyalgia are not exempt from having superimposed regional myofascial pain associated with trigger points. Trigger points are hyperirritable spots in the fascia surrounding skeletal muscle. The painful point can be felt as a nodule or band in the muscle, and a twitch response can be elicited on stimulation of the trigger point. It is crucial to identify trigger points on examination since specific interventions are available (see Procedures section). Recognizing and treating myofascial pain and other common musculoskeletal pathology, like bursitis, tendinitis, radiculopathy, etc., helps isolate the pain secondary to fibromyalgia and better understand its response to treatment.