Fibromyalgia

Fibromyalgia appears to have been identified in approximately 2% to 4% of the general population. Fibromyalgia is predominantly diagnosed in subjects between the ages of 20 and 60 years old, with approximately 80% of cases being female. Less cases of fibromyalgia being identified/diagnosed in men could be a function of a missed diagnosis. There is a high aggregation of fibromyalgia in families of patients with fibromyalgia.

Despite the high prevalence of fibromyalgia, as well as the increasing public awareness and physician acceptance of the syndrome, understanding its pathophysiology and finding effective treatments continues to be a complex endeavor.

Fibromyalgia syndrome involves a constellation of symptoms, which may include chronic disseminated pain without synovitis, aches, and/or myofascial tenderness, fatigue, cognitive impairment, sleep disturbances (commonly alpha wave electroencephalographic anomaly), morning stiffness, prior disease and anxiety symptoms, impaired social occupational functioning, and sexual dysfunction.

The four most frequently described symptoms in clinical practice are:

• Amplified pain
• Sleep deficits
• Daytime fatigue
• Altered cognition/mood

Wolfe et al initially published the American College of Rheumatology (ACR) criteria for fibroyalgia in 1990. The classification criteria then include a history of chronic widespread pain and the presence of 11 or more out of 18 tender points (TPs). Widespread pain was defined as ‘3 out of 4 quadrant’ pain, including left- and right-sided and upper- and lower-segment pain, and axial pain.

The 1990 ACR criteria required tender point examination—found to be a barrier in the primary care setting. Also, they created the erroneous impression that fibromyalgia is a peripheral musculoskeletal disease with the pathology centered on the tender points. Since then, understanding about the under lying pathophysiology of this complex pain syndrome has evolved and the need to develop new diagnostic criteria has grown.

A patient satisfies the diagnostic criteria for FMS if the following 3 conditions are met:

• Widespread pain index (WPI) ≥ 7 and symptom severity (SS) scale score ≥ 5 or WPI 3 – 6 and SS scale score ≥ 9.
• Symptoms have been present at a similar level for at least 3 months.
• The patient does not have a disorder that would otherwise explain the pain.

Although the precise mechanisms contributing to the pathophysiology of
FMS remain to be fully elucidated, it is thought that patients with fibromyalgia have impaired endogenous analgesic systems, in particular suboptimally functioning descending inhibitory pathways, which normally function to ameliorate pain as well as abnormal pain processing. These pathways are both serotonergic (eg, rostral ventral medulla) and noradrenergic (eg, dorsolateral pontine tegmentum), converging into the dorsal lateral funiculus, which synapse in rexed’s laminae I, II and V in the spinal cord dorsal horn. Abnormalities of sensitization in FMS may be seen in peripheral spinal and/or central supraspinal sites (central sensitization, neuroplasticity, hyperalgesia).

Evidence for genetic abnormalities in fibromyalgia has also been elucidated, with family studies showing that first-degree relatives of individuals with FMS display an eight-fold risk of developing the syndrome as compared to family members of patients with rheumatoid arthritis (RA). Furthermore, those related to fibromyalgia patients also had lower pain thresholds and more tender points than the RA relatives.10 These familial associations have led to attempts to identify genes involved in pain transmission that may be differentially expressed in fibromyalgia.

Serum ferritin levels were found to be significantly lower in FMS patients, perhaps due to the role of iron as a cofactor in enzymes involved in neurotransmitter synthesis. Levels of magnesium and zinc were found to be low in some studies. Association between serum zinc level and number of tender points and between fatigue and magnesium level was also found to be meaningful. Serum IL-8 levels were elevated in fibromyalgia patients as well, and these levels were reduced to near normal levels within 6 months after brief inpatient multidisciplinary pain therapy.

While studies attempting to localize the pathology in FMS to peripheral tissues have failed in showing any abnormalities in muscle tissue, Staud and coworkers did show that enhanced central pain processing can occur via continued peripheral muscle afferent input, Their study demonstrated that muscle lidocaine injections increased local pain thresholds and decreased remote secondary heat hyperalgesia in fibromyalgia patients, emphasizing the important role of peripheral impulse input in maintaining central sensitization.

Assessment of fibromyalgia is all about the degree of impact it has on patients function and quality of life. The Revised Fibromylagia Impact Questionnaire (FIQR) is an updated version of the FIQ that has recognized psychometric properties, can be completed by the patient in less than 2 minutes, and is easy to score. It differs from the FIQ in having modified function questions and the inclusion of questions on memory, tenderness, balance and environmental sensitivity.

• Rule out other causes of widespread pain
• Address yellow flags (factors that impede progress)
• Management of pain (Non pharmacological, medications, interventional treatments)
• Improve patient understanding and allay fears regarding exercise
• Rehabilitation (Physiotherapy, Hydrotherapy)
• Psychotherapeutic options