Description

• Chronic, widespread noninflammatory musculoskeletal pain syndrome with multisystem manifestations; although the specific pathophysiology has not been fully elucidated, it is generally thought to be a disorder of altered central pain regulation.
• Synonym(s): FMS; fibrositis, fibromyositis (misnomers)

Epidemiology

Incidence

• Predominant sex: female (70–90%) > male
• Predominant age range: 20 to 65 years

Prevalence
2–5% of adult U.S. population (1); 8% of primary care patients

Etiology and Pathophysiology

• Idiopathic; appears to be a primary disorder of central pain processing (central sensitization) with afferent augmentation of peripheral nociceptive stimuli
• Alterations in neuroendocrine, neuromodulation, neurotransmitter, neurotransporter, biochemical, and neuroreceptor function/physiology
• Sleep abnormalities—α-wave intrusion
• Systemic inflammation is not a feature of fibromyalgia, although localized immunologic and inflammatory processes in the CNS may play a role. There may be a distinctive cytokine profile in patients with fibromyalgia.

Genetics

• Genetics
  • High familial aggregation
  • Inheritance is unknown but likely polygenic.
  • Odds ratio may be as high as 8.5 for a first-degree relative of a familial proband.
• Environmental—several triggers have been described:
  • Physical trauma or severe illness
  • Stressors (e.g., work, family, life events, and physical or sexual abuse)
  • Viral and bacterial infections

Risk Factors

• Female gender
• Poor functional status
• Negative/stressful life events
• Low socioeconomic status

General Prevention

No known strategies for prevention

Commonly Associated Conditions

• Often a comorbid condition with other rheumatologic or neurologic disorders
• Psychiatric comorbidities, including depression, anxiety, and posttraumatic stress disorder (PTSD) occur in two-thirds of patients—similar to findings in other chronic pain conditions.
• Obesity is common and associated with increased severity of symptoms.