Abstract

Characterized by widespread musculoskeletal pain, fatigue, and sleep disturbances, fibromyalgia (FM) is a debilitating syndrome affecting approximately 2% of the US population. Disordered central pain processing likely plays a role in the pathogenesis of FM and treatment strategies primarily focus on alleviating pain and addressing associated symptoms and comorbid conditions. Despite evidence suggesting efficacy of various agents that act on the central nervous system and modulate pain perception (ie, antidepressants, anticonvulsants, and muscle relaxants), no one drug or class of drugs has proven to completely address all symptoms of FM. Evidence-based recommendations utilize an integrated approach that combines nonpharmacologic approaches (specifically patient education, exercise, and cognitive behavioral therapy) and pharmacologic approaches in the management of FM. (Formulary. 2009; 44:362-373.)

The second most common diagnosis after osteoarthritis in patients seen by rheumatologists, fibromyalgia (FM) is a chronic and debilitating central pain disorder.1 FM affects approximately 2% of the US population, with prevalence rates of 3.4% in women and 0.5% in men.2 Characterized by widespread musculoskeletal pain, fatigue, and sleep disturbances, the lack of overt inflammation or joint destruction often associated with numerous other rheumatologic disorders makes the diagnosis and management of FM difficult. Symptoms typically appear between the ages of 20 and 55, but FM can be diagnosed at any age.3 In addition, patients with FM often present with a number of comorbid chronic medical and psychiatric illnesses or pain syndromes.4 Consequences associated with FM include daytime fatigue,

impaired concentration, poor job performance, and decreased patient self-efficacy beliefs.1 Treatment of FM focuses on reducing pain and improving sleep and overall quality of life.

No laboratory or diagnostic tests can definitively confirm FM. A diagnosis is made by a careful review of patient medication, psychosocial and family history, physical examination, laboratory evaluations, and exclusion of other conditions with symptoms of chronic pain, such as chronic fatigue syndrome, rheumatoid arthritis, or Sjogren’s syndrome.4 The American College of Rheumatology (ACR) has compiled the criteria for diagnosing FM.5 However, failure to meet these criteria does not rule out a diagnosis of FM, as the number of tender points may change over time.6,7

The clinical presentation of FM is heterogeneous and in addition to the ACR criteria, other symptoms commonly occur. Musculoskeletal symptoms of FM include widespread pain at multiple sites, stiffness, sensation of hurting all over, and diffuse soft tissue swelling.4 Nonmusculoskeletal symptoms often include difficulty falling or staying asleep, fatigue, paresthesias, and difficulties with concentration and memory. The pain associated with FM can be variable and is often described as a widespread, deep, burning, or gnawing ache.4,7 Physical or emotional stress, nonrestorative sleep, and a decrease in physical activity often worsen symptoms. Fibromyalgia may occur concurrently with hypothyroidism, and other commonly comorbid conditions include anxiety and depressive disorders, insomnia, migraine headache, irritable bowel syndrome, restless leg syndrome, temporomandibular pain syndrome, and Raynaud’s phenomenon.4

While the exact cause of FM remains unknown, genetic influences, physical or psychological trauma or stress, disturbances in the neuroendocrine and autonomic nervous systems, abnormalities in pain perception, and various biochemical changes are all proposed to play a role in its etiology.1,6-9 Many of these findings individually are not specific to FM or sufficient to explain the pain associated with FM. However, it is well accepted that patients with FM experience pain differently than pain-free controls and they do so in the absence of any identifiable underlying disease.1,6

Many of the available pharmacotherapeutic treatment options are based on the proposed pathophysiology of FM and associated comorbid conditions. Recommendations for the management of FM published by the American Pain Society (APS) in 2004 and the European League Against Rheumatism (EULAR) in 2007 employ differing criteria for evidence-based ratings, yet both sets of recommendations support the incorporation of nonpharmacologic and pharmacologic strategies.10,11