[Functional somatic pain syndromes-nomenclature]

The Iceberg Nature of Fibromyalgia Burden: The Clinical and Economic Aspects

This review has focused on important but less visible aspects of fibromyalgia (FM) with respect to the high impact of this disorder on patients and societies. FM is a common but challengeable illness. It is characterized by chronic widespread pain, which can be accompanied by other symptoms including fatigue, sleep disturbances, cognitive dysfunction, anxiety and depressive episodes. While our understanding of this debilitating disorder is limited, diagnosis and treatment of this condition is very difficult, even in the hands of experts. Due to the nature of disease, where patients experience invalidation by medical services, their families and societies regarding the recognition and management of disease, direct, indirect and immeasurable costs are considerable. These clinical and economic costs are comparable with other common diseases, such as diabetes, hypertension and osteoarthritis, but the latter usually receives much more attention from healthcare and non-healthcare resources. Present alarming data shows the grave and "iceberg-like" burden of FM despite the benign appearance of this disorder and highlights the urgent need both for greater awareness of the disease among medical services and societies, as well as for more research focused on easily used diagnostic methods and target specific treatment.

Fibromyalgia: from pathophysiology to therapy

Individuals with fibromyalgia generally experience chronic widespread pain, which can be accompanied by further symptoms including fatigue, sleep disturbances, cognitive dysfunction, anxiety and depressive episodes. As the recognition and diagnosis of fibromyalgia has improved, the availability of therapeutic options for patients has increased. Furthermore, research into the neurobiological mechanisms that contribute to the chronic pain and concomitant symptoms experienced by patients with fibromyalgia has advanced our understanding of this debilitating disorder. In this Review, we aim to provide an overview of existing pathophysiological concepts. The roles of biological and psychological stress, genetic factors, and pain and sensory processing in the pathophysiology of fibromyalgia and related conditions are discussed. In addition, pharmacological treatments, including monoamine modulators, calcium channel modulators and γ-aminobutyric acid modulators, as well as nonpharmacological treatment options are considered.

Variations in brain volume and regional morphology associated with chronic pain

Various peripheral and spinal mechanisms have been hypothesized to contribute to pain amplification and chronicity. However, the role of the brain in chronic pain states remains to be fully elucidated. Functional brain imaging techniques, such as positron emission tomography and functional magnetic resonance imaging, have frequently been used to investigate brain activity during acute/experimental pain perception, which has helped to establish the notion of the human pain network. In the context of chronic pain, the assessment of brain chemistry (by way of spectroscopy) and brain morphology is of growing interest, and there is a quickly expanding body of evidence that persons with chronic pain conditions, including chronic low back pain, chronic tension-type headache, and fibromyalgia, display changes in global and regional brain morphology. It has been suggested that prolonged nociceptive input to the brain might induce functional and morphologic maladaptive processes that in turn further exacerbate the experience of chronic pain. Alternatively, morphologic changes might predispose toward vulnerability to develop a chronic pain state. The purpose of this review is to examine current literature regarding altered brain morphology in patients with various chronic pain states, summarize these findings, and evaluate their implications for our understanding of the pathophysiology of chronic pain.

[Definition, classification and diagnosis of fibromyalgia syndrome]

BACKGROUND

Interdisciplinary guidelines for the definition, classification and diagnosis of chronic widespread pain (CWP) and fibromyalgia syndrome (FMS) were developed by collaboration of 10 German medical and psychological associations and 2 patient self-help organizations.

METHODS

A systematic literature search was performed in the Cochrane Library (1993-12/2006), Medline (1980-2006), PsychInfo (1966-12/2006), and Scopus (1980-12/2006). Levels of evidence were assigned according to the classification system of the Oxford Centre for Evidence-Based Medicine. Grading of the strength of recommendation was done according to the German program for disease management guidelines. Standardized procedures to reach a consensus on recommendations were used.

RESULTS

CWP is defined by the criteria of the American College of Rheumatology (ACR--strong consensus). FMS can be diagnosed for clinical purposes by symptom-based criteria (without tender point examination) as well as by the ACR criteria (strong consensus).

[Fibromyalgia -- a somatoform (pain) disorder?]

The hypothesis that fibromyalgia (FM) should be classified as a somatoform disorder was assessed by reviewing current clinical studies. According to the ICD-10, somatic illness beliefs of the patient, high health care utilization, and frustrating patient-doctor relationships are diagnostic criteria of somatoform disorders. For the diagnosis of a somatoform pain disorder, a temporal association between the manifestation of pain and emotional or psychosocial conflicts and the exclusion of a depressive disorder are additionally required. Empirical studies demonstrate a higher lifetime and current prevalence of psychiatric disorders, childhood adversities, life events, and daily hassles and a higher health care utilization of FM patients. Studies also reveal that most patients believe that both somatic and psychosocial factors have caused their disorder. The patient-doctor relationship is characterized to be disappointing for both. Yet in all studies there were patients who did not fulfill the ICD-10 criteria of a somatoform (pain) disorder. A biopsychosocial model of FM differentiating between biological as well as psychosocial predisposing, triggering, and perpetuating factors in the pathogenesis of FM is presented as an alternative model. Hopefully the biopsychosocial model and the distinction of subgroups will enable more differentiated and tailored psychotherapeutic and pharmacological treatment strategies.