Clin Exp Rheumatol
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Fibromyalgia (FM) is a chronic musculoskeletal pain syndrome which is characterised by clinical pain as well as widespread hyperalgesia/allodynia to mechanical, thermal, electrical, and chemical stimuli. Lack of consistent tissue abnormalities in FM patients has more and more shifted the focus away from peripheral factors and towards central nervous system abnormalities including central sensitisation as well as aberrant pain facilitation and inhibition. Besides quantitative sensory testing, functional brain imaging has been increasingly utilised to characterise the abnormal pain processing of FM patients. ⋯ Additionally, magnetic resonance spectroscopy studies demonstrated high concentration of the excitatory neurotransmitter glutamate in FM patients in pain-related brain areas which correlated not only with experimental but also with clinical pain ratings. Overall, functional brain imaging studies have provided compelling evidence for abnormal pain processing in FM, including brain activity that correlated with patients' augmented pain sensitivity (hyperalgesia/allodynia), temporal summation of pain, and prolonged pain aftersensations. Future imaging work needs to focus on identifying the neural correlates of FM patients' abnormal endogenous pain modulation which will likely not only shed more light on this important pain regulatory mechanism but may also provide useful information for future treatments of FM symptoms.
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Chronic widespread pain (CWP) is a common symptom within the community, and may be part of or arise as a result of various diseases or conditions. Fibromyalgia (FM) is probably the most common and best known disease whose cardinal symptom is CWP. Many authors, however, indistinctively describe pain as 'widespread', 'diffuse' or 'generalised', and this may lead to misunderstandings about true clinical or scientific significance. ⋯ There is no clear-cut evidence of FM or CWP due to infections or vaccinations, no correlations with persistent infection, and no proven relationship between infection, antimicrobial therapies and pain improvement. A higher prevalence of FM and chronic pain has been found in patients with Lyme disease, and HIV or HCV infection, and, perhaps, also in patients with mycoplasmas, HBV, HTLV I, and parvovirus B19 infections. Some unconfirmed evidence and case reports suggest that vaccinations may trigger FM or chronic pain.