Neurobiology of fibromyalgia syndrome

Department of Neuroscience, University of Florida, Gainesville, Florida, USA.
Journal of Rheumatology Supplement 09/2005; 75:22-8.
Source: PubMed

ABSTRACT Accumulating evidence suggests that fibromyalgia syndrome (FM) pain is maintained by tonic impulse input from deep tissues, such as muscle and joints, in combination with central sensitization mechanisms. This nociceptive input may originate in peripheral tissues (trauma and infection) resulting in hyperalgesia/allodynia and/or central sensitization. Evidence for abnormal sensitization mechanisms in FM includes enhanced temporal summation of delayed pain in response to repeated heat taps and repeated muscle taps, as well as prolonged and enhanced painful after-sensations in FM patients but not control subjects. Moreover, magnitudes of enhanced after-sensations are predictive of FM patients' ongoing clinical pain. Such alterations of relevant pain mechanisms may lead to longterm neuroplastic changes that exceed the antinociceptive capabilities of affected individuals, resulting in ever-increasing pain sensitivity and dysfunction. Future research needs to address the important role of abnormal nociception and/or antinociception for chronic pain in FM.

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    • "Despite these limitations, the current study represents a novel contribution to the literature by identifying factors that influence CPM stability in two different musculoskeletal shoulder pain models. Evidence suggests that altered central processing of noxious stimuli might be relevant in the pathogenesis of pain disorders [55-58]. However, establishing the stability of a measurement is essential before consider CPM a clinically useful measure. "
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    ABSTRACT: Background Several chronic pain populations have demonstrated decreased conditioned pain modulation (CPM). However there is still a need to investigate the stability of CPM paradigms before the measure can be recommended for implementation. The purpose of the present study was to assess whether shoulder pain intensity and gender influence CPM stability within and between sessions. Methods This study examined two different musculoskeletal pain models, clinical shoulder pain and an experimental model of shoulder pain induced with eccentric exercise in healthy participants. Patients in the clinical cohort (N = 134) were tested before surgery and reassessed 3 months post-surgery. The healthy cohort (N = 190) was examined before inducing pain at the shoulder, and 48 and 96 hours later. Results Our results provide evidence that 1) stability of inhibition is not related to changes in pain intensity, and 2) there are sex differences for CPM stability within and between days. Conclusions Fluctuation of pain intensity did not significantly influence CPM stability. Overall, the more stable situations for CPM were females from the clinical cohort and males from the healthy cohort.
    BMC Musculoskeletal Disorders 06/2013; 14(1):182. DOI:10.1186/1471-2474-14-182 · 1.72 Impact Factor
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    • "Studies of experimentally induced pain demonstrate that these patients have a lower pain threshold, as lower intensity stimuli are needed to evoke pain (Price and Staud, 2005). Imaging work provides evidence of central pain augmentation in this condition. "
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    ABSTRACT: OBJECTIVE: The precise pathophysiology of fibromyalgia, a syndrome characterized by chronic widespread pain, remains to be clarified. When subjected to the same amount of stimulation, patients show enhanced brain responses as compared to controls, providing evidence of central pain augmentation in this syndrome. We aimed to characterize brain response differences when stimulation is adjusted to elicit similar subjective levels of pain in both groups. METHODS: Magnetoencephalography (MEG) was used to investigate the brain responses to pressure stimulation applied both above and below the pain threshold in nine patients and nine control subjects. A device was developed to deliver pressure pulses in a quantifiable and precise manner. The amount of pressure was adjusted to produce similar subjective pain in both groups. RESULTS: A between-group comparison of differences between responses evoked by stimulation above and below the pain threshold was performed using cluster-based permutation testing. Increases in signal amplitude in somatosensory, temporal and parietal areas at short latencies, and in prefrontal areas at both short and long latencies, were found to be larger for patients than for control subjects. CONCLUSION: Fibromyalgia patients show enhanced brain responses after reducing the amount of pressure to produce similar subjective levels of pain than to the control subjects. SIGNIFICANCE: The present results suggest that central pain augmentation is present in fibromyalgia, not only when the objective level of stimulation is kept the same as for control subjects, but also when stimulation is adjusted to produce similar levels of pain in patients and controls.
    Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology 10/2012; 124(4). DOI:10.1016/j.clinph.2012.09.015 · 3.10 Impact Factor
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    • "The FSDC has been validated in English and in Japanese patients with FM, as well as patients with non-FM rheumatic disease [10,12]. This recognition of co associated symptoms with pain in FM is in line with increased neurophysiologic understanding of this condition [20]. "
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    ABSTRACT: Background Fibromyalgia (FM) is a pain condition with associated symptoms contributing to distress. The Fibromyalgia Survey Diagnostic Criteria and Severity Scale (FSDC) is a patient-administered questionnaire assessing diagnosis and symptom severity. Locations of body pain measured by the Widespread Pain Index (WPI), and the Symptom Severity scale (SS) measuring fatigue, unrefreshing sleep, cognitive and somatic complaints provide a score (0–31), measuring a composite of polysymptomatic distress. The reliability and validity of the translated French version of the FSDC was evaluated. Methods The French FSDC was administered twice to 73 FM patients, and was correlated with measures of symptom status including: Fibromyalgia Impact Questionnaire (FIQ), Health Assessment Questionnaire (HAQ), McGill Pain Questionnaire (MPQ), and a visual analogue scale (VAS) for global severity and pain. Test-retest reliability, internal consistency, and construct validity were evaluated. Results Test-retest reliability was between .600 and .888 for the 25 single items of the FSDC, and .912 for the total FSDC, with all correlations significant (p < 0.0001). There was good internal consistency measured by Cronbach’s alpha (.846 for FSDC assessment 1, and .867 for FSDC assessment 2). Construct validity showed significant correlations between the FSDC and FIQ 0.670, HAQ 0.413, MPQ 0.562, global VAS 0.591, and pain VAS 0.663 (all p<0.001). Conclusions The French FSDC is a valid instrument in French FM patients with reliability and construct validity. It is easily completed, simple to score, and has the potential to become the standard for measurement of polysymptomatic distress in FM.
    BMC Musculoskeletal Disorders 09/2012; 13(1):179. DOI:10.1186/1471-2474-13-179 · 1.72 Impact Factor
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