Mechanisms of disease: pain in fibromyalgia syndrome.
ABSTRACT Despite extensive research, the pathogenesis of pain in fibromyalgia syndrome is incompletely understood. Fibromyalgia pain is consistently felt in deep tissues including ligaments, joints and muscles. Increasing evidence points towards these tissues as relevant contributors of nociceptive input that might either initiate or maintain central sensitization, or both. Persistent or intense nociception can lead to transcriptional and translational changes in the spinal cord and brain resulting in central sensitization and pain. This mechanism represents a hallmark of fibromyalgia and many other chronic pain syndromes, including irritable bowel syndrome, temporomandibular disorder, migraine, and low back pain. Importantly, after central sensitization has been established, only minimal nociceptive input is required for the maintenance of the chronic pain state. Other factors, including pain-related negative affect, have been shown to significantly contribute to clinical fibromyalgia pain. An improved understanding of the mechanisms that characterize central sensitization and clinical pain will provide new approaches for the prevention and treatment of fibromyalgia and other chronic pain syndromes.
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ABSTRACT: Musculoskeletal pain from the upper extremity and shoulder region is commonly reported by computer users. However, the functional status of central pain mechanisms, i.e., central sensitization and conditioned pain modulation (CPM), has not been investigated in this population. The aim was to evaluate sensitization and CPM in computer users with and without chronic musculoskeletal pain. Pressure pain threshold (PPT) mapping in the neck-shoulder (15 points) and the elbow (12 points) was assessed together with PPT measurement at mid-point in the tibialis anterior (TA) muscle among 47 computer users with chronic pain in the upper extremity and/or neck-shoulder pain (pain group) and 17 pain-free computer users (control group). Induced pain intensities and profiles over time were recorded using a 0 -10 cm electronic visual analogue scale (VAS) in response to different levels of pressure stimuli on the forearm with a new technique of dynamic pressure algometry. The efficiency of CPM was assessed using cuff-induced pain as conditioning pain stimulus and PPT at TA as test stimulus. The demographics, job seniority and number of working hours/week using a computer were similar between groups. The PPTs measured at all 15 points in the neck-shoulder region were not significantly different between groups. There were no significant differences between groups neither in PPTs nor pain intensity induced by dynamic pressure algometry. No significant difference in PPT was observed in TA between groups. During CPM, a significant increase in PPT at TA was observed in both groups (P < 0.05) without significant differences between groups. For the chronic pain group, higher clinical pain intensity, lower PPT values from the neck-shoulder and higher pain intensity evoked by the roller were all correlated with less efficient descending pain modulation (P < 0.05). This suggests that the excitability of the central pain system is normal in a large group of computer users with low pain intensity chronic upper extremity and/or neck-shoulder pain and that increased excitability of the pain system cannot explain the reported pain. However, computer users with higher pain intensity and lower PPTs were found to have decreased efficiency in descending pain modulation.BMC Musculoskeletal Disorders 12/2014; 15(1):412. · 1.90 Impact Factor
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ABSTRACT: Fibromyalgia (FM) is a rheumatic disease which affects fibrous tissues and muscles; it is characterized by chronic pain and it is often associated with craniomandibular disorders (CMD). 31 patients were assessed from March 2012 to October 2012 through the administration of specific questionnaires and following neurologic and gnatologic assessment. A relevant corre-lation between FM and CMD emerges from the present study, as 80.6% of our patients report CMD symptoms with high prevalence of myofascial pain (84%). Multivariate regression analysis revealed that the patients in the present study did not differ in score of quality of life questionnaires from patients with fibromyalgia. The neuropathic pain diagnostic question-naire (DN4) scores were positively affected by belonging to group II of Research Diagnostic Criteria of Temporomandibular Disorders (RDC/ TDM) classification, suggesting the possibility of a neuropathic component in chronic pain in this CMD group, as already speculated in our study on the correlation between burning mouth syndrome and CMD and by other au-thors in studies on chronic low back pain. However, further clinic and instrumental studies are needed in order to test this as-sumption.The Open Dentistry Journal 01/2015; 9(1):9-14.
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ABSTRACT: To identify distinct groups of patients with fibromyalgia (FM) with respect to multiple outcome measures. Data from 631 duloxetine-treated women in 4 randomized, placebo-controlled trials were included in a cluster analysis based on outcomes after up to 12 weeks of treatment. Corresponding classification rules were constructed using a classification tree method. Probabilities for transitioning from baseline to Week 12 category were estimated for placebo and duloxetine patients (Ntotal = 1188) using logistic regression. Five clusters were identified, from "worst" (high pain levels and severe mental/physical impairment) to "best" (low pain levels and nearly normal mental/physical function). For patients with moderate overall severity, mental and physical symptoms were less correlated, resulting in 2 distinct clusters based on these 2 symptom domains. Three key variables with threshold values were identified for classification of patients: Brief Pain Inventory (BPI) pain interference overall scores of <3.29 and <7.14, respectively, a Fibromyalgia Impact Questionnaire (FIQ) interference with work score of <2, and an FIQ depression score of >=5. Patient characteristics and frequencies per baseline category were similar between treatments; >80% of patients were in the 3 worst categories. Duloxetine patients were significantly more likely to improve after 12 weeks than placebo patients. A sustained effect was seen with continued duloxetine treatment. FM patients are heterogeneous and can be classified into distinct subgroups by simple descriptive rules derived from only 3 variables, which may guide individual patient management. Duloxetine showed higher improvement rates than placebo and had a sustained effect beyond 12 weeks.BMC Musculoskeletal Disorders 12/2014; 15(1):450. · 1.90 Impact Factor