European journal of pain : EJP
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Current rodent models of neuropathic pain produce pain hypersensitivity in almost all lesioned animals and not all identified experimental effects are pain specific. 18G needlestick-nerve-injury (NNI) to one tibial nerve of outbred Sprague-Dawley rats models the phenotype of Complex Regional Pain Syndrome (CRPS), a post-traumatic neuropathic pain syndrome, leaving roughly half of NNI rats with hyperalgesia. We compared endoneurial data from these divergent endophenotypes searching for pathological changes specifically associated with pain-behaviors. Tibial, sural, and common sciatic nerves from 12 NNI rats plus 10 nerves from sham-operated controls were removed 14 days post-surgery for morphometric analysis. ⋯ Similar pathological changes have been identified in CRPS-I patients. The current findings suggest that severity of endoneurial vasculopathy and inflammation may correlate better with neuropathic pain behaviors than degree of axonal loss. Spread of pathological changes to nearby ipsilateral and contralateral nerves might potentially contribute to extraterritorial pain in CRPS.
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There is generally good evidence that pain management interventions that include self-management strategies can substantially reduce disability and improve psychological well-being in patients with chronic pain. Reductions in unhelpful responses, especially catastrophising and fear-avoidance beliefs, have been established as key contributors to these gains. In contrast, there is surprisingly little evidence that adherence to self-management strategies contributes to achieving these outcomes. ⋯ Consistent with previous research, reductions in catastrophising and fear-avoidance beliefs, and increased pain self-efficacy beliefs, were also associated with these gains. But the key new finding was that there was a clear gradient between adherence to specific self-management strategies and reductions in pain, disability and depressive symptoms. Furthermore, adherence to the self-management strategies was predictive of better outcomes even after controlling for the moderating effects of initial catastrophising, fear-avoidance and pain self-efficacy beliefs.
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Inflammatory and immune responses following nerve injury have been shown to play an important role in neuropathic pain. Lipoxins are endogenous lipoxygenase-derived eicosanoids performing protective roles in a range of pathophysiologic processes. Here, we examined the effects of intrathecal lipoxinA4 (LXA4) on NF-κB activation and pro-inflammatory cytokine (TNF-α, IL-1β and IL-6) expression in dorsal root ganglia (DRG) following chronic compression of DRG (CCD), a model of neuropathic pain. ⋯ CCD induced both mechanical allodynia and thermal hyperalgesia, and increased the expression of TNF-α, IL-1β, IL-6 and NF-κB. Intrathecal injection of LXA4 prevented the development of neuropathic pain and inhibited NF-κB activation and pro-inflammatory cytokine upregulation in a dose-dependent manner. In this study, we have shown the strong protective effect of intrathecal LXA4 on the development of nociceptive behaviors induced by CCD and that these effects might be associated with its anti-inflammatory and pro-resolution properties.
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Radiotherapy (XRT) is the gold standard treatment for cancer-induced bone pain (CIBP), but only 50% of patients achieve adequate pain relief within 6 weeks. No predictors of analgesic response to XRT are known. The aim of this preliminary study was to explore the effect of XRT on sensory changes in CIBP with a view to predicting response. ⋯ This is the first clinical study to demonstrate alterations in sensory responses in CIBP. Alterations in specific sensory characteristics seem to be associated with an increased likelihood of successful analgesia from palliative XRT. This supports the use of QST in further biomarker studies to predict response to therapy and aid clinical decision making.
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Pain and factors related to it constitute serious health problems in the older population. This populationbased cross-sectional study aimed to investigate whether musculoskeletal pain is associated with mobility limitation and whether the relationship between pain and mobility limitation varies according to the use of analgesics among community-dwelling older people. A total of 622 community-dwelling participants aged 75 years and older (mean age 80.4, 74% women) were interviewed about presence and severity of musculoskeletal pain. ⋯ The risk of mobility limitation was highest among those who reported severe or moderate pain (1.84; 1.13, 3.13) and among those who used analgesics (2.37; 1.37, 4.11). In conclusion, musculoskeletal pain increases the risk for mobility limitation. The present findings underline the importance of the careful assessment and pharmacological and nonpharmacological management of pain in promoting mobility in older age.