Pain
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Glial activation is known to contribute to pain hypersensitivity following spinal sensory nerve injury. In this study, we investigated mechanisms by which glial cell activation in medullary dorsal horn (MDH) would contribute to tactile hypersensitivity following inferior alveolar nerve and mental nerve transection (IAMNT). Activation of microglia and astrocytes was monitored at 2 h, 1, 3, 7, 14, 28, and 60 days using immunohistochemical analysis with OX-42 and GFAP antibodies, respectively. ⋯ There was no significant loss of trigeminal ganglion neurons by 28 days following IAMNT, suggesting that degenerative changes in central terminals of primary afferents might not contribute to glial activation. Minocycline, an inhibitor of microglial activation, reduced microglial activation, inhibited p38 mitogen-activated protein kinase (MAPK) activation in microglia, and significantly attenuated the development of pain hypersensitivity in this model. These results suggest that glial activation in MDH plays an important role in the development of neuropathic pain and activation of p38 MAPK in hyperactive microglia contributes to pain hypersensitivity in IAMNT model.
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The cognitive-behavioral, fear-avoidance (FA) model of chronic pain (Vlaeyen JWS, Kole-Snijders AMJ, Boeren RGB, van Eek H. Fear of movement/(re)injury in chronic low back pain and its relation to behavioral performance. Pain 1995a;62:363-72) has found broad empirical support, but its multivariate, predictive relationships have not been uniformly validated. ⋯ For older chronic pain patients, a stronger mediating role for pain-related fear was supported. Results are consistent with a FA model of chronic pain, while indicating some important age group differences in this model and in levels of pain-related fear. Longitudinal testing of the multivariate model is recommended.
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Comment Letter Case Reports
Intrathecal S(+)-ketamine in refractory neuropathic cancer pain.
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Meta Analysis
Bias from industry trial funding? A framework, a suggested approach, and a negative result.
Bias from funding sources of trials would threaten their validity. Meta-analyses of high quality acute pain and migraine trials were used to explore the hypothesis that industry funding of clinical trials produced more favourable results than non-profit sponsorship. Analyses were planned to evaluate whether industry-sponsored trials had different results from trials funded by academic or other non-profit sources, but of 176 trials, only two were supported by non-profit sources, while 31 provided no statement of support. ⋯ Investigating potential industry bias through the funding source of trials is unlikely to be adequate because of a dearth of trials funded by non-profit organisations. We propose a method based on potential conflict of interest within industry-sponsored trials. Using this method, established clinical trial results in acute pain and migraine appear to be unbiased.
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Randomized Controlled Trial
Short- and long-term efficacy of brief cognitive-behavioral therapy for patients with chronic temporomandibular disorder pain: a randomized, controlled trial.
We evaluated the short- and long-term efficacy of a brief cognitive-behavioral therapy (CBT) for chronic temporomandibular disorder (TMD) pain in a randomized controlled trial. TMD clinic patients were assigned randomly to four sessions of either CBT (n=79) or an education/attention control condition (n=79). Participants completed outcome (pain, activity interference, jaw function, and depression) and process (pain beliefs, catastrophizing, and coping) measures before randomization, and 3 (post-treatment), 6, and 12 months later. ⋯ In addition, more CBT than control group patients had clinically meaningful improvement in pain intensity (50% versus 29% showed > or =50% decrease, P=0.01), masticatory jaw function (P<0.001), and depression (P=0.016) at 12 months (intent-to-treat analyses). The two groups improved equivalently on a measure of TMD knowledge. A brief CBT intervention improves one-year clinical outcomes of TMD clinic patients and these effects appear to result from specific ingredients of the CBT.