Pain
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Review Meta Analysis
Randomized controlled trials of psychological therapies for management of chronic pain in children and adolescents: an updated meta-analytic review.
The purpose of this meta-analytic review was to quantify the effects of psychological therapies for the management of chronic pain in youth. Specifically, in this review we updated previous systematic reviews of randomized controlled trials by including new trials, and by adding disability and emotional functioning to pain as treatment outcomes. Electronic searches of the Cochrane Register of Randomised Controlled Trials, MEDLINE, PsycLIT, EMBASE, and the Social Sciences Citation Index were conducted from inception through August 2008. ⋯ Studies directly comparing the effects of self-administered versus therapist-administered interventions found similar effects on pain reduction. Psychological therapies result in improvement in pain relief across several different pain conditions in children. Future trials are needed that incorporate non-pain outcome domains, that focus significant therapeutic content on reductions in disability, and that include extended follow-up to better understand maintenance of treatment effects.
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Clinical Trial
NGF induces non-inflammatory localized and lasting mechanical and thermal hypersensitivity in human skin.
Nerve growth factor (NGF) modulates sensitivity and sprouting of nociceptors. We explored the spatial and temporal sensitization induced by NGF injection (1 microg) in human skin. Hyperalgesia was investigated in 16 volunteers (36+/-9 years) at day 1, 3, 7, 21, and 49. ⋯ Spatially restricted hyperalgesia indicates a peripheral rather than central mechanism. The temporal profile of lasting nociceptor sensitization suggests an altered peripheral axonal expression of sensory proteins specifically leading to mechanical and thermal sensitization. Intradermal NGF administration provokes a pattern of sensitization that can be used as experimental model for neuropathic pain.
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Expectations and beliefs modulate the experience of pain, which is particularly evident in placebo analgesia. The dorsolateral prefrontal cortex (DLPFC) has been associated with pain regulation and with the generation, maintenance and manipulation of cognitive representations, consistent with its role in expectation. ⋯ While rTMS did not affect pain experience, it completely blocked placebo analgesia. These findings suggest that expectation-induced placebo analgesia is mediated by symmetric prefrontal cortex function.
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High density Nociceptin/Orphanin FQ (N/OFQ) and its receptor (NOPr) have been found in the ventrolateral periaqueductal gray (vlPAG), a main output pathway involved in the descending pain-control system. Our previous study demonstrated that the microinjection of N/OFQ into the vlPAG markedly facilitated nociceptive responses of spinal dorsal horn neurons. The aim of the present work was to further provide evidence for the supraspinal mechanisms of action for N/OFQ-mediated nociceptive facilitation by examining the effect of N/OFQ in the vlPAG on neurotransmitter release in the descending pain-control system, including the nucleus raphe magnus (NRM), nucleus reticularis gigantocellularis (NGC) and dorsal horn of the spinal cord. ⋯ In the NRM, intra-vlPAG injection of N/OFQ significantly decreased 5-HT, NE, and Glu, but increased GABA release. Differently, in the NGC, both NE and GABA releases were attenuated by intra-vlPAG of N/OFQ, whereas the concentration of 5-HT and Glu exhibited a trend to increase. These findings provide direct support for the hypothesis that intra-PAG of N/OFQ-induced facilitation of nociceptive responses is associated with the release of 5-HT, NE, and amino acids.