European journal of pain : EJP
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Adolescents with chronic pain report disability, distress and reduced social functioning. A clinical sample of 110 adolescents, with a mean four year history of pain, was investigated for the psychosocial impact of pain on social development. All participants completed a range of self-report measures of pain intensity, disability, distress, social and family functioning. ⋯ Pain intensity had a negative effect on all three factors. Findings suggest that adolescents with chronic pain judge themselves to be less developed than their peers. Pain intensity has a negative effect on this perception, but peer relations may play a protective role: strong peer relationships are associated with positive social comparisons of the level of social development.
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Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels contribute to stabilizing resting membrane potential, thus controlling neuron excitability. Subclasses of nociceptive neurons differ in their excitability, therefore, these channels could be a distinguishing marker. We investigated isolated dorsal root ganglion neurons from a non-rodent species, the pig, Sus scrofa domesticus. ⋯ Western blot analysis showed protein products of sizes similar to those of HCN-1 and HCN-2 channel isoforms. Functionally, in patch-clamp experiments, some neurons were unresponsive to membrane hyperpolarization, thus, probably lacking HCN channels. In conclusion, in porcine dorsal root ganglion neurons there is a subset of capsaicin-positive, IB4-negative neurons lacking HCN-1 and/or HCN-2 channel isoforms.
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Loss of spinal inhibitory mechanisms is thought to contribute to the pathophysiology of abnormal pain states, including neuropathic pain. By using an evoked spinal field potential technique, the hypothesis was tested here that decreased spinal GABAergic control underlies poor response to morphine (MOR) that often accompanies neuropathic pain. Therefore, field potentials evoked by electrical peripheral nerve stimulation during spinal superfusion with MOR were recorded in rats rendered neuropathic by a spinal nerve ligation (SNL) procedure, and compared to responses recorded in naïve rats. ⋯ Two-way analysis of variance revealed no interaction of MOR with either CGP354348 (p = 0.42) or BIC (p = 0.14). Evidence is presented here that injury to the primary afferent system results in significant changes in the ability of spinal MOR to depress field potentials evoked by peripheral input. However, the present findings do not support a pathogenic role for decreased GABAergic inhibition in such changes.
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It was previously shown in a group of 9 patients with complex regional pain syndrome type 1 (CRPS1) that levels of the proinflammatory cytokines tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) are higher in blister fluid from the involved side. We hypothesize that local inflammation is responsible for the characteristics of CRPS1. The aim of this study was to confirm the previous observation in a large group of CRPS1 patients, repeating the measurement of TNF-alpha and IL-6 in blister fluid. ⋯ Our findings confirm the presence of local inflammation in a population of 66 patients in the first 2 years of CRPS1. Proinflammatory cytokines seem to be only partly involved in the pathophysiology of CRPS1, as indicated by the lack of coherence between TNF-alpha and IL-6 levels and the signs and symptoms of inflammation and disease duration. Other inflammatory mediators and mechanisms, such as central sensitization, are probably involved in the early stages of CRPS1.
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Randomized Controlled Trial Multicenter Study
Prolonged-release oxycodone enhances the effects of existing gabapentin therapy in painful diabetic neuropathy patients.
Neuropathic pain remains one of the most challenging pain syndromes; under-diagnosed, poorly managed and associated with significant co-morbidity. With standard therapeutic treatments, responders rarely exceed 50% pain relief and the majority suffer from residual pain. Titration to optimum dose is often limited by dose-related adverse events. ⋯ This study provides the first evidence that co-administration of prolonged-release oxycodone and existing gabapentin therapy has a clinically meaningful effect in painful diabetic neuropathy.