Pain
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Cancer-induced bone pain is a major clinical problem. A rat model based on intra-tibial injection of MRMT-1 mammary tumour cells was used to mimic progressive cancer-induced bone pain. At the time of stable behavioural changes (decreased thresholds to mechanical and cold stimuli) and bone destruction, in vivo electrophysiology was used to characterize natural (mechanical, thermal, and cold) and electrical-evoked responses of superficial and deep dorsal horn neurones in halothane-anaesthetized rats. ⋯ Deep WDR neurones showed less pronounced changes to the superficial dorsal horn, however, the response to thermal and electrical stimuli, but not mechanical, were significantly increased in the MRMT-1-injected rats. In conclusion, the spinal cord is significantly hyperexcitable with previously superficial NS cells becoming responsive to wide-dynamic range stimuli possibly driving this plasticity via ascending and descending facilitatory pathways. The alterations in superficial dorsal horn neurones have not been reported in neuropathy or inflammation adding to the evidence for cancer-induced bone pain reflecting a unique pain state.
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The use of percentage pain reduction is increasingly used to evaluate the effectiveness of pain treatments, but the degree of agreement between calculated percentage pain reduction (CPPR) as calculated from pre- and post-treatment levels of pain intensity and those reported directly by patients is unknown. Lack of agreement between these two measures could lead to errors in the determination of treatment effectiveness. We aimed to determine the agreement between CPPR and patient-reported percentage pain reduction (PRPPR). ⋯ The agreement between percentage pain reductions calculated from NRS scores and those estimated by patients did not vary according to gender or age. The good overall agreement between percentage pain reductions calculated from NRS scores and those estimated by patients suggests that these indices may be used interchangeably. The findings of this study extend existing patient-centered pain research and may be applied for the evaluation and comparison of pain treatments.
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In painful inflammation, exogenous as well as endogenous corticotropin-releasing hormone (CRH) can release opioid peptides (mainly beta-endorphin) from various types of immune cells and produce antinociception by activating opioid receptors on peripheral sensory nerve endings. CRH mediates its central effects through two high-affinity membrane receptors, the CRH receptor subtypes 1 and 2. It is unclear at present whether the peripheral antinociceptive effects of CRH are mediated through CRH receptor 1 (CRH R1) or CRH receptor 2 (CRH R2). ⋯ Also we observed a high degree of co-localization of CRH R1 and CRH R2 receptors on circulating and resident immune cells. Both the selective CRH R1 antagonist CP-154,526 and the selective CRH R2 antagonist astressin 2B significantly attenuated peripheral antinociceptive effects of CRH indicating the involvement of both CRH receptor subtypes. Taken together, these findings suggest that in inflammatory pain CRH-induced peripheral antinociception is mediated via both CRH R1 and CRH R2 located on END containing immune cells within inflamed sites.
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Randomized Controlled Trial Comparative Study Clinical Trial
The placebo needle, is it a valid and convincing placebo for use in acupuncture trials? A randomised, single-blind, cross-over pilot trial.
The issue of what constitutes an effective and realistic acupuncture placebo control has been a continuing problem for acupuncture research. In order to provide an effective placebo, the control procedure must be convincing, visible and should mimic, in all respects, apart from a physiological effect, the real active treatment. The 'Streitberger' needle might fulfil these criteria and this paper reports on a validation study. ⋯ No major differences in outcome between real and placebo needling could be found. The fact that nearly 40% of subjects did not find that the two interventions were similar, however, raises some concerns with regard to the wholesale adoption of this instrument as a standard acupuncture placebo. Further work on inter-tester reliability and standardisation of technique is highly recommended before we can be confident about using this needle in further studies.
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Randomized Controlled Trial Clinical Trial
Pain coping strategies play a role in the persistence of pain in post-herpetic neuralgia.
Post-herpetic neuralgia (PHN) is a neuropathic pain state that is often difficult to treat. Although frequently discussed in the clinical literature, little is known about the impact of pain on daily function and the extent to which psychosocial factors, in particular pain coping strategies, influence adaptation to this chronic illness. In the context of a crossover pharmacological trial, 68 patients with PHN completed a battery of psychological measures during a first drug-free baseline period. ⋯ Patients who reported increasing their activity in response to pain also reported more perceived interference due to pain 8 weeks later. Higher levels of ignoring pain sensations at baseline were prospectively correlated with more depressive symptoms 8 weeks later. These findings support a role for the continued investigation of cognitive-behavioral factors affecting the adaptation of elderly individuals experiencing PHN.