Pain
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Randomized Controlled Trial
Placebo analgesia induced by social observational learning.
Although it has long been known that psychosocial factors play a crucial role in placebo responses, no attempt has been made to understand if social observation shapes the placebo analgesic effect. To address this question, we compared placebo analgesia induced through social observation (Group 1) with first-hand experience via a typical conditioning procedure (Group 2) and verbal suggestion alone (Group 3). In Group 1, subjects underwent painful stimuli and placebo treatment after they had observed a demonstrator (actually a simulator) showing analgesic effect when the painful stimuli were paired to a green light. ⋯ We found that observing the beneficial effects in the demonstrator induced substantial placebo analgesic responses, which were positively correlated with empathy scores. Moreover, observational social learning produced placebo responses that were similar to those induced by directly experiencing the benefit through the conditioning procedure, whereas verbal suggestions alone produced significantly smaller effects. These findings show that placebo analgesia is finely tuned by social observation and suggest that different forms of learning take part in the placebo phenomenon.
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Randomized Controlled Trial
A randomized trial of a tailored barriers intervention for Cancer Information Service (CIS) callers in pain.
Cancer pain management can be improved by overcoming patients' attitudinal barriers to reporting pain and using analgesics. A simple cost-effective barriers intervention designed to reach a large number of persons with cancer has not yet been tested. Such an intervention should be tested against barriers' assessment-alone, as well as no-treatment control. ⋯ At follow-up the TBI group had significantly lower attitudinal barriers scores compared to assessment-alone and control, but the groups did not differ on the pain outcome variables. TBI and assessment-alone had similar cost effectiveness. The TBI needs to be strengthened to achieve reductions in pain severity.
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Randomized Controlled Trial
The effect of local anaesthetic on age-related capsaicin-induced mechanical hyperalgesia--a randomised, controlled study.
Adults over 65 years exhibit a prolonged punctate hyperalgesia induced by topical application of capsaicin. The aim of this study was to investigate the role of peripheral afferent input in the slowed resolution of punctate hyperalgesia in older people. Twenty young (25.7+/-4.8 years) and 19 old (74.9+/-4.4 years) healthy adults were recruited, and subjects in each age group were randomly assigned to receive either EMLA cream (a local anaesthetic) (n=10 in each age group) or Sorbolene treatment (n=9 in the older group, n=10 in the young group) after the development of punctate hyperalgesia. ⋯ Stoicism and cautiousness measured with Pain Attitude Questionnaire were negatively correlated with highest pain rating in the young, but not in the older groups. We suggest that the prolonged punctate hyperalgesia in older adults is possibly sustained by central mechanisms, indicating age differences in central plasticity following acute injury. The relationship between such age-related changes and the chronicity of pain in older adults should be further explored.
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The objective of the present research was to develop a single measure of the major symptoms of both neuropathic and non-neuropathic pain that can be used in studies of epidemiology, natural history, pathophysiologic mechanisms, and treatment response. We expanded and revised the Short-form McGill Pain Questionnaire (SF-MPQ) pain descriptors by adding symptoms relevant to neuropathic pain and by modifying the response format to a 0-10 numerical rating scale to provide increased responsiveness in longitudinal studies and clinical trials. ⋯ The data suggest that the SF-MPQ-2 has excellent reliability and validity, and the results of both exploratory and confirmatory factor analyses provided support for four readily interpretable subscales-continuous pain, intermittent pain, predominantly neuropathic pain, and affective descriptors. These results provide a basis for use of the SF-MPQ-2 in future clinical research, including clinical trials of treatments for neuropathic and non-neuropathic pain conditions.
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Clinical Trial
Similar itch and nociceptive sensations evoked by punctate cutaneous application of capsaicin, histamine and cowhage.
Itch evoked by cowhage or histamine is reduced or blocked by capsaicin desensitization, suggesting that pruriceptive neurons are capsaicin-sensitive. Topical capsaicin can evoke both nociceptive sensations and itch, whereas intradermal injection of capsaicin evokes only burning pain. To dissociate the pruritic and nociceptive sensory effects caused by the chemical activation of sensory neurons, chemicals were applied in a punctiform manner to the skin of the forearm using individual, heat-inactivated cowhage spicules treated with various concentrations of capsaicin (1-200 mg/ml) or histamine (0.01-100 mg/ml). ⋯ Each type of spicule also produced comparable areas of dysesthesias (enhanced mechanically evoked itch or pain) and/or skin reactions (wheal and/or flare) in surrounding skin, though inconsistently. The incidence of flare was greater in response to histamine than to capsaicin or cowhage. These results suggest the possibility that capsaicin, histamine and cowhage activate common peripheral or central neural mechanisms that mediate pruritic sensations and associated dysesthesias.