European journal of pain : EJP
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Emotions and attention have been shown to influence the perception of pain and several psychophysiological studies have suggested an implication of descending modulatory mechanisms to explain these effects. However, the specificity of the neurophysiological mechanisms underlying the emotional and attentional modulation of pain still remains unclear. In order to differentiate the supra-spinal and spinal mechanisms involved in emotional and attentional modulation of pain, we measured pain perception (self-ratings) and the RIII reflex in healthy volunteers during the presentation of pleasant, unpleasant and neutral pictures, as well as during a baseline condition with no visual distractor (Experiment 1). ⋯ Increased arousal further potentiated the effects of negative valence on both pain and the RIII reflex and the effects of positive emotions on pain, as previously reported. However, arousal did not potentiate the inhibitory effect of positive pictures on the RIII and seems insufficient to account for the effect of distraction on the RIII. Overall, these data provide further evidence that attention and emotion modulate pain through partially dissociable neurophysiological mechanisms.
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The use of anesthetics to stabilize animals for the purpose of electroacupuncture (EA) analgesic studies can be problematic because of the interference of differential physiological responses to EA and pain. In this study, EA-induced physiological profiles were surveyed under a sub-minimal alveolar concentration (sub-MAC) of two different anesthetics in a previously proposed minimal stress model. First, to select an adequate concentration, compliance with EA and tail-flick stimulation was evaluated under various concentrations of halothane and isoflurane. ⋯ The ratios of EA non-responders in the isoflurane and halothane groups were 32.4% and 26.7%, respectively, without statistical difference. We concluded that sub-MAC halothane and isoflurane provide optimal conditions for the study of EA-induced analgesia in rats. In this model, 0.75% isoflurane appears to be a better choice than 0.5% halothane in terms of EA compliance.
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Sex differences in pain perception have been reported in an expanding literature based on adult samples in epidemiological as well as laboratory studies. Especially with respect to the latter, studies with children and adolescents do not consistently show that females report higher pain ratings and display lower pain tolerance than males. The first aim of the presented studies is to comparably examine sex differences in children and adolescents based on experimental and questionnaire approach indices of pain perception. ⋯ In Study 2, sex differences are also present for masculinity, femininity, catastrophizing as well as pain self-efficacy. However, while the relation between sex and the CPT rating is partially mediated by pain self-efficacy, catastrophizing partially mediates the relation between sex and the questionnaire based pain ratings. The results of both studies are discussed with respect to the difference between experimental assessments of pain perception and assessments by questionnaire in children and adolescents.
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Minimal access surgery (MAS) in adults is associated with less postoperative pain in comparison to conventional 'open' surgery. It is not known whether this holds true for neonates as well. Less pain would imply that opioid consumption can be reduced, which has a beneficial effect on morbidity. ⋯ Minimal access surgery for the repair of esophageal atresia or congenital diaphragmatic hernia is not associated with less cumulative opioid doses.
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Randomized Controlled Trial
The anticonvulsant levetiracetam for the treatment of pain in polyneuropathy: a randomized, placebo-controlled, cross-over trial.
Levetiracetam is an anticonvulsant which is assumed to act by modulating neurotransmitter release via binding to the vesicle protein SV2A. This could have an impact on signaling in the nociceptive system, and a pilot study indicated relief of neuropathic pain with levetiracetam. ⋯ This study indicates that the anticonvulsant levetiracetam has no clinically relevant effect on painful polyneuropathy.