European journal of pain : EJP
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Efficacy of pain modulation is assessed as the difference in pain sensitivity during a painful conditioning, compared to before (conditioning pain modulation, CPM). Attention can be assessed with the Stroop task, in which participants report the number of words on a screen; either congruent or incongruent with the value of the words. Attention away from painful stimuli during CPM enhances the CPM effect. However, it is unknown if attention influences CPM effects when the two are done in sequence. ⋯ Pain sensitivity is reduced after an attention task in healthy men. The delayed effects from attention only have minor effects on Conditioned Pain Modulation (CPM), and results support that attention-driven analgesia works independently of CPM. Results indicate that individual strategies for pain inhibition exist and that an overlap between the mechanisms of CPM and selective attention is limited. Moreover, painful phasic stimuli may increase the number of healthy volunteers with negative CPM effects.
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Conditioned pain modulation (CPM) and offset analgesia are different features of descending pain inhibition. This study investigated CPM, offset analgesia and clinical pain measures in patients with knee osteoarthritis (KOA) before and after treatment with the combination of a non-steroidal anti-inflammatory drug (NSAIDs) plus acetaminophen. ⋯ This study demonstrated that conditioned pain modulation is correlated with the response to a standard pharmaceutical interventions treating osteoarthritis pain. Furthermore, we demonstrated that a decrease in clinical pain intensity is not associated with a normalization of conditioned pain modulation or offset analgesia, which questions if restoring these descending pain inhibitory mechanisms are pain intensity driven.
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Delayed onset muscle soreness (DOMS) is characterized by mechanical hyperalgesia after lengthening contractions (LC). It is relatively common and causes disturbance for many people who require continuous exercise, yet its molecular and peripheral neural mechanisms are poorly understood. ⋯ Here, we show that not only C- but also Aδ-fibre nociceptors in the muscle are involved in mechanical hypersensitivity after lengthening contractions, and that acid-sensing ion channel (ASIC)-3 expressed in the thin-fibre nociceptors is responsible for the mechanical hypersensitivity. ASIC3 might be a novel pharmacological target for pain after exercise.
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The ontogenetic perspective on the development of emotional expressions in infants holds that infants' facial and vocal expressions evolved to serve crucial communicative functions in infancy and contribute to infants' survival. Infants' facial expressions should be contextualized by their own developmental stage rather than presuppositions from verbal populations. The overall aim of this paper was to examine age differences in the temporal patterning of elucidated facial expressions in the first minute following vaccination injections. ⋯ An important developmental milestone was identified in infants' ability to regulate distress at 6 months. Supporting parents' infant pain management is particularly critical in the first months of life as infants' initial facial expressions appear to be more reflective of an organism overwhelmed by distress.
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Randomized Controlled Trial
Masseter corticomotor excitability is decreased after intramuscular administration of nerve growth factor.
Quantification of motor-evoked potentials (MEPs) can contribute to better elucidate the central modulation of motor pathways in response to nociceptive inputs. The primary aim of this study was to assess the modulatory effects of nerve growth factor (NGF) injection on masseter corticomotor excitability. ⋯ Intramuscular administration of nerve growth factor into masseter muscle causes inhibitory corticomotor plasticity, which likely occurs to prevent further damage and seems associated with lower pain intensity on function.