European journal of pain : EJP
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The autonomic nervous system (ANS) reacts to nociceptive stimulation during sleep, but whether this reaction is contingent to cortical arousal, and whether one of the autonomic arms (sympathetic/parasympathetic) predominates over the other remains unknown. We assessed ANS reactivity to nociceptive stimulation during all sleep stages through heart rate variability, and correlated the results with the presence of cortical arousal measured in concomitant 32-channel EEG. Fourteen healthy volunteers underwent whole-night polysomnography during which nociceptive laser stimuli were applied over the hand. ⋯ This RR decrease was associated with an increase in sympathetic LF(WV) and LF(WV)/HF(WV) ratio without any parasympathetic HF(WV) change. Albeit RR decrease existed even in the absence of arousals, it was significantly higher when an arousal followed the noxious stimulus. These results suggest that the sympathetic-dependent cardiac activation induced by nociceptive stimuli is modulated by a sleep dependent phenomenon related to cortical activation and not by sleep itself, since it reaches a same intensity whatever the state of vigilance.
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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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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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The aim of the study was to investigate the effect of acute trapezius pain, induced by delayed onset of muscle soreness (DOMS), on habitual trapezius activity. Long-term (5 h) surface electromyographic (sEMG) activity was recorded bilaterally from the clavicular, descending, transverse, and ascending trapezius on two consecutive weekdays in eleven female subjects (mean age 22 years, range 20-24 years). Body and arm posture were recorded by inclinometers. ⋯ In contrast, trapezius sEMG activity remained unchanged for all other trapezius parts and postures. This study indicates that acute trapezius pain induces elevated habitual trapezius activity during periods with low biomechanical loading of the shoulder/neck muscles with the elevated sEMG activity being restricted to the painful part of the muscle. In contrast to the pain-adaption model, the current study indicates a relation between acute muscle pain and elevated low-level muscle activity; however, it remains unknown if development of chronic muscle pain can be preceded by an initial stage with elevated muscle activity.
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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.