European journal of pain : EJP
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The precise mechanism by which gonadal hormones influence pain perception is still obscure. However, no studies have examined experimental pain responses at supra-physiological hormone levels. This study explored the influence of pharmacological estradiol (E2) levels on the stability of pain perception obtained via quantitative sensory testing. ⋯ Mixed model repeated measures ANOVA indicated that participants who over-responded to the ovarian stimulation session (E2 > 10,500 pmol/l) showed significant enhanced pain responses under this condition (p=0.004). No correlations between progesterone, LH and experimental pain perception were found in any of the study sessions. Although pain perceptions at different E2 levels remained constant, the enhancement of pain scoring at supra-physiological E2 levels, underscore the possible role of sex hormones in pain modulation and experience.
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The effects of gentle mechanical skin stimulation on reflex discharges in cardiac sympathetic nerve evoked by somatic afferent stimulation were studied in anesthetized rats. Mass discharges were recorded from cardiac sympathetic efferent nerve while somatocardiac sympathetic A- and C-reflexes were elicited by single electrical stimuli to myelinated A- and unmyelinated C-afferent fibers of the tibial nerve. Continuous touch was applied to inner thigh skin with a force of 0.12 N for 10 min periods by a soft elastomer "brush" (1.1cm in diameter with 417 microcones). ⋯ We recorded unitary afferent activity from thigh branches of the saphenous nerve and found fibers excited by touch were low-threshold mechanoreceptive Abeta, Adelta and C fibers that have rapidly or slowly adapting properties. In all units tested, average discharge rates during touch period were less than 4 Hz. The results suggest that touch-induced excitation of low threshold cutaneous mechanoreceptive fibers inhibits nociceptive transmission conveyed by C-primary-afferents, via the release of both opioid and non-opioid inhibitory mediators.
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Randomized Controlled Trial
Driving plasticity in the motor cortex in recurrent low back pain.
The sensory and motor systems can reorganise following injury and learning of new motor skills. Recently we observed adaptive changes in motor cortical organisation in patients with recurrent low back pain (LBP), which are linked to altered motor coordination. Although changes in motor coordination can be trained and are associated with improved symptoms and function, it remains unclear whether these training-induced changes are related to reorganisation of the motor cortex. ⋯ Changes were not observed following unskilled walking exercise. This is the first observation that motor training can reverse reorganisation of neuronal networks of the motor cortex in people with recurrent pain. The observed relationship between cortical reorganisation and changes in motor coordination following motor training provides unique insight into potential mechanisms that underlie recovery.
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Accurate assessment of adolescent chronic pain is critical to guiding treatment decisions. Given the multifaceted role of the parents in their children's lives, parents, and patients often each provide reports of adolescents' pain-related functioning. In order to make sense of these data, clinicians should be aware of patterns of discordance in perspectives. ⋯ Analyses suggested that high pain and being older predicted greater concordance in ratings. Findings suggest that mothers and adolescents tended to have greater concordance for more observable and shared disability (e.g., physical disability, family functioning) and greater discordance for internal experiences (e.g., pain-specific anxiety, depression). Awareness of these patterns of concordance and discordance should help clinicians in interpreting mothers' proxy-reports and adolescents' self-reports of chronic pain-related functioning.
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A previous study has reported that chronic pain is associated with a higher incidence of overall and site-specific cancer in subsequent years. The aim of this study was to confirm or refute these findings. In 1996, a cohort of 6940 individuals was recruited, and information on chronic pain, general health and socio-demographic details collected. ⋯ After adjustment, these trends remained, although most of the associations were no longer significant. There were no significant differences between those with severe chronic pain compared to those with mild chronic pain. The findings suggest that those with chronic pain are not at a significantly increased risk of developing cancer.