Pain
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In the peripheral nervous system, spontaneous activity in sensory neurons is considered to be one of the 2 main drivers of chronic pain states, alongside neuronal sensitization. Despite this, the precise nature and timing of this spontaneous activity in neuropathic pain is not well-established. Here, we have performed a systematic search and data extraction of existing electrophysiological literature to shed light on which fibre types have been shown to maintain spontaneous activity and over what time frame. ⋯ However, because of the highly specialised nature of the electrophysiological methods used to measure spontaneous activity, there is also a high degree of variability and uncertainty around these results. Specifically, there are very few directly controlled experiments, with less directly comparable data between human and animals. Given that spontaneous peripheral neuron activity is considered to be a key mechanistic feature of chronic pain conditions, it may be beneficial to conduct further experiments in this space.
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Chronic orofacial pain (COP) is relieved by duloxetine (DLX) and frequently causes depressive symptoms. The aim of this study was to confirm effects of DLX on pain and depressive symptoms, and to associate with their effectiveness in platelet serotonin transporter (SERT) expression, which is a target molecule of DLX and plasma serotonin concentration in COP patients with depressive symptoms. We assessed for the severity of pain and depressive symptoms using the Visual Analog Scale (VAS) and 17-item Hamilton Depression Rating Scale (HDRS), respectively. ⋯ Our findings indicate that DLX improves not only pain but also comorbid depressive symptoms of COP-D patients. Duloxetine also reduces platelet SERT through upregulation of ubiquitinated SERT. As the result, decrease of plasma serotonin concentrations may be related to the efficacy of DLX in relieving pain and depression in COP patients.
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Individuals vary significantly in their pain sensitivity, with contributions from the brain, genes, and psychological factors. However, a multidimensional model integrating these factors is lacking due to their complex interactions. To address this, we measured pain sensitivity (ie, pain threshold and pain tolerance) using the cold pressor test, collected magnetic resonance imaging (MRI) data and genetic data, and evaluated psychological factors (ie, pain catastrophizing, pain-related fear, and pain-related anxiety) from 450 healthy participants with both sexes (160 male, 290 female). ⋯ Notably, pain catastrophizing was negatively correlated with pain tolerance, and this relationship was mediated by the multimodal covarying brain patterns in male participants only. Furthermore, we identified an association between the single-nucleotide polymorphism rs4141964 within the fatty acid amide hydrolase gene and pain threshold, mediated by the identified multimodal covarying brain patterns across all participants. In summary, we suggested a model that integrates the brain, genes, and psychological factors to elucidate their role in shaping interindividual variations in pain sensitivity, highlighting the important contribution of the multimodal covarying brain patterns as important biological mediators in the associations between genes/psychological factors and pain sensitivity.
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Many gaps remain in finding effective, safe, and equitable treatments for children and adolescents with chronic pain and in accessing treatments in different settings. A major goal of the field is to improve assessment of pain and related experience. Valid and reliable patient-reported outcome measures are critical for advancing knowledge of clinical interventions for pediatric chronic pain. ⋯ Final recommendations included 9 patient-reported measures. Important contextual considerations are discussed, and guidance is provided regarding strengths and limitations of the recommendations. Implementation of these recommendations may be enhanced by widespread dissemination and ease of access to measurement tools.
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Preliminary evidence suggests that there are significant associations between bullying and chronic pain, as well as between the quality of peer relationships and psychological function in youth with chronic pain. However, these findings have yet to be replicated, and the role that bullying plays in anxiety in children and adolescents with chronic pain has not yet been examined. This study sought to expand our understanding of the associations between measures of bullying and quality of peer relationships and pain-related function domains in a community sample of schoolchildren with chronic pain. ⋯ In the group of youth with chronic pain, the measures of past and current bullying, and quality of peer relationships, were not significantly associated with pain intensity, pain interference, or anxiety. However, having a history of being bullied and the quality of peer relationships were significantly associated with depressive symptom severity. The findings indicate that research to evaluate the potential causal role of bullying and the quality of peer relationships on pain-related function domains in youth with chronic pain is warranted.