Pain
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Limited information on the prevalence and risk factors for chronic pain is available for developing countries. Therefore, we investigated the prevalence of chronic pain and the association between this pain and various personal and sociodemographic factors by including questions in the South Africa Demographic and Household Survey 2016. The survey was conducted by face-to-face interviews with a nationally representative sample of the adult population (ages 15 and older, n = 10,336). ⋯ The body sites affected most frequently were the limbs (43.6% [95% CI: 40.4-46.9]), followed by the back (30.5% [95% CI: 27.7-33.6]). This article presents the prevalence of chronic pain in the general population of a middle-income African country. These data give much needed insights into the burden of, and risk factors for, chronic pain in low-resource settings, and identify priority groups for intervention.
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Distorted representations of the body and peripersonal space are common in complex regional pain syndrome (CRPS), and might modulate its symptoms (eg, asymmetric limb temperature). In pain-free people, such representations are malleable, and update when we interact with objects in our environment (eg, during tool-use). Distortions are also common after immobilisation, but quickly normalise once movement is regained. ⋯ Furthermore, people with CRPS showed more pronounced updating of peripersonal space than the controls. We did not observe any modulation of hand temperature asymmetries by the arrangement of hands or tools. Our findings show enhanced malleability of bodily and spatial representations in CRPS, which may suggest that central mechanisms are altered in this condition.
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EphrinB-EphB receptor tyrosine kinases have been demonstrated to play important roles in pain processing after peripheral nerve injury. We have previously reported that ephrinB-EphB receptor signaling can regulate excitability and plasticity of neurons in spinal dorsal horn, and thus contribute to spinal central sensitization in neuropathic pain. How EphB receptor activation influences excitability of primary neurons in dorsal root ganglion (DRG), however, remains unknown. ⋯ In nerve-injured DRG neurons, elevated expression and activation of EphB1 and EphB2 receptors contributed to the increased intracellular Ca concentration and NMDA-induced Ca influx. Repetitive intrathecal administration of EphB2-Fc inhibited the increased phosphorylation of NR2B and Ca-dependent subsequent signals Src, ERK, and CaMKII as well as behaviorally expressed pain after nerve injury. These findings demonstrate that activation of EphB receptors can modulate DRG neuron excitability by facilitating Ca influx directly or through Src kinase activation-mediated NMDA receptor phosphorylation and that EphB receptor activation is critical to DRG neuron hyperexcitability, which has been considered critical to the subsequent spinal central sensitization and neuropathic pain.
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Dorsal root ganglion (DRG) neurons detect sensory inputs and are crucial for pain processing. They are often studied in vitro as dissociated cell cultures with the assumption that this reasonably represents in vivo conditions. However, to the best of our knowledge, no study has directly compared genome-wide transcriptomes of DRG tissue in vivo versus in vitro or between laboratories and culturing protocols. ⋯ We found that the expression of a subset of genes typically expressed in neurons increased in human and mouse DRG cultures relative to the intact ganglion, including genes associated with nerve injury or inflammation in preclinical models such as BDNF, MMP9, GAL, and ATF3. We also found a striking upregulation of a number of inflammation-associated genes in DRG cultures, although many were different between mouse and human. Our findings suggest an injury-like phenotype in DRG cultures that has important implications for the use of this model system for pain drug discovery.
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In laparoscopic nephrectomy patients, early post-operative pain is associated with 30-day infectious complications.
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