Pain
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Skeletal metastases are frequently accompanied by chronic pain that is mechanoceptive in nature. Mechanistically, cancer-induced bone pain (CIBP) is mediated by peripheral sensory neurons innervating the cancerous site, the cell bodies of which are housed in the dorsal root ganglia (DRG). How these somatosensory neurons encode sensory information in CIBP remains only partly explained. ⋯ Distinct clusters of responses to peripheral stimuli were revealed. In CIBP rats, upon knee compression of the leg ipsilateral to the tumour, (1) 3 times as many sensory afferents responded (repeated-measures analysis of variance: P < 0.0001 [vs sham]); (2) there were significantly more small neurons responding (Kruskal-Wallis for independent samples (vs sham): P < 0.0001); and (3) approximately 13% of traced tibial cavity afferents responded (no difference observed between CIBP and sham-operated animals). We conclude that an increased sensory afferent response is present in CIBP rats, and this is likely to reflect afferent recruitment from outside of the bone rather than increased intraosseous afferent activity.
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Pain signals the presence of potential harm, captures attention, and can inhibit performance on concurrent tasks. What is less well known, however, is whether such attentional capture also occurs in a wider social context, such as when observing people in pain. To explore this possibility, we adopted a novel social-cue detection methodology: the bodies-in-the-crowd task. ⋯ They also showed slower disengagement from female expressions overall. Male observers showed no variation based on target or distractor gender. Implications and potential directions for future research are discussed.
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Although a fluctuating pattern of orofacial pain across the life span has been proposed, data on its natural course are lacking. The longitudinal course of orofacial pain in the general population was evaluated using data from routine dental check-ups at all Public Dental Health services in Västerbotten, Sweden. In a large population sample, 2 screening questions were used to identify individuals with pain once a week or more in the orofacial area. ⋯ Longitudinal data for 135,800 individuals were available for incidence analysis. Women were at higher risk of both developing orofacial pain (incidence rate ratio 2.37; 95% CI 2.25-2.50) and reporting pain in consecutive check-ups (incidence rate ratio 2.56; 95% CI 2.29-2.87). In the northern Swedish population studied, the prevalence of orofacial pain increases over time and more so in women, thus indicating increasing differences in gender for orofacial pain.
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The prefrontal cortex undergoes functional and structural reorganization in chronic pain conditions in both rodents and humans. We provide an illustrated overview of the molecular, functional, and connectivity pathology occurring in the prefrontal cortex in chronic pain states.