Pain
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We described trends in pelvic pain characteristics over 2 years of follow-up among adolescents and adults with and without endometriosis participating in the longitudinal observational cohort of the Women's Health Study: From Adolescence to Adulthood, using data reported at baseline and at years 1 and 2 of follow-up. Participants completed a questionnaire at baseline (between November 2012 and May 2019) and annually thereafter that included validated measures of severity, frequency, and life interference of dysmenorrhea, acyclic pelvic pain, and dyspareunia. Our study population included 620 participants with surgically confirmed endometriosis (rASRM stage I/II = 95%) and 671 community-based and hospital-based controls, with median age = 19 and 24 years, respectively. ⋯ Trends among controls remained fairly stable across 2 years. Among endometriosis cases who completed the questionnaire at all 3 time points, 18% reported persistent, severe acyclic pelvic pain at all 3 time points. Over time, different trends were observed by pelvic pain type among endometriosis cases and controls, supporting the importance of assessing multidimensional features of pelvic pain.
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Despite a preponderance of pain-related attentional bias research, little is known about how these biases arise and change over time. We tested whether the degree of attentional bias malleability , that is, ability to acquire and relinquish patterns of selective attention towards pain information, predicts daily pain interference. Individuals with chronic pain (N = 66) completed a novel attentional bias malleability procedure based on a modified dot-probe paradigm. ⋯ Greater attentional bias (F 1,391 = 3.97, P = 0.047), greater readiness to acquire an attentional bias (F 1,389 = 4.92, P = 0.027), and less readiness to lose an acquired attentional bias toward pain (F 1,354 = 5.18, P = 0.024) all predicted less pain interference. There was also an interaction between pain severity and overall attentional bias malleability (F 1,62 = 5.48, P = 0.023), such that as pain severity increased, those who showed greater attentional bias malleability showed less corresponding increase in their pain interference than those who showed less attentional bias malleability. This study adds new thinking to the dynamic nature of attentional bias and how such biases might arise and influence pain outcomes.
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Irritable bowel syndrome is a functional gastrointestinal disorder characterized by chronic visceral pain with complex etiology and difficult treatment. Accumulated evidence has confirmed that the sensitization of the central nervous system plays an important role in the development of visceral pain, whereas the exact mechanisms of action of the neural pathways remain largely unknown. In this study, a distinct neural circuit was identified from the paraventricular hypothalamic (PVH) to the ventral of lateral septal (LSV) region. ⋯ The PVH-LSV CaMKIIα + projection pathway was further confirmed by experiments containing a viral tracer. Optogenetic inhibition of PVH CaMKIIα + inputs to LSV CaMKIIα-positive neurons suppressed visceral pain, whereas selective activation of the PVH-LSV CaMKIIα + projection evoked visceral pain. These findings suggest the critical role of the PVH-LSV CaMKIIα + circuit in regulating visceral pain.
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The thermal grill illusion of pain (TGIP) is a paradoxical burning pain sensation elicited by the simultaneous application of innocuous cutaneous warm and cold stimuli with a thermode ("thermal grill") consisting of interlaced heated and cooled bars. Its neurophysiological mechanisms are unclear, but TGIP may have some mechanisms in common with pathological pain, including central sensitization in particular, through the involvement of N-methyl- d -aspartate receptors. However, few studies have investigated TGIP in patients with chronic pain and its clinical relevance is uncertain. ⋯ The percentage of TGIP responses and the intensity and unpleasantness of TGIP were significantly greater in patients than controls. Furthermore, positive correlations were found between TGIP intensity and clinical pain intensity and between TGIP intensity and the cold pain threshold measured on the hand. These results are consistent with our working hypothesis of shared mechanisms between TGIP and clinical pain mechanisms in patients with nociplastic chronic pain syndromes and suggest that TGIP might represent a clinical marker of central sensitization in these patients.
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A reciprocity between the stress and the pain system is recognized; however, the manner by which sex affects this reciprocity is unclear. Understanding the interactions of stress, pain, and sex may shed light on the apparent women's vulnerability to chronic pain, which often coexists with increased distress, and to affective disorders, which often coexist with chronic pain. The study's aim was to examine the effect of acute, validated, psychosocial stress on pain perception and modulation of women and men in a controlled manner. ⋯ Among men, TSP increased following the MIST but was not predicted by the stress variables. In conclusion, acute stress manipulation seems to differentially affect both stress and pain responses of women and men: women exhibited stress-induced antinociception and men exhibited stress-induced pronociception. Higher perceived stress levels among women may trigger a temporary increase in pain inhibition mechanisms to serve evolutionary purposes.