Pain
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Research has shown that pain and sleep disturbance often co-occur and influence each other over time in children and adolescents with chronic pain. Longitudinal studies examining the underlying mechanisms of this association are scarce and have focused primarily on the role of internalizing mental health symptoms and mood. This longitudinal study aimed to determine whether fatigue underlies the co-occurrence and mutual maintenance of sleep disturbance and pain over time in children and adolescents with chronic pain. ⋯ Higher levels of pain interference at first assessment predicted higher levels of sleep disturbance at follow-up while controlling for initial levels of sleep disturbance. Furthermore, fatigue was found to mediate the association between first assessment and follow-up sleep disturbance, the association between first assessment and follow-up pain interference, and the association between first assessment pain interference and follow-up sleep disturbance. The findings highlight the need to assess and address fatigue in children and adolescents with chronic pain and sleep disturbance.
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Developmental trajectories for neck disability after whiplash injury have been identified. Their relationship to cold and mechanical sensitivity trajectories is not known. We aimed to (1) identify recovery trajectories of cold and mechanical sensitivity, (2) explore their codevelopment with disability trajectories, (3) identify predictors of sensitivity trajectories, and (4) explore codevelopment of cold and mechanical sensitivity trajectories. ⋯ We found no associations between baseline characteristics and mechanical sensitivity. There is an interplay between cold allodynia, pain, and hyperarousal symptoms in development of ongoing disability after whiplash injury. Different mechanisms likely underlie cold and mechanical sensitivity.
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The higher incidence of migraines in women compared with men has led to the inclusion of female animals in pain research models. However, the critical role of the hormonal cycle is frequently overlooked, despite its clear correlation with migraine occurrences. In this study, we show in a rat model of migraine induced by repeated dural infusions of an inflammatory soup (IS) that a second IS (IS2) injection performed in proestrus/estrus (PE, high estrogen) female rats evokes higher cephalic mechanical hypersensitivities than when performed in metestrus/diestrus (MD, low estrogen) or ovariectomized (OV) rats. ⋯ Second inflammatory soup depolarizes neurons in PE and MD but not in OV rats and enhances excitatory synaptic inputs in PE animals to a greater extent compared with MD and OV rats. These findings show that central TCC sensitization triggered by meningeal nociceptor activation and the resulting cephalic hypersensitivity are modulated by the estrous cycle. This highlights the crucial need to account for not just sex, but also the female estrous cycle in pain research.
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The nociceptive withdrawal reflex (NWR) is a spinal withdrawal reflex induced by painful stimulation. It is a measure of spinal hyperexcitability, which is believed to contribute to chronic musculoskeletal pain (MSKP) and headache. Previous syntheses of the evidence for alterations in the NWR in patients with chronic MSKP and headache needed a comprehensive update. ⋯ Spinal hyperexcitability as evidenced by lowered NWR threshold values and temporal summation of the NWR is present in patients with chronic MSKP and headache. No evidence was found for alterations in NWR duration and NWR magnitude. Future research is needed to address the gap in research on NWR-related outcome measures other than NWR threshold.
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Although opioids continue to be used internationally for noncancer pain, evidence to date on the comparative safety of different opioids is sparse and conflicting. The aim of this study was to examine the comparative risk of all-cause mortality in patients newly initiated on opioids for noncancer pain, across 3 jurisdictions in the United Kingdom (UK), United States, and Canada. A multicentre retrospective, population-based cohort study was conducted. ⋯ In addition, other factors associated with higher mortality were being on combination opioids, fentanyl, buprenorphine, and oxycodone. Compared with those on <50 morphine milligram equivalents/day, patients on higher-doses experience an incremental increase in risk. In new users of opioids, compared with codeine, strong opioids, including morphine, fentanyl, buprenorphine, oxycodone, and combination opioids, and those on ≥50 morphine milligram equivalent/day were associated with a higher subsequent risk of all-cause mortality.