Pain
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Inflammatory pain hypersensitivity is associated with activation of primary afferent neurons. This study investigated the existence of the inflammasome in dorsal root ganglion (DRG) and the functional significance in the development of inflammatory pain hypersensitivity. Tissue inflammation was induced in male C57BL/6 mice with complete Freund's adjuvant (CFA) or ceramide injection into the hind paw. ⋯ NLRP2 siRNA inhibited ceramide-induced pain hypersensitivity. These results confirmed the existence of NLRP2 inflammasome in DRG neurons. Activation of the NLRP2 inflammasome leads to activation of DRG neurons and subsequent development of pain hypersensitivity in various types of tissue inflammation.
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The aims of this study were to review the psychometric properties of the widely used Pain Catastrophizing Scale (PCS) using meta-analytic methods and to investigate the relationship between PCS scores and participant characteristics. A systematic search from 1995 found 229 experimental, quasi-experimental, and correlational studies that report PCS scores. Multivariate regression explored variables related to pain catastrophizing and participant demographics. ⋯ Study type influenced PCS scores with nonrandomized controlled trials reporting higher PCS scores than other study types, but results were confounded with pain diagnosis, as controlled trials were more likely than quasi-experimental studies to recruit clinical samples. The meta-analytic results provide insights into demographic influences on pain catastrophizing scores and highlight areas for further research. The advantages of systematic review and meta-analytic methods to achieve greater understanding and precision of psychometric properties-in this case, of the PCS-are applicable to other widely used outcome tools.
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Comorbidity of pain and posttraumatic stress disorder is well recognized, but the reason for this association is unclear. This study investigated the direction of the relationship between pain and traumatic stress and the role that pain-related fear plays, for patients with acute whiplash-associated disorder. Participants (n = 99) used an electronic diary to record hourly ratings of pain, traumatic stress, and fear of pain (FOP) symptoms over a day. ⋯ Differences between this study and others that reported mutual maintenance can be understood in terms of different stages of whiplash-associated disorder and different intervals between repeated measurements. Traumatic stress may affect pain over longer time intervals than measured in this study. Future research could explore how relationships between traumatic stress symptoms, pain, and FOP change over time, and whether previous experiences of traumatic stress influence these relationships.