Pain
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Partial sciatic nerve injury causes neuropathic pain associated with behavioral changes such as spontaneous pain, hyperalgesia and allodynia. Both central and peripheral sensitization of pain pathways are likely to be involved in these alterations. Nerve injury induced plastic changes in the dorsal horn, where the second relay nociceptive neurons are located, may contribute to the central sensitization process. ⋯ Using immunocytochemistry, we found that 3 weeks following PSNL, the number of phosphorylated (p) CREB-IR cells was significantly increased in the injured side dorsal horn of rats, particularly in the superficial laminae. Interestingly, the majority of pCREB-IR cells expressed protein kinase Cgamma, an enzyme shown to be involved in the development of neuropathic pain in PSNL model. Taken together, these results suggest that increased CREB phosphorylation induced by PSNL may be one of the key molecular events leading to synaptic alterations and persistent pain in the PSNL model of neuropathic pain.
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The Faces Pain Scale (FPS; Bieri et al., Pain 41 (1990) 139) is a self-report measure used to assess the intensity of children's pain. Three studies were carried out to revise the original scale and validate the adapted version. In the first phase, the FPS was revised from its original seven faces to six, while maintaining its desirable psychometric properties, in order to make it compatible in scoring with other self-rating and observational scales which use a common metric (0-5 or 0-10). ⋯ There were no significant differences between the means on the FPS-R and either of the analogue scales. The FPS-R is shown to be appropriate for use in assessment of the intensity of children's acute pain from age 4 or 5 onward. It has the advantage of being suitable for use with the most widely used metric for scoring (0-10), and conforms closely to a linear interval scale.
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In order to analyze the pathophysiology behind the clinical similarity acutely after limb trauma and in acute stages of complex regional pain syndrome (CRPS), 20 patients with external fixation after distal radius fracture (3.5 days after surgery) without signs of CRPS and 24 patients suffering from acute CRPS I (without nerve lesion; duration, 5 weeks) were investigated. Hyperalgesia to heat was tested by a feedback-controlled thermode, and to mechanical stimuli by an impact stimulator. The sympathetic nervous system was examined by measuring skin temperature (infra-red thermography), testing different sympathetic vasoconstrictor reflexes (laser-Doppler flowmetry) and quantitative sudometry after thermal load (thermoregulatory sweat test). ⋯ Our results indicate that pain and vasomotor disturbances may be generated by different mechanisms acutely after trauma and in acute CRPS. Despite the clinical similarity, additional changes in the peripheral or central nervous system are required for CRPS. In the light of our observations, it seems unlikely that CRPS is a simple exaggeration of post-traumatic inflammation.
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Comparative Study
Effect of gabapentin and lamotrigine on mechanical allodynia-like behaviour in a rat model of trigeminal neuropathic pain.
Injury to the trigeminal nervous system may induce severe pain states. This study examined the antinociceptive effect of the novel anticonvulsants, gabapentin and lamotrigine, in a rat model of trigeminal neuropathic pain produced by chronic constriction of one infraorbital nerve. Responsiveness to von Frey filament stimulation of the vibrissal pad was evaluated 2 weeks post-operation. ⋯ Repeated (30 and 50 mg/kg), but not single (30-100 mg/kg) injections of i.p. gabapentin partially alleviated the mechanical allodynia-like behaviour. Repeated injections of gabapentin at 50 but not at 30 mg/kg produced motor deficits. The results indicate that gabapentin rather than lamotrigine may be a better therapeutic approach for the clinical management of some trigeminal neuropathic pain disorders.
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A number of ergonomic, workplace and individual psychosocial factors and health behaviors have been associated with the onset, exacerbation and/or maintenance of low back pain (LBP). The functional impact of these factors may be influenced by how a worker approaches problems in general. The present study was conducted to determine whether problem-solving orientation was associated with physical and mental health outcomes in fully employed workers (soldiers) reporting a history of LBP in the past year. ⋯ Among those with a longer history of low-grade LBP, an avoidant approach to problem-solving was also associated with a steeper gradient of functional loss (three-way interaction; F(1,458)=4.58). These results suggest that the prolonged impact of LBP on daily function may be reduced by assisting affected workers to conceptualize LBP as a problem that can be overcome and using strategies that promote taking an active role in reducing risks for LBP. Secondary prevention efforts may be improved by addressing these factors.