European journal of pain : EJP
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Comparative Study
The contribution of self-efficacy and depression to disability and work status in chronic pain patients: a comparison between Australian and Brazilian samples.
There is evidence that cognitions (beliefs) and mood contribute to physical disability and work status in people with chronic pain. However, most of the current evidence comes from North America and Europe. This study examined the contribution of demographic, pain and psychosocial factors to disability and work status in chronic pain patients in two matched samples from quite different countries (Australia and Brazil). ⋯ Catastrophising and pain acceptance did not contribute to disability or unemployment in either sample. These findings confirm key aspects of biopsychosocial models of pain in two culturally and linguistically different chronic pain samples from different countries. They suggest that different chronic pain populations may share more similarities than differences.
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Little is known about the variables that account for why parents underestimate the pain of their child. In the present experiment, the joint impact of parental catastrophizing about their child's pain and children's facial pain expressions was examined upon pain estimates of their child undergoing a pressure pain test. ⋯ An intriguing finding was that catastrophizing about their child's pain was related to less parent-child incongruence in pain ratings. The discussion addresses the possible functions of catastrophizing of parents about their children's pain, and delineates avenues for future research.
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Activation of spinal cord microglia and astrocytes is a common phenomenon in nerve injury pain models and is thought to exacerbate pain perception. Following a nerve injury, a transient increase in the presence of microglia takes place while the increased numbers of astrocytes stay elevated for an extended period of time. It has been proposed that activated microglia are crucial for the development of neuropathic pain and that they lead to activation of astrocytes which then play a role in maintaining the long term pathological pain sensation. ⋯ We found that two different types of cancer induced pain resulted in severe spinal astrogliosis without activation of microglia. In contrast, sciatic nerve injury led to a transient activation of microglia and sustained astrogliosis. These results show that development of hypersensitivity and astrocyte activation in pain models can take place independent of microglial activation.
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The present study investigated the effects of different doses of intrathecal lidocaine on established thermal hyperalgesia and tactile allodynia in the chronic constriction injury model of neuropathic pain, defined the effective drug dose range, the duration of pain-relief effects, and the influence of this treatment on the body and tissues. Male Sprague-Dawley rats were divided into five groups and received intrathecal saline or lidocaine (2, 6.5, 15, and 35 mg/kg) 7 days after loose sciatic ligation. Respiratory depression and hemodynamic instability were found to become more severe as doses of lidocaine increased during intrathecal therapy. ⋯ These findings indicate that intrathecal lidocaine has prolonged therapeutic effects on established neuropathic pain. The balance between sympathetic and parasympathetic nervous activities could be well preserved in most cases, except for 35 mg/kg. Considering the ratio between useful effects and side effects, doses of 15 mg/kg are suitable for intrathecal injection for relief of neuropathic pain.
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Electrical low-frequency stimulation (LFS) of spinal afferents induces long-term depression (LTD) of nociceptive processing in rodents. LTD and its parameters in man are largely unknown. This study addresses the hypothesis that LTD of spinal nociception and pain in man depends on LFS frequency (0.5, 1, 2 Hz), number of electrical pulses (300, 600, 1200), intensity (relating to pain threshold I(P): 1 x I(P), 2 x I(P), 4 x I(P)), and on LFS repetition. ⋯ LFS with intensities 2 x I(P) and 4 x I(P) evoked sustained depression of SEP and pain perception in comparison to Control and 1 x I(P) LFS. Established LTD after single LFS was amplified by an additional second LFS. Hence this study provides electrophysiological and psychophysical evidence for LTD of spinal nociceptive processing and pain perception in man and indicates appropriate LFS parameters 1 Hz, 1200 pulses and 4 x I(P) for future studies on human LTD.