Pain
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The neural mechanisms whereby placebo conditioning leads to placebo analgesia remain unclear. In this study we aimed to identify the brain structures activated during placebo conditioning and subsequent placebo analgesia. We induced placebo analgesia by associating a sham treatment with pain reduction and used fMRI to measure brain activity associated with three stages of the placebo response: before, during and after the sham treatment, while participants anticipated and experienced brief laser pain. ⋯ However, during altered pain experience only aMCC, post-central gyrus and posterior cingulate demonstrated altered activity. The common frontal cortical areas modulated during anticipation in both the placebo conditioning and placebo analgesia phases have previously been implicated in placebo analgesia. Our results suggest that the main effect of placebo arises from the reduction of anticipation of pain during placebo conditioning that is subsequently maintained during placebo analgesia.
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Complex Regional Pain Syndrome type 1 (CRPS1) is a complication after trauma or surgery. Its pathophysiology is still a matter of debate, and psychological factors have been suggested to play a role, although their influence is unclear. The aim of this study was to investigate the evidence for the influence of psychological factors on the onset and maintenance of CRPS1 in adults. ⋯ Although many patients with CRPS1 are stigmatized as being psychologically different, this literature review identified no relationship between CRPS1 and several psychological factors. Only life events seemed to be associated with CRPS1: patients who experienced more life events appeared to have a greater chance of developing CRPS1. More studies with greater methodological quality and more participants should be performed on the association between psychological factors and the development and course of CRPS1.
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The primary purpose of this study was to analyze the sequential relationships proposed by the fear-avoidance model of pain [Vlaeyen JWS et al. The role of fear of movement/(re)injury in pain disability. J Occup Rehab 1995;5:235-52]. ⋯ Multiple logistic regression analyses revealed that early change in catastrophizing, late changes in fear of movement and late change in pain severity were significant predictors of return-to-work, while late changes in depression were not. These findings highlight the importance of reductions in psychosocial risk factors in augmenting return-to-work outcomes. Implications for the fear-avoidance model and future research are discussed.