European journal of pain : EJP
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Randomized Controlled Trial
Fear of pain and cortisol reactivity predict the strength of stress-induced hypoalgesia.
Acute stress can have an effect on pain sensitivity, yet the direction of the effect - whether it is hypoalgesic or hyperalgesic - is mixed across studies. Moreover, which part of the stress response influences pain sensitivity is still unclear. In the current experimental study, we aim to examine the effect of acute stress on heat pain thresholds and pain tolerance levels in healthy participants, while taking into account individual differences in stress responses. ⋯ This experimental study shows that an acute stress induction - that combines physical and psychological stressors - increases heat pain thresholds, but not tolerance in healthy participants. Furthermore, the magnitude of this stress-induced hypoalgesic effect is predicted by cortisol reactivity and fear of pain, revealing specific involvement of the HPA axis stress system and interactions with pain-related psychosocial aspects.
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Cold pressor test was recently reported to significantly reduce painful cutaneous electrical stimulation (PCES)-induced pain and corresponding evoked potentials (PCES-EPs), but whether this reduction is an effect of conditioned pain modulation (CPM) remains unknown. To what extent these findings are confounded by habituation is also unknown. We thus compared the effect of CPM and habituation on PCES-induced pain and PCES-EPs and analysed whether increased attention by a random change of electric stimulation would intensify this possible habituation effect. ⋯ Painful cutaneous electrical stimulation leads to moderate habituation of pain and evoked potential amplitudes, but the conditioned pain modulation effect using this method is significantly larger, which might indicate a different mechanism in central processing.
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Traditional psychometric measures aimed at characterizing the pain experience often show considerable overlap, due to interlinked affective and modulatory processes under central nervous system control. Neuroimaging studies have been employed to investigate this complexity of pain processing, in an attempt to provide a quantifiable, adjunctive description of pain perception. In this exploratory study, we examine psychometric and neuroimaging data from 38 patients with painful osteoarthritis of the carpometacarpal joint. We had two aims: first, to utilize principal component analysis (PCA) as a dimension reduction strategy across multiple self-reported endpoints of pain, cognitive and affective functioning; second, to investigate the relationship between identified dimensions and regional cerebral blood flow (rCBF) as an indirect measure of brain activity underpinning their ongoing pain experiences. ⋯ This study demonstrates that dimension reduction using PCA allows insight into pain perception and its affective components in relation to brain activation patterns in patients with painful hand osteoarthritis.
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Confusion remains over the definition of breakthrough cancer pain (BTcP) potentially leading to delayed diagnosis and treatment. ⋯ Many cancer patients suffered episodes of BTcP needlessly over many months due to missed diagnosis. Even after diagnosis, many physicians were not fully confident in their choice of 'rescue' therapy which perhaps is not surprising given the very low level of awareness of treatment guidelines, both national and international.
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Complex regional pain syndrome (CRPS) is associated with deficits in limb recognition. The purpose of our study was to determine whether mental load during this task affected performance, sympathetic nervous system activity or pain in CRPS patients. ⋯ The effects of mental load need to be considered when patients with CRPS-I are investigated for diagnostic or therapeutic reasons.