European journal of pain : EJP
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Chronic pain is often associated with sensorimotor dysfunction but little is known about the early impact of limb fracture on sensory and motor performance. This exploratory study sought to assess these changes in patients with recent wrist and ankle fractures. A secondary aim was to determine the incidence of Complex Regional Pain Syndrome (CRPS) and its clinical features. ⋯ Limb fracture is associated with changes in pain perceptions, motor planning, and disruption to body perception. Signs and symptoms of CRPS, ongoing pain and delayed recovery post-fracture are common. WHAT DOES THIS STUDY ADD?: In the immediate post-fracture period: Body perception disturbance is reported in the fractured limb. Imagined movements of the fractured limb are less vivid and associated with pain This study contributes to the incidence literature on CRPS.
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We have recently shown that visual deprivation from birth exacerbates responses to painful thermal stimuli. However, the mechanisms underlying pain hypersensitivity in congenital blindness are unclear. ⋯ The increased sensitivity to painful thermal stimulation in congenital blindness may be due to more efficient central processing of C-fibre-mediated input, which may help to avoid impending dangerous encounters with stimuli that threaten the bodily integrity. WHAT DOES THIS STUDY ADD?: Hypersensitivity to heat pain in congenital blindness is associated with faster responses to C-fibre activation, likely caused by more efficient central processing of C-fibre-mediated input.
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Observational Study
Perceived pain extent is associated with disability, depression and self-efficacy in individuals with whiplash-associated disorders.
Completion of a pain drawing is a familiar task in those presenting with whiplash-associated disorders (WAD). Some people report pain almost over their entire body. Yet the reasons for larger pain extent have not been fully explored. ⋯ By utilizing a novel method for pain extent quantification, this study shows that widespread pain is associated with a number of factors including perceived disability, depression and self-efficacy in individuals with chronic WAD. Widespread pain should alert the clinician to consider more specific psychological screening, particularly for depression and self-efficacy, in patients with WAD. WHAT DOES THIS STUDY ADD?: Women with chronic WAD, those with unsettled insurance claims and those with poorer financial status perceive more widespread pain. When controlling for these factors, larger pain areas remain associated with perceived pain and disability, depression and self-efficacy. The pain drawing is useful to support psychological screening in people with chronic WAD.
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Stressful experiences can produce analgesia, termed stress-induced analgesia (SIA). Meanwhile, it has been widely established that the mesolimbic dopamine pathway and nucleus accumbens (NAc) have a profound role in pain modulation. In this study, we examined the role of accumbal dopamine receptors in antinociception caused by forced swim stress (FSS) in order to understand more about the function of these receptors within the NAc in FSS-induced analgesia. ⋯ Forced swim stress (FSS) induces the antinociception in both phases of formalin test. Blockade of accumbal dopamine receptors attenuate the antinociception induced by FSS. Stress-induced analgesia is dose-dependently reduced by dopamine receptor antagonists in both phases, although it is more prominent during the late phase.
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At high concentration, the TRPV-1 agonist capsaicin de-sensitizes nociceptors and reduces the intra-epidermal nerve density. ⋯ Axonal nociceptor function assessed by electrical excitability tests supplements threshold tests of nociceptive endings. The differential analgesic effects of 8% capsaicin patches may be attributed to the kinetics of capsaicin and the different depth of nociceptive nerve fibres, yet, the time course does not match the long-lasting analgesia observed in neuropathic pain patients treated with the same patch. WHAT DOES THIS STUDY ADD?: Axonal nociceptor function assessed by supra-threshold electrical excitability tests did not coincide with capsaicin-induced transduction changes supplementing threshold measures of terminal nociceptor endings. Threshold measurements do not reflect the sustained effect of pain relief seen in neuropathic pain patients. Capsaicin-sensitive nociceptors responsible for spontaneous pain are either not specifically tested with currently available sensory stimulation protocols or have higher capsaicin sensitivity or slower recovery under neuropathic conditions.