Pain
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The frequency of not being able to self-report pain after a stroke has not been previously assessed in a population-based sample. We studied the epidemiology of this problem using a cohort of patients hospitalized after a stroke in Olmsted County, Minnesota, from June 1, 2008, to June 1, 2012. Overall, 52 of 388 (13.4%) individuals were unable to provide a meaningful response to either a Faces Pain Scale or Numerical Rating Scale on admission. ⋯ Inability to self-report pain on admission was further associated with either subsequent death during the hospitalization (P<.0001) or an inability to provide self-report on dismissal (P<.0001). Our study further defines the epidemiology of the inability to self-report pain after a stroke as being less common than previously thought. Attempts to validate observational pain scales for poststroke patients should focus on those individuals with aphasia and/or depressed levels of consciousness.
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Randomized Controlled Trial
Nocebo hyperalgesia induced by social observational learning.
Nocebo effects can be acquired by verbal suggestion, but it is unknown whether they can be induced through observational learning and whether they are influenced by factors known to influence pain perception, such as pain anxiety or pain catastrophizing. Eighty-five female students (aged 22.5 ± 4.4 years) were randomly assigned to one of three conditions. Participants in the control condition (CC) received information that an ointment had no effect on pain perception. ⋯ The nocebo response correlated with pain catastrophizing but not with pain anxiety or somatosensory amplification. A nocebo response to pressure pain was induced by observational learning but not by verbal suggestion. This finding highlights the importance of investigating the influence of observational learning on nocebo hyperalgesia.
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Oxytocin (OT) and arginine vasopressin (AVP) are 2 neuropeptides that display well-known effects on the reproductive system. Although still controversial, oxytocin and vasopressin were demonstrated to exert potent effects on the nociceptive system when administered directly in various central nervous structures. On the other hand, little is known about their peripheral (hormonal) actions on nociception and pain responses. ⋯ Stress-induced analgesia was transiently lost after i.v. administration of OTR antagonist. Together, the present work provides straightforward evidence that blood levels of OT and AVP modulate nociception, windup plasticity and pain responses. The final target structures explaining these effects remains to be identified but are likely to be C-type nociceptors.
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Few studies have examined abuse of prescription opioids among individuals with chronic pain under buprenorphine/naloxone (Bup/Nx) maintenance. The current 7-week inpatient study assessed oral oxycodone self-administration by patients with chronic pain who had a history of opioid abuse. Participants (n=25) were transitioned from their preadmission prescribed opioid to Bup/Nx. ⋯ However, factors associated with oxycodone preference were lower Bup/Nx maintenance dose, more withdrawal symptoms and more pain. These data suggest that Bup/Nx was effective in reducing pain and supplemental oxycodone use. Importantly, adequate management of pain and withdrawal symptoms by Bup/Nx may reduce oxycodone preference in this population.