Articles: hyperalgesia.
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Review
The Underestimated Significance of Conditioning in Placebo Hypoalgesia and Nocebo Hyperalgesia.
Placebo and nocebo effects are intriguing phenomena in pain perception with important implications for clinical research and practice because they can alleviate or increase pain. According to current theoretical accounts, these effects can be shaped by verbal suggestions, social observational learning, and classical conditioning and are necessarily mediated by explicit expectation. In this review, we focus on the contribution of conditioning in the induction of placebo hypoalgesia and nocebo hyperalgesia and present accumulating evidence that conditioning independent from explicit expectation can cause these effects. ⋯ Because only few studies have investigated clinical samples, the picture seems less clear when it comes to patient populations with chronic pain. However, conditioning appears to be a promising means to optimize treatment. In order to get a better insight into the mechanisms of placebo and nocebo effects in pain and the possible benefits of conditioning compared to explicit expectation, future studies should carefully distinguish both methods of induction.
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Learning is a key mechanism underpinning the development of the nocebo effect. The learning literature has cataloged and explored numerous ways in which the environment can be manipulated to prevent, reduce, or eradicate learning. ⋯ These learning strategies include overshadowing, latent inhibition, extinction, and contingency degradation. These strategies represent important new avenues for investigation and should be used by researchers to design and test interventions to reduce nocebo effects.
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Best Pract Res Clin Anaesthesiol · Dec 2017
ReviewDo we feel pain during anesthesia? A critical review on surgery-evoked circulatory changes and pain perception.
The difficulty of defining the three so-called components of « an-esthesia » is emphasized: hypnosis, absence of movement, and adequacy of anti-nociception (intraoperative « analgesia »). Data obtained from anesthetized animals or humans delineate the activation of cardiac and vasomotor sympathetic reflex (somato-sympathetic reflex) and the cardiac parasympathetic deactivation observed following somatic stimuli. Sympathetic activation and parasympathetic deactivation are used as monitors to address the adequacy of intraoperative anti-nociception. Finally, intraoperative nociception through the administration of nonopioid analgesics vs. opioid analgesics is considered to achieve minimal postoperative side effects.
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Best Pract Res Clin Anaesthesiol · Dec 2017
ReviewOpioid-free anesthesia opioid side effects: Tolerance and hyperalgesia.
Opioids are the most potent drugs used to control severe pain. However, neuroadaptation prevents opioids' ability to provide long-term analgesia and produces opposite effects, i.e., enhancement of existent pain and facilitation of chronic pain development. Neuroadaptation to opioids use results in the development of two interrelated phenomena: tolerance and "opioid-induced hyperalgesia" (OIH). ⋯ Conversely, observations of improved patient's recovery after opioid-sparing anesthesia techniques stand as an indirect evidence that perioperative opioid administration deserves caution. To date, perioperative OIH has rarely been objectively assessed by psychophysics tests in patients. A direct relationship between the presence of perioperative OIH and patient outcome is missing and certainly deserves further studies.
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Best Pract Res Clin Anaesthesiol · Dec 2017
ReviewDifferent protocols used today to achieve total opioid-free general anesthesia without locoregional blocks.
With increasing awareness of both short- and long-term problems associated with liberal perioperative opioid administration, the need for routinely and clinically feasible alternatives is greater than ever. Opioid-free anesthesia-previously reserved for bariatric surgery-is receiving increasing attention in mainstream anesthesia. ⋯ For a concrete clinical perspective, we present in depth our opioid-free protocol for bariatric surgery. However, clinicians must be aware of potential problems related to opioid-free anesthesia.