Articles: hyperalgesia.
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Randomized Controlled Trial
Time course of copeptin during a model of experimental pain and hyperalgesia: A randomised volunteer crossover trial.
A reliable biomarker for quantifying pain or hyperalgesia has yet to be found. A surrogate marker of arginine vasopressin, copeptin, is elevated in a number of states of physiological and psychological stress and may have a role in quantifying pain and/or hyperalgesia. ⋯ Copeptin concentrations do not appear to be associated directly with pain and hyperalgesia. Instead, some fentanyl-mediated effect or effects appear to have greatly increased copeptin concentrations from baseline to 120 min.
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Repetitive painful laser stimuli lead to physiological laser-evoked potential (LEP) habituation, measurable by a decrement of the N2/P2 amplitude. The time course of LEP-habituation is reduced in the capsaicin model for peripheral and central sensitization and in patients with migraine and fibromyalgia. In the present investigation, we aimed to assess the time course of LEP-habituation in a neuropathic pain syndrome, i.e. painful radiculopathy. ⋯ Abnormal central pain processing in neuropathic pain conditions may be revealed with the laser-evoked potential habituation paradigm. In painful radiculopathy patients, LEP-habituation is reduced compared to healthy controls.
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Randomized Controlled Trial
Measuring expectation of pain: Contingent negative variation in placebo and nocebo effects.
Expectation is an important mechanism underlying placebo response. Here, we analysed expectation of placebo hypoalgesia and nocebo hyperalgesia by using, for the first time, the contingent negative variation (CNV), also known as expectancy wave. ⋯ Dissection of placebo hypoalgesia, differentiating the sensory component (pain perception) from the motor component (pain avoidance). Study of these components using the contingent negative variation (CNV) as an electrophysiological objective measure.
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The complex regional pain syndrome (CRPS) is characterized by distal generalisation of pain beyond the initial trauma. This might be the result of impaired endogenous pain inhibition. ⋯ Conditioned pain modulation (CPM) is not impaired in the early phase of complex regional pain syndrome (CRPS) and neuralgia. Only in CRPS higher CPM was associated with lower cold pain thresholds.
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Spinal cord stimulation (SCS) has been shown to be effective in the management of certain neuropathic pain conditions, however, the underlying mechanisms are incompletely understood. In this study, we investigated repetitive SCS in a rodent neuropathic pain model, revealing long-lasting and incremental attenuation of hyperalgesia and a mechanism of action involving endocannabinoids. ⋯ Alternative parameters for repetitive spinal cord stimulation (SCS) at 25/10 Hz elicit particularly long-lasting and incremental reversal of hyperalgesia in a neuropathic pain model through a mechanism involving endocannabinoids.