Articles: hyperalgesia.
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Am J Phys Med Rehabil · May 2016
Randomized Controlled TrialEffects of Virtual Walking Treatment on Spinal Cord Injury-Related Neuropathic Pain: Pilot Results and Trends Related to Location of Pain and at-level Neuronal Hypersensitivity.
Previous studies have shown that virtual walking to treat spinal cord injury-related neuropathic pain (SCI-NP) can be beneficial, although the type of SCI-NP that may benefit the most is unclear. This study's aims were to (1) determine the effect of location of SCI-NP on pain outcomes after virtual walking treatment and (2) examine the potential relationship between neuronal hyperexcitability, as measured by quantitative sensory testing, and pain reduction after virtual walking treatment. Participants were recruited from a larger ongoing trial examining the benefits of virtual walking in SCI-NP. ⋯ In addition, quantitative sensory testing was performed on a subset of individuals at a nonpainful area corresponding to the level of their injury before virtual walking treatment and was used to characterize treatment response. These pilot results suggest that when considered as a group, SCI-NP was responsive to treatment irrespective of the location of pain (F1, 44 = 4.82, P = 0.03), with a trend for the greatest reduction occurring in at-level SCI-NP (F1, 44 = 3.18, P = 0.08). These pilot results also potentially implicate cold, innocuous cool, and pressure hypersensitivity at the level of injury in attenuating the benefits of virtual walking to below-level pain, suggesting certain SCI-NP sensory profiles may be less responsive to virtual walking.
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Randomized Controlled Trial
From Pavlov to pain: How predictability affects the anticipation and processing of visceral pain in a fear conditioning paradigm.
Conditioned pain-related fear may contribute to hyperalgesia and central sensitization, but this has not been tested for interoceptive, visceral pain. The underlying ability to accurately predict pain is based on predictive cue properties and may alter the sensory processing and cognitive-emotional modulation of pain thus exacerbating the subjective pain experience. In this functional magnetic resonance imaging study using painful rectal distensions as unconditioned stimuli (US), we addressed changes in the neural processing of pain during the acquisition of pain-related fear and subsequently tested if conditioned stimuli (CS) contribute to hyperalgesia and increased neural responses in pain-encoding regions. ⋯ With regard to activation in response to painful stimuli, the unpredictable compared to the predictable group revealed greater activation in pain-encoding (somatosensory cortex, insula) and pain-modulatory (prefrontal and cingulate cortices, periaqueductal grey, parahippocampus) regions. In the test phase, no evidence of hyperalgesia or central sensitization was found, but the predictable group demonstrated enhanced caudate nucleus activation in response to CS(-)-signaled pain. These findings support that during fear conditioning, the ability to predict pain affects neural processing of visceral pain and alters the associative learning processes underlying the acquisition of predictive properties of cues signaling pain, but conditioned pain-related fear does not result in visceral hyperalgesia or central sensitization.
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Randomized Controlled Trial
Gradual withdrawal of remifentanil infusion may prevent opioid-induced hyperalgesia.
The aim of this study was to examine if gradual withdrawal of remifentanil infusion prevented opioid-induced hyperalgesia (OIH) as opposed to abrupt withdrawal. OIH duration was also evaluated. ⋯ NCT 01702389. EudraCT number 2011-002734-39.
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Randomized Controlled Trial
Does Fentanyl Lead to Opioid-induced Hyperalgesia in Healthy Volunteers?: A Double-blind, Randomized, Crossover Trial.
Although opioids in general and remifentanil in particular have been shown to induce hyperalgesia, data regarding fentanyl are scarce. Thus, the authors investigated the effect of fentanyl dosing on pain perception and central sensitization in healthy volunteers using established pain models. ⋯ A higher dose of fentanyl increased hyperalgesia from 4.5 to 6.5 h in healthy volunteers while simultaneously decreasing pain scores.
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Randomized Controlled Trial
Disambiguating Pharmacodynamic Efficacy from Behavior with Neuroimaging: Implications for Analgesic Drug Development.
Attrition rates of new analgesics during drug development are high; poor assay sensitivity with reliance on subjective outcome measures being a crucial factor. ⋯ Functional imaging with central sensitization can be used as a sensitive mechanism-based assay to guide go/no-go decisions on selecting analgesics effective in neuropathic pain in early human drug development. We also show analgesic modulation of neural activity by using resting-state functional connectivity, a less challenging paradigm that is ideally suited for patient studies because it requires no task or pain provocation.