The journal of pain : official journal of the American Pain Society
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Adverse life experiences (ALEs) are associated with hyperalgesia and chronic pain, but the underlying mechanisms are poorly understood. One potential mechanism is hyperexcitability of spinal neurons (ie, central sensitization). Given that Native Americans (NAs) are more likely to have ALEs and to have a higher prevalence of chronic pain, the relationship between ALEs and spinal hyperexcitability might contribute to their pain risk. ⋯ Although relationships between ALEs and the nociceptive flexion reflex/pain were not stronger in NAs, given prior evidence that NAs experience more ALEs, this factor might contribute to the higher prevalence of chronic pain in NAs. PERSPECTIVE: This study found a dose-dependent relationship between ALEs and spinal neuron excitability. Although the relationship was not stronger in NAs than non-Hispanic whites, given prior evidence that NAs experience more ALEs, this could contribute to the higher prevalence of chronic pain in NAs.
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There is substantial evidence supporting the notion that the primary somatosensory (S1) cortex is an important structure involved in the perceptional component of pain. However, investigations have mainly focused on other pain-related formations, and few reports have been provided to investigate the synaptic plasticity in the S1 cortex in response to persistent pain. In the present study, we report that bee venom (BV) injection triggered an imbalance between excitatory and inhibitory synaptic transmission in the S1 cortex in rats. ⋯ Perspective: Increased synaptic plasticity was detected in S1 after peripheral nociception, with enhanced excitatory and decreased inhibitory synaptic transmissions. Increased GluR1, and decreased GABAAα1 and GluR2 membrane trafficking were detected. Therefore, the disrupted excitatory/inhibitory balance in transmissions is involved in nociception processing, and S1 can be a potential antinociceptive site.
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Review Meta Analysis
Reward for pain. Hyperalgesia and allodynia induced by operant conditioning: systematic review and meta-analysis.
Learning processes have been discussed in the context of pain chronicity for decades. Particularly, operant conditioning has been used to experimentally induce and modulate pain in healthy humans. In this systematic review and meta-analysis, research findings on pain facilitation (hyperalgesic effect) and pain elicitation (allodynic effect) are evaluated. ⋯ PERSPECTIVE: Operant conditioning can be a mechanism of pain chronicity. All experimental studies investigating this hypothesis have been identified and summarized. It has been demonstrated that allodynic and hyperalgesic effects can be induced by operant conditioning.
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Randomized Controlled Trial Multicenter Study
Perioperative Pregabalin and Intraoperative Lidocaine Infusion to Reduce Persistent Neuropathic Pain After Breast Cancer Surgery: A Multicenter, Factorial, Randomized, Controlled Pilot Trial.
Persistent postsurgical pain is defined as pain localized to the area of surgery of a duration of ≥2 months and is, unfortunately, a common complication after breast cancer surgery. Although there is insufficient evidence to support any preventative strategy, prior literature suggests the possible efficacy of intravenous lidocaine and perioperative pregabalin in preventing persistent pain after surgery. To determine feasibility of conducting a larger definitive trial, we conducted a multicenter 2 × 2 factorial, randomized, placebo-controlled pilot trial of 100 female patients undergoing breast cancer surgery. ⋯ Our pilot trial successfully demonstrated feasibility and provided promising data for conducting further trials of intraoperative lidocaine infusions during breast cancer surgeries. Clinical trial number: NCT02240199 PERSPECTIVE: This article reports the findings of a pilot randomized, controlled trial evaluating the effects of perioperative pregabalin and intraoperative lidocaine infusions in patients undergoing breast cancer surgery. This trial demonstrated the feasibility of conducting a larger trial and provided promising data that these interventions may decrease the development of persistent pain.