Pain
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Animal and human studies have shown that exercise prior to nerve injury prevents later chronic pain, but the mechanisms of such preconditioning remain elusive. Given that exercise acutely increases the formation of free radicals, triggering antioxidant compensation, we hypothesized that voluntary running preconditioning would attenuate neuropathic pain by supporting redox homeostasis after sciatic nerve injury in male and female rats. We show that 6 weeks of voluntary wheel running suppresses neuropathic pain development induced by chronic constriction injury across both sexes. ⋯ The protective effects of prior voluntary wheel running were mediated by Nrf2, as suppression was abolished across both sexes when Nrf2 activation was blocked during the 6-week running phase. This study provides insight into the mechanisms by which physical activity may prevent neuropathic pain. Preconditioning by voluntary wheel running, terminated prior to nerve injury, suppresses later neuropathic pain in both sexes, and it is modulated through the activation of Nrf2-antioxidant signaling.
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In this case report, we used virtual reality (VR) to explore pain evoked by only the appearance of being touched (rather than actually being touched) in a person with complex regional pain syndrome type II. Furthermore, we explored the degree to which this visually evoked pain could be extinguished by applying exposure principles in VR. In stage 1, we identified 4 specific scenarios where pain was triggered by visually simulated touch (without physical stimulation) and used these scenarios to quantify baseline sensitivity to visuotactile stimulation. ⋯ This case report describes the phenomena of visually evoked pain. Moreover, it describes the near complete extinguishing of visually evoked pain through virtual graded exposure. How improvements gained in VR might be better transferred to real-word improvements merits further investigation.