Papers of the Week

Virtual reality (VR) has been shown to produce analgesic effects during different experimental and clinical pain states. Despite this, the top-down mechanisms are still poorly understood. In this study, we examined the influence of both a real and sham (i.e. the same images in 2D) immersive arctic VR environment on conditioned pain modulation (CPM) and in a human surrogate model of central sensitisation in 38 healthy volunteers. CPM and acute heat pain thresholds (HPT) were assessed before and during VR/sham exposure in the absence of any sensitisation. In a follow-on study, we used the cutaneous high frequency stimulation (HFS) model of central sensitisation and measured changes in mechanical pain sensitivity (MPS) in an area of heterotopic sensitisation before and during VR/sham exposure. There was an increase in CPM efficiency during the VR condition compared to baseline (P<0.01). In the sham condition, there was a decrease in CPM efficiency compared to baseline (P<0.01) and the real VR condition (P<0.001). Neither real nor sham VR had any effect on pain ratings reported during the conditioning period or on HPT. There was also an attenuation of MPS during the VR condition indicating a lower sensitivity compared to sham (P<0.05). We conclude that exposure to an immersive VR environment has no effect over acute pain thresholds but can modulate dynamic CPM responses and mechanical hypersensitivity in healthy volunteers. Perspective: This study has demonstrated that exposure to an immersive virtual reality environment can modulate perceptual correlates of endogenous pain modulation and secondary hyperalgesia in a human surrogate pain model. These results suggest that virtual reality could provide a novel mechanism-driven analgesic strategy in patients with altered central pain processing.