Who can benefit from virtual reality to reduce experimental pain? A crossover study in healthy subjects

Background The present study aimed to identify predicting factors affecting experimental pain stimuli reduction by using 'EyeToy', which is an Immersive Virtual Reality System (IVRS). Methods Sixty-two healthy subjects (31 M, 31 F) underwent a battery of pain tests to determine each participant's baseline sensitivity to nociceptive. The battery included thermal pain tests (hot and cold) as well as a paradigm to induce conditioned pain modulation (CPM). Later on, each subject participated in two study conditions in random order: (1) An exposure to tonic heat stimulation (46.5 °C/135 s) to the ankle while participating in VR environment which included an activity requiring limb movements; (2) Same heat stimulation with no exposure to VR. Six pain measures were taken during each study condition (baseline, test 1-5). Results An interaction of time × treatment was found (RM ANOVA, F_{(5, 305)} = 24.33, p < 0.001, η² = 0.28). Specifically, the reduction in pain score between baseline and test 1 was significantly greater in VR condition than in control (p < 0.001). The maximal pain reduction in both conditions was between baseline and test 1. Hierarchical regression revealed gender and the extent of CPM as predictive factors for pain reduction in the VR condition (6.1% and 7.5%, respectively). Conclusions It can be concluded that VR can serve as an effective manipulation for pain reduction in individuals with efficient CPM and in women. These findings constitute a promising platform for future research and hold potential for the improvement and facilitation of clinical treatment.