Background: Immersive virtual reality (VR) is a novel form of distraction analgesia, yet its effects on pain-related brain activity when used adjunctively with opioid analgesics are unknown. We used subjective pain ratings and functional magnetic resonance imaging to measure pain and pain-related brain activity in subjects receiving opioid and/or VR distraction.
Methods: Healthy subjects (n = 9) received thermal pain stimulation and were exposed to four intervention conditions in a within-subjects design: (a) control (no analgesia), (b) opioid administration [hydromorphone (4 ng/mL target plasma level)], (c) immersive VR distraction, and (d) combined opioid + VR. Outcomes included subjective pain reports (0-10 labeled graphic rating scales) and blood oxygen level-dependent assessments of brain activity in five specific, pain-related regions of interest.
Results: Opioid alone significantly reduced subjective pain unpleasantness ratings (P < 0.05) and significantly reduced pain-related brain activity in the insula (P < 0.05) and thalamus (P < 0.05). VR alone significantly reduced both worst pain (P < 0.01) and pain unpleasantness (P < 0.01) and significantly reduced pain-related brain activity in the insula (P < 0.05), thalamus (P < 0.05), and SS2 (P < 0.05). Combined opioid + VR reduced pain reports more effectively than did opioid alone on all subjective pain measures (P < 0.01). Patterns of pain-related blood oxygen level-dependent activity were consistent with subjective analgesic reports.
Conclusions: These subjective pain reports and objective functional magnetic resonance imaging results demonstrate converging evidence for the analgesic efficacy of opioid administration alone and VR distraction alone. Furthermore, patterns of pain-related brain activity support the significant subjective analgesic effects of VR distraction when used as an adjunct to opioid analgesia. These results provide preliminary data to support the clinical use of multimodal (e.g., combined pharmacologic and nonpharmacologic) analgesic techniques.