The analgesic effects of opioids and immersive virtual reality distraction: evidence from subjective and functional brain imaging assessments.
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.
Department of Mechanical Engineering, University of Washington, Seattle, Washington 98195, USA. hunter@HITL.washington.edu
Hunter G
HG
Hoffman
Todd L
TL
Richards
Trevor
T
Van Oostrom
Barbara A
BA
Coda
Mark P
MP
Jensen
David K
DK
Blough
Sam R
SR
Sharar
D000328:Adult; D000701:Analgesics, Opioid / Q000494:pharmacology*; D001931:Brain Mapping / Q000379:methods; D003198:Computer Simulation; D004644:Emotions / Q000502:physiology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000523:psychology; D008297:Male; D010147:Pain Measurement / Q000187:drug effects* / Q000379:methods* / Q000523:psychology; D014584:User-Computer Interface
D000701:Analgesics, Opioid