Publications
APS Bulletin • Volume 15, Number 2, Spring 2005
Innovations in Practice
Debra Gordon, MS RN, Department Editor
Virtual Reality Pain Distraction
Hunter Hoffman, PhD, and David Patterson, PhD ABPP ABPH
Introduction
Patients commonly report experiencing excessive pain during medical procedures (Melzack, 1990), especially during severe burn wound care (Carrougher et al., 2003). Although opioid analgesics are currently essential for pain control during burn wound care, dosage amounts are limited by side effects (e.g., nausea, constipation, interference with appetite, sleep cycles) and other concerns associated with this class of medications (Cherny et al., 2001). Pain control is particularly challenging for patients with severe burn injuries. Patients treated for this form of trauma typically undergo daily wound care to clean, prevent infection, monitor the healing progress, and bandage again. Most burn patients report severe to excruciating pain during these medical procedures (Carrougher et al., 2003).
SnowWorld
Psychological factors can influence the perception of pain (Melzack, 1998). For example, pain can be exacerbated by anxiety and expectations (Turk, Meichenbaum, & Genest, 1983). In contrast, pain may be reduced by interventions that address psychological factors: e.g., traditional distraction can be an effective adjunctive treatment for pain (Fernandez & Turk, 1989; McCaul & Mallott, 1984). To help reach their goal of maximizing the potential for distraction to reduce pain, researchers have begun recently to explore whether allowing patients to escape mentally into an immersive virtual world can help reduce their pain experience (Hoffman, Doctor, Patterson, Carrougher, & Furness, 2000; Hoffman, Patterson, & Carrougher, 2000). SnowWorld is the first virtual world custom-designed for burn patients. In one series of studies, patients don a virtual reality (VR) helmet, which blocks their view of the burn wound care, and they float through an icy 3-D canyon during severe burn wound care or physical therapy sessions. Aiming with head-tracked gaze, patients shoot snowballs at snowmen, igloos, and robots (which explode with 3-D animations and sound effects) or at penguins (which turn upside down with a quack; Hoffman, Patterson, et al., 2004; Hoffman, Sharar, et al., 2004).
 University of Washington Harborview/HIT Lab's SnowWorld, pain distraction for burn patients (image by Stephen Dagadakis, copyright Hunter Hoffman, U.W. HITLab) | |
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A pediatric burn patient shooting snowballs in SnowWorld while undergoing physical therapy (photo and copyright Hunter Hoffman, U.W. HITLab) |
 A burn patient in VR during wound care in the hydrotank using a unique water-friendly fiberoptic VR helmet created at the U. W. Human Interface Technology Lab in Seattle (photo and copyright Hunter Hoffman, U.W. HITLab) | |
Preliminary Results
In preliminary clinical studies, researchers have found that immersive VR distraction can reduce patient’s pain ratings during severe burn wound care by 30%–50% (Das et al., 2005; Hoffman, Patterson, et al., 2004; Hoffman, Patterson, & Carrougher, 2000). In addition to their usual opioid medications, patients received VR during some of their wound care and no VR during an equivalent portion of their wound care. Relative to medications alone, patients receiving adjunctive VR during physical therapy reported large reductions in the amount of time spent thinking about pain, pain intensity (worst pain), and in how unpleasant they found their pain (Hoffman, Patterson, et al., 2001). In one case study, a patient experiencing VR distraction during staple removals from a severe burn skin graft reported a 90% reduction in subjective pain ratings (compared to pain ratings while playing a Nintendo video game control condition during the same wound care session). This patient also reported a strong illusion of going into the virtual world during VR. Using the same protocol with another patient, this time the patient showed a more moderate reduction in worst pain and reported only a moderate illusion of going into the virtual world (Hoffman, Doctor, et al., 2000). Although this study is preliminary, the pattern of clinical results is consistent with the notion that the stronger the patients’ illusions of going into VR, the more effectively they are distracted from pain (Hoffman, Patterson, & Carrougher, 2000).
Rationale
To explain these nonpharmacologic analgesic effects, investigators propose that the illusion of going into the virtual world draws the patient’s attention into that perceptual framework. VR is interactive and multisensory (e.g., patients aim and shoot a snowball, hear a splash sound and simultaneously see a snowball splash into the icy virtual river). These qualities help make VR unusually attention-grabbing, leaving less attention available to process incoming pain signals (Hoffman, Doctor, et al., 2000; Hoffman, Patterson, & Carrougher, 2000). Conscious attention is required for the experience of pain (Chapman & Nakamura, 1999; Eccleston & Crombez, 1999). Consistent with this attentional hypothesis of how VR reduces pain, a recent double-blind, laboratory-controlled, thermal-pain study found significantly greater pain reduction in a group that received high-tech VR distraction (designed to maximize the participants’ illusion of going into the virtual world) compared to a group that received a low-tech VR (designed to minimize the illusion of going inside the computer-generated environment) (Hoffman, Sharar, et al., 2004). The study showed a VR dose-response relationship.
Neural Correlates of VR Analgesia
In a recent fMRI brain-scan study, healthy volunteers experienced a series of six 30-s thermal pain stimuli at a painful but tolerable temperature (participants pre-approved their custom temperature prior to the study). They received three of the stimuli during VR, and three while looking at a fixation cross (condition order randomized). Thermal pain (30 s on, 30 s off for approximately 6 min) activated pain-related brain activity in the five regions-of-interest of the brain identified a priori (SS1, SS2, ACC, Insula, and Thalamus). Virtual reality analgesia, the reduction in subjective experience of pain while in VR, was evident. Participants reported large reductions in subjective pain when in SnowWorld compared to no VR (fixation cross) during their scan. The controlled laboratory fMRI study further showed that VR analgesia was accompanied by large reductions in pain-related brain activity. Participants showed large (> 50%) reductions in pain-related brain activity when in SnowWorld compared to no VR during their scan. VR appeared to change the way their brains processed incoming nociceptive signals. During VR, fewer pain signals were processed in all five brain regions-of-interest (Hoffman, Richards, et al., 2004; Hoffman, 2004). These results provide converging evidence for VR analgesia from both subjective pain ratings and from the objective neural correlates of pain.
 Graphic depiction of a patient in SnowWorld in an fMRI magnet, via a magnet-friendly virtual reality helmet created at the U. W. HITLab (image by Duff Hendrickson, U.W. HITLab, copyright Hunter Hoffman, U.W. HITLab) |
Conclusion
The results collected to date, although preliminary, encourage further exploration of the potential value of VR distraction as a powerful nonpharmacologic analgesic. Thanks to funds and encouragement from NIH, and gifts made from the Paul Allen Family Foundation to the University of Washington’s Harborview Burn Center, and recent support from Randolph Hearst Burn Center in New York to help upgrade SnowWorld, SnowWorld VR pain reduction software is being made available free of charge to eligible hospitals (i.e., hospitals treating excessive pain that are able to acquire their own expensive VR computer hardware). In addition to University of Washington’s Harborview Burn Center, a small but growing number of determined innovative burn/medical centers are making efforts to start exploring the use of SnowWorld with their patients: e.g., Randolph Hearst Burn Center in New York, Shriners Children’s Hospital in Galveston, Johns Hopkins, the University of Wisconsin Burn Center, the Tripler-VA Hui in Honolulu, Copenhagen Burn Center, and Martini Ziekenhuis Groningen in Holland (see also Das et al., 2005 from Australia).
 Results from Hoffman, Richards, et al., (2004) showed significant reductions in pain-related brain activity during VR analgesia. (images by Todd Richards and Aric Bills, copyright Hunter Hoffman, U.W. HITLab) |
VR analgesia is not limited to burn patients, however. Immersive VR distraction is being used to treat a growing number of painful procedures:
- endoscopic urological procedures
- physical therapy after single event multilevel surgery (SEMLS) for cerebral palsy (Steele et al., 2003)
- dental pain and anxiety (Hoffman, Garcia, et al., 2001)
- pain during cancer procedures (Gershon et al., 2004)
- pain/anxiety during injections (Gold et al., 2005).
For more information about VR analgesia and related VR therapy applications, please visit www.vrpain.com.
References
Carrougher, G. J., Ptacek, J. T., Sharar, S. R, Wiechman, S., Honari, S., Patterson, D. R., et al. (2003). Comparison of patient satisfaction and self-reports of pain in adult burn-injured patients. Journal of Burn Care and Rehabilitation, 24(1), 1–8.
Chapman, C. R., & Nakamura, Y. (1999). A passion of the soul: An introduction to pain for consciousness researchers. Consciousness and Cognition, 8, 391–422.
Cherny, N., Ripamonti, C., Pereira, J., Davis, C., Fallon, M., McQuay, H., et al. (2001). Strategies to manage the adverse effects of oral morphine: An evidence-based report. Journal of Clinical Oncology, 19(9), 2542–2554.
Das, D. A., Grimmer, K. A., Sparnon, A. L., McRae, S. E., & Thomas B. H. (2005, March 3). The efficacy of playing a virtual reality game in modulating pain for children with acute burn injuries: A randomized controlled trial. BMC Pediatrics,5(1):1.
Eccleston, C., & Crombez, G. (1999). Pain demands attention: A cognitive-affective model of the interruptive function of pain. Psychological Bulletin, 125, 356–366.
Fernandez, E., & Turk, D. C. (1989). The utility of cognitive coping strategies for altering pain perception: A meta-analysis. Pain, 38, 123–135.
Gershon, J., Zimand, E., Pickering, M., Rothbaum, B. O., & Hodges, L. (2004). A pilot and feasibility study of virtual reality as a distraction for children with cancer. Journal of the American Academy of Child Adolescent Psychiatry, 43(10), 1243–1249.
Gold, J., Reger, G., Rizzo, A., Buckwalter, G., Kim, S., & Joseph, M. (2005, March 30–April 3). Virtual reality in outpatient phlebotomy: Evaluating pediatric pain distraction during blood draw. Poster presented at 25th meeting of the American Pain Society, Boston, MA. Hypnosis/Distraction Poster #797, http://www.ampainsoc.org /abstract /2005 /data /797.
Hoffman, H. G. (2004). Virtual-reality therapy. Scientific American, 291(2), 58–65.
Hoffman, H. G., Doctor, J. N., Patterson, D. R., Carrougher G. J., & Furness T. A., III. (2000). Use of virtual reality for adjunctive treatment of adolescent burn pain during wound care: A case report. Pain,85(1–2), 305–309.
Hoffman, H. G., Garcia-Palacios, A., Patterson, D. R., Jensen, M., Furness, T. A., III, & Ammons, W. F., Jr. (2001). The effectiveness of virtual reality for dental pain control: A case study. Cyberpsychological Behavior, 4, 527–535.
Hoffman, H. G., Patterson, D. R., Carrougher, G. J. (2000). Use of virtual reality for adjunctive treatment of adult burn pain during physical therapy: A controlled study. The Clinical Journal of Pain, 16(3), 244–250.
Hoffman, H. G., Patterson, D. R., Carrougher, G. J., & Sharar, S. (2001, September). The effectiveness of virtual reality-based pain control with multiple treatments. The Clinical Journal of Pain, 17(3), 229–235.
Hoffman, H. G., Patterson, D. R., Magula, J., Carrougher, G. J., Zeltzer, K., Dagadakis, S., et al. (2004). Water-friendly virtual reality pain control during wound care. Journal of Clinical Psychology, 60(2), 189–195.
Hoffman, H. G., Richards, T. L., Coda, B., Bills, A. R., Blough, D., Richards, A. L., et al. (2004). Modulation of thermal pain-related brain activity with virtual reality: Evidence from fMRI. Neuroreport, 15(8), 1245–1248.
Hoffman, H. G., Sharar, S. R., Coda, B., Everett, J. J., Ciol, M., Richards, T. L., et al. (2004). Manipulating presence influences the magnitude of virtual reality analgesia. Pain, 111(1–2), 162–168.
McCaul, K. D., & Malott, J. M. (1984). Distraction and coping with pain. Psychological Bulletin 95(3), 516–533.
Melzack, R. (1990). The tragedy of needless pain. Scientific American, 262(2), 27–33.
Melzack, R. (1998). Psychological aspects of pain: Implications for neural blockade. In M. J. Cousins, P. O. Bridenbaugh (Eds.), Neural blockade in clinical anesthesia and management of pain. Philadelphia: Lippincott-Rave, 781–792.
Steele, E. B., Grimmer, K., Thomas, B., Mulley, B., Fulton, I., & Hoffman H. (2003). Virtual reality as a pediatric pain modulation technique: A case study. Cyberpsychological Behavior, 6, 633–638.
Turk, D. C., Meichenbaum, D., & Genest, M. (1983). Pain and behavioral medicine: A cognitive-behavioral perspective. New York: Guilford Press.
Hunter Hoffman, PhD, is Research Scientist, Human Interface Technology Laboratory (HITLab), University of Washington, Seattle, e-mail: hunter@hitL.washington.edu Web site: www.vrpain.com
David R. Patterson, PhD ABPP ABPH, is Professor, University of Washington, Department of Rehabilitation Medicine, Seattle, e-mail: davepatt@u.washington.edu, Web site: http://depts.washington.edu /rehab /contacts /patterson.html
Please direct your comments or suggestions about this article or department to Debra Gordon, MS RN, Department Editor, at db.gordon@hosp.wisc.edu.