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Volume 41 Number 5, September/October 2004
Pages vii — x

Guest Editorial

The potential of virtual reality for rehabilitation

Today's clinician is privileged to have access to a variety of technologies that provide tools for both research and clinical intervention. The papers in this issue illustrate some of the ways in which technology improves therapy and enhances evaluation. We learn how dynamic posturography can lead to a better understanding of standing balance in clinical settings, how a variety of innovative biomechanical techniques (e.g., polycentric knee mechanism, optical scanner imaging of the transtibial residua) may improve gait for people with amputations, how automatic speech recognition is being used as a computer input method, and how ultrasound and laser treatments may benefit wound healing.

An equally innovative technology that has not yet been presented within these pages is virtual reality (VR), the use of interactive simulations created with computer hardware and software to present users with opportunities to engage in environments that appear and feel similar to real-world objects and events [1-3]. VR is considered one of the most innovative technologies and promises to have a considerable impact on neurorehabilitation over the next 10 years [4].

Patrice L. (Tamar) Weiss, PhD; Noomi Katz, OTR, PhD Department of Occupational Therapy, University of Haifa, Haifa, Israel; School of Occupational Therapy, Hadassah-Hebrew University, Jerusalem, Israel

Virtual environments are usually experienced with the aid of special hardware and software for input (transfer of information from the user to the system) and output (transfer of information from the system to the user). The selection of appropriate hardware and software is important because their characteristics may greatly influence the way users respond to a virtual environment [5]. The output to the user can be delivered by different modalities including visual, auditory, haptic, vestibular, and olfactory stimuli, although, to date, most VR systems deliver primarily visual-auditory feedback. Visual information is commonly displayed by head-mounted displays, projection systems, or flat screens of varying size. In addition to specialized hardware, application software is also necessary. In recent years, off-the-shelf, ready-for-clinical-use VR software has become available for purchase. However, more frequently, special software development tools are required for the design and coding of an interactive simulated environment that will achieve a desired rehabilitation goal. In many cases, innovative intervention ideas may entail customized programming for the construction of a virtual environment from scratch, with the use of traditional programming languages.

VR technologies have now begun to be used as an assessment and treatment tool in rehabilitation [3,6]. Applications have been directed at a variety of clinical populations including those with cognitive [7-11] and metacognitive [12-14] deficits. Other applications are being directed at the rehabilitation of motor deficits [15-17] to help provide recreational opportunities for people with severe disabilities [18]. VR also shows promise for training in activities of daily living with different populations, including use of a virtual kitchen and vending machine, street crossing, and a hospital and university way-finding environment [11,19,20]. The rehabilitation of driving skills following traumatic brain injury is one example in which individuals may begin at a simple level (i.e., straight, nonpopulated roads) and gradually progress to more challenging situations (i.e., crowded highways, night driving) [21].

The rationale for the use of VR in rehabilitation is based on a number of unique attributes of this technology [3,22]. These attributes include the opportunity for experiential, active learning that encourages and motivates the participant [23]. Another is the ability of therapists to objectively measure behavior in challenging but safe and ecologically valid environments, while maintaining strict experimental control over stimulus delivery and measurement [24]. VR also gives therapists the ability to individualize treatment needs, while providing increased standardization of assessment and retraining protocols. Virtual environments provide the opportunity for repeated learning trials and offer the capacity to gradually increase the complexity of tasks while decreasing therapist support and feedback. Moreover, the automated nature of stimulus delivery within virtual environments enables a therapist to focus on the provision of maximum physical support when needed without detracting from the complexity of the task. For example, objects within a video-capture environment (e.g., the GX VR System by Vivid Group, Toronto, Ontario, Canada) can be displayed simultaneously from different directions while the therapist supports the patient's paretic shoulder. Finally, the ability to change the virtual environments relatively easily enables clinicians to assess more efficiently different environmental modifications, which endeavor to enhance clients' accessibility.

Indeed, the future holds great promise for the further development of applications of VR to rehabilitation. In addition to the many exciting rehabilitation applications just mentioned, VR-based therapy has been very effective in other realms of medicine such as in the treatment of phobias [25] and the reduction of pain during burn care [26] and venipuncture [27]. VR has also proven highly effective for providing alternate modes of feedback in cases of sensory impairment such as the substitution of auditory [28] and/or haptic [29] cues for individuals with severe visual impairment via interactive virtual environments.

The cost of equipment is decreasing and the availability of off-the-shelf software is growing such that many clinical facilities can now feasibly embrace this new technology. As just presented, the literature to date strongly suggests that these technologies are poised to have a major impact on evaluation and intervention for cognitive, motor, and functional rehabilitation because of the unique attributes of VR-based therapy. These attributes make it highly suitable for the achievement of many rehabilitation goals, including the encouragement of experiential, active learning; the provision of challenging but safe and ecologically valid environments; the flexibility of individualized and graded treatment protocols; the power to motivate patients to perform to their utmost ability; and the capacity to record objective measures of performance.

Nevertheless, further development of VR-based rehabilitation depends, to some extent, on the resolution of certain issues that currently present either technological or financial limitations. The cost of some of the more immersive VR systems is still prohibitive, rendering them more suitable to investigative studies than to routine clinical applications. Continued development of off-the-shelf, low-cost virtual environments that can be displayed on standard desktop equipment or via dedicated microprocessors (e.g., the Sony PlayStation II's "EyeToy" application, will make the use of VR affordable to a variety of treatment and educational settings. Of course, the clinical effectiveness of these less-expensive applications must be verified prior to their wide promotion and adoption.

A need also exists to address issues related to the number and quality of feedback channels used with virtual environments. As just indicated, visual and auditory feedback is extensively used; haptic, vestibular, and olfactory feedback is far less commonly available. The cost of devices capable of transmitting high-quality feedback is often high, and their potential for encumbering users is also significant. Neither is the relationship between feedback quality and effectiveness certain nor is the relationship between the number of feedback channels and effect of therapy known. Considerably more research on the impact that VR feedback has on clinical intervention is therefore needed.

Finally, it is encouraging to note that much progress has been made in the demonstration of the transfer of abilities and skills acquired within virtual environments to the real-world performance. Although continued efforts are needed to firmly establish that attainments with virtual environments are both transferable and generalizable to function within the real world, the evidence to date substantiates the initial promise of these dynamic technologies.


We warmly thank our research team, Rachel Kizony, Meir Shahar, Debbie Rand, Naomi Josman, Uri Feintuch, Orit Palmon, and Assaf Dvorkin, for the creative development and application of virtual environments for rehabilitation. We are greatly indebted to our colleagues Albert "Skip" Rizzo and Hunter Hoffman for their groundbreaking efforts in this field.

1. Sheridan TB. Musings on telepresence and virtual presence. Presence. 1992;1:120-25.
2. Weiss PL, Jessel AS. Virtual reality applications to work. Work. 1998;11:277-93.
3. Rizzo AA, Kim GJ. A SWOT analysis of the field of VR rehabilitation and therapy. Presence Teleoper Virtual Environ. In press 2005.
4. Rizzo AA, Schultheis MT, Kerns K, Mateer C. Analysis of assets for virtual reality in neuropsychology. Neuropsychol Rehabil. 2004;14:207-39.
5. Rand D, Kizony R, Feintuch U, Katz N, Josman N, Rizzo AA, Weiss PL. Comparison of two VR platforms for rehabilitation: Video capture versus HMD. Presence Teleoper Virtual Environ. In press 2005.
6. Weiss PL, Kizony K, Feintuch U, Katz N. Virtual reality in neurorehabilitation. In: Textbook of neural repair and neurorehabilitation. Selzer ME, Cohen L, Gage FH, Clarke S, Duncan PW, editors. New York: Cambridge Press. In press 2004.
7. Rizzo AA, Buckwalter JG, Bowerly T, van der Zaag C, Humphrey L, Neumann U, Chua C, Kyriakakis C, van Rooyen A, Sisemore D. The virtual classroom: A virtual environment for the assessment and rehabilitation of attention deficits. Cyberpsychol Behav. 2000;3:483-500.
8. Zhang L, Abreu BC, Masel B, Scheibel RS, Christiansen CH, Huddleston N, Ottenbacher KJ. Virtual reality in the assessment of selected cognitive function after brain injury. Am J Phys Med Rehabil. 2001;80:597-604.
9. Grealy MA, Johnson DA, Rushton SK. Improving cognitive function after brain injury: the use of exercise and virtual reality. Arch Phys Med Rehabil. 1999;80:661-67.
10. Brooks BM, Rose FD, Potter EA, Attree S, Jayawardena S, Morling A. Assessing stroke patients' ability to remember to perform actions in the future using virtual reality. In: Sharkey P, Lanyi CS, Stanton P, editors. Proceedings of the 4th International Conference on Disability, Virtual Reality and Associated Technology. Vresprem, Hungary: University of Reading (United Kingdom); 2002. p. 239-45.
11. Weiss PL, Naveh Y, Katz N. Design and testing of a virtual environment to train stroke patients with unilateral spatial neglect to cross a street safely. Occup Ther Int. 2003;10: 39-55.
12. Lam YS, Tam SF, Man DW, Weiss PL. Evaluation of a computer-assisted 2D interactive virtual reality system in training street survival skills of people with stroke. Proceedings of the 5th International Conference on Disability, Virtual Reality & Associated Technology. Oxford, United Kingdom; 2004.
13. Pugnetti L, Mendozzi L, Attree EA, Barbieri E, Brooks BM, Cazzullo CL, Motta A, Rose FD. Probing memory and executive functions with virtual reality: Past and present studies. Cyberpsychol Behav. 1998;1:151-62.
14. Morris RG, Kotitsa M, Bramham J, Brooks B, Rose FD. Virtual reality investigation of strategy formation, rule breaking and prospective memory in patients with focal prefrontal neurosurgical lesions. In: Sharkey P, Lanyi CS, Stanton P, editors. Proceedings of the 4th International Conference on Disability, Virtual Reality and Associated Technology. Vresprem, Hungary: University of Reading (United Kingdom); 2002. p. 101-8.
15. Kizony R, Katz N, Weiss PL. Adapting an immersive virtual reality system for rehabilitation. J Visual Comput Anim. 2003;14:261-68.
16. Sveistrup H, McComas J, Thornton M, Marshall S, Finestone H, McCormick A, Babulic K, Mayhew A. Experimental studies of virtual reality-delivered compared to conventional exercise programs for rehabilitation. Cyberpsychol Behav. 2003;6:245-49.
17. Merians A, Jack D, Boian R, Tremaine M, Burdea GC, Adamovich SV, Recce M, Poizner H. Virtual reality-augmented rehabilitation for patients following stroke. Phys Ther. 2002;82:898-915.
18. Weiss PL, Bialik P, Kizony R. Virtual reality provides leisure time opportunities for young adults with physical and intellectual disabilities. Cyberpsychol Behav. 2003;6: 335-42.
19. Davies RC, Lofgren E, Wallergard M, Linden A, Boschain K, Minor U, Sonesson B, Johansson G. Three applications of virtual reality for brain injury rehabilitation of daily tasks. Proceedings of the 4th International Conference on Disability, Virtual Reality and Associated Technology. Vresprem, Hungary: University of Reading (United Kingdom); 2002. p. 93-100.
20. Gourlay D, Lun KC, Lee YN, Tay J. Virtual reality for relearning daily living skills. Int J Med Inform. 2000;60: 255-61.
21. Schultheis MT, Mourant RR. Virtual reality and driving: The road to better assessment of cognitively impaired populations. Presence Teleoper Virtual Environ. 2001;10: 436-44.
22. Rizzo AA. Virtual reality and disability: emergence and challenge. Disabil Rehabil. 2002;24:567-69.
23. Mantovani F, Castelnuovo G. Sense of presence in virtual training: Enhancing skills acquisition and transfer of knowledge through learning experience in virtual environments. In: Riva G, Davide F, Ijsselsteijn WA, editors. Being there: Concepts, effects and measurement of user presence in synthetic environments. Amsterdam (The Netherlands): IOS Press; 2003.
24. Rizzo A, Buckwalter JC, van der Zaag C. Virtual environment applications in clinical neuropsychology. In: Stanney K, editor. The handbook of virtual environments. New York: Erlbaum Publishing; 2002. p. 1027-64.
25. Hodges LF, Anderson P, Burdea G, Hoffman HG, Rothbaum BO. VR as a tool in the treatment of psychological and physical disorders. IEEE Comput Graph Appl. 2001; 21:25-33.
26. Hoffman HG, Patterson DR, Carrougher GJ. Use of virtual reality for adjunctive treatment of adult burn pain during physical therapy: a controlled study. Clin J Pain. 2000; 16(3):244-50.
27. Reger GM, Rizzo AA, Buckwalter JG, Gold J, Allen R, Augustine R, Mendelowitz E. Effectiveness of virtual realty for attentional control to reduce children's pain during venipuncture. Proceedings of the 2nd International Workshop on Virtual Reality. Piscataway (NJ); 2003.
28. Sanchez J, Jorquera L, Munoz E, Valenzuela E. Virtual-Aurea: perception through spatialized sound. Proceedings of the 3rd International Conference on Disability, Virtual Reality and Associated Technology. Alghero, Sardnia: University of Reading (United Kingdom); 2000.
29. Yu W, Brewster SA. Multimodal virtual reality versus printed medium in visualization for blind people. Proceedings of the 5th International ACM SIGCAPII Conference on Assistive Technologies; 2002 Jul 8-10; Edinburgh, Scotland. New York; 2002. p. 57-64.

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