Our paper describes the development of a novel multi-user virtual reality (VR) system for post-stroke rehabilitation that can be used independently in the home to improve upper extremity motor function. This is the pre-clinical phase of an ongoing collaborative, interdisciplinary research project at the Rehabilitation Institute of Chicago involving a team of engineers, researchers, occupational therapists and artists. This system was designed for creative collaboration within a virtual environment to increase patients’ motivation, further engagement and to alleviate the impact of social isolation following stroke. This is a low-cost system adapted to everyday environments and designed to run on a personal computer that combines three VR environments with audio integration, wireless Kinect tracking and hand motion tracking sensors. Three different game exercises for this system were developed to encourage repetitive task practice, collaboration and competitive interaction. The system is currently being tested with 15 subjects in three settings: a multi-user VR, a single-user VR and at a tabletop with standard exercises to examine the level of engagement and to compare resulting functional performance across methods. We hypothesize that stroke survivors will become more engaged in therapy when training with a multi-user VR system and this will translate into greater gains.
Stroke is the leading cause of major, long-term disability in adults in the United States . Every 40 seconds someone in
the U.S. has a stroke  and more than 700,000 people suffer a new or recurrent stroke each year. The majority of stroke survivors endure chronic impairment , which dramatically impacts their lives physically, psychologically and socially. Stroke incidence is even greater in low to middle income countries. Around 50% of all stroke survivors will have residual hemiparesis involving the upper extremity [4, 5], which can have a profound, adverse impact on self-care, employment, and overall quality of life. A number of studies [6, 7, 8, 9] have shown that upper extremity motor control can still be improved, even in stroke survivors with chronic hemiparesis subsequent to stroke. Many patients continue to be highly motivated to achieve further gains after standard rehabilitation has been completed, seeking out new methods, technologies and practices that can improve upper extremity motor control.
Repetitive movement practice proved to be crucial for maximizing therapeutic benefits . The necessary repetition of rehabilitation exercises can be tedious, however [10, 11, 12] and many patients, including stroke survivors, discontinue treatment long before optimal results have been achieved. Lack of motivation, disengagement, and boredom contribute to impeded progress in rehabilitation . Additionally, opportunities for task practice in the clinic are becoming increasingly limited due to shortened hospital stays  and a reduced number of allotted outpatient therapy sessions (Figure 1). Furthermore, lack of transportation can prevent outpatient stroke survivors from taking full advantage of the available therapy sessions.
Tele-rehabilitation seems a possible solution, but current telerehabilitation systems [7, 16] largely consist of teleconferencing between the therapist and the client. Therapist-client interaction is limited and quantitative measurement of performance is lacking. Instead, we propose a multi-user virtual reality environment (VRE) in which the therapist and client can interact with each other and with objects in the VRE.
An inexpensive motion capture system allows control of avatars, as well as collection of movement kinematics. Our system is innovative, because it brings the therapist and client together in the virtual space to work together in real-time. Alternatively, or additionally, the client can participate with a training partner, potentially another patient, providing additional motivation and encouragement. One study showed that impaired subjects prefer competitive/cooperative multi-user rehabilitation games compare to single-user rehabilitation games . This system can mitigate issues related to transportation and limited clinical access by providing home-based training environment developed specifically for upper extremity rehabilitation.