A virtual reality ball grasp and sort task for the enhancement of phantom limb pain proprioception

Mirror box therapy helps reduce phantom limb pain by enhancing virtual agency, the intentional initiation of movement by an amputee of his or her missing limb. However, mirror box therapy is limited by a restriction to symmetrical movement and by the lack of user interaction with objects, making it difficult for the user to remain engaged. As an emerging therapy, the addition of virtual reality more readily offers an environment that is immersive and reconfigurable. The virtual reality therapy described herein seeks to provide an engaging, therapeutic illusion that allows asymmetric limb movement. In the virtual environment, the amputee user interacts with balls in a task that involves picking up one of six colored balls and dropping the ball into a bin. The image is produced by reflecting projected light off of a mirror and onto a tabletop where the user views virtual environment. The particular training procedures were designed to incorporate two separately controllable motor actions, afford immersive feedback through the visual channel, give the user a sense of hand to object interaction, and account for user comfort and sustained attention engagement. This task poses minimal strain on the residual limb and minimizes the number of non-invasive sensors. Future testing will determine the device's effectiveness in alleviating phantom limb pain in transradial individuals.