David J. Reinkensmeyer, Ph.D.Wojceich Timoszyk, M.S.Craig Takahashi, M.S.Clifton Pang, B.S.Jeff Nessler, M.S.Chris Painter, M.S.Department of Mechanical and Aerospace EngineeringCenter for Biomedical EngineeringUniversity of California, Irvine
Lennie Kahn, M.S.Michele Averbach, P.T.W. Zev Rymer, M.D., Ph.D.Sensory Motor Performance ProgramRehabilitation Institute of Chicago
Ray de Leon, Ph.D.Nicolas London, B.S.V. Reggie Edgerton, Ph.D.Brain Research InstituteUniversity of California, Los Angles
Mechatronic and robotic devices that are designed to physically interact with patients, or "rehabilitators," are powerful new tools for understanding and enhancing movement therapy. We are developing several devices for retraining movement following stroke and spinal cord injury. The ARM Guide is a singly actuated, trombone-like rehabilitator that can mechanically assist a weakened arm in reaching across its workspace. Using the ARM Guide, we are evaluating whether active-assist therapy is differentially beneficial as compared to a matched amount of unassisted reaching exercise in chronic stroke patients. Our preliminary results indicate that active-assist therapy (provided three times per week over a two month period) significantly improves active range of motion of reaching, increases maximum speed of reaching, and decreases tone, defined as the force resisting passive extension of the arm. Surprisingly, however, the amount of benefit is comparable to that generated by a matched amount of free-reaching exercise. We therefore hypothesize that it is the repetitive movement attempts by the subjects that provide the primary stimulus for recovery (compatible with "constraint-induced" therapy results), rather than the active assistance provided by the mechanical device. We are investigating three additional rehabilitator-based therapy techniques. First, using a commercially available three degrees-of-freedom haptic robot, we are using novel force fields to understand motor learning following stroke. Our preliminary results suggest that motor learning is often impaired following stroke, and that this impairment is caused by weakness in stereotypical movement directions. Second we have developed a Web-based telerehabilitation system (www.javatherapy.com) that incorporates a low-cost, commercially available force feedback joystick, a customizable library of on-line movement exercises, and automated progress reports that provide quantitative feedback of hand movement parameters such as speed and strength. Preliminary results demonstrate that chronic stroke patients can improve hand movement ability using the system from home. This improvement apparently accrues between therapy sessions, rather than within single therapy sessions, suggesting a mechanism besides normal motor learning. Third, we are developing rehabilitators for retraining locomotion after spinal cord injury. We have developed a miniature robotic system for retraining bipedal stepping in spinal cord injured rodents, and are using it to evaluate the physiological and engineering principles for a human step-training device. Using the rat rehabilitator, we have demonstrated that the swing phase of locomotion can be enhanced by transiently loading the paw during stance. We are currently evaluating this robotic "hyper-loading" technique as a chronic step training procedure.
Supported by NIH, NIDRR, the Whitaker Foundation, Microsoft Corporation, and Christopher Reeve Paralysis Foundation.