Comparison of Robot-Assisted Reaching to Free Reaching in Promoting Recovery From Chronic Stroke

Recent studies have suggested that physical rehabilitation performed with robotic devices can enhance arm movement recovery following stroke. In these studies, the robotic devices mechanically assisted arm movement as the patient attempted to move. Although this “robotic active assist” technique has shown promise, a key question remains unanswered: is the mechanical assistance provided by the robots necessary, or is it primarily the repetitive movement attempts by the patients that stimulate recovery? We are using a novel robotic device called the Assisted Rehabilitation and Measurement (ARM) Guide to investigate this question. To date, ten subjects have completed twenty-four therapy sessions over an eight-week period, randomized to either a robot exercise group (N = 6) or non-robotic exercise group (N = 4). For the robot exercise group, the ARM Guide mechanically assisted in reaching to a series of targets. For the non-robotic group, the subjects performed unassisted, unrestrained reaching exercises to the same targets for the same number of repetitions as the ARM Guide group. All subjects have been evaluated using a set of clinical and biomechanical measures of arm movement. The ten subjects tested so far have shown improvement in the measures after completion of both exercise programs. However, the amount of improvement has been comparable for the robot and free reaching groups. Although the subject numbers are currently insufficient to draw a definitive conclusion, these results are suggestive that the repetitive movement attempts by the patient, rather than the active assistance from the ARM Guide, are the primary stimuli to recovery.