Are Wearable Robots Effective for Gait Recovery After Stroke?

After stroke, gait impairment affects as many as 65% of survivors. Such impairment is associated with substantial limitations in independence and quality of life. This is an issue of considerable impact for the US healthcare system: there are ≈6.6 million Americans suffering from stroke with 795 000 new (or recurrent) cases joining this group every year. The number of new cases is climbing rapidly because of population aging, and the resulting growth in related expenses will place increasing pressure on the US healthcare budget. By 2030, stroke-related healthcare costs are expected to climb to a staggering $240 billion dollars annually, a 445% increase from the current annual cost of $53.9 billion. Given these facts, minimizing gait impairment is of high priority. We urgently need evidence-based restorative therapies that increase the extent and rate at which these patients regain their functional independence. Robot-assisted therapy is among the innovations proposed for achieving this. A robot, defined as a programmable, multifunctional manipulator designed to move material, parts or specialized devices through variable programmed motions for the performance of a variety of tasks, allows repetitive, high-dose, high-intensity, and task-oriented training in a safe manner. In the context of gait rehabilitation, such training is a basic premise of the recovery from impairment. Recent research has shown that the use of robots can be effective in improving gait function after stroke. However, these effects are rather small and inconsistent. One possible explanation for small effect sizes may be the type of robots investigated so far, that is, fixed-type or static (devices in which the patient is moved in a fixed place). Precisely, during fixed-type robots intervention, the patient is exposed to high-intensity repetitive movements while balance is controlled (via harness) and the patient’s legs are guided in a preprogrammed gait pattern (via robots). Increasing evidence shows that skill learning rather than exposure to a repetitive movement guides neuroplasticity and recovery after stroke. Put differently, to improve, a patient should be constantly challenged during task execution. The use of wearable or dynamic robots (devices which move leg’s joints in coordination with gait phases around the environment) may overcome the limitations of the static robots. These wearable devices enable the combination of high-dose practice (via robotic assistance) with the challenge of over-ground walking. However, as suggested by Morone et al, some of these robotic devices require long periods of training and, more importantly, a certain level of patient independence. Clinical research on the efficacy of wearable robots-assisted interventions in stroke patients is quite limited but encouraging. The article by Lee et al in this journal provides reassurance in this respect. This is the first randomized controlled trial to consider the effects of a short-term training protocol with a wearable hip-assisted robot (Gait Enhancing Motivating System [GEMS]) on walking efficiency in chronic stroke survivors exhibiting moderate to mild gait impairment. GEMS is a lightweight, comfortable, and powerful robot (Samsung Advanced Institute of Technology, Suwon, Republic of Korea) providing interactively assistance of hip motion according to the user’s voluntary efforts during gait training on the treadmill and over ground. By demonstrating a positive effect of GEMS training on gait function and efficiency compared to conventional gait training, Lee et al have provided further evidence that supports the effectiveness of using a wearable robot in gait rehabilitation after stroke. It should be emphasized that the authors also took into account the changes in level of cardiorespiratory efficiency in evaluating robot-assisted therapy efficiency and showed for the first time that gait training with GEMS favors the restoration of an adequate level of cardiorespiratory efficiency. This is a very important feature because stroke survivors who exhibit reduced mobility often suffer from poor cardiovascular fitness, which in turn leads to a substantial decline of their quality of life. As stated above, this trial included patients in the chronic stage of stroke, when neural plasticity is relatively stable. By including this subpopulation, the authors minimized the confounding effect of spontaneous recovery, reported earlier after stroke, on the intervention effects of GEMS. Furthermore, the patients studied in this trial were mobile and able to maintain a standing position with minimal assistance. Yet, it would be intriguing to investigate whether this device (or a modified form) has promise early after stroke, when immobility peaks. Applying this approach to acute and subacute stroke survivors might result in better clinical outcomes, primarily due to additional brain capacity for plasticity earlier after The opinions expressed in this article are not necessarily those of the editors or of the American Heart Association. From the Department of Physical Medicine and Rehabilitation, University of Missouri, Columbia. Correspondence to Carmen M. Cirstea, MD, PhD, Department of Physical Medicine and Rehabilitation, University of Missouri, One Hospital Dr, DC046.00, Columbia, MO 65212. Email cirsteac@health. missouri.edu Are Wearable Robots Effective for Gait Recovery After Stroke?