The future role of robots in neuro-rehabilitation

Abstract

The World Health Organization estimates that about 15% of the world’s population has some form of disability [1]. Rehabilitation has a key role in decreasing the level of disability. Application of advanced technologies in rehabilitation is a promising opportunity to attain this goal. The development of rehabilitation robots started in the late 1980s. The following decade was a pioneering phase. After the year 2000, the first representatives of commercially available robots appeared. These devices can assist in practicing upper or lower limb movements and motor relearning, and in developing proprioception, cognitive functions, and attention. There is equipment that patients can use to practice the same movements as with the robots, but it does not provide mechanical assistance; so patients have to rely on their own strength. The emphasis is on high repetition, interactive and personalised therapy. The aim is to attain a higher level of function in a shorter time frame. The philosophy of the application of robots in rehabilitation is not to replace the therapist, but to widen treatment options [2]. The two main goals of therapy with rehabilitation robots are to develop upper limb function and to support gait re-education. Rehabilitation robots are used mainly following central nervous system damage, primarily after stroke. Multiple clinical trials and meta-analyses have been conducted regarding these robots. Concerning the efficacy of electromechanical arm training, Mehrholz et al. [3] analysed 45 randomized controlled trials with 1619 participants. They found that this kind of therapy promotes improvement in arm function and muscle strength, as well as execution of activities of daily living. Nevertheless, the methodologies of the studies were quite different, and 24 different devices were used. Robot-mediated training on a treadmill is a widely used method for gait re-education. Mehrholz et al. [4] selected 36 trials with 1472 subjects in a Cochrane review and found that poststroke patients who received such training in addition to traditional physiotherapy were more likely to achieve independent walking, than subjects who received traditional therapy alone. These results suggest that robot-mediated therapy gives certain advantages for patients, at least in motor relearning; but several unanswered questions remain: Which kind of exercises are most beneficial, in which phase, how often, and for how long in order to yield optimal results? To compare routinely used types of upper limb therapy, Pollock et al. evaluated 40 reviews covering 18 different interventions (including robotics) in a Cochrane review [5] and stated that the available evidence is insufficient to determine the most effective therapy for improving upper limb function. The authors urged researchers to conduct large randomized controlled trials to find the best practice. Although thousands of patients took part in research trials, it is difficult to compare the results. As yet, no unifiedmethodology or generally used outcome measures for the trials exist; this makes evaluation uncertain [6]. However, some initiatives have been proposed for harmonizing methodologies. The European Network for Robotics in Neurorehabilitation (in the scope of the European Cooperation in Science and Technology – EU COST Action) has published recommendations on protocols for assessment in clinical practice and research in rehabilitation robotics [7]. There is another reason that can make the evaluation more difficult: there are non-robotic devices which provide similar exercises but without robotic assistance. In several studies such devices are used and mentioned as ‘robots’. Studies conducted on the basis of harmonized methodologies could result in a higher level of evidence, which could help create clinical guidelines for application of rehabilitation robotics. According to the present American guidelines for rehabilitation for adults post-stroke, the application of robotic devices for improving mobility ‘may be considered’; and in improving upper limb function, it is ‘reasonable to consider’ [8]. The British guidelines accredited by the National Institute of Health and Care Excellence (NICE) recommend the consideration of electromechanically assisted gait training for those who cannot walk independently after stroke, but also recommend offering robot-assisted arm training to patients only in the context of a research study [9]. The reason for these quite cautious guidelines could be that only weak evidence can be established based on the diverse, hardly comparable trials. It seems that low treatment dose and duration can negatively affect the results. Nevertheless, robot-mediated therapy is considered also because it has very few side effects [10]. Most of the devices make it possible to exercise in a virtual environment [11]. Very few robots provide practice using real objects in a real environment; one of them is the Reharob system [12]. Application of virtual reality is easier to solve technically than practicing in a real environment, but does it