Innovations and challenges in the use of virtual reality technologies for rehabilitation

The use of virtual reality (VR) and associated technologies for health, wellbeing and support is a growing field, with an increasing body of expert knowledge and a wide range of potential application domains. Virtual rehabilitation has been the focus of considerable research for many years, but the recent upsurge in consumer-reader virtual reality hardware and software has led to an increase in interest in its use in a variety of clinical and home settings. Balancing the upsurge in demand for innovative technological healthcare tools is the need for a credible evidence base for its use and guidance for practitioners on which systems and applications are suitable for different patient populations and rehabilitation goals.
There is increasing evidence that virtual reality is a useful tool for a wide range of health conditions and clinical applications, including pain management, physical rehabilitation, treatment of anxiety disorders and post-traumatic stress, and many other physical, neurological and psychological conditions. However, it is important to bear in mind that these emerging technologies are not intended to replace the clinical expertise and human factors which are an integral part of the healthcare journey, but rather to provide a set of tools to supplement and support rehabilitation and to empower patients to participate in their own wellbeing. The complexity of this emerging area of healthcare should not be underestimated, with different patient groups requiring very different adaptations and interventions in order to achieve the desired outcomes. Fortunately, rigorous investigation and innovative development by practitioners working across the clinical, technical and human factors disciplines is improving our understanding, and supporting us to make better informed healthcare choices which optimise the benefits of this emerging technology.
A key area of concern is that of usability. Whilst this is of course important in any human-computer interaction, many patient populations present unique challenges, with cognitive or physical impairments rending conventional interaction techniques impractical, and often requiring bespoke or customisable interfaces in order to translate the intent of the user into meaningful interaction. Innovative solutions include brain-computer interaction or gaze-directed selection for patients with significant paralysis, and partial hand support for gestural input post-stroke. Usability is of course not confined to the input techniques, but also the way in which content and feedback is presented to the user, which may require the use of iconography and audio prompts for users with learning disability or cognitive impairment, as well as the more conventional text based or visual cues. In addition, the acceptability of a system should also be considered, as a therapeutic intervention may be usable, but not necessarily something a patient or clinician would wish to engage with. For example, patients are often given home exercises using a mirror for retraining facial muscles after stroke, but compliance with this type of exercise can be poor (usable, but not necessarily acceptable). The use of VR technology can provide interactive feedback and gamification of the facial exercises, an approach which may be more acceptable to patients and lead to greater engagement with the therapeutic program.
Having designed a usable and engaging system appropriate to the target population, we come to the question of clinical efficacy - does it actually produce the desired outcomes? No matter how much a patient enjoys the virtual rehabilitation process, it is of little use unless it can be designed to elicit the desired behaviour leading to therapeutic gains. Studies which evaluate the way in which users interact and respond to feedback can give us valuable insights into both expected and unexpected ways in which users respond to the system, and the ability to tightly control almost every aspect of interaction with VR, and to monitor and record performance can provide data which not only allows us to monitor patient progress over time, but also leads to improve application design.
An additional benefit of technology-enhanced rehabilitation is the ability to individualise treatment programs dynamically, with either intelligent algorithms which respond to patient performance, or customisable programs which allow clinicians to create individualised treatment plans within the VR software.
Finally, the growing use of wearable devices allows us to harness additional physiological metrics such as breathing, heart rate or activity level during rehabilitation, even when it is carried out in a setting remote from the supervising practitioner, or in situations where intrusive monitoring is undesirable. This data can be streamed into the VR system and used to dynamically change the user experience, for example altering the level of fear stimulus in virtual reality exposure therapy in response to changing heart rate.
This promising branch of healthcare is already being used to benefit many patients in homes and clinics around the world, but it is evident that there is still much more to learn if we are to continue to push the boundaries of clinical innovation and excellence. In this special issue we present recent research addressing a number of these important topics, adding to our understanding of the complex issues and clinical considerations in virtual rehabilitation research and application.