Virtual reality-robotic applications in rehabilitation

Author(s): Joel Stein, MD, Hannah Aura Shoval, MD, Ethan Rand, MD

Originally published:09/20/2014

Last updated:09/20/2014

1. OVERVIEW AND DESCRIPTION

Definition

Robotics and virtual reality are technologies utilized in the field of rehabilitation medicine to facilitate and complement conventional rehabilitation strategies.

A robot can be defined as “a machine that performs various complex acts of a human being” and “automatically performs complicated, often repetitive, tasks.”1Current robotic systems include therapeutic robots, such as large stationary exercise robots or wearable exoskeletal robots (powered braces). There are also functional robots such as assistant robots for activities of daily living (ADL), and companion robots.2

Virtual reality (VR) is defined as a human-computer interface that allows a user to interact with a computer-generated environment, using multiple sensory channels.3,4 The virtual environment (VE) can provide users with visual, auditory, or tactile feedback. Current systems vary in size, scope and level of immersion, from cave automatic virtual environments (CAVE), which are room-sized installations containing three-dimensional visual and auditory systems, to head-mounted visual displays (HMD), as well as commercially available interactive gaming consoles (e.g., Nintendo’s Wii, or Microsoft’s Xbox Kinect). A variety of motion tracking sensors or cameras has been developed in order to incorporate user movement and position.

Conceptual Model

In the field of rehabilitation medicine, robotics and VR systems have the potential to measure abilities, as well as to serve as therapeutic tools. These systems can be used to assess and measure motor abilities, posture and limb position, strength, gait, and balance. Real-time feedback regarding performance can be provided to patients and clinicians. Reports can also be generated to provide objective data regarding patient progress in comparison to themselves or other users. Therapeutically, they provide users with repetitive, contextualized, task-specific training in a stimulating and entertaining manner. These types of exercises are fundamental in neurorehabilitation as they aid in promoting neuroplasticity and recovery.5

Furthermore, robotic systems can facilitate or assist movement of paretic limbs in performing functional movements and actions, enabling patients to increase social engagement and increase autonomy and independence. VR systems can also provide cognitive exercises and measures as well as simulation of real-world activities in a safe context (e.g., driving simulation or street crossing).6 By combining robotics and VR systems, the benefits of both technologies can be achieved to provide precise, repetitive training in engaging and safe virtual environments.

Targeted Disorders

Robotic and VR systems have primarily been studied for use in patients with motor and sensory disorders of the central nervous system (CNS), including stroke, traumatic brain injury (TBI), multiple sclerosis (MS), spinal cord injury (SCI), and cerebral palsy (CP).

Robotic systems are uniquely suited to also provide functional assistance with mobility and activities of daily living. For example, robotic exoskeletons can allow paraplegic individuals with SCI to walk independently. Brain-computer interfaces, where computers analyze brain signals and use them to control robotic devices are being studied for patients with neuromuscular disorders such as amyotrophic lateral sclerosis.7 Robotic systems can also serve as companions with sociopsychosoical and physiological benefits.8

VR systems are also being used in the field of orthopedics and sports medicine in order to provide an engaging, structured environment for performing strengthening, stretching, cardiovascular exercise, and for prosthetic training. Additionally, VR systems have been used to treat cognitive disorders resulting from CNS disorders.

2. RELEVANCE TO CLINICAL PRACTICE

Clinical Justification for Use

Robotics and VR can be utilized at any point in the process of rehabilitation, from the acute to late stages. These technologies may be used to supplement conventional therapy to achieve the relevant goals at each stage of recovery and rehabilitation. Evidence regarding robotics and VR is still too limited to provide definitive clinical practice recommendations, however, and additional research is required.

Workstation robotics/gait trainers are stationary robots (due to their large bulky nature) that are used to provide therapeutic exercise, generally in a clinical setting, such as a physical therapy gym. One study for upper extremity robotic systems for shoulder and elbow rehabilitation in stroke patients in acute rehabilitation facilities showed benefits lasting three years.9 Another study showed improvements in both subacute and chronic population.10 For the lower extremities, robot-delivered body weight-supported treadmill training has been used for gait training. There is some evidence for use of robot-assisted gait training in patients with stroke, Parkinson’s disease (PD), CP, and possibly SCI.11

Wearable powered orthoses can serve both functional and therapeutic goals by compensating for a patient’s neurological deficits while training muscles and coordination. Stroke patients using an electromyogram (EMG)-controlled exoskeletal upper limb-powered orthosis showed improvement in function and spasticity.12 In a study of powered exoskeletal robots for the lower extremities in patients with motor complete SCI, exoskeletal robots were shown to be safe and well tolerated, and participants were able to walk independently for periods of five to ten minutes with reported physical and psychological benefits.13 Exoskeletons can also be used for individuals with movement disorders such as tremors, to help monitor, diagnose and dampen tremors. A study of five subjects showed statistically significant decreases in all subjects with the use of an exoskeleton.14

Functional, independent robots can perform activities of daily living, supervisory tasks, or function as a companion. These robots are still in development and limited in function. Other robots that help primarily with function include single point-of-contact, end effectors that aid with ADL performance. These can be difficult to master in terms of proprioceptive feedback, especially given that the weight of the device can affect positioning and control of actions.15

In VR systems, the largest amount of research has investigated its use for patients with motor impairments due to stroke.16,17,18 A 2011 Cochrane review found that VR was more effective than conventional therapy in retraining upper limb function and with improving ADL function; however, no statistically significant increase in grip strength or gait speed was found.18 In addition to the motor and sensory training, VR can also be used to assess and perform cognitive exercises to work on executive function, memory, attention, planning, and visuospatial processing.19 The technology also has been studied in multiple simulation settings with virtual offices, kitchens and driving environments.19 Within the pediatric population, VR has been used among children with CP, and was found to be effective in improving engagement and motor function, proximal stability, postural tone and range of motion.20,21

Factors that Influence Clinical Application

Historically, robotics and VR systems have often been relatively inaccessible for routine clinical use because of the high cost of these technologies. However, with advances in technology, prices continue to steadily decline. In VR, commercial gaming consoles provide a cost-effective means of accessing many of the advantages of this technology conveniently from home. Additional advances in technology include decreasing bulk, weight, ease of donning and doffing, improvement of aesthetics, and portability and reliability of power sources. While robotic therapy and VR have been shown to be superior to “usual care” in a number of studies, there is little convincing evidence that they are superior to dose-matched conventional rehabilitation therapy.22,15 While this technology has the potential to provide labor savings and potentially financial savings, these benefits remain difficult to achieve with existing technologies.

Potential Disadvantages and Adverse Effects

A general limitation to some technological systems is that a population with cognitive, visual, perceptual impairments may find them difficult to use.11Safety issues are also critical to consider, especially given that primary user groups have functional deficits that may make them vulnerable to technological malfunctioning, especially if unsupervised. Several safety mechanisms have been employed in robotics in order to prevent injury. For instance, some systems allow for deviation of force or movement by the user, preventing the patient from being forced into dangerous positions by the machine. Padding is also utilized to decrease pressure and potential for skin injury. Overall, rehabilitation robots have had a very impressive safety record, and no serious injuries have been reported from their use.

With regard to VR, few adverse events are reported in literature and VR appears to be an inherently safe therapeutic modality. The most common adverse effect is transient visually-induced motion sickness, known as cyber sickness or simulation sickness. Symptoms are similar to motion sickness, but generally less severe, and include dizziness, headache, sweating and nausea.18,19 Cyber sickness occurs more frequently with immersive VR systems, such as HMD, compared with less immersive systems, such as projected VE. Occasionally, patient may also complain of transient eye strain.16 There are no explicit contraindications for VR identified in the literature. However, caution is warranted with patients who have communication disorders, such as aphasia, which may prevent one from identifying discomfort during the intervention; or with patients who have certain psychiatric disorders, for instance delusional conditions with symptoms that could be potentiated by the VR experience.

3. CUTTING EDGE/UNIQUE CONCEPTS/EMERGING ISSUES

Both robotics and virtual reality, individually or in combination, can potentially provide a wide range of therapies in an engaging and cost-effective manner. In countries with an aging population, such as Japan, emphasis is being placed on robot technology to fill the gap created by an insufficient number of caregivers.23Emerging issues involve concerns for accessibility, cost, patient autonomy, and privacy, as well as the potential use/misuse of these technologies to replace rather than supplement the skilled practitioner. Compassionate care is an invaluable component of the rehabilitation process, and one that is unlikely to be automated in the near future.

4. GAPS IN KNOWLEDGE/EVIDENCE BASE

Additional research is required to further investigate robotic and VR systems in order to determine which designs are most efficacious, the appropriate dosing and timing of intervention, as well as motivation and adherence to therapeutic programs. Methodologically, current research efforts in the field of robotics and VR are limited by heterogeneity among interventional approaches, outcome measures, and control groups, limiting the ability to pool and compare studies.24 Additionally, these studies generally utilize small sample sizes, and few studies have examined whether effects are sustained. One review of clinical trials of robot rehabilitation showed that most studies were suboptimally designed, contributing to the dearth of phase II and III clinical trials.25 Also, there is often limited funding in the area of rehabilitation research, and treatment using robotics is currently not well reimbursed.26 Compounding the challenges of clinical research in robotic rehabilitation is the constant and rapid advancement of technology. Alternative pathways for evaluation of novel robotic systems may need to be considered so that patients can benefit from up-to-date technological advances while ensuring patient safety.

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Author Disclosure

Joel Stein, MD
Nothing to Disclose

Hannah Aura Shoval, MD
Nothing to Disclose

Ethan Rand, MD
Nothing to Disclose

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