Virtual Reality for Individuals Affected by Stroke

Contributors: Sarah Kelly, Avery Michels, Kaitlin Proksch and Dayna Webster

Introduction

It is estimated that stroke affects approximately 15 million people worldwide every year and among those, between 55% and 75% of these survivors continue with motor deficits and a reduced quality of life following the event. These motor deficits include motor control, strength, fine motor skills and dual task coordination abilities, which all have potential for significant effects on an individuals’ independence and quality of life. In effort to assist these individuals with motor recovery, virtual reality (VR) systems were developed. VR is defined as a “computer-based technology that allows users to interact with multisensory simulated environment and receive ‘real-time’ feedback on performance”. The interactive games are designed to provide the patient with real- life scenarios and activities relevant to daily living. The software is able to provide key concepts required for motor learning including frequency, intensity, repetition and task-oriented training while enabling the user to feel involved in their rehabilitation. These systems have many settings that allow accommodation for patient needs, abilities and goals through manipulation of the degree of difficulty, focus on extremity of choice as well as options for game tasks.

VR systems incorporate several theories of neuroscience and motor learning. The games allow for task-oriented practice, repetitive, intensive yet modifiable difficulty to promote an optimal practice schedule. Some VR games have an option of a VR teacher that performs the task, enabling the chance for “learning by imitation” by stimulating mirror neurons. In addition, the VR system provides the use of augmented feedback on performance that is provided concurrently with performance, immediately following a performance based on results (knowledge of results) or after several trials as summary feedback. Ample research has been conducted on the effects of these types of feedback for learning. Therefore, VR systems allow for individualized training sessions that allow patients to practice practical skills in an engaging way.

This video created by Bruyer (2016) demonstrates the use of virtual reality in stroke rehabilitation. The game of choice creates both upper and lower extremity motor demands as the patient is required to kick the soccer ball or reach left and right to block the net. This example demonstrates the vast variability in games for use of VR in rehab, the flexibility, adaptability and applicable nature of the tasks.

Background

Thorough research has been conducted in order to examine the effects and efficiency of conventional rehabilitation in regards to improvements in motor function post-stroke. The systematic review performed by Saposnik and Levin, shows that only modest improvements were made using conventional therapy approaches such as neurodevelopmental techniques, PNF and motor re-learning strategies (2011). Following the release of this knowledge, new approaches were studied in order to create a novel approach to motor skill re-learning and amongst this - virtual reality. Research on virtual reality in sport in the mid '90s was conducted to determine its potential benefits for athletes. This research found that there was a positive correlation to an athlete’s performance in practice following a VR session involving the skill at hand, such as a golf swing. From these studies in the 1990s, VR has been further investigated for its use in clinical settings and in rehabilitation.

Principle

Neuroplasticity and CNS Reorganization

Later recovery of function in post-stroke patients is associated with central nervous system reorganization, which can be influenced in part by relearning through rehabilitation training. Neurological reorganization and its impact on functional recovery can continue for a much longer period than the acute neurological post-stroke recovery process (reduction of edema, reperfusion of the penumbra, etc.). Following a stroke, this neurological reorganization of the undamaged cortex occurs to allow for motor and somatosensory recovery. In the end, this reorganization is not an acquisition of new neurons, but an adjustment of the undamaged connections to create new functional connections.

Motor Learning and its Application to Functional Recovery in Stroke Patients

The motor cortex in the brain is composed of interconnected cortical areas that function together to bring about movement. Different areas of the motor cortex are shown to be active when performing different functional tasks, this is called cortical motor mapping. Research shows that motor learning causes morphological changes or reorganization in the motor cortex influencing these cortical maps. First, newly acquired movements or skills have been shown to expand across a larger cortical area. Moreover, in both intact and injured brains learned motor tasks demonstrate reorganization of the cerebral cortex. The reorganization of the cortex is improved through enriched environments and repetition of a task.

In patients affected by stroke, research shows that movement of the affected limb(s) demonstrates greater cortical recruitment of the ipsilateral (unaffected) hemisphere, the contralateral (affected) hemisphere secondary cortical areas and/or around the cortical rim of the lesion. This demonstrates functional reorganization and connectivity of the uninjured cortical areas to compensate for the abilities lost with the lesion. Although these cortical reorganizations may not occur at the same time and depend to some extent on the severity of the stroke, motor and functional recovery relies on cortical reorganization of ipsilateral or contralateral undamaged cortical tissue.

In patient’s post-stroke it is well known that increased intensity and early rehabilitation results in better functional outcomes. In alignment with principles of motor cortex reorganization, it is important to provide early stroke rehabilitation to patients that is intense, repetitive, and occurs in stimulating and complex environments.

Virtual Reality and Functional Recovery in Stroke Patients

There is modest evidence showing that neuroplasticity occurs after virtual reality (VR) training in stroke patients. Studies show that functional activities prior to VR training activate the contralesional hemisphere, whereas post-training incorporates ipsilesional representation.

One use of VR provides discordant visual feedback to the patient where the therapist can manipulate the patient’s virtual perceived environment. This type of movement feedback for the patient can be controlled through up-scaling, down-scaling or completely altering the movements seen in their virtual environments from the patient executed movement. Discordant feedback is shown to cause greater activation of primary motor regions than non-discordant feedback. When applied to stroke patients, discordant feedback and movement of the affected hand was shown to recruit the contralateral (affected) primary motor region. Mirror feedback can also be applied using VR where the patient perceives their affected side moving when it is really their unaffected side executing the movement. Studies show that when virtual mirror feedback was applied the affected primary motor region was recruited.

VR allows a more interesting and engaging environment for goal-oriented tasks to be performed in. It also creates a safe environment that can be easily manipulated to advance tasks as stroke patient’s functional abilities progress. Moreover, VR can be performed without supervision meaning that VR therapy can be performed more often than standard supervised physiotherapy sessions. This intervention fulfills the important principles of neurological rehabilitation needed in stroke patients for functional recovery by using goal-oriented tasks, enriched environments and allowing high repetition and intensity of therapy.

Application in Physiotherapy

As this technology is relatively new within the field of physiotherapy, the techniques and application of VR vary greatly. To create a VR environment, a computer with a unique graphics system is required. The software and hardware components of the device can be programed to create the virtual environment and provide simulation/ feedback to subjects. Before implementing or incorporating VR within rehabilitation, a therapist must choose which type of VR they want to use with their patients. The two types most commonly used in rehabilitation are immersive and non-immersive. The immersive style of VR, typically delivered through a head mounted device, creates a realistic environment for the user. However, one of the major side effects of this style of VR is the associated motion-like sickness, cybersickness, which can be very uncomfortable for the user and may alter their level of participation. The other type of VR is non-immersive. This branch of VR typically comes in the form of a video game device. These systems are more cost effective, but do not create the same high level of engagement within the environment as the immersive systems. Many clinicians have begun testing the non-immersive tools within rehabilitation settings. In their Cochrane review, Laver et al. (2017) outlined that the severity of the stroke and type of VR device did not have an influence on the outcome, but suggest that more time with the device could have influenced the data. More research is needed to determine the influence of VR systems specifically with individuals who have experienced a stroke to create best practice guidelines for physiotherapists.

One of the most exciting aspects of VR research within rehabilitation is the ability to record and measure more data than with standard physical therapy measures. It is essential that validated outcome measures specific to VR techniques are developed to allow use this data within a rehabilitation setting. As well, by using the data collected for each individual, the software of the systems can easily be programed and tailored to each user. This individualization of treatment would allow therapists to work with each patient on their specific needs, while using VR as a tool to aid their recovery. Again, more research is needed before it is a general practice of physiotherapists to include VR as part of their rehabilitation plans.

Evidence

In 2011, a meta-analysis completed by Saposnik and Levin looked at the effects of VR as an adjunctive therapy in neurorehabilitation for arm motor recovery post stroke. Among the twelve studies analyzed, 5 were randomized controlled trials and 7 were observational studies. These studies looked at patients suffering from both acute/subacute and chronic stroke effects and ranging in age from 26 to 88 years. Outcome measurements used in these studies included the Fugl-Meyer Assessment, Wolf Motor Function Test (WMFT), and Functional Independence Measure (FIM). Favouring the VR group, the results displayed a significant benefit for arm strength, improvement in arm motor impairment and arm motor function through the selected outcomes.

A more recent systematic review was conducted by Laver et al (2017) included 72 studies with objectives to identify the efficacy of VR interventions in stroke patients. This particular review had a primary focus on upper limb function and activity and a secondary focus on gait, balance, global motor function, cognitive function, activity limitation, participation restriction, quality of life, and adverse events. Studies included in this review were randomized and quasi-randomized trials, which compared the efficacy of VR based interventions to a control group receiving standard-care approaches or no intervention. The results of this review identified a significant difference favouring the intervention between groups for upper limb function when the intervention group received VR in combination with usual care. This review also identified significant difference between groups favouring VR for activities of daily living (ADLs), which were addressed using outcomes such as the Functional Independence Measure (FIM), Barthel Index, and on-road driving test. The other outcomes tested were not statistically significant based on the results of this review. As this topic remains relatively novel in the realm of stroke rehabilitation, current research concludes that future investigations will be required to provide higher quality evidence to identify the effects of VR interventions on various components of stroke rehabilitation.

Summary

The use of virtual reality (VR) has dated back to the 1990s where the effects were studied in athlete’s performance. VR is a computer-based intervention providing patients with a virtual interactive and applicable treatment setting for skills practice with real-time feedback. This intervention incorporates many therapeutic motor learning rehabilitation principles that have shown to be most effective for skill retention in patients affected by stroke. In addition, the technology provides diverse applications that can be tailored to the patient. The concept of VR is based off of the neuroscience evidence of brain neuroplasticity following injury. VR systems are shown to provide widespread cortical activation, which is important in promoting neuroplastic changes and thus functional improvement following stroke. There are millions of people affected by stroke worldwide and therefore encouraging research into the most effective treatment methods is important. The use of VR in rehabilitation is still being studied as it is a new concept recently introduced to the rehabilitation setting. There are several systematic reviews that demonstrate the potential benefits VR systems may provide for patients, however more research is required to provide higher quality of evidence and direction with specific interventions.