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Article

Immersive Virtual Reality Application for Rehabilitation in Unilateral Spatial Neglect: A Promising New Frontier in Post-Stroke Rehabilitation

by
Katarzyna Matys-Popielska
1,*,†,‡,
Krzysztof Popielski
1,†,‡,
Paulina Matys
2 and
Anna Sibilska-Mroziewicz
3
1
Institute of Metrology and Biomedical Engineering, Warsaw University of Technology, 02-525 Warsaw, Poland
2
Department of Neurology, Medical University of Bialystok, 15-089 Bialystok, Poland
3
Institute of Micromechanics and Photonics, Warsaw University of Technology, 02-525 Warsaw, Poland
*
Author to whom correspondence should be addressed.
†
Current address: Faculty of Mechatronics, Warsaw University of Technology, 8 Boboli St., 02-525 Warsaw, Poland.
‡
These authors contributed equally to this work.
Appl. Sci. 2024, 14(1), 425; https://doi.org/10.3390/app14010425
Submission received: 18 November 2023 / Revised: 31 December 2023 / Accepted: 1 January 2024 / Published: 3 January 2024
(This article belongs to the Special Issue The Use of Virtual Reality (VR) in Medical Rehabilitation: Assessment Tools, Application Methods, VR Technology and Clinical Applications)
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Versions Notes

Abstract

:
Stroke is a leading cause of disability among adults in Europe. Complications following stroke include limb paresis and unilateral spatial neglect (USN) syndrome. These complications significantly reduce the patient’s ability to function normally both in the short and long term. The chance to regain function is rehabilitation. One of the techniques in USN’s rehabilitation is repetitive visual scanning training, and the effects of rehabilitation can be enhanced by limb activation, such as moving objects from one side to the other. However, rehabilitation carried out in this way is monotonous, and the assistance of a physiotherapist is necessary. This paper proposes an alternative method of rehabilitation, using virtual reality. The created application contains the most important element that occurs during rehabilitation, which is a movement pattern. At the same time, it diversifies the rehabilitation process and allows rehabilitation without constant contact with a physiotherapist. This paper presents the most important strategies to minimize the occurrence of cybersickness, which were applied in the developed application. The created application was approved by a physician and tested with the participation of five post-stroke patients. The first results were positive. Increased motivation was observed among patients using VR in therapy. Patients noticed an improvement in motor function, as well as a reduction in reaction times. In addition, physiotherapists observed an improvement in the range of motion during virtual reality therapy compared to traditional therapy. This gives hope that the app can be used in clinical practice. However, in order for the app to be incorporated into clinical practice, it is necessary to conduct studies with a larger group of patients.

1. Introduction

Stroke is a sudden life-threatening neurological emergency, characterized by impaired perfusion in the central nervous system, which leads to brain tissue injury. Based on etiology, there are two types of impaired perfusion in blood vessels: ischemic stroke, when there is occlusion in cerebral arteries, or cerebral venous and hemorrhagic, when there is a leakage of blood vessels and bleeding [1]. Regardless of the cause, stroke is the second most common cause of death worldwide and the third cause of disability and death combined [2]. In Australia, the US, and Europe, stroke is the leading cause of disability among adults [3,4]. One of the main complications of stroke is motor impairment of varying degrees, from limitations to losses of muscle control, movement, or mobility. It is estimated that at the onset of stroke, approximately 80% of patients have a loss of muscle control [5]. Immediately after the acute phase of a stroke, two-thirds of survivors have mobility deficits, and 6 months after the stroke, more than 30% of patients still struggle with motor disability. Another complication occurring in about 25–30% of individuals with stroke, predominantly right-hemisphere stroke, is unilateral spatial neglect (USN) syndrome [6,7].
Hemineglect syndrome, also known as spatial neglect syndrome or unilateral spatial neglect syndrome, is a neuropsychological disorder of spatial awareness, which is contralateral to brain lesions. Patients pay little or insufficient attention to stimuli presented on the side opposite to the injured cerebral hemisphere. They are unable to report, respond, or orient toward these stimuli [8]. Unilateral spatial neglect is a risk factor associated with poor outcomes in recovery. USN can affect a person’s ability to perform everyday activities. They may omit food from the contralateral side of the plate and wash only the ipsilesional parts of the body. As a result, they become functionally dependent. Individuals also have an increased risk of falls and may require longer hospitalization [9,10,11].
One way to treat the above-mentioned complications after a stroke is rehabilitation. It aims to recover damaged neuronal connections. This results in the restoration of impaired functional abilities, which offers the possibility of improving the quality of life for those struggling with complications, which is why every stroke patient should have access to both early rehabilitation in neurological rehabilitation units and long-term rehabilitation on an outpatient or home basis. The demand for stroke rehabilitation services is still increasing because of the current trends; for example, forecasts for Europe from 2017 to 2047 predict a 17% decrease in stroke mortality but a 27% increase in stroke prevalence [4].
If there are no contraindications, guidelines assume the possibility of using virtual reality (VR) as an alternative method to traditional therapy [12]. Studies such as [13,14,15,16,17] present the use of virtual reality for patient rehabilitation. Initially, these applications were aimed at children and teenagers, as they encouraged the youngest to exercise. In particular, they were concerned with the rehabilitation of the musculoskeletal system and also with speech training or pain reduction [18]. Later, VR appeared in applications aimed at adults. VR applications have been used in the treatment/rehabilitation of orthopedic conditions (such as ankle sprains and shoulder pain and impingement) [19], neurological rehabilitation [20], the general rehabilitation of the upper body, particularly the upper extremities [21,22], Parkinson’s disease, Alzheimer’s disease, and eating disorders [23]. Many studies show the effectiveness of VR in neurological rehabilitation [24,25,26,27], including post-stroke rehabilitation [15,26,28]. The use of virtual reality in general rehabilitation has many advantages [29]. Among them is increasing the patient motivation by providing an interesting and interactive environment; additionally, virtual reality is easy to modify, allowing rehabilitation to be tailored to meet the needs of a particular group of patients or even a specific individual. In addition, in some cases VR rehabilitation is available remotely, making it more accessible to patients, often reducing its cost. The use of virtual reality may have greater benefits in post-stroke patients in terms of balance, mobility, or walking speed compared to standard rehabilitation [30].
Speaking of VR applications, one can distinguish between immersive and non-immersive VR. Immersive VR allows for deeper interaction and "immersion" in the virtual environment [31]. Immersion is usually considered on a scale or along a continuum, from least immersive to fully immersive, and typically involves elements such as a continuity of surroundings, physical interaction, and 3D audio. This effect is achieved through the use of appropriate devices (most often head-mounted displays (HMDs)) and innovative software to create realistic visuals, smooth interactions, and unique experiences. All of this is designed to make the user feel as if they are in a virtual environment. Non-immersive VR systems rely on a computer or video game console, a display, and input devices, such as keyboards, mice, and controllers. In non-immersive virtual reality, users can control characters or actions in the virtual environment but the virtual environment does not interact with them directly [32].
Many more studies on the use of non-immersive VR have been described in the literature [22,23,30,33,34,35]. The reason is that the availability of VR devices that allow deep immersion has been significantly reduced in previous years. Nowadays, due to the rapid development of head-mounted devices, immersive applications are gaining popularity. Thus, the advantages of using immersive VR over non-immersive VR is more realistic and fully immersive experiences, which can lead to a greater sense of presence and engagement. In addition, immersive VR can also be a more effective tool for learning and training, as it allows users to experience and interact with a simulated environment in a more realistic and engaging way [22].
But the use of virtual reality is also associated with risks: decreased visual–motor stability, which can have a detrimental effect on eye-directed motor skills, mental disorders manifested by not distinguishing between the virtual and real worlds [36], and cybersickness [37]. Problems with motor skills, in particular, manifest in complex precision movements such as throwing darts [38], where there were noticeable differences between those trained in VR and in reality. These differences were largely due to the mapping of the environment in VR and thus resulted in learning different movement patterns than those used in reality. According to studies [39,40], varying degrees of severity of cybersickness symptoms have been reported in 22–80% of those using the technology. The symptoms of this disease are similar to motion sickness and occur during and after immersive VR use [41]. Symptoms include headaches, paleness, eye fatigue, sweating, fullness in the stomach, a dry mouth, disorientation, ataxia, dizziness, nausea, or vomiting [42]. Due to the possibility of cybersickness, it is essential to take this factor into account when developing the game, as well as when using it with patients.
The purpose of this paper is to propose a new way of rehabilitating post-stroke patients with upper limb paresis or unilateral spatial neglect using a virtual reality application. The novelty of the created game is its immersiveness and focus on the rehabilitation of patients with USN syndrome, which will entail a number of advantages, as described below. The study presented in this article aims to expand the knowledge of the use of VR in medicine and rehabilitation, particularly post-stroke neurological rehabilitation.

2. Materials and Methods

In order to create a new way of rehabilitating patients using virtual reality, the most important aspects of stroke patient rehabilitation have been identified.
A feasibility study was performed, divided into three stages. In stage one, the feasibility of using VR technology for post-stroke patients was assessed. Risks were examined, primarily the availability of the technology, the willingness of patients to participate in the study, as well as their fear of using the new technology, and the risks associated with the use of VR technology, as presented in the introduction. Consultations were held with rehabilitation therapists as well as neurologists, resulting in the identification of the requirements and limits of the application, as described below, which were the basis for the development of the rehabilitation application. The second stage, described in this article, was to determine the feasibility of providing therapy using VR technology as a supplementary method to enhance traditional rehabilitation. The premise of this stage was to conduct a study of the effectiveness of long-term (monthly) training in the app at a rehabilitation facility. During this study, a patient survey was conducted to determine the impact of cybersickness, the optimal duration of therapy, and the results obtained by patients. For this purpose, cooperation was established with the rehabilitation facility, and a rehabilitation game was developed. The next stage will be to perform a study on a larger group of patients. This stage will be aimed at testing the effectiveness of the method compared to the conventional method.

2.1. Conventional Rehabilitation Methods

Rehabilitation should begin as soon as possible, which means when the patient is medically stable. Rehabilitation should engage the patient. This is an important factor on which the patient’s willingness to exercise, and thus the success of rehabilitation, depends. Therefore, the use of virtual reality is justified. The range of motion of the limb and the degree of difficulty of the exercises should be gradually increased, and the exercises themselves should be repetitive and focused on defined tasks, e.g., buttoning buttons and moving objects [12]. In the case of USN syndrome, the foundation of rehabilitation is an attempt to redirect attention to the neglected side [43].
Visuospatial search training throughout the space (both neglected and non-neglected) is widely used, with the patient encouraged to turn toward the neglected side. One method is based on moving objects starting from the non-neglected side to the destination on the neglected side; e.g., the patient throws an object into a basket placed by the physiotherapist at various locations in the neglected space. This method is shown graphically in Figure 1.
Another strategy in therapy is to place a visually salient stimulus (e.g., a brightly colored strip) at the edge of the visual area (e.g., newspaper, table) and search from the salient stimulus toward the non-neglected side. This strategy helps patients read and locate objects. Another technique is the lighthouse strategy, during which patients, like a beam of a lighthouse, scan space from one side to the other. Such training improves both functional activities and spatial perception [44]. Visual scanning training in USN syndrome, as well as motor rehabilitation in stroke, is an effective form of therapy [45]. However, studies indicate that a combination of motor, cognitive, and affective function development shows better results in post-stroke hemiparesis [46], and the beneficial effects of visual scanning training can be enhanced by somatosensory stimulation and limb activation [47,48].

2.2. Methods of Minimalization of VR Risks

When using immersive virtual reality, the game should be adjusted to minimize the risk of cybersickness. This element is crucial due to the overall scale of the problem. In addition, the risk of symptoms may be increased due to the disease of the participants. A complete solution to this problem has not been developed, but ways to minimize it have been proposed in the literature [37,49]. For the sake of clarity, they have been divided into three categories: those related to the viewing angle, the way the environment is displayed and generated, and programmed movements. The first category mixes techniques for narrowing the field of view (FOV). This method reduces the optical flow and amount of visual information available to users by obscuring the edges of their vision. The second method included in this group is incorporating spatial blur in stereoscopic 3D stimuli. The second group includes techniques related to maintaining high image refresh rates, ensuring the lowest possible latency and therefore optimizing the designed application. A higher refresh rate means that the screen can update the displayed image more frequently, resulting in smoother motion and potentially improved visual clarity, while low latency ensures minimal delay between the user input and system response, contributing to a more immersive and comfortable experience Techniques included in group three are mainly ensuring a realistic reproduction of movements and their fluidity and an avoidance of involuntary movements. These techniques aim to minimize sensory conflicts and discomfort experienced by users, ultimately reducing the likelihood of cybersickness. Moreover, this approach involves intentional head-motion assisted locomotion, which aligns visual and vestibular-induced self-motion illusions to reduce cybersickness.
In the case of rehabilitation exercises, the risks of decreased visual–motor stability and mental disorders can be minimized by using large pieces that neither require precise movements nor one specific movement pattern. In addition, testing should take place under the supervision of specialized rehabilitation therapists, in short sessions that will reduce the risks of problems with distinguishing the real world from the virtual world, and with conventional therapy.

2.3. Identify the Main Objectives of the Application

Physiotherapists were consulted to determine the necessary limitations and requirements of the app under development based on the patients’ fitness and health status. Among them, due to the condition of the patients, the most important was to minimize the stimuli reaching the patient by simplifying the principle of the app and the exercise performed in it. In addition, many of the limitations are related to the average age of stroke patients. Patients are mostly people over the age of 65. As a result, they may not have used virtual reality technology before and may not use it efficiently. Therefore, the physiotherapists pointed out that it was necessary to limit the number of buttons used on the controllers. This limitation enforces the lack of complicated actions or the lack of movement of the user in the app. Another important aspect that was signaled by physiotherapists and exercise therapists is the need to simulate the virtual environment in such a way as not to include elements that mimic the user’s ability to hold or to lean on, which could result in the subject falling.
After consultations with doctors, physiotherapists, and group therapists and a literature analysis, the most important requirements that the application should meet were identified. These include engaging the patient, varying the range of motion, addressing the difficulty of seeing one side of space, combining both visual and motor training, and reducing cybersickness.
It was decided that the application should combine different methods of visuospatial search training. Accordingly, the items into which the object will be thrown should be at the edge of the visual field and should be in bright colors, which is the basis of the strategy with a visual stimulus. The movement should be repetitive from one side to the other, which includes the lighthouse strategy. In addition, the objects to be moved should be on the non-skipped side, which is implied by the first of the strategies outlined in Section 2.1.
A block diagram of how the application works was developed (Figure 2). The created diagram was the basis for creating the application. The rectangles contain commands executed by the application, while the diamonds contain user actions. The block diagram includes key elements, such as the adjustment to the side and level of neglect, the correct placement of objects in relation to the neglected side, and the principle of the rehabilitation (moving objects from side to side).

3. Results and Discussion

Access to rehabilitation for post-stroke patients, both early and long-term, is essential for a patient’s return to physical health. The present study aimed to demonstrate a new tool for the rehabilitation of post-stroke patients with USN syndrome or upper limb paresis using virtual reality. An application dedicated to post-stroke patients was developed as a result of a review of current rehabilitation methods, consultations with physiotherapists, and a review of methods to reduce the adverse effects of virtual reality.

3.1. Created VR Application for Rehabilitation

An application was developed using the Unity 2021.3.19f1 engine and the Unity XR Toolkit toolbox. The application is dedicated to the Meta Quest 2 headset. The application was designed according to the block diagram to meet the guidelines for the rehabilitation of USN patients and patients with motor deficits as defined above. It is operated with controllers using the right, left, or both upper limbs, depending on the ability of the upper limbs of the patient. The basic premise of the exercise is simple and is based on transferring objects from one side to the other, similar to conventional rehabilitation.

3.1.1. Basis of the Application

In the first step, the patient selects an object on the right or left side (Figure 3a). The choice of object determines the side from which he or she will grasp objects. For patients who will use the game to increase motor skills, the choice of side is less important than for patients with USN syndrome, as side selection is not linked to hand selection, which is performed before the game by taking the appropriate controller. The importance of side selection is due to the fact that on the selected side there are objects to be grasped and on the opposite side there are boxes into which the object must be moved. It is suggested that the patient has objects to grasp on the non-neglected side and boxes on the neglected side. The grasped object must then be transferred by the patient to a box on the other side. This arrangement allows the patient to grasp the object (Figure 3b) in the area they can see well and move it to the skipped area. Because the target box (Figure 3c) is significantly larger than the target item, the patient’s movement may be less precise than when grasping, which is intended to motivate the patient to exercise and turn toward the neglected side. The use of virtual reality and the transfer of exercise to a different, more engaging environment engages the patient and increases their motivation to exercise. The increase in motivation with using virtual reality is confirmed by studies [50,51].

3.1.2. Components Providing Proper Rehabilitation

The crates appear in one of four different, bright colors. The color of the box determines the color of the object to be placed in them. In this way, the game provides a visually relevant stimulus at the border of the patient’s visual area. Visual scanning is then directed to the non-neglected side. In addition to training visual scanning, upper limb activation is included by having to move the object to the box. The application has four levels of difficulty, which differ in the location of the boxes. Levels 1–3 differ in the location of the crate. With each successive level, the crate is advanced farther and farther to the neglected side, allowing the difficulty level to be adjusted to the patient’s range of vision. In addition, level 4 features two boxes in random locations. In addition to motor exercises, this level also develops cognitive functions, making it an ideal complement to therapy. During the game, an object is dropped into a box in the same color, all items go to their original place on the shelf, the box changes its color, and points are added (varying amounts depending on the level). However, when the moved item does not have the right color, none of the above-mentioned events will happen, and the patient must keep trying. To ensure that the application provides continuous training, a reset button has been implemented in the game, which restores objects to their original places. This allows the game to continue if an object is dropped in such a way that the patient is unable to pick it up.

3.1.3. Motivation Enhancement

The proposed solution takes the form of a game in which points can be earned (Figure 3d). The points and other statistics in the application have been written in Polish so that they can be understood by the potential group of patients using the game for rehabilitation. With the collection of points, not only can the patient’s progress be measurably tracked but it is also an additional motivating factor for exercise. Studies show increased motivation when using gamification in immersive VR for gait rehabilitation [52], as well as for upper limb rehabilitation after stroke [53].

3.1.4. Minimization of Cybersickness

During the game, the patient moves neither in the real world or in the virtual world. The stationarity of the patient in the real world allows the game to be operated in a sitting position, for example, on a hospital bed or chair, which minimizes the risk of injury or falls. In addition, using the game in a seated position reduces the fatigue caused when the patient has to maintain a standing position and thus allows for longer rehabilitation time using virtual reality. Given that the effects of stroke affect people of all ages but with a predominance of people older than 65, the lack of mobility in the virtual world is intended to simplify the game, as well as minimize the effects of cybersickness.
In addition, cybersickness minimization strategies described in the literature were used. During the development of the application, parameters dedicated to the Meta Quest 2 headset used were set. Among them, first of all, the design was created using Universal Render Pipeline technology, which allowed the creation of optimized graphics in the application. After the application was developed, the number of frames per second (FPS) was also checked, which for the designed application was approximately 400, but for the headset it lowered to around 120, because of the equipment limitation. The frequency should be as high as possible [20], in order to ensure the smoothest possible image and minimize the effects of cybersickness. Referring to the literature data, it was assumed that the frequency obtained was sufficient for the designed application. In addition, part of the strategy for minimizing the negative effects of being in the headset is included in the device itself. For this reason, the developed application is dedicated exclusively to the headset, rather than the more economical option, the use of the phone. The correctness of the identification of the position of the controllers results in a smooth and realistic reproduction of hand movements. It should also be noted that the technologies used in VR hardware are constantly being developed and upgraded. Through the use of more modern displays, better mounts, and more accurate controllers, they have the potential to improve the user experience while reducing the impact of cybersickness.

3.2. Game Evaluation by Medical Experts

The process of planning the course of rehabilitation with VR was carried out with the active consultation of medical experts (physiotherapists, neurological physicians, and group therapists). The game was created iteratively, by making corrections and suggestions indicated by them. The final result, as described above, was assessed by the physiotherapists. They tested the application and concluded that it transferred the movement patterns and therapeutic assumptions of conventional rehabilitation to VR. Moreover, they appreciated the interesting environment and the level of immersion, which enhanced the attractiveness of the application. The physiotherapists additionally found the game simple enough, relative to the patients’ potential abilities. All these elements and their experience allowed them to conclude that the application satisfactorily fulfills the premise of rehabilitation and therefore is suitable for conducting research with individuals.

3.3. Studies Involving Post-Stroke Individuals

The created application was subjected to preliminary testing. This study took place under the supervision of a qualified occupational therapist, who qualified the patients for this study, supervised their progress, and qualitatively assessed the patients’ progress. This study involved five post-stroke patients between the ages of 59 and 72 residing in a long-term care facility (Table 1). Therapy using the created app was applied for 5 days a week for 10 min each for 4 weeks.

3.3.1. Cybersickness Incidents

Three patients tolerated the therapy very well. Two patients experienced dizziness during the therapy. According to studies, the duration of exposure to VR experiences can increase discomfort in a proportional way [54]; therefore, the first step was to reduce the duration of therapy. In one patient, shortening the time eliminated the cybersickness symptoms he was experiencing, so the patient continued therapy. The other patient continued to experience dizziness and nausea after the reduction in therapy time, which was the reason for discontinuing therapy.

3.3.2. Study Results and Further Development

After completing therapy, the four patients noticed an increased muscle strength, faster response, or smoother limb movement. While observing the course of rehabilitation using VR, physiotherapists noticed patients’ increased range of motion compared to exercising during conventional rehabilitation. Examples of such movement included reaching farther into space, with greater body leaning or with greater extension of the upper limb. Physiotherapists explained this fact by the high level of involvement, as well as the high level of immersion (patients were not fully aware of how far they were reaching while they had a sense of purpose). In addition, group therapists assessed that the movement pattern performed by patients during exercise was similar to that performed during traditional rehabilitation.
Although this preliminary study is promising, studies on a larger group of participants should be performed to confirm the effectiveness of the presented approach for the rehabilitation of patients suffering from USN syndrome. In future studies, special attention should be paid to comparing with objective indicators the research group (using virtual reality during rehabilitation) and the control group (rehabilitating with traditional rehabilitation only). These indicators could be line bisection tests and cancellation tests [33], which are based on drawing or crossing out items placed on two parts of a piece of paper. The use of such indicators would make it possible to compare the study group and the control group. This would make it possible to assess the effectiveness of VR-based therapy relative to traditional therapy. In addition, the use of statistics from the game, i.e., the number of correctly completed exercises per therapy series, could allow for an ongoing evaluation of therapy progress.
Study [55] on the impact of immersive post-stroke rehabilitation showed that repetitive functional exercises increase neuroplastic activation and thus reduce motor impairment, which is potentially promising for the app described in the article. In addition, fully immersive VR shows beneficial effects on motor recovery, function, and quality of life for post-stroke patients, providing a basis for the development of rehabilitation apps toward increasing their immersiveness. The virtual reality application show significant improvement in patients with neglect and therefore helps in everyday activities, which is the aim of the therapy [34]. Similar effects are shown in the study of Fordell and others [35]. The studies of Ekman and others [56] show that using virtual reality changes the brain and improves strategic processes in patients with neglect. Another study of Wåhlin and others [57] shows that using virtual reality improved left-sided awareness, which is the most important aspect of rehabilitation. This eliminates the biggest problem and therefore improves the quality of life, which is the aim of the created application. The results of the studies mentioned above, in which they tested the effectiveness of using low-impact virtual reality, provide the basis that the use of VR technology in the rehabilitation of USN syndrome is effective. At the same time, the solution presented in this article is the next step in the development of this type of rehabilitation.

4. Conclusions

This article presents a new tool for the rehabilitation of post-stroke patients with unilateral neglect syndrome. During the development and testing of this tool, the following aspects were considered.
Traditional methods of rehabilitation were analyzed, which allowed for the development of an application that fulfills the principles of rehabilitation. VR-based rehabilitation involves the patient. It was based on visual scanning training with motor function training. Different levels of difficulty have also been implemented, which enables the personalization of the application.
A feasibility analysis was performed, including the risks of using VR technology. The identification of risks made it possible to minimize them by using a high refresh rate, ensuring smooth and realistic hand movements, and using optimal methods for rendering graphic elements.
The advantage of the created application as a new rehabilitation tool is that it increases the attractiveness of rehabilitation, which is crucial as it affects the patient’s motivation to exercise. In addition, the use of the VR app allows rehabilitation without the full involvement of a physical therapist to conduct therapy, which not only allows several patients to be rehabilitated at the same time but also enhances access to rehabilitation at home.
Tests of the app have been conducted with a small group of patients. They indicate the possibility of using the created application in the rehabilitation of some stroke patients. They also made it possible to indicate the necessity of the individual adjustment of the VR therapy time, depending on the presence of cybersickness symptoms.
Despite the first positive results, it would be necessary to conduct more extensive research to widely use the created application. In future studies, the patient group should be expanded. Objective techniques must also be used to evaluate the patient’s condition before and after virtual reality therapy. It could also be valuable to compare three groups of patients: a first group, in which patients use only virtual reality during rehabilitation; a second group, in which patients perform both traditional and virtual therapy; and a third group, in which only traditional therapy is used. A comparison of the three groups could undoubtedly show whether virtual reality therapy has better or the same effects compared to traditional therapy.
The article presented indicates a new possibility for the rehabilitation of post-stroke patients. It isolates the most important requirements and possible risks when using VR technology. Further research is necessary and in the future may lead to the introduction of virtual reality into the standard of therapy for post-stroke patients.

Author Contributions

K.M.-P.: Conceptualization, Methodology, Writing—Original Draft, Software, Validation, and Investigation; K.P.: Methodology, Writing—Original Draft, Software, and Validation; P.M.: Conceptualization, Methodology, and Writing—Review and Editing; A.S.-M.: Investigation, Writing—Review and Editing, and Supervision. All authors have read and agreed to the published version of this manuscript.

Funding

The research leading to these results received funding from the State Fund For Rehabilitation Of Disabled People under Grant Agreement No. BEA/000064/BF/D.

Institutional Review Board Statement

This study and all procedures were approved by the Warsaw University of Technology Ethics of Research with Human Subject Team (protocol code 1/2023 and date of approval 22 February 2023) for studies involving humans.

Informed Consent Statement

Informed consent was obtained from all subjects involved in this study.

Data Availability Statement

Publicly available datasets were analyzed in this study. This data can be found here: https://powerstudpw.itch.io/colors-game-for-stroke-rehabilitation.

Acknowledgments

The authors would like to thank all the participants who took part in this study and Łukasz Wieczorkowski and Kazimiera Grzywacz for their assistance with the patients.

Conflicts of Interest

The authors declare that they have no conflicts of interest.

Abbreviations

The following abbreviations are used in this manuscript:
USNUnilateral spatial neglect
VRVirtual reality
HMDHead-mounted device
FOVField of view
FPSFrames per second

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Figure 1. Rehabilitation principle for neglecting the left side.
Figure 1. Rehabilitation principle for neglecting the left side.
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Figure 2. Rehabilitation principle for neglecting the left side.
Figure 2. Rehabilitation principle for neglecting the left side.
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Figure 3. VR application: (a) choosing side, (b) objects in different colors, (c) target boxes, (d) game statistics.
Figure 3. VR application: (a) choosing side, (b) objects in different colors, (c) target boxes, (d) game statistics.
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Table 1. Summary of patients receiving therapy using the created application.
Table 1. Summary of patients receiving therapy using the created application.
AgeDisease UnitDaily Therapy TimeNumber of Therapy DaysSide EffectsPatient Comments
Patient 159ischemic stroke10 min20nonepatient notices increased muscle strength
Patient 264ischemic stroke10 min20nonepatient notices a faster response and smoother movement
Patient 364ischemic stroke10 min20nonepatient notices a faster response
Patient 472ischemic stroke10 min/5 min3 1/17 2dizziness, which resolved after reducing the daily treatment timepatient notices smoother movement
Patient 568ischemic stroke10 min/5 min2 1/3 2dizziness and nausea, which did not subside when the daily therapy time was reduced, leading to the discontinuation of therapyn/a
1 Number of therapy days with a daily therapy time of 10 min. 2 Number of therapy days with a daily therapy time of 5 min.
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Matys-Popielska, K.; Popielski, K.; Matys, P.; Sibilska-Mroziewicz, A. Immersive Virtual Reality Application for Rehabilitation in Unilateral Spatial Neglect: A Promising New Frontier in Post-Stroke Rehabilitation. Appl. Sci. 2024, 14, 425. https://doi.org/10.3390/app14010425

AMA Style

Matys-Popielska K, Popielski K, Matys P, Sibilska-Mroziewicz A. Immersive Virtual Reality Application for Rehabilitation in Unilateral Spatial Neglect: A Promising New Frontier in Post-Stroke Rehabilitation. Applied Sciences. 2024; 14(1):425. https://doi.org/10.3390/app14010425

Chicago/Turabian Style

Matys-Popielska, Katarzyna, Krzysztof Popielski, Paulina Matys, and Anna Sibilska-Mroziewicz. 2024. "Immersive Virtual Reality Application for Rehabilitation in Unilateral Spatial Neglect: A Promising New Frontier in Post-Stroke Rehabilitation" Applied Sciences 14, no. 1: 425. https://doi.org/10.3390/app14010425

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