A Comparative Analysis of 2D and 3D Tasks for Virtual Reality Therapies Based on Robotic-Assisted Neurorehabilitation for Post-stroke Patients

You'll have to see what this means to your doctor and your stroke rehab. No knowledge of this by your doctor means they should be fired. They should have already known about this research in its starting stages, not just waiting for you to ask about it. Lots of research being referred to which your doctor should be up-to-date on.
http://journal.frontiersin.org/article/10.3389/fnagi.2016.00205/full?

Luis D. Lledó^*, Jorge A. Díez, Arturo Bertomeu-Motos, Santiago Ezquerro, Francisco J. Badesa, José M. Sabater-Navarro and Nicolás García-Aracil

• Biomedical Neuroengineering Group, Miguel Hernández University of Elche, Elche, Spain

Post-stroke neurorehabilitation based on virtual therapies are performed completing repetitive exercises shown in visual electronic devices, whose content represents imaginary or daily life tasks. Currently, there are two ways of visualization of these task. 3D virtual environments are used to get a three dimensional space that represents the real world with a high level of detail, whose realism is determinated by the resolucion and fidelity of the objects of the task. Furthermore, 2D virtual environments are used to represent the tasks with a low degree of realism using techniques of bidimensional graphics. However, the type of visualization can influence the quality of perception of the task, affecting the patient's sensorimotor performance. The purpose of this paper was to evaluate if there were differences in patterns of kinematic movements when post-stroke patients performed a reach task viewing a virtual therapeutic game with two different type of visualization of virtual environment: 2D and 3D. Nine post-stroke patients have participated in the study receiving a virtual therapy assisted by PUPArm rehabilitation robot. Horizontal movements of the upper limb were performed to complete the aim of the tasks, which consist in reaching peripheral or perspective targets depending on the virtual environment shown. Various parameter types such as the maximum speed, reaction time, path length, or initial movement are analyzed from the data acquired objectively by the robotic device to evaluate the influence of the task visualization. At the end of the study, a usability survey was provided to each patient to analysis his/her satisfaction level. For all patients, the movement trajectories were enhanced when they completed the therapy. This fact suggests that patient's motor recovery was increased. Despite of the similarity in majority of the kinematic parameters, differences in reaction time and path length were higher using the 3D task. Regarding the success rates were very similar. In conclusion, the using of 2D environments in virtual therapy may be a more appropriate and comfortable way to perform tasks for upper limb rehabilitation of post-stroke patients, in terms of accuracy in order to effectuate optimal kinematic trajectories.

1. Introduction

Virtual Reality (VR) is a technology platform that allows developing computer generated environments which the subjects can explore and interact with any type of object or events to perform perspectives and motor tasks. VR gives an accurate way to control all the elements of a scene and the objectives, adjusting each task to a specific user. The main feature that the VR provides is the possibility of repeating the same task in any moment, modifying factors such as level of complexity, time and intensity of the practice. In this way, the virtual therapy may be used to promote motor learning and rehabilitation due to the VR can be adjusted to generate environment, scenario, or activity that allows for the user practice motor skills to improve the experience-dependent neural plasticity (Doyon and Benali, 2005). The possibility of modifying factors such as the repetition, intensity, time, and specificity of the activities of the virtual therapies is beneficial for this type of neural recovery (Kleim and Jones, 2008). In recent years, some scientific and clinical trials have demonstrated the effectiveness of VR as an intervention tool for the rehabilitation of different injuries with specific neurological conditions (Burdea, 2002; Crosbie et al., 2007). However, a control device to interact with virtual activities is required, depending of the limb affected by the disease. There is a wide panorama on rehabilitation systems for upper limb that use robotic technology including virtual reality visualization (Maciejasz et al., 2014). In some studies, repetitive movements guiaded by robotic devices and directed by virtual reality improve the motor control in patients with upper limb injuries (Merians et al., 2006). Beside this, there are some clinical studies about the development of VR systems to deliver rehabilitation therapies for motor recovery of hand function (Jack et al., 2001) or to improve the performance of activities of daily living in post-stroke patients (Laver et al., 2012; Turolla et al., 2013). Furthermore, a navigation environment in three dimensions (3D) has been implemented to explore the influence on aging in the episodic memory (Jebara et al., 2014). In Fluet and Deutsch (2013), an overview of virtual reality studies for sensorimotor rehabilitation post-stroke has been performed to evaluate a comparative efficacy between VR and standard of care and/or differences in VR delivery methods, using different categories.

Several studies suggest that the robotic technology can be used to improve the quality and the evaluation in the neurological rehabilitation (Garcia et al., 2011), enhancing the productivity and reducing costs in that field. Recent developments in robotic technology can help to perform a most objective and reliable analysis of the therapies that are applied to the patients with neurological injuries (Badesa et al., 2012, 2014a,c). That is because this type of devices are able to record kinematic and kinetic data. From this data, useful markers can be extracted to quantify the motor recovery process during the therapy (Volpe et al., 2009; Einav et al., 2011; Bertomeu-Motos et al., 2015; Papaleo et al., 2015). Recently in Norouzi-Gheidari et al. (2012), it is shown that the rehabilitation sessions performed with the robotic device get better recovery outcomes than the conventional therapy during the rehabilitation of the upper limb of stroke patients. For these reasons, the rehabilitation with robotic devices can provide an enhancement in the quality of patient's life, giving them most independence in the daily life activities (Pollock et al., 2014).

The use of more complex and realistic VR systems in the neurorehabilitation therapies assisted by robotic device is increasing. The combination of robotic systems for neuromotor rehabilitation and virtual reality takes advantages of both techniques such as: to increase the patient's motivation; to enhance the variability and adaptability; transparent storage of the data provided by the robotic system and the VR system separately; online recording of the data for remote verification; possibility to replicate any environment of the daily life without having the physical. With this methodology, a more effective therapeutic treatment and a better recovery of the patient is accomplished (González et al., 2015).

There are a two important issues concerning the virtual reality: one is related to how the virtual environment may be perceived by the user using different visualization platforms, and the other one is related to graphic content. Regarding the first appointment, different visualization platforms exist such as computer monitors, head-mounted-displays (HMDs) or large screen-projection-systems (SPS). Each platform has a particular way to apply the virtual therapies taking into account therapeutic goals and may provide different benefits that are suitable for the patient's needs. In Rand et al. (2005), the effects of viewing the same virtual environment through a HMD (3D platform) and a computer monitor (2D platform) have been compared in young and older subjects. Conversely, a 3D virtual enviroment shown through a HMD and a SPS (2D platform) have been analyzed by Subramanian and Levin (2011), evaluating the motor performance with respect to the kinematic movements in healthy and post-stroke subjects. In both studies, better outcomes have been obtained when the virtual environment was shown in the 2D platform visualization, in a computer monitor and a SPS respectively. However, this studies have focused in the visualization platform and the same environments have been presented respectively in the experiments without taking account the type of graphic content that are shown (2D or 3D graphics).

Regarding the second issue appointed above about the graphic content, there are studies about VR systems with environments based on 2D graphics and others in 3D graphics. In García-Betances et al. (2015) an overview of recent VR technology for Alzheimer's disease applications has performed, and these systems use conventional 2D graphics display or 3D graphics indistinctly. Similarly occurs with the brain damage rehabilitation in Rose et al. (2005), post-stroke studies such as Merians et al. (2006), Saposnik (2016), Henderson et al. (2007), Mottura et al. (2015). Therefore, there is a wide panorama on virtual rehabilitation in the scientific literature. However, an objective comparison about how affects the visualization of 2D graphics display and 3D virtual environment to the motion perception in post-stroke subjects have not been addressed yet. That means, there is no evidence that shows if it is better or not to perform virtual rehabilitation tasks produced by 2D or 3D graphics. The visual perception of the virtual objects can be incremented using 3D graphics, in such a way that tasks based in the daily life designs are more similar to the reality. While a 2D graphics allow a more simple representation of the tasks. The two perspectives must be tested to evaluate what kind of visual representation provides better quality of motor performance in terms of movement kinematics. This evaluation can be carried out when the subject performs the same movement to complete the targets in both types of visualization. Therefore, the robotic devices can be used to restrict this movement and extract objectively quantitative data. This way, the neuro-rehabilitation therapies can be adapted to each patient (Morales et al., 2014; Lledó et al., 2015a).

In this study, the effects of applying therapeutic games in two or three dimensions in the virtual therapies assisted by a robotic device are evaluated and their outcomes are compared. In this way, quantitative data is provided to evaluate the influence of the virtual therapy and to asses what kind of virtual environment is adjusted better to each patient in terms of usability, confidence, and comfort. Therefore, the main objective of this study was to determine if there are differences in the movement kinematics parameters recorded by the robotic device that assess the patient's motor performance in 2D and 3D virtual tasks. To do this, two visual tasks have been designed modifying the immersion level using graphics in two and three dimensions, but the kinematic target of the two visual tasks was remained.

More at link.