| 1.BACKGROUNDWith rapidly increasing prevalence rates in the past few years, stroke has become one of the most common diseases for the elderly in China. The occurrence of stroke usually brings serious problems as high morbidity and mortality rates, which worsens the ultimate outcome of the post—troke patients. The mechanisms of stroke accidents are mainly associated with cerebral artery stenosis, thrombosis, blockage or rupture of blood vessels. The acute stress of cerebral circulation disorder thus leads to a transient or permanent damage to the brain and central nervous system, followed by a series of functional disabilities including paralysis, aphasia, agnosia, bowel and bladder dysfunction and even death. Previous studies have shown that more than50%of stroke patients have varied degrees of post—stroke sequelae of physical dysfunction, which undoubtedly undermine their quality of life, and result in a heavy burden for their family and the whole society.Brain plasticity is the core underlying mechanism for post—stroke functional recovery and rehabilitation. There are a large number of synapses in the human central nervous system, but few synapses are activated for use. Within the few weeks to months after stroke accident, structural remodeling and functional adjustment will take place in the cerebral cortex. This kind of remodeling has been reported to have emerged early soon after the onset of stroke. Therefore,early initiation of rehabilitation program for stroke patients such as limb motor functional training has a crucial positive and far—reaching impact on the reshaping of central nervous system, providing a better functional restoration outcome for the patients.Hemiplegic gait is one of the main sequelae post stroke. The typical hemiplegic gait is a "circle—like" pattern. Stroke patients are often associated with increased muscle tone in abductors and extensors in the lower limb, but weakness in ankle dorsiflexors. The imbalance of muscle function leads to decreased knee flexion, limited ankle dorsiflexion, foot varus or drop foot, which results in a longer limb in the affected side than the unaffected one and contributes to the formation of "circle—like" gait. This type of pathological gait is characterized as gait asymmetry, higher energy exertion and instability. The restoration of walking ability in stroke patients is the key to improve their self—care function and quality of life.Holden et al.firstly introduced virtual reality (VR) training for post—stroke rehabilitation. It has been demonstrated that patients guided by "virtual teacher" showed significant improvement in the progress of physical rehabilitation.Virtual Reality (VR) technology has three important features namely motivation maintenance, repetitive training and information feedback during training for stroke patients. With this technology, interaction and feedback in visual, tactile, auditory and even sports can be achieved, such that patients are able to engage in controlled motor training and experience different activities in a virtual environment, thereby facilitating the ultimate goal of functional rehabilitation. VR is also capable to provide real—time feedbacks to stroke patients for each training exercise, which will help improve their awareness of the current outcomes and establish a more preferred result in the next round of trial. Instead of repetitive and boring training exercises in the traditional way of rehabilitation, virtual reality technology aims to entertain the patients with live scenes and interesting training programs in the form of virtual games. Varieties of games are designed to meet the needs of patients in different ages. For example, household scene with a kitchen and vegetables is for housewives patients. Moreover, popular games in the youngsters such as Aircraft Hitting or Fish Eating are also included in the VR training mode.Blending treatment into games, these games allow patients to receive training in a relaxed atmosphere. The live scenes and animation in the virtual reality stimulate patients’ interest and attention to participate in the training. And the immediate feedback of the games strengthens the awareness of engagement and the desire of progression.In short, the main characteristics of VR technology include the following:①real scene, rich content:Simulation is the most important technology for VR. Especially combined with3"Dimension animation, VR can simulate a virtual game scene that is almost similar to real—life environment, providing real information feedback that far outweighs the ordinary game.②image of clarity, colors of varieties:different varieties of colors can effectively stimulate the nervous system by vision, which attracts the patients’ attention during training.③purposeful, incentive and interesting:The game—irected training mode encourages the patients to participate in the training with a clear purpose and task—oriented approach as in a athletic competition. There is a corresponding reward prompt after completion of each task, which prompts the patients to redouble their efforts to continue. However, they fail to achieve the target, virtual feedback and punishment will be given. In this way, patients have an incentive and interest to engage, as well as a sense of achievement thus are willing to continue training in order to achieve better results.④game diversity, moderate difficulty coefficient:The modes of game and difficulty level are set depending on the levels of the individual’s functional limitations and it can be gradually modified according to their functional improvement progress. The adjustments avoid a single mode of game, and make patients more concentrated in training.⑤comfortable, relaxed environment:Music can soothe the individual’s emotions. The game combines music, animations, sounds, language tips and other techniques so as to provide patients with a comfortable and relaxed environment, which makes it one of the means for psychotherapy.In terms of the research on walking difficulty, gait analysis provides a way to study different walking patterns. Through biomechanics and kinematics, gait analysis investigates the environment and key factors associated with the abnormal gait, which thus guides physical assessment and treatment in clinical practice, and also facilitates clinical diagnosis, efficacy evaluation and research on mechanisms of action.A review of previous literature has revealed that evidence is still lacking to demonstrate the efficacy of virtual reality training on specific post—troke hemiplegic gait via precise gait analysis system.2.PURPOSEStroke is prone to induce abnormal postural control, causing walking difficulty and gait dysfunction. Previous research has suggested that virtual reality technology provide meaningful task—riented training and precise sensory feedback. The present study aims to establish a virtual reality system that induces postural control reaction, so as to stimulate awareness of postural adjustment in stroke patients’. By using gait analysis system, this study would also like to investigate the effect of VR technology on the gait pattern of patients after stroke.3.METHODS3.1ParticipantsWith their written consent, thirty participants (n=30) were recruited from the post—troke patients with hemiplegia enrolled in the Department of Rehabilitation Medicine, Zhujiang Hospital of Southern Medical University from May to November,2013. Among the30participants, there were17males and13females;17cases were right—ided hemiparesis and13cases left—ided affected.The inclusion criteria and exclusion criteria are as follows.Inclusion criteria:a. Participants met the criteria listed in the act of "Diagnostic Criteria for all types of Cerebrovascular Disease" approved by the Fourth Conference on Cerebrovascular Disease of the Chinese Medical Association,1995;b. Participants had confirmatory clinical diagnosis of cerebral infarction or hemorrhage with CT or MR evidence; andc. Participants had fulfilled the following:①stable vital signs;②first onset and duration<8months;③presence of hemiplegic gait;④without severe cognitive dysfunction and mental illness;⑤lower extremity function: Brunnstrom phase Ⅱ or above, Modified Ashworth level Ⅱ or below;⑥walking independently or with crutches over12meters.Exclusion criteria:①unstable medical condition;②severe speech and cognitive dysfunction;③walking dysfunction caused by cerebellum, spinal cord, peripheral neuropathy or traumatic brain injury;④lower limb fractures and other musculoskeletal disorders or nerve lesions that affect the functional recovery of lower extremity;⑤walking dysfunction left because of a past history of diseases in brain tissue or the nervous system.All participants recruited were then randomly allocated into two groups, namely experimental group (n=15) and control group (n=15). Two groups were given basic medication plus conventional rehabilitation therapy, and the experimental group was added with virtual reality therapy. The baseline data between the two groups were comparable. There were no significant differences in age, gender, and height between the two groups (P>0.05). No statistical differences were found in terms of the nature of intracranial lesions (infarct or hemorrhage), duration of time (weeks), and the the lower extremity dysfunction index between the experimental group and the control group (P>0.05)3.2Intervention AllocationThe two groups of participants received baseline medication targeted at the nervous system.Control group:Routine rehabilitation protocol including muscle strength and endurance training by the physiotherapists, parallel bars walking, walking training with walker or crutches. Duration:30minutes/time, once per day,6days a week for two weeks.Experimental groups:Routine rehabilitation protocol as illustrated in the control group except for the traditional walking training, plus VR treatment. The affected lower extremity was put on with sensors. A computer with36inches monitor screen was placed in front of each participant, with a series of simulated scenes such as fruit cognition, basic tools in daily life, feeding frenzy (Fish eating), flight simulation and walks through the forest and so on. Through these live scenes in the virtual games, strengthening and endurance training were completed. Walking exercise was trained by forest stepping game scene. Duration: 45minutes/time, once per day,6days a week for two weeks.3.3Outcome measuresGait Watch (Guangzhou Chapter Electrical Equipment Co., Ltd) was employed for three dimensional gait analysis. The procedure of data collection was as follows. Firstly, seven sensors were fixed on different body regions of the participants including sacral, front thigh, medial calf and dorsum of the foot with relatively flat surfaces. The special sensor contains inertial measurement modules such ad gyroscopes and accelerometers, and embedded microprocessor DSP data acquisition and processing module. In order to ensure the precision of data acquisition, the sensor must be firmly bound to the participant who was required to walk straight for at least12meters in a quiet environment without other interferences. Then, the sampling frequency of the system was adjusted to500Hz. The real—time walking information of each participant was acquired and recorded synchronously. With the motor information of pelvis, hip, knee and ankle in three planes (vertical, horizontal and frontal), the virtual gait of the participants could be restored. These data were immediately transferred to the computerized system to analyze specific spatial and temporal parameters of each gait.Outcome measures:The parameters of walking time, walking space and the phases of walking as well as the range of motion of the affected lower limb were recorded. The asymmetry index of the hemiplegic gait and the ratio of stance time between the affected and unaffected limb were calculated for statistical comparison and analysis.3.4Statistical analysisSPSS13.0was employed for statistical analysis. Measurement data were expressed as mean±standard deviation. Between—group comparison was conducted using independent sample t test and paired t test was used to compare the differences within the two groups. Significance level was set at0.05.4.RESULTSIt was found that the experimental group with VR training showed significantly increased walking pace, cadence and stride length and narrowed step width after2weeks of treatment(P<0.05). The walking cycle and proportion of double—leg stance phase was significantly shortened (P<0.05), while the proportions of swing phase for both affected and unaffected leg were elevated.The ratio of unaffected side stance phase over the affected one was significantly reduced (P<0.05). There was a remarkably decrease in the gait asymmetry index after2weeks of VR training (P<0.05)Furthermore, the maximal ROM of hip extension and knee flexion of the affected side in participants of the experimental group were significantly improved (P<0.05) after the VR training.5.CONCLUSIONThe present study has showed that rehabilitation program via VR technology improved the spatial and temporal parameters of gait as well as the range of motion during the gait for stroke patients, which thus has a positive therapeutic impact on gait stability, walking ability and the whole physical rehabilitation.The reason why participants engaged in rehabilitation treatment in the virtual simulated environment is superior to traditional rehabilitation protocol in improving walking capacity, is that VR can bring real sensory feedback and in turn enhance plasticity of the cerebral cortex. VR involves training exercise of interest and task—oriented, instead of the tedious, repetitive training mode, which contributes to a more incentive and motivated approach for the patients to actively participate in the training, finally resulting in a better return to their family and the society.In conclusion, VR technology combined with conventional rehabilitation therapy promotes more appreciated outcomes in the ability of walking and self—care activities in daily life for patients after stroke. |
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