Youn Joo Kang

A Virtual Reality System for the Assessment and Rehabilitation of the Activities of Daily Living

Successful rehabilitation with respect to the activities of daily living (ADL) requires accurate and effective assessment and training. A number of studies have emphasized the requirement for rehabilitation methods that are both relevant to the patients real world environment, and that can also be transferred to other daily living tasks. Virtual reality (VR) has many advantages over other ADL rehabilitation techniques, and offers the potential to develop a human performance testing and training environment. Therefore, in this study, the virtual supermarket was developed and the possibility of using a VR system to assess and train cognitive ability in ADL investigated. This study demonstrates that VR technology offers great promise in the field of ADL training.

Development and clinical trial of virtual reality-based cognitive assessment in people with stroke: preliminary study.

Stroke and traumatic brain injury affect an increasing number of people, many of whom retain permanent damage in cognitive functions. Conventionally, cognitive function has been assessed by a paper-based neuropsychological evaluation. However these test environments differ substantially from everyday life. This problem can be overcome by using virtual reality (VR) to objectively evaluate behaviors and cognitive function in simulated daily activities. With our virtual shopping simulation, we compared people who had undergone a stroke with control participants in an immersive VR program that used a head-mounted display (HMD). We evaluated user satisfaction with the tests, complications, and the user interface. Significant differences were consistently found between the stroke group and the control group for the following tasks: stage 1 performance index, interaction error; stage 2 delayed recognition memory score, attention index; and stage 3 executive index (p < 0.001). Perceptive dysfunction, visuospatial dysfunction, level of computer experience, and level of education affected the performance of the stroke group. The frequency of complications in the stroke group, calculated using the cut-off score for the Simulator Sickness Questionnaire, was 9.6% for nausea, 41.9% for oculomotor complications, and 25.8% for disorientation. The frequency of complications between the stroke and control groups was not significantly different. Thirty-five percent of participants in the stroke group and 13% in the control group reported difficulties with using the joystick. This computer-generated VR-based cognitive test shows promise in assessing cognitive function in patients with stroke. More refinements are needed in the user interface and the projection methods.

Development of virtual reality proprioceptive rehabilitation system for stroke patients

In this study, the virtual reality (VR) proprioception rehabilitation system was developed for stroke patients to use proprioception feedback in upper limb rehabilitation by blocking visual feedback. To evaluate its therapeutic effect, 10 stroke patients (onset>3 month) trained proprioception feedback rehabilitation for one week and visual feedback rehabilitation for another week in random order. Proprioception functions were checked before, a week after, and at the end of training. The results show the click count, error distance and total error distance among proprioception evaluation factors were significantly reduced after proprioception feedback training compared to visual feedback training (respectively, p=0.005, p=0.001, and p=0.007). In addition, subjects were significantly improved in conventional behavioral tests after training. In conclusion, we showed the effectiveness and possible use of the VR to recover the proprioception of stroke patients.

Facilitation of Corticospinal Excitability According to Motor Imagery and Mirror Therapy in Healthy Subjects and Stroke Patients

Objective To delineate the changes in corticospinal excitability when individuals are asked to exercise their hand using observation, motor imagery, voluntary exercise, and exercise with a mirror. Method The participants consisted of 30 healthy subjects and 30 stroke patients. In healthy subjects, the amplitudes and latencies of motor evoked potential (MEP) were obtained using seven conditions: (A) rest; (B) imagery; (C) observation and imagery of the hand activity of other individuals; (D) observation and imagery of own ipsilateral hand activity; (E) observation and imagery of the hand activity of another individual with a mirror; (F) observation and imagery of own symmetric ipsilateral hand activity (thumb abduction) with a mirror; and (G) observation and imagery of own asymmetric ipsilateral hand activity (little finger abduction) with a mirror. In stroke patients, MEPs were obtained in the A, C, D, E, F conditions. Results In both groups, increment of the percentage MEP amplitude (at rest) and latency decrement of MEPs were significantly higher during the observation of the activity of the hand of another individual with a mirror and during symmetric ipsilateral hand activity on their own hand with a mirror than they were without a mirror. In healthy subjects, the increment of percentage MEP amplitude and latency decrement were significantly higher during the observation of the symmetric ipsilateral hand activity with a mirror compared to the observation of the activity of the asymmetric ipsilateral hand with a mirror of their own hand. Conclusion In both groups, corticospinal excitability was facilitated by viewing the mirror image of the activity of the ipsilateral hand. These findings provide neurophysiological evidence supporting the application of various mirror imagery programs during stroke rehabilitation.

Validity and Reliability of Cognitive Assessment Using Virtual Environment Technology in Patients with Stroke

Ku J, Lee JH, Han K, Kim SI, Kang YJ, Park ES: Validity and reliability of cognitive assessment using virtual environment technology in patients with stroke. Objectives: We assessed the validity and reliability of a virtual environment technology (VET)-based cognitive assessment program that was developed as a measurement tool of cognitive abilities in patients after a stroke. Design: Twenty participants diagnosed with stroke caused by unilateral brain lesions were enrolled to assess the VET programs validity and test-retest reliability. Participants underwent evaluation by paper-based neuropsychological tests including the Korean Mini-Mental Status Examination, the Korean-Wechsler Adult Intelligence Scale, the Motor Free Visual Perception Test, Rey-Kim Memory Test, and Kims Frontal-Executive Neuropsychologic Test as well as the VET-based cognitive assessment. Major variables and indices of the VET program were calculated. The VET program validity was evaluated using a simple correlation analysis between variables from the VET program and conventional paper-based neuropsychological measurements, and the reliability was evaluated by investigating the test-retest correlation coefficients. Results: Major variables and indices of the VET program in patients with stroke correlated significantly with the related scores of paper-based neuropsychological tests. In addition, the test-retest reliability analysis revealed that the correlation coefficients ranged from 0.528 to 0.926. Conclusion: The VET-based cognitive assessment program showed adequate reliability and validity as a method of cognitive assessment in patients after stroke.

Utility of a Three-Dimensional Interactive Augmented Reality Program for Balance and Mobility Rehabilitation in the Elderly: A Feasibility Study

Objective To improve lower extremity function and balance in elderly persons, we developed a novel, three-dimensional interactive augmented reality system (3D ARS). In this feasibility study, we assessed clinical and kinematic improvements, user participation, and the side effects of our system. Methods Eighteen participants (age, 56-76 years) capable of walking independently and standing on one leg were recruited. The participants received 3D ARS training during 10 sessions (30-minute duration each) for 4 weeks. Berg Balance Scale (BBS) and the Timed Up and Go (TUG) scores were obtained before and after the exercises. Outcome performance variables, including response time and success rate, and kinematic variables, such as hip and knee joint angle, were evaluated after each session. Results Participants exhibited significant clinical improvements in lower extremity balance and mobility following the intervention, as shown by improved BBS and TUG scores (p<0.001). Consistent kinematic improvements in the maximum joint angles of the hip and knee were observed across sessions. Outcome performance variables, such as success rate and response time, improved gradually across sessions, for each exercise. The level of participant interest also increased across sessions (p<0.001). All participants completed the program without experiencing any adverse effects. Conclusion Substantial clinical and kinematic improvements were observed after applying a novel 3D ARS training program, suggesting that this system can enhance lower extremity function and facilitate assessments of lower extremity kinematic capacity.

Virtual Reality-Guided Motor Imagery Increases Corticomotor Excitability in Healthy Volunteers and Stroke Patients

Objective To investigate the effects of using motor imagery (MI) in combination with a virtual reality (VR) program on healthy volunteers and stroke patients. In addition, this study investigated whether task variability within the VR-guided MI programs would influence corticomotor excitability. Methods The present study included 15 stroke patients and 15 healthy right-handed volunteers who were presented with four different conditions in a random order: rest, MI alone, VR-guided MI, and VR-guided MI with task variability. The corticomotor excitability of each participant was assessed before, during, and after each condition by measuring changes in the various parameters of motor-evoked potentials (MEPs) of the extensor carpi radials (ECR). Changes in intracortical inhibition (ICI) and intracortical facilitation (ICF) were calculated after each condition as percentages of inhibition (%INH) and facilitation (%FAC) at rest. Results In both groups, the increases in MEP amplitudes were greater during the two VR-guided MI conditions than during MI alone. Additionally, the reductions in ECR %INH in both groups were greater under the condition involving VR-guided MI with task variability than under that involving VR-guided MI with regular interval. Conclusion The corticomotor excitability elicited by MI using a VR avatar representation was greater than that elicited by MI with real body observations. Furthermore, the use of task variability in a VR program may enhance neural regeneration after stroke by reducing ICI. The present findings support the use of various VR programs as well as the concept of combining MI with VR programs for neurorehabilitation.

Effect of Proprioception Training of patient with Hemiplegia by Manipulating Visual Feedback using Virtual Reality: The Preliminary results

In this study, we confirmed proprioception training effect of patients with hemiplegia by manipulating visual feedback. Six patients with hemiplegia were participated in the experiment. Patients have trained with the reaching task with visual feedback without visual feedback for two weeks. Patients were evaluated with pre-, middle test and post-test with the task with and without visual feedback. In the results, the first-click error distance after the training of the reaching task was reduced when they got the training with the task removed visual feedback. In addition, the performance velocity profile of reaching movement formed an inverse U shape after the training. In conclusion, visual feedback manipulation using virtual reality could provide a tool for training reaching movement by enforcing to use their proprioception, which enhances reaching movement skills for patients with hemiplegia.

Suppression of human arthritis synovial fibroblasts inflammation using dexamethasone-carbon nanotubes via increasing caveolin-dependent endocytosis and recovering mitochondrial membrane potential

Dexamethasone (DEX), a non-particulate glucocorticoid (GC) to inhibit anti-inflammatory response, has been widely used for the treatment of various diseases such as arthritis, cancer, asthma, chronic obstructive pulmonary disease, cerebral edema, and multiple sclerosis. However, prolonged and/or high-dose GC therapy can cause various serious adverse effects (adrenal insufficiency, hyperglycemia, Cushing’s syndrome, osteoporosis, Charcot arthropathy, etc). In this study, developed DEX-carbon nanotube (CNT) conjugates improved intracellular drug delivery via increased caveolin-dependent endocytosis and ultimately suppressed the expression of major pro-inflammatory cytokines in tumor necrosis factor-α (TNF-α)-stimulated human fibroblast-like synoviocytes (FLS) at low drug concentrations. Specifically, DEX on polyethylene-glycol (PEG)-coated CNTs induced caveolin uptake, recovered mitochondrial disruption, and inhibited reactive oxygen species production by targeting mitochondria that was released from the early endosome in TNF-α-stimulated FLS. The obtained results clearly demonstrated that DEX-PEG-coated CNTs significantly inhibited the inflammation by FLS in rheumatoid arthritis (RA) by achieving greater drug uptake and efficient intracellular drug release from the endosome, thus suggesting a mechanism of effective low-dose GC therapy to treat inflammatory diseases, including RA and osteoarthritis.

Development of a Modified Naturalistic Action Test for Korean Patients With Impaired Cognition

Objective To develop and evaluate the psychometric properties of a modified Naturalistic Action Test (m-NAT) for Korean patients with impaired cognition. The NAT was originally designed to assess everyday action impairment associated with higher cortical dysfunction. Methods We developed the m-NAT by adapting the NAT for the Korean cultural background. The m-NAT was modeled as closely as possible on the original version in terms of rules and scoring. Thirty patients receiving neurorehabilitation (twenty-three stroke patients, five traumatic brain injury patients, and two dementia patients) and twenty healthy matched controls were included. Inter-rater reliability was assessed between two raters. Validity was evaluated by comparing the m-NAT score with various measures of attention, executive functions, and daily life. Results Performance on the m-NAT in terms of the total score was significantly different between patients and controls (p<0.01). Patients made significantly more total errors than controls (p<0.01). Omissions error was the most frequent type of error in patient group. Intraclass correlation coefficients for total m-NAT score was 0.95 (95% confidence interval [CI], 0.92 to 0.97; p<0.001); total error was 0.91 (95% CI, 0.89 to 0.92; p<0.001). Total m-NAT score showed moderate to strong correlations with Stroop test interference score & index, Trail Making Test parts A and B, Sustained Attention to Response Task commission error, Functional Independence Measure, Korean instrumental activities of daily living, Korean version of the Cognitive Failures Questionnaire, and Executive Behavior Scale (p<0.05). Conclusion The m-NAT showed very good inter-rater reliability and adequate validity. The m-NAT adjusted to Korean cultural background can be useful in performance-based assessment of naturalistic action for clinical and research purposes.