Deog Young Kim

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.

The characteristics of sit-to-stand transfer in young children with spastic cerebral palsy based on kinematic and kinetic data

The aim of this study is to investigate the kinetic and kinematic characteristics of sit-to-stand transfer in children with spastic cerebral palsy (CP) in comparison with normal children. Fifteen spastic diplegic children, 12 spastic hemiplegic children and 21 normally developed children participated in this study. The sit-to-stand task was evaluated using a Motion analyzer (Vicon 370 MA with six infrared cameras). The consistent pattern of sit-to-stand transfer and six transitional points were identified in normal children. The motion analysis of sit-to-stand in children with CP showed slowness in the task, increased anterior pelvic tilting, and hip flexion during the task. An early abrupt knee extension was noted in diplegic children, as compared with normal controls. Decreased maximal knee extensor moment and decreased extensor power generation of the hip and knee joints were the major kinetic characteristics of the involved limbs of both diplegic and hemiplegic CP.

Virtual environment training system for rehabilitation of stroke patients with unilateral neglect: crossing the virtual street.

In this paper, we propose a system for training of stroke patients with unilateral neglect by using technology of virtual reality (VR). The proposed system is designed to compensate for unilateral neglect. This system contains the calibration of unilateral neglect and the training of this disease. The calibration procedure is implemented by aligning the virtual object at a subjective middle line. The training procedure is implemented by completing the missions that are used to keep the virtual avatar safe during crossing the street in a virtual environment. The results of this study show that the proposed system is effective to train unilateral neglect. The left to right ratio scores extracted from this system gradually decrease as the sessions of training are repeated. To validate the VR system parameters, the parameters are analyzed by correlation with those of traditional unilateral neglect assessment methods (such as the line bisection test and the cancellation test).

Safety study of high-frequency transcranial magnetic stimulation in patients with chronic stroke ☆ ☆☆

OBJECTIVE Repetitive transcranial magnetic stimulation (rTMS) is a potential therapeutic tool to rehabilitate chronic stroke patients. In this study, the safety of high-frequency rTMS in stroke was investigated (Phase I). METHODS The safety of 20 and 25 Hz rTMS over the motor cortex (MC) of the affected hemisphere, with intensities of 110-130% of the motor threshold (MT), was evaluated using surface electromyography (EMG) of hand and arm muscles. RESULTS Brief EMG bursts, possibly representing peripheral manifestations of after discharges, and spread of excitation to proximal muscles are considered to be associated with a high risk of seizure occurrence. These events were recorded after the rTMS trains. Neither increased MC excitability nor improved pinch force dynamometry was found after rTMS. CONCLUSIONS Stimulation parameters for rTMS, which are safe for healthy volunteers, may lead to a higher risk for seizure occurrence in chronic stroke patients. SIGNIFICANCE rTMS at rates of 20 and 25 Hz using above threshold stimulation potentially increases the risk of seizures in patients with chronic stroke.

Enhancing motor performance by anodal transcranial direct current stimulation in subacute stroke patients.

Kim DY, Ohn SH, Yang EJ, Park C-I, Jung KJ: Enhancing Motor Performance by Anodal Transcranial Direct Current Stimulation in Subacute Stroke Patients. Objective:To investigate whether anodal transcranial direct current stimulation enhances motor performance in the paretic hand of subacute poststroke patients and how long the improvement persisted after the session. Design:Ten subacute poststroke patients who suffered stoke within 12 wks were recruited for this single-blinded, sham-controlled, crossover study. Anodal transcranial direct current stimulation or sham stimulation was randomly delivered on the hot spot of the first dorsal interosseous in the affected hemisphere. The duration of transcranial direct current stimulation was 20 mins and sham was 30 secs. The Box and Block test and finger acceleration measurement were performed before, during, immediately after, and 30 and 60 mins after anodal or sham stimulation to assess time-dependent changes in motor performance. Results:Finger acceleration measurement and Box and Block test were significantly improved after anodal transcranial direct current stimulation compared with sham stimulation (P < 0.05). Anodal transcranial direct current stimulation significantly improved Box and Block test for at least 60 mins and finger acceleration until 30 mins after stimulation (P < 0.05) without significant differences in attention and fatigue. Conclusions:Anodal transcranial direct current stimulation on the affected hemisphere can enhance motor performance of the hemiparetic hand transiently, outlasting the stimulation session.

A Virtual Reality Assessment and Training System for Unilateral Neglect

Patients with unilateral neglect have problems reporting, responding, or orienting to novel or meaningful stimuli that is presented to the side opposite to that of a brain lesion. This creates a serous problem in regards to daily living activities. However, the established methods for assessing and training of unilateral neglect patients have several deficits. Recently, virtual reality (VR) technologies have been used as an assessment and treatment tool for rehabilitation. Hence, this study designed a VR system to assess and train unilateral neglect patients. In addition, the suitability and feasibility of our VR system for unilateral neglect patients was verified.

Assessment of post-stroke extrapersonal neglect using a three-dimensional immersive virtual street crossing program

Kim DY, Ku J, Chang WH, Park TH, Lim JY, Han K, Kim IY, Kim SI. Assessment of post‐stroke extrapersonal neglect using a three‐dimensional immersive virtual street crossing program
Acta Neurol Scand: 2010: 121: 171–177.
© 2009 The Authors Journal compilation

Biomechanical Assessment with Electromyography of Post-Stroke Ankle Plantar Flexor Spasticity

Spasticity has been defined as a motor disorder characterized by a velocity-dependent increase in tonic stretch reflex (muscle tone). Muscle tone consists of mechanical-elastic characteristics, reflex muscle contraction and other elements. The aims of this study were to determine whether to assess spasticity quantitatively, and to characterize biomechanical and electromyographic spasticity assessment parameters. These assessment parameters were described by investigating the correlation between clinical measures and the response to passive sinusoidal movement with consecutive velocity increments. Twenty post-stroke hemiplegic patients and twenty normal healthy volunteers were included in the study. Five consecutive sinusoidal passive movements of the ankle were performed at specific velocities (60, 120, 180, and 240 degrees/sec). We recorded the peak torque, work, and threshold angle using a computerized isokinetic dynamometer, and simultaneously measured the rectified integrated electromyographic activity. We compared these parameters both between groups and between different velocities. The peak torque, threshold angle, work, and rectified integrated electromyographic activity were significantly higher in the post-stroke spastic group at all angular velocities than in the normal control group. The threshold angle and integrated electromyographic activity increased significantly and linearly as angular velocity increased, but the peak torque and work were not increased in the post-stroke spastic group. Peak torque, work, and threshold angle were significantly correlated to the Modified Ashworth scale, but the integrated electromyographic activity was not. The biomechanical and electromyographic approach may be useful to quantitatively assess spasticity. However, it may also be very important to consider the different characteristics of each biomechanical parameter.

Anterior pituitary dysfunction in moderate-to-severe chronic traumatic brain injury patients and the influence on functional outcome

Objective: The objective of this study is to determine the prevalence of anterior pituitary dysfunction in moderate-to-severe chronic traumatic brain injury (TBI) patients. The investigation of a relationship between pituitary hormonal status and body mass index (BMI) in TBI patients by observing changes in BMI was conducted as well as an assessment of whether there is a difference in functional outcome related to anterior pituitary dysfunction in TBI patients. Methods: Forty-five TBI patients and 30 normal controls underwent a series of standard endocrine tests for anterior pituitary hormone function. It was studied whether changes in BMI correlated with anterior pituitary hormone levels. This study also compared changes in mini-mental state examination (K-MMSE) and functional independence measure (FIM) scores between patients in the hormone-sufficient and -deficient groups. Results: Anterior pituitary dysfunction was found in 31.1% of TBI patients. Changes in BMI statistically correlated with IGF-1 and basal cortisol levels. A meaningful difference was found between the hormone-sufficient and -deficient groups in light of the K-MMSE and FIM score gains. Conclusions: These findings strongly suggest that patients who suffer head trauma should be routinely tested for anterior pituitary hormone deficiency.

Implementation and performance evaluation of mobile ad hoc network for Emergency Telemedicine System in disaster areas

So far we have developed Emergency Telemedicine System (ETS) which is a robust system using heterogeneous networks. In disaster areas, however, ETS cannot be used if the primary network channel is disabled due to damages on the network infrastructures. Thus we designed network management software for disaster communication network by combination of Mobile Ad hoc Network (MANET) and Wireless LAN (WLAN). This software maintains routes to a Backbone Gateway Node in dynamic network topologies. In this paper, we introduce the proposed disaster communication network with management software, and evaluate its performance using ETS between Medical Center and simulated disaster areas. We also present the results of network performance analysis which identifies the possibility of actual Telemedicine Service in disaster areas via MANET and mobile network (e.g. HSDPA, WiBro).