Browsing by Author "Chuang, Wei-Yi"

Now showing 1 - 4 of 4

Adjusting Electrode Potentials to Compensate Thermal/Tissue Effects in Deep Brain Stimulation via Finite Element Electromagnetic Analysis
(2010-06-01)
Chuang, Wei-Yi
;
Chao, Paul C. -P.
;
Young, Kuu-Young
;
影像與生醫光電研究所
;
電機工程學系
The proposed method is intended to adjust the electrode potentials used in deep brain stimulation (DBS) with the consideration of both tissue transform and thermal effects caused by stimulation. During a typical DBS process, it is essential, for an effective treatment, to control the stimulation strength and region with varied applied electrode potentials. Some previous studies have been devoted for numerical simulations to find suitable electrode voltage levels for pre-desired stimulated strength and region. These studies consider only one of the two complexity factors due to the intrusion of the DBS lead: 1) a layer of extracellular fluid and giant cell often formed around the DBS leads, called the peri-electrode space and 2) thermal effects. These two factors should both be considered in finite element electromagnetic analysis (FEA), which provides the means to adjust electrode potential for the originally-desired DBS region-called the volume of tissue activated (VTA). Simulation results show that there should be a limiting stimulation voltage to meet the temperature constraint.
Computerized Stimulation Parameter Adjustment of Deep Brain Stimulation Minimizing Side Effects and Power Consumption for Parkinson\'s Disease
(2014-01-01)
Chuang, Wei-Yi
;
Chao, Paul Chang-Po
;
Young, Kuu-Young
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Deep brain stimulation (DBS) is broadly applied for neuropsychiatric diseases and thus determining its mechanism is of interest, especially in terms of the neural structure surrounding the DBS probe and the volume of tissue activated (VTA) during DBS. For re-operations for battery replacement, a major issue is reducing treatment power consumption without compromising clinical benefits. To avoid side effects and to minimize power consumption, optimized adjustment of the stimulation parameters is required. This study thus proposes a scheme for determining the optimal stimulation parameters. An electromagnetic finite element model for a patient-specific physiological brain model is first established using magnetic resonance imaging (MRI) data. Using finite element analysis (FEA), varied stimulation parameters are applied to the electromagnetic model for VTA estimation. Optimal electrode contact(s) are selected based on the estimated VTA to avoid side effects. Moreover, a nonlinear programming method for optimizing the stimulation voltage and the pulse width is applied to minimize power consumption in DBS. The effectiveness of the model parameters was verified using five Parkinson\'s disease patients. The results demonstrate that the estimates of the VTA are consistent with the observations within the desired region of the brain while avoiding side effects and reducing power consumption by 13% on average. The proposed method allows clinicians and researchers to efficiently select the optimal stimulation parameters. Moreover, it provides valuable information for closed-loop stimulation protocols in DBS.
Computing stimulation voltage in a bipolar electrode configuration to avoid side effects during deep brain stimulation
(2015-09-01)
Chuang, Wei-Yi
;
Chao, Paul C. -P.
;
Chen, Shin-Yuan
;
Tsai, Sheng-Tzung
;
Young, Kuu-Young
Deep brain stimulation (DBS) in the subthalamic nucleus (STN) has been applied for advanced Parkinson\'s disease (PD). In clinical practices, monopolar configuration is often utilized based on clinical efficiency. Meanwhile, the volume of tissue activated (VTA) by DBS is estimated for controlling and/or limiting the stimulated region. However, side effects like dyskinesia and tremor were accompanied during stimulation. Most studies had found that bipolar stimulation is an alternative approach for side effects avoidance. The goal of this paper is to develop a quantified relationship of stimulation voltage from monopolar to bipolar configuration to improve neural stimulation. In this paper, an electromagnetic finite element model is first built for a patient-specific physiological brain model, which is established by magnetic resonance imaging (MRI) data. The model is then used for finite element analysis (PEA) to estimate VTA with varied electrode voltage in monopolar and bipolar configurations. With the goals to avoid side effects and achieve symptoms suppression, the stimulation voltage of bipolar configuration is successfully computerized based on the electromagnetic PEA simulations. Experiments are conducted successfully to validate simulation results. (C) 2015 Elsevier B.V. All rights reserved.
Dorsolateral subthalamic neuronal activity enhanced by median nerve stimulation characterizes Parkinson\'s disease during deep brain stimulation with general anesthesia
(2015-12-01)
Tsai, Sheng-Tzung
;
Chuang, Wei-Yi
;
Kuo, Chung-Chih
;
Chao, Paul C. P.
;
Chen, Tsung-Ying
OBJECT Deep brain stimulation (DBS) surgery under general anesthesia is an alternative option for patients with Parkinson\'s-disease (PD). However, few studies are available that report whether neuronal firing can be accurately recorded during this condition. In this study the authors attempted to characterize the neuronal activity of the subthalamic nucleus (STN) and elucidate the influence of general anesthetics on neurons during DBS surgery in patients with PD. The benefit of median nerve stimulation (MNS) for localization of the dorsolateral subterritory of the STN, which is involved in sensorimotor function, was explored. METHODS Eight patients with PD were anesthetized with desflurane and underwent contralateral MNS at the wrist during microelectrode recording of the STN. The authors analyzed the spiking patterns and power spectral density (PSD) of the background activity along each penetration track and determined the spatial correlation to the target location, estimated using standard neurophysiological procedures. RESULTS The dorsolateral STN spiking pattern showed a more prominent bursting pattern without MNS and more oscillation with MNS. In terms of the neural oscillation of the background activity, beta-band oscillation dominated within the sensorimotor STN and showed significantly more PSD during MNS (rho < 0.05). CONCLUSIONS Neuronal firing within the STN could be accurately identified and differentiated when patients with PD received general anesthetics. Median nerve stimulation can enhance the neural activity in beta-band oscillations, which can be used as an index to ensure optimal electrode placement via successfully tracked dorsolateral STN topography.