Sources and effects of electrode impedance during deep brain stimulation
Sources and effects of electrode impedance during deep brain stimulation
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DOI：
10.1016/j.clinph.2005.10.007
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发表时间：
2006-02-01
影响因子：
4.7
通讯作者：
McIntyre, CC
中科院分区：
文献类型：
--
作者：
Butson, CR;Maks, CB;McIntyre, CC
目的：人类患者脑深部电刺激（DBS）电极的临床阻抗测量值通常在500-1500 Ω范围内。DBS器械采用电压控制刺激;因此，输送至组织的电流与阻抗成反比。本研究的目的是评估各种电性能的组织介质和电极-组织界面上的阻抗的影响，并确定临床相关的阻抗变化的影响，在DBS.Methods：轴对称有限元模型的体积上的组织激活（VTA）。(FEM)的DBS系统的构造与周围的电极和植入的脉冲发生器的封装层的显式表示。通过将刺激电压除以沿有源电极触点沿着的积分电流密度来计算阻抗。该模型使用傅立叶FEM求解器，该求解器考虑了电压控制刺激期间电极-组织界面的电容分量。所产生的时间和空间相关的电压波形中产生的组织介质被叠加到电缆模型轴突计算VTA.Results：电极阻抗的主要决定因素是周围的电极接触和散装组织介质的导电性的封装层的厚度和导电性。我们的低水平和低水平之间的VTA差异（790 Ω）和更高具有典型DBS设置的（1244 Omega）阻抗模型（-3 V，90 μ s，130 Hz脉冲序列）为121 mm（3），表示体积减少52%。电极阻抗对腹侧被盖区有很大的影响，电极阻抗的精确表示应该是计算模型的一个明确组成部分重要性：阻抗通常用于识别断裂的导线（对于值> 2000 Ω）或硬件中的短路（对于值< 50 Ω）;然而，临床阻抗值也代表了定义DBS期间刺激扩展的重要参数。(c)2005年国际临床神经生理学联合会。由Elsevier爱尔兰有限公司出版。保留所有权利。
Objective: Clinical impedance measurements for deep brain stimulation (DBS) electrodes in human patients are normally in the range 500-1500 Omega. DBS devices utilize voltage-controlled stimulation; therefore, the current delivered to the tissue is inversely proportional to the impedance. The goals of this study were to evaluate the effects of various electrical properties of the tissue medium and electrode-tissue interface on the impedance and to determine the impact of clinically relevant impedance variability on the volume of tissue activated (VTA) during DBS.Methods: Axisymmetric finite-element models.(FEM) of the DBS system were constructed with explicit representation of encapsulation layers around the electrode and implanted pulse generator. Impedance was calculated by dividing the stimulation voltage by the integrated current density along the active electrode contact. The models utilized a Fourier FEM solver that accounted for the capacitive components of the electrode-tissue interface during voltage-controlled stimulation. The resulting time- and space-dependent voltage waveforms generated in the tissue medium were superimposed onto cable model axons to calculate the VTA.Results: The primary determinants of electrode impedance were the thickness and conductivity of the encapsulation layer around the electrode contact and the conductivity of the bulk tissue medium. The difference in the VTA between our low (790 Omega) and high (1244 Omega) impedance models with typical DBS settings (-3 V, 90 mu s, 130 Hz pulse train) was 121 mm(3), representing a 52% volume reduction.Conclusions: Electrode impedance has a substantial effect on the VTA and accurate representation of electrode impedance should be an explicit component of computational models of voltage-controlled DBS.Significance: Impedance is often used to identify broken leads (for values > 2000 Omega) or short circuits in the hardware (for values < 50 Omega); however, clinical impedance values also represent an important parameter in defining the spread of stimulation during DBS. (c) 2005 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.