Kim Donghyeon, Jun Sung Chan, Kim Hyoung-Ihl
School of Information and Communications, Gwangju Institute of Science and Technology, Gwangju, South Korea.
Annu Int Conf IEEE Eng Med Biol Soc. 2011;2011:7226-9. doi: 10.1109/IEMBS.2011.6091826.
Cortical stimulation (CS) has gained wide attention for its use in augmenting neurological recovery in various conditions. Noninvasive cortical stimulations using transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) are less invasive when delivering the electrical current to the patient's brain, but have several limitations. Direct cortical stimulation (DCS) using an implantable stimulation system consisting of epidurally or subdurally placed electrodes and pulse generators, provides cortical stimulation and concurrent rehabilitative training in a stable fashion without limiting a patient's activities. The effectiveness of these two types of DCS--epidural cortical stimulation (ECS) and subdural cortical stimulation (SCS)--has not been compared. In this work, a computer simulation study was conducted to predict the current density distributions (CDD) through cortical stimulations using subdurally or epidurally placed electrodes. The simulation study is based on the human motor cortex model with a three-dimensional finite element model (FEM). The change in CDD depending on the shape of the electrode (disc or ring) is discussed. The output current induced by SCS was about four times larger than that of ECS when voltage stimulations with the same magnitude were regulated. Thus, SCS showed substantially better penetration of the current into gray or white matter. Further, the ring electrode performed comparably or slightly inferior to the disc electrode in both cortical stimulations.
皮质刺激（CS）因其在多种情况下增强神经功能恢复方面的应用而受到广泛关注。使用经颅磁刺激（TMS）和经颅直流电刺激（tDCS）的非侵入性皮质刺激在向患者大脑输送电流时侵入性较小，但存在一些局限性。使用由硬膜外或硬膜下放置的电极和脉冲发生器组成的可植入刺激系统进行的直接皮质刺激（DCS），能够以稳定的方式提供皮质刺激并同时进行康复训练，且不限制患者的活动。这两种类型的DCS——硬膜外皮质刺激（ECS）和硬膜下皮质刺激（SCS）——的有效性尚未进行比较。在这项工作中，进行了一项计算机模拟研究，以预测使用硬膜下或硬膜外放置的电极进行皮质刺激时的电流密度分布（CDD）。该模拟研究基于具有三维有限元模型（FEM）的人类运动皮质模型。讨论了CDD随电极形状（圆盘或环形）的变化。当调节相同幅度的电压刺激时，SCS诱导的输出电流约为ECS的四倍。因此，SCS显示出电流对灰质或白质的穿透性明显更好。此外，在两种皮质刺激中，环形电极的表现与圆盘电极相当或略逊一筹。
