Understanding the Effects and Adverse Reactions of Deep Brain Stimulation: Is It Time for a Paradigm Shift Toward a Focus on Heterogenous Biophysical Tissue Properties Instead of Electrode Design Only?
Understanding the Effects and Adverse Reactions of Deep Brain Stimulation: Is It Time for a Paradigm Shift Toward a Focus on Heterogenous Biophysical Tissue Properties Instead of Electrode Design Only?
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DOI：
10.3389/fnhum.2018.00468
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发表时间：
2018-11-27
影响因子：
2.9
通讯作者：
Sueruecue, Oguzkan
中科院分区：
文献类型：
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作者：
Ineichen, Christian;Shepherd, Naomi Ruth;Sueruecue, Oguzkan
脑深部电刺激（DBS）已被证明是治疗各种晚期神经和精神疾病的有效方法。然而，关于脑组织中的电场分布的知识仍然很少。最近试图了解电场传播主要集中在不同电极对相当简单的组织模型的影响。特别是显微解剖学、生物物理组织特性的影响尚未深入研究。伦理问题限制了对人脑组织中电场分布的深入研究。利用简化模型，研究了丘脑底核（subthalamic nucleus，简称丘脑核）更大范围内的电场分布。模型中加入了脑组织的电导率、介电常数和磁导率等基本生物物理参数。用有限元法建立脑组织模型。刺激是用用于帕金森病患者单极刺激的参数来模拟的。我们的结果是可视化的全向和分段电极。在立体定向图谱（Morel）上叠加观察刺激电场。由于刺激电极附近的区域组织特性的影响，发生显著的场失真。这样的作用包括，例如，隔离严重髓鞘化的相邻结构的作用，例如，内囊特别地，这可以通过对较大冠状区域的分析来说明。虽然全向刺激与巨大的电流泄漏相关，但使用分段电极获得了更高的靶向精度。最后，当考虑微解剖结构对电扩散的影响时，靶向得到改善。我们的研究结果证实，铅的设计是不是电流传播的唯一影响。全向电极导线配置不会自动导致电流的全向扩散。进而，分段电极并不自动地意味着电流的改进的转向。我们的研究结果可能会提供一个解释的副作用继发于电流泄漏。此外，一个可能的解释分歧的结果在比较术中清醒的病人和术后设置。由于生物物理组织特性对电场形状的主要影响，因此应考虑局部显微解剖结构以实现精确的手术靶向和最佳硬件植入。
Deep brain stimulation (DBS) has been proven to be an effective treatment modality for various late-stage neurological and psychiatric disorders. However, knowledge on the electrical field distribution in the brain tissue is still scarce. Most recent attempts to understand electric field spread were primarily focused on the effect of different electrodes on rather simple tissue models. The influence of microanatomic, biophysical tissue properties in particular has not been investigated in depth. Ethical concerns restrict thorough research on field distribution in human in vivo brain tissue. By means of a simplified model, we investigated the electric field distribution in a broader area of the subthalamic nucleus (STN). Pivotal biophysical parameters including conductivity, permittivity and permeability of brain tissue were incorporated in the model. A brain tissue model was created with the finite element method (FEM). Stimulation was mimicked with parameters used for monopolar stimulation of patients suffering from Parkinson's disease. Our results were visualized with omnidirectional and segmented electrodes. The stimulated electric field was visualized with superimpositions on a stereotactic atlas (Morel). Owing to the effects of regional tissue properties near the stimulating electrode, marked field distortions occur. Such effects include, for example, isolating effects of heavily myelinated neighboring structures, e.g., the internal capsule. In particular, this may be illustrated through the analysis of a larger coronal area. While omnidirectional stimulation has been associated with vast current leakage, higher targeting precision was obtained with segmented electrodes. Finally, targeting was improved when the influence of microanatomic structures on the electric spread was considered. Our results confirm that lead design is not the sole influence on current spread. An omnidirectional lead configuration does not automatically result in an omnidirectional spread of current. In turn, segmented electrodes do not automatically imply an improved steering of current. Our findings may provide an explanation for side-effects secondary to current leakage. Furthermore, a possible explanation for divergent results in the comparison of the intraoperative awake patient and the postoperative setting is given. Due to the major influence of biophysical tissue properties on electric field shape, the local microanatomy should be considered for precise surgical targeting and optimal hardware implantation.