Zyss T, Krawczyk A, Drzymała P, Starzyński J
Katedry Psychiatrii Collegium Medicum UJ w Krakowie.
Psychiatr Pol. 1999 Nov-Dec;33(6):909-23.
The essential issue of electroshock therapy (ECT) is the activity of physical stimulus, i.e., the electric current, on the disturbed structures of the brain. ECT sessions--when chronically applied for evoking antidepressive effects--are responsible for the appearance of excessive incitement in the neuronal net in the brain tissue in a form of self-sustaining after-discharge (SSAD) (convulsive attack characteristic for ECT). The study presents the computer research on basic biophysical phenomena of electroshock therapy (flow of electric current in the structures of the head just before convulsive attack). Five-layer 3-D model of the head was created in OPERA-3D (Vector Fields Ltd., Oxford), general 3 dimensional issues solver. Geometrical dimensions and electrophysical properties of each layer correspond with natural properties. The model was subjected to the action of electric stimulation (parameters identical to those applied in clinical conditions). Analysis of the flow in particular layers revealed the crawling/spreading effect present not only in the scalp layer but also in the layer of cerebrospinal fluid. The effect is conditioned by "deeper situated" lesser conduction of electricity-respectively skull bones, brain tissue. Crawling effect is the reason why only 5-15% of the electricity applied on the surface of the head reaches the surface of the brain. Electro-stimulation examinations also showed that the values of the so called density of the current in layers of brain tissue balanced between 1-10 mA/mm2. The current parameters of ECT were effective in evoking subsequent convulsive attack and safe for the brain tissue. The model was subjected to the action of magnetic stimulation according to the parameters of neurologic technique of transcranial magnetic stimulation (TMS). ELECTRA module was used to solve wire-current issues. The examination showed more regular distribution of current vectors in all layers of the head. The density of cerebral cortex was 0.1-1 mA/mm2, confirming markedly lesser current charge than that observed during ECT. The problem of magnetic stimulation efficacy in irritating deep structures of the brain demands further studies.
电休克疗法（ECT）的核心问题是物理刺激（即电流）对大脑紊乱结构的作用。当长期应用ECT来诱发抗抑郁效果时，ECT疗程会导致脑组织中神经元网络出现过度兴奋，表现为持续的后放电（SSAD）（ECT特有的惊厥发作）。该研究展示了关于电休克疗法基本生物物理现象的计算机研究（惊厥发作前头部结构中的电流流动）。在OPERA - 3D（牛津Vector Fields有限公司）这个通用三维问题求解器中创建了头部的五层三维模型。每层的几何尺寸和电物理特性与自然特性相对应。该模型接受了电刺激（参数与临床应用的相同）。对各层电流流动的分析表明，不仅在头皮层，而且在脑脊液层都存在爬行/扩散效应。这种效应是由“位置更深”的导电性较差的结构（分别是颅骨、脑组织）所导致的。爬行效应就是为什么施加在头部表面的电只有5 - 15%能到达大脑表面的原因。电刺激检查还表明，脑组织层中所谓的电流密度值在1 - 10 mA/mm²之间平衡。ECT的当前参数在诱发后续惊厥发作方面是有效的，并且对脑组织是安全的。该模型根据经颅磁刺激（TMS）神经技术的参数接受了磁刺激。使用ELECTRA模块来解决线电流问题。检查显示头部所有层中的电流矢量分布更规则。大脑皮层的密度为0.1 - 1 mA/mm²，证实电流电荷明显低于ECT期间观察到的电荷。磁刺激对大脑深部结构的刺激效果问题需要进一步研究。
