Prime David, Woolfe Matthew, O'Keefe Steven, Rowlands David, Dionisio Sasha
Griffith University School of Engineering, Nathan, QLD, Australia; Mater Advanced Epilepsy Unit, Brisbane, QLD, Australia.
Griffith University School of Engineering, Nathan, QLD, Australia; Mater Advanced Epilepsy Unit, Brisbane, QLD, Australia.
J Neurosci Methods. 2020 May 1;337:108639. doi: 10.1016/j.jneumeth.2020.108639. Epub 2020 Mar 7.
Cortico-cortical evoked potentials (CCEP) are a technique using low frequency stimulation to infer regions of cortical connectivity in patients undergoing Stereo-electroencephalographic (SEEG) monitoring for refractory epilepsy. Little attention has been given to volume conducted components of CCEP responses, and how they may inflate CCEP connectivity.
Using data from 37 SEEG-CCEPs patients, a novel method was developed to quantify stimulation artefact by measuring the peak-to-peak voltage difference in the first 10 ms after CCEP stimulation. Early responses to CCEP stimulation were also quantified by calculating the root mean square of the 10-100 ms period after each stimulation pulse. Both the early CCEP responses and amplitude of stimulation artefact were regressed by physical distance, stimulation waveform, stimulation intensity and tissue type to identify conduction related properties.
Both stimulation artefact and early responses were correlated strongly with the inverse square of the distance from the stimulating electrode. Once corrected for the inverse square distance from the electrode, stimulation artefact and CCEP responses showed a linear relationship, indicating a volume conducted component.
This is the first study to use stimulation artefact to quantify volume conducted potentials, and is the first to quantify volume conducted potentials in SEEG. A single prior study utilizing electrocorticography has shown that parts of early CCEP responses are due to volume conduction.
The linear relationship between stimulation artefact amplitude and CCEP early responses, once corrected for distance, suggests that stimulation artefact can be used as a measure to quantify the volume conducted components.
皮质-皮质诱发电位（CCEP）是一种利用低频刺激来推断接受立体定向脑电图（SEEG）监测的难治性癫痫患者皮质连接区域的技术。CCEP反应的容积传导成分以及它们如何可能夸大CCEP连接性一直很少受到关注。
利用37例SEEG-CCEP患者的数据，开发了一种新方法，通过测量CCEP刺激后最初10毫秒内的峰-峰值电压差来量化刺激伪迹。还通过计算每个刺激脉冲后10-100毫秒期间的均方根来量化对CCEP刺激的早期反应。早期CCEP反应和刺激伪迹的幅度均通过物理距离、刺激波形、刺激强度和组织类型进行回归分析，以确定传导相关特性。
刺激伪迹和早期反应均与距刺激电极距离的平方成反比密切相关。一旦校正了距电极的平方反比距离，刺激伪迹和CCEP反应呈现线性关系，表明存在容积传导成分。
这是第一项利用刺激伪迹来量化容积传导电位的研究，也是第一项在SEEG中量化容积传导电位的研究。此前一项利用皮质脑电图的研究表明，早期CCEP反应的部分原因是容积传导。
校正距离后，刺激伪迹幅度与CCEP早期反应之间的线性关系表明，刺激伪迹可作为量化容积传导成分的一种指标。
