Objective

The aim of the present study was to investigate the optimal stimulation parameters for eliciting cortico-cortical evoked potentials (CCEPs) for mapping functional and epileptogenic networks.

Methods

We studied 13 patients with refractory epilepsy undergoing intracranial EEG monitoring. We systematically titrated the intensity of single-pulse electrical stimulation at multiple sites to assess the effect of increasing current on salient features of CCEPs such as N1 potential magnitude, signal to noise ratio, waveform similarity, and spatial distribution of responses. Responses at each incremental stimulation setting were compared to each other and to a final set of responses at the maximum intensity used in each patient (3.5–10 mA, median 6 mA).

Results

We found that with a biphasic 0.15 ms/phase pulse at least 2–4 mA is needed to differentiate between non-responsive and responsive sites, and that stimulation currents of 6–7 mA are needed to maximize amplitude and spatial distribution of N1 responses and stabilize waveform morphology.

Conclusions

We determined a minimum stimulation threshold necessary for eliciting CCEPs, as well as a point at which the current-dependent relationship of several response metrics all saturate.

Significance

This titration study provides practical, immediate guidance on optimal stimulation parameters to study specific features of CCEPs, which have been increasingly used to map both functional and epileptic brain networks in humans.

中文翻译：

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刺激强度对颅内皮质诱发电位的影响：一项滴定研究

客观的

本研究的目的是研究引发皮质-皮质诱发电位 (CCEP) 以绘制功能和致癫痫网络的最佳刺激参数。

方法

我们研究了 13 名接受颅内脑电图监测的难治性癫痫患者。我们系统地滴定了多个站点的单脉冲电刺激强度，以评估增加电流对 CCEP 显着特征的影响，例如 N1 电位幅度、信噪比、波形相似性和响应的空间分布。将每个增量刺激设置的响应相互比较，并与每个患者使用的最大强度（3.5-10 mA，中位数 6 mA）的最终一组响应进行比较。

结果

我们发现，对于双相 0.15 ms/相脉冲，至少需要 2-4 mA 来区分无响应和响应位点，并且需要 6-7 mA 的刺激电流来最大化 N1 响应的幅度和空间分布和稳定波形形态。

结论

我们确定了引发 CCEP 所需的最小刺激阈值，以及几个响应指标的电流依赖性关系全部饱和的点。

意义

这项滴定研究为研究 CCEP 的特定特征的最佳刺激参数提供了实用、直接的指导，CCEP 已越来越多地用于绘制人类功能性和癫痫脑网络的图谱。