de Goede Annika A, van Putten Michel J A M
Department of Clinical Neurophysiology, MIRA - Institute for Biomedical Technology and Technical Medicine, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
Department of Neurology and Clinical Neurophysiology, Medisch Spectrum Twente, P.O. Box 50000, 7500 KA Enschede, The Netherlands.
Clin Neurophysiol Pract. 2016 Dec 21;2:26-34. doi: 10.1016/j.cnp.2016.12.004. eCollection 2017.
Transcranial magnetic stimulation (TMS) is widely used to assess cortical excitability. To detect changes in excitability with longitudinal studies, it is important to validate the repeatability of excitability measures within a subject between different sessions. Repeatability studies on long intracortical inhibition (LICI) are limited and reported agreement ranges from poor to good. This study aims to evaluate the repeatability of LICI in healthy subjects using paired pulse TMS. In addition, it investigates whether LICI repeatability differs for manual and robot-guided coil positioning.
Thirty healthy subjects (10 males, mean age 28.4 ± 8.2 years) were studied twice, approximately one week apart. Both motor cortices were stimulated with 50 paired pulses (intensity 120% of resting motor threshold) at interstimulus intervals (ISIs): 50, 100, 150, 200, 250 and 300 ms. In twenty subjects a figure-of-eight coil was positioned and held in place manually during both sessions, while in ten subjects a robot-navigated arm was used. LICI repeatability was assessed using the intraclass correlation coefficient (ICC).
For manual and robot-guided coil positioning we found a large variation in repeatability at the subject level and ISI level, ranging from poor to good agreement. On a group level, we found good repeatability for averaged LICI curves (manual: ICC = 0.91, robot-guided: ICC = 0.95), which decreased when individual curves were correlated between sessions (manual: ICC = 0.76, robot-guided: ICC = 0.84).
For a correct interpretation of longitudinal study outcomes it is important to know the subject specific LICI repeatability and to analyze each ISI individually. Furthermore, the added value of robot-guided coil positioning for paired pulse TMS seems limited.
The large variation in LICI repeatability at the subject level and ISI level should be taken into account in longitudinal studies, while robot-guided coil positioning seems unnecessary.
经颅磁刺激（TMS）被广泛用于评估皮质兴奋性。为了通过纵向研究检测兴奋性的变化，在不同时间段内验证个体受试者兴奋性测量的可重复性很重要。关于长时程皮质内抑制（LICI）的可重复性研究有限，报告的一致性范围从差到好。本研究旨在使用配对脉冲TMS评估健康受试者中LICI的可重复性。此外，研究手动和机器人引导的线圈定位时LICI的可重复性是否存在差异。
30名健康受试者（10名男性，平均年龄28.4±8.2岁）接受了两次研究，间隔约一周。在运动皮质上施加50对脉冲（强度为静息运动阈值的120%），刺激间隔（ISI）分别为：50、100、150、200、250和300毫秒。20名受试者在两次测试中均由人工定位并固定一个8字形线圈，而另外10名受试者使用机器人导航手臂。使用组内相关系数（ICC）评估LICI的可重复性。
对于手动和机器人引导的线圈定位，我们在个体受试者水平和ISI水平上发现可重复性存在很大差异，一致性范围从差到好。在组水平上，我们发现平均LICI曲线具有良好的可重复性（手动：ICC = 0.91，机器人引导：ICC = 0.95），但当各时间段的个体曲线进行相关性分析时，可重复性降低（手动：ICC = 0.76，机器人引导：ICC = 0.84）。
为了正确解释纵向研究结果，了解个体受试者特定的LICI可重复性并分别分析每个ISI很重要。此外，机器人引导的线圈定位在配对脉冲TMS中的附加价值似乎有限。
在纵向研究中应考虑个体受试者水平和ISI水平上LICI可重复性的巨大差异，而机器人引导的线圈定位似乎没有必要。
