Department of Clinical Neurophysiology, Aarhus University Hospital, Aarhus, Denmark.
Department of Clinical Neurophysiology, National Hospital for Neurology and Neurosurgery, Queen Square, WC1N 3BG, London, United Kingdom.
Neurophysiol Clin. 2021 Mar;51(2):153-160. doi: 10.1016/j.neucli.2021.01.001. Epub 2021 Jan 16.
The transcranial magnetic stimulation (TMS) technique of threshold-tracking short-interval intracortical inhibition (T-SICI) has been proposed as a diagnostic tool for amyotrophic lateral sclerosis (ALS). Most of these studies have used a circular coil, whereas a figure-of-8 coil is usually recommended for paired-pulse TMS measurements. The aim of this study was to compare figure-of-8 and circular coils for T-SICI in the upper limb, with special attention to reproducibility, and the pain or discomfort experienced by the subjects.
Twenty healthy subjects (aged: 45.5 ± 6.7, mean ± SD, 9 females, 11 males) underwent two examinations with each coil, in morning and afternoon sessions on the same day, with T-SICI measured at interstimulus intervals (ISIs) from 1-7 ms. After each examination the subjects rated degree of pain/discomfort from 0 to 10 using a numerical rating scale (NRS).
Mean T-SICI was higher for the figure-of-8 than for the circular coil at ISI of 2 ms (p < 0.05) but did not differ at other ISIs. Intra-subject variability did not differ between coils, but mean inhibition from 1-3.5 ms was less variable between subjects with the figure-of-8 coil (SD 7.2% vs. 11.2% RMT, p < 0.05), and no such recordings were without inhibition (vs. 6 with the circular coil). The subjects experienced less pain/discomfort with the figure-of-8 coil (mean NRS: 1.9 ± 1.28 vs 2.8 ± 1.60, p < 0.005).
The figure-of-8 coil may have better applicability in patients, due to the lower incidence of lack of inhibition in healthy subjects, and the lower experience of pain or discomfort.
经颅磁刺激（TMS）技术的阈下短程抑制（T-SICI）已被提议作为肌萎缩侧索硬化症（ALS）的诊断工具。这些研究大多使用圆形线圈，而双脉冲 TMS 测量通常推荐使用 8 字形线圈。本研究旨在比较上肢的 8 字形线圈和圆形线圈的 T-SICI，特别关注重复性以及受试者的疼痛或不适。
20 名健康受试者（年龄：45.5±6.7，平均值±标准差，9 名女性，11 名男性）在同一天的上午和下午进行了两次检查，使用 1-7ms 的刺激间隔（ISIs）测量 T-SICI。每次检查后，受试者使用数字评分量表（NRS）从 0 到 10 对疼痛/不适程度进行评分。
ISI 为 2ms 时，8 字形线圈的 T-SICI 高于圆形线圈（p<0.05），但在其他 ISI 下则没有差异。线圈之间的个体内变异性没有差异，但 8 字形线圈的 1-3.5ms 抑制的平均变异性较小（SD 7.2%与 RMT 的 11.2%，p<0.05），并且没有记录到没有抑制（与圆形线圈的 6 个相比）。受试者使用 8 字形线圈时疼痛/不适的程度较轻（平均 NRS：1.9±1.28 与 2.8±1.60，p<0.005）。
8 字形线圈在患者中的适用性可能更好，因为健康受试者中缺乏抑制的发生率较低，并且疼痛或不适的体验较低。
