The diaphragmatic motor evoked potential (MEP) induced by transcranial magnetic stimulation (TMS) permits electrophysiological assessment of the cortico-diaphragmatic pathway. Despite the value of TMS for investigating diaphragm motor integrity in health and disease, reliability of the technique has not been established. The study aim was to determine within- and between-session reproducibility of surface electromyogram recordings of TMS-evoked diaphragm potentials. Fifteen healthy young adults participated (6 females, age=29±7 years). Diaphragm activation was determined by gradually increasing the stimulus intensity from 60-100% of maximal stimulator output (MSO). A minimum of seven stimulations were performed at each intensity. A second block of stimuli was delivered 30 minutes later for within-day comparisons, and a third block performed on a separate day for between-day comparisons. Reliability of diaphragm MEPs was assessed at 100% MSO using intraclass correlation coefficients (ICC) and 95% limits of agreement (LOA). MEPlatency (ICC=0.984, p<0.001), duration (ICC=0.958, p<0.001), amplitude (ICC=0.950, p<0.001) and area (ICC=0.956, p<0.001) were highly reproducible within-day. Between-day reproducibility was good to excellent for all MEP characteristics (latency ICC=0.953, p<0.001; duration ICC=0.879, p=0.002; amplitude ICC=0.789, p=0.019; area ICC=0.815, p=0.012). Data revealed less precision between-day versus within-day, as evidenced by wider LOA for all MEP characteristics. Large within- and between-subject variability in MEP amplitude and area was observed. In conclusion, TMS is a reliable means of inducing diaphragm potentials in most healthy individuals.

中文翻译：

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经颅磁刺激诱发的膈肌运动诱发电位的可靠性

由经颅磁刺激 (TMS) 诱导的膈肌运动诱发电位 (MEP) 允许对皮质-膈肌通路进行电生理评估。尽管 TMS 在研究健康和疾病中的膈肌运动完整性方面具有价值，但该技术的可靠性尚未确定。该研究的目的是确定 TMS 诱发的膈肌电位的表面肌电图记录的会话内和会话间再现性。15 名健康的年轻人参加了（6 名女性，年龄 = 29±7 岁）。通过从最大刺激器输出 (MSO) 的 60-100% 逐渐增加刺激强度来确定隔膜激活。每种强度至少进行七次刺激。30 分钟后提供第二组刺激以进行日内比较，并且在单独的一天执行第三个块以进行日间比较。使用组内相关系数 (ICC) 和 95% 的一致性限制 (LOA) 在 100% MSO 下评估隔膜 MEP 的可靠性。MEPlatency (ICC=0.984, p<0.001)、持续时间 (ICC=0.958, p<0.001)、振幅 (ICC=0.950, p<0.001) 和面积 (ICC=0.956, p<0.001) 在一天内具有高度可重复性。所有 MEP 特征的日间重现性从好到极好（延迟 ICC=0.953，p<0.001；持续时间 ICC=0.879，p=0.002；振幅 ICC=0.789，p=0.019；面积 ICC=0.815，p=0.012）。数据显示，与日内相比，日间精度较低，所有 MEP 特征的 LOA 范围更广就证明了这一点。观察到 MEP 振幅和面积的受试者内和受试者间的巨大变异。综上所述，