BACKGROUND Transcranial magnetic stimulus induced motor evoked potentials (MEPs) are quantified either with a single suprathreshold stimulus or using a stimulus response curve. Here, we explored variability in MEPs influenced by different stimulus intensities for the tibialis anterior muscle in stroke. METHODS MEPs for the paretic and non-paretic tibialis anterior (TA) muscle representations were collected from 26 participants with stroke at seven intensities. Variability of MEP parameters was examined with coefficients of variation (CV). RESULTS CV for the non-paretic TA MEP amplitude and area was significantly lower at 130% and 140% active motor threshold (AMT). CV for the paretic TA MEP amplitude and area did not vary with intensity. CV of MEP latency decreased with higher intensities for both muscles. CV of the silent period decreased with higher intensity for the non-paretic TA, but was in reverse for the paretic TA. CONCLUSION We recommend a stimulus intensity of greater than 130% AMT to reduce variability for the non-paretic TA. The stimulus intensity did not affect the MEP variability of the paretic TA. Variability of MEPs is affected by intensity and side tested (paretic and non-paretic), suggesting careful selection of experimental parameters for testing.

中文翻译：

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刺激强度影响非卒中而非卒中胫骨前肌的运动诱发反应的变异性。

背景技术通过单个阈上刺激或使用刺激响应曲线来量化经颅磁刺激诱发的运动诱发电位（MEP）。在这里，我们探讨了中风胫骨前肌的不同刺激强度对MEPs的影响。方法从26名中风强度为中风的26名参与者中收集了运动性和非运动性胫骨前（TA）肌肉表征的MEP。MEP参数的变化通过变异系数（CV）进行了检查。结果非parmet TA MEP振幅和面积的CV在130％和140％有效运动阈值（AMT）时显着降低。相对应的TA MEP振幅和面积的CV不随强度变化。MEP潜伏期的CV随两条肌肉的强度增加而降低。对于非paretic TA，静默期的CV随强度的增加而降低，但对于paretic TA，则相反。结论我们建议刺激强度大于AMT的130％，以减少非统计性TA的变异性。刺激强度不影响模型TA的MEP变异性。MEPs的可变性受强度和侧面测试（paretic和非paretic）的影响，建议仔细选择实验参数进行测试。