不同强度重复外周磁刺激对运动皮质兴奋性影响的比较

Comparison of Effects of Repetitive Peripheral Magnetic Stimulation of Different Intensities on Motor Cortex Excitability

摘要: 目的：比较不同强度的重复外周磁刺激对运动皮质兴奋性的影响。方法：招募右利手的健康志愿者20名，采用随机数法进行排序。所有受试者均在四个不同的日期(为避免出现任何持久的刺激后效应，每次接受实验间隔至少7天)接受阈值强度(T0组)、阈下80% (T1组)、阈上120% (T2组)、阈上150% (T3组)的rPMS刺激，实验环境舒适安静。每次接受刺激的受试者由电脑随机抽取，每位受试者每次接受刺激的强度由电脑随机选择，后另由一名试验者在不知刺激条件的情况下使用TMS测量MEP振幅、潜伏期、静息运动阈值，并通过配对脉冲刺激测量MEP振幅，并将测量指标与常规测量振幅指标相除得到比值，记为抑制百分比。结果：1) T1组强度刺激前后MEP振幅、潜伏期、静息运动阈值各项指标无明显差异，其余各组在刺激前后振幅指标差异均有统计学意义(P < 0.05)，且样本相关的α值随刺激强度变化逐渐增大(T3 > T2 > T0 > T1)。2) T1、T2组接受刺激前后抑制百分比无统计学差异(P > 0.05)，但样本相关的显著性(α值)提示其刺激前后指标仍存在一定差异。其余各组在刺激前后抑制百分比指标差异均有统计学意义(P < 0.05)，且样本相关的α值随刺激强度变化逐渐增大(T3 > T2 > T0 > T1)。结论：以引起肌肉明显收缩的刺激强度为阈值，一定范围内的刺激强度均可对大脑皮质的兴奋性产生促进作用，且呈正相关关系。

Abstract: Objective: Comparison of the effects of repetitive peripheral magnetic stimulation of different intensities on motor cortical excitability. Method: With inclusion and exclusion criteria, 20 healthy volunteers with right-handedness were recruited and ranked using the random number method. All subjects received rPMS stimulation at threshold intensity (T0 group), subthreshold 80% (T1 group), suprathreshold 120% (T2 group), and suprathreshold 150% (T3 group) on four different dates (to avoid any lasting post-stimulus effects, each receiving experiment was separated by at least 7 days) in a comfortable and quiet experimental environment. Subjects receiving each stimulation were randomly selected by computer, and the intensity of each stimulation received by each subject was randomly selected by computer, after which another experimenter used TMS to measure MEP amplitude, latency, and resting motor threshold without knowing the stimulation conditions. The MEP amplitude was also measured by paired-pulse stimulation, and the ratio was obtained by dividing the measured metrics with the conventionally measured amplitude metrics, which was recorded as the percent inhibition. Results: 1) There were no significant differences in MEP amplitude, latency, and resting motor threshold indices before and after intensity stimulation in the T1 group, and the differences in amplitude indices before and after stimulation were statistically significant for the remaining groups (P < 0.05), and the sample-related α values gradually increased with changes in stimulus intensity (T3 > T2 > T0 > T1); 2) there was no statistically significant difference in the percentage of inhibition before and after stimulation in the T1 and T2 groups (P > 0.05), but the significance of the sample correlation (α value) suggested that there were still some differences in the indicators before and after stimulation. The differences in the percentage of inhibition before and after stimulation in the remaining groups were statistically significant (P < 0.05), and the sample-related α value gradually increased with the change of stimulation intensity (T3 > T2 > T0 > T1). Conclusion: With the stimulation intensity causing obvious muscle contraction as the threshold, the stimulation intensity within a certain range can promote the excitability of the cerebral cortex, and there is a positive correlation.