經皮神經電刺激作用於主要動作皮質區對大腦皮質興奮性和動作表現的效果

Abstract

前言：近來經顱磁刺激、經顱直流電刺激和經顱交流電刺激等非侵入性腦刺激在研究介入和臨床評估上都成為一項有力的工具。目前關於交流電刺激的研究認為交流電刺激會影響皮質的活性，但其相關應用與機轉依然不清楚。由於交流電刺激的技術規格和傳統刺激神經肌肉的經皮神經電刺激相似，因此可進一步了解使用經皮神經電刺激作為一種非侵入性腦刺激器的可能性。目的：本研究將觀察大腦主要動作皮質區之皮質興奮性和手部動作表現改變情形在提供二十分鐘、三種經皮神經電刺激(120赫茲、15赫茲和偽電流刺激)介入後的改變。方法：收集平均年齡為22.45±1.17歲的二十四位健康受試者，並給予隨機安排次序的120赫茲、15赫茲和偽電流刺激三次經皮神經電刺激，利用經顱磁刺激器和手部動作表現的評估，觀察其介入前、介入後和追蹤刺激後三十分鐘、六十分鐘的皮質興奮性之改變和動作上的影響。結果：介入二十分鐘經皮神經電刺激後，所有受試者皆無不適的情形。15赫茲的刺激對於動作誘發電位(motor evoked potential, MEP)、標準化動作誘發電位(normalized motor evoked potential, normalized MEP)、二毫秒差的皮質內抑制(2ms of intracortical inhibition, ICI2)和十五毫秒的皮質內興奮(15ms of intracortical facilitation, ICF15)皆有顯著上升的表現(p=0.029, 0.002, 0.002, <0.001)，且追蹤30至60分鐘後，皆顯著下降(p=0.005, <0.001, 0.038, 0.001)；120赫茲的刺激則只有標準化動作誘發電位(normalized MEP)在介入後有顯著上升(p=0.007)，動作誘發電位(MEP)和標準化動作誘發電位(normalized MEP)在追蹤60分鐘後顯著下降的表現(p=0.026, 0.034)。另外，無論何種刺激，動作表現的結果皆無顯著差異(p>0.05)。結論：本研究證實經皮神經電刺激作為一調節皮質興奮性工具的安全性和可行性，二十分鐘的刺激對於大腦主要動作皮質區之皮質興奮性有顯著的改變，且15赫茲的刺激效果較120赫茲和偽電流刺激的效果佳，其結果將可提供更多有效之臨床試驗，以利於未來再回饋至臨床復健的訓練上。

Background: Recently, transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS) become powerful tools for both basic research and clinical application. Researches revealed that AC stimulation might alter the cortical excitability. However the mechanism of this phenomenon was still unclear. Although the stimulator to provide AC stimulation has the similar technological specification for a traditional neuromuscular stimulator, like transcutaneous electrical nerve stimulation (TENS), it should be clarified the possibility to use a TENS as a noninvasive brain stimulator. Purpose: The purpose of this study was to evaluate the cortical excitability and motor performance after 20 minutes TENS intervention by 15, 120Hz and sham stimulation applied on primary motor cortex. Methods: Twenty-four healthy adults, mean age of 22.45±1.17 years old, were participated in this study. Three different TENS interventions (15, 120Hz and sham stimulation) was provided in random order. Measurements including cortical excitability and motor performance by TMS and motor task of finger pinch will be evaluated at baseline, after intervention and follow-up (30 and 60 minutes after stimulation). Results: After intervention, motor evoked potential (MEP), normalized MEP, 2ms of intracortical inhibition (ICI2) and 15ms of intracortical facilitation (ICF15) immediately significantly increased (p=0.029, 0.002, 0.002, <0.001) and then significantly decreased at follow-up (p=0.005, <0.001, 0.038, 0.001) in 15Hz stimulation group. Only normalized MEP found significant increase immediately (p=0.007) and MEP and normalized MEP showed significant decrease (p=0.026, 0.034) after 60 minutes follow-up in 120Hz stimulation group. No significant change about motor performance was revealed in any kind of stimulation. Conclusion: The results of our study confirmed that TENS could be a safe and feasible tool for cortical excitability modulation. Twenty minutes TENS stimulation could significantly change the cortical excitability. The effect of 15 Hz TENS stimulation was more significant than 120 Hz. The results would provide some evidence for clinical trials in order to advance clinical training on rehabilitation in the future.