Kasai T, Hayes K C, Wolfe D L, Allatt R D
Department of Physical Medicine and Rehabilitation, Parkwood Hospital, University of Western Ontario, London, Canada.
Electroencephalogr Clin Neurophysiol. 1992 Apr;85(2):95-101. doi: 10.1016/0168-5597(92)90074-l.
The present study determined the effects of percutaneous electrical stimulation of the plantar surface on motor evoked potentials (MEPs) in tibialis anterior (TA) and soleus (SOL) of normal subjects following transcranial magnetic stimulation of motor cortex. The conditioning stimulation consisted of a 20 msec train of electrical pulses (500 Hz; 0.1 msec rectangular) delivered to the medial border of the sole of the foot at an intensity just subthreshold for evoking a flexion reflex. The conditioning (C) stimulation preceded the test (T) cortical stimulation by intervals of 20-130 msec. Magnetic stimulation of motor cortex (Cadwell MES-10) was delivered through a 9.5 cm focal point coil positioned tangential to the scalp and located with the rim over vertex. Five healthy adults served as subjects and each was investigated on at least 2 occasions. At C-T intervals 20-50 msec there was a mild inhibition of MEPs in both TA and SOL. This was followed by marked facilitation (greater than 300%) of MEPs at C-T intervals 50-85 msec in both TA and SOL in all subjects. At longer C-T intervals greater than 110 msec, there was an inhibition of MEPs in TA but not in SOL. Based on the time course of these 3 phases of MEP amplitude modulation, and different stimulation thresholds for each phase, it appears that separate neurophysiological processes underlie each phase of MEP modulation. These observations also suggest that percutaneous electrical stimulation may be useful as a means of enhancing low amplitude or subliminal MEPs in normal subjects or patients with myelopathy.
本研究确定了在对正常受试者的运动皮层进行经颅磁刺激后，经皮电刺激足底表面对胫前肌（TA）和比目鱼肌（SOL）运动诱发电位（MEP）的影响。条件刺激包括一系列持续20毫秒的电脉冲（500赫兹；0.1毫秒矩形波），以刚好低于引发屈肌反射阈值的强度施加于足底内侧边缘。条件（C）刺激在测试（T）皮层刺激之前，间隔时间为20 - 130毫秒。通过一个9.5厘米的聚焦线圈进行运动皮层的磁刺激（Cadwell MES - 10），该线圈与头皮相切放置，边缘位于头顶上方。五名健康成年人作为受试者，每人至少接受2次研究。在C - T间隔为20 - 50毫秒时，TA和SOL的MEP均有轻度抑制。随后，在所有受试者中，当C - T间隔为50 - 85毫秒时，TA和SOL的MEP均出现明显易化（大于300%）。在大于110毫秒的较长C - T间隔时，TA的MEP受到抑制，但SOL不受影响。基于MEP幅度调制这三个阶段的时间进程以及每个阶段不同的刺激阈值，似乎每个MEP调制阶段都有独立的神经生理过程作为基础。这些观察结果还表明，经皮电刺激可能作为增强正常受试者或脊髓病患者低幅度或阈下MEP的一种手段。
