Jennum P, Winkel H, Fuglsang-Frederiksen A
Department of Clinical Neurophysiology, Hvidovre Hospital, University of Copenhagen, Denmark.
Electroencephalogr Clin Neurophysiol. 1995 Apr;97(2):96-101. doi: 10.1016/0924-980x(94)00293-g.
The aim of the study was to evaluate the effect of varying stimulus rates of repetitive transcranial magnetic stimulation (RTMS) on the motor evoked potentials (MEPs) recorded from the right abductor pollicis brevis muscle (APB). Thirteen normals were included. Stimuli were applied to the cortex and to the median nerve at the wrist. The cortical stimuli were applied without and with facilitation. Stimulus intensity was 1.2 times the motor threshold (TmAPB) for cortical stimulation and supramaximal for peripheral stimulation. Stimulus rates were 1, 2, 3, 5, 10 and 20 Hz. Nine pulses were applied in each stimulus series. At stimulus rates between 1 and 3 Hz no amplitude changes were observed throughout the stimulation. At 5 Hz stimulation inhibition of some of the MEPs was observed followed by MEPs with increased amplitude. At 10 Hz stimulation some MEPs were totally inhibited, interrupted by an MEP with increased amplitude, resembling clonic contraction. At 20 Hz the inhibition of the MEPs decreased (P < 0.05) compared to 10 Hz stimulation. Facilitation decreased the inhibition at 5 and 10 Hz stimulation (P < 0.01). On peripheral stimulation a decrement was observed with stimulus rates of 10 and 20 Hz. The study shows that RTMS exerts a complex influence on the MEPs depending upon stimulus rates. The pronounced inhibition and excitation of the MEPs at 5 and 10 Hz stimulation possibly reflects inhibition and excitation in the cortico-spinal neurons.
本研究的目的是评估重复经颅磁刺激（RTMS）不同刺激频率对从右侧拇短展肌（APB）记录的运动诱发电位（MEP）的影响。纳入了13名正常人。刺激分别施加于皮层和腕部的正中神经。皮层刺激分为不施加易化和施加易化两种情况。皮层刺激的强度为运动阈值（TmAPB）的1.2倍，外周刺激为超强刺激。刺激频率分别为1、2、3、5、10和20Hz。每个刺激系列施加9个脉冲。在1至3Hz的刺激频率下，整个刺激过程中未观察到波幅变化。在5Hz刺激时，观察到一些MEP受到抑制，随后波幅增大。在10Hz刺激时，一些MEP完全被抑制，中间被一个波幅增大的MEP打断，类似阵挛性收缩。在20Hz时，与10Hz刺激相比，MEP的抑制作用减弱（P<0.05）。易化作用使5Hz和10Hz刺激时的抑制作用减弱（P<0.01）。在外周刺激中，10Hz和20Hz刺激频率下观察到波幅递减。该研究表明，RTMS对MEP的影响复杂，取决于刺激频率。5Hz和10Hz刺激时MEP明显的抑制和兴奋可能反映了皮质脊髓神经元的抑制和兴奋。
