肌肉磁刺激脑诱发电位传入机制的研究

目的：研究磁刺激肌肉脑诱发电位（ＭＭＳＥＰ）的传入机制。方法：对肌松弛下腓肠肌ＭＭ－ＳＥＰ及电刺激踝部胫后神经体感诱发电位（ＳＥＰ）进行配对对比研究。结果：（１）肌松弛无肌收缩时仍可记录到ＭＭＳＥＰ；（２）配对腓肠肌ＭＭＳＥＰ与胫后神经ＳＥＰＰ４０潜伏期差值伴与不伴肌收缩相差显著；（３）伴肌收缩时，ＭＭＳＥＰ较配对ＳＥＰＰ４０潜伏期显著延长，不伴肌收时则相差不显著。结论：正常伴肌收缩时，磁刺激很可能先兴奋肌肉运动神经末梢致肌肉运动，间接兴奋肌肉Ｉａ纤维或（和）肌肉深部感受器；由此可解释ＭＭＳＥＰ较电刺激同等水平ＳＥＰＰ４０潜伏期长。

Afferent mechanism of magnetic stimulation of muscle for cerebral evoked potentials.

The afferent mechanism of magnetic stimulation of muscle for evoked cerebral potentials(MMSEP) was studied through comparison of magnetic stimulation of the peroneus muscle under relaxation with electric stimulation of the posterior tibial nerve at the ankle site.The result showed that MMSEP could be recorded when musle contraction was absent during relaxation.A significant difference between MMSEP of the peroneus mulsle and the P 40 latency of the posterior tibial nerve was noted when there was no muscle contraction,and MMSEP was much more prolonged than P 40 latency during contraction.However,no significant difference was noted during relaxation.It was showed that under normal contraction,the motor nerve terminals of the muscle were initially excited by magnetic stimulation and the Ia fiber and / or the receptors of the muscle were indirectly excited.This might therefore,be an interpretation why P 40 latency of MMSEP is longer than under the same electric stimulation level in normal subjects.