重症肌无力的重复电刺激研究

Study on the repetitive nerve electric stimulation in myasthenia gravis.

目的 确定重复电刺激（ＲＮＳ） 检查对重症肌无力（ＭＧ） 的诊断价值，探讨提高诊断敏感度的方法。方法 对８０ 例ＭＧ 进行了不同肌肉、运动前后的低频ＲＮＳ对比研究，同时比较了面神经高低频ＲＮＳ 的结果。结果 ＭＧ 患者ＲＮＳ 的波幅衰减主要出现在低频刺激时，三角肌的诊断敏感度最高（６８％ ） ，小指外展肌最低（２３ ％ ），口轮匝肌（４８ ％ ） 、斜方肌（４６ ％ ） 、肘肌（４１ ％ ） 介于二者之间。五块肌肉ＲＮＳ的总阳性率为７９ ％ ，１２－５ ％ 的肌肉出现了“运动或强直后衰竭”现象。结论 ＲＮＳ检查对于ＭＧ的诊断有很大的价值，通过运动或强直刺激肌肉以及增加所查肌肉数目，可以提高ＲＮＳ的诊断阳性率。

Objective To assess the diagnostic value of repetitive nerve stimulation (RNS) and find the ways to improve the diagnostic sensitivity of RNS in myasthenia gravis(MG). Methods The results of RNS at low freguancies in different muscles before and after exercise and the ones of RNS of facial nerve at low and high frequancies were respectively compared in 80 patients with MG. Results The decrement response of RNS was more prominent at low rate in MG; deltoid was the muscle of the highest diagnostic sensitivity (68%): abductor digiti quinti the lowest (23%); between them were orbicularis oris (48%), trapezius (46%) and anconeus (41%). The total positive rate of RNS in five muscles was 79%, 12.5% of muscles showed “posttetanic or postexercise exhaustion”. Conclusions RNS tests have great diagnostic value in MG. There are two methods which can be employed to increase the diagnostic sensitivity of RNS, one is exercising or tetanis stimulating the muscle and the other is increasing the number of muscles examined.