重症肌无力常规针极肌电图表现

A Study on the Routine Needle Electromyography Findings in Patients with Myasthenia Gravis

目的研究重症肌无力(MG)患者常规针极肌电图(EMG)表现及其诊断价值。方法回顾性分析83例完成右侧三角肌针极EMG、腋神经低频重复电刺激(RNS)和伸指总肌单纤维肌电图(SFEMG)检查的MG患者的有关资料,分析针极EMG的表现及其与RNS的相关性。结果83例中EMG检查结果正常12例(14.5%),异常71例(85.5%)。在EMG异常者中,出现平均运动单位电位(MUAP)时限缩短67例(94.4%),多项波增多者37例(52.1%),大力收缩时募集电位呈病理干扰相19例(26.8%),异常自发电位3例(4.2%),结果符合"肌源性损害"表现19例(26.8%)。腋神经RNS时三角肌波幅衰减幅度与三角肌平均MUAP时限呈负相关。结论MG患者常规EMG检查主要异常表现为MUAP时限缩短,少数可见"肌源性损害"的EMG表现。对于临床表现不典型的MG患者应检查EMG并结合RNS和SFEMG检查进行诊断和鉴别诊断。

Objective To investigate the routine needle electromyography （EMG） findings and its diagnostic value in patients with myasthenia gravis （MG）. Methods Eighty-three MG patients underwent needle EMG on right deltoid muscle, repetitive nerve stimulation （RNS） of axillary at low rates and single fiber electromyography （SFEMG） on extensor digitorum communis. The needle EMG findings and their relationship with RNS were analyzed retrospectively. Results The needle EMG was normal in 12/83 （14.5%） and abnormal in 71/83 （85.5%） patients. Among the abnormal 71 patients, 67（94. 4%） patients had a shortening of the mean duration of motor unit action potential（MUAP）, 37 （52.1%）an increase in polyphasia, 19 （26.8%） a full interference pattern of reduced amplitude during maximal voluntary effort and 3 （4.2%） abnormal fibrillations and positive sharps, 19 （26.8%） definite ＂myopathic changes＂. There was a significantly negative correlation between the amplitude decrement of deltoid in RNS and the mean duration of MUAP in deltoid. Conclusions The main abnormal findings were a shortening of the mean duration of MUAP and minority might show ＂myopathic changes＂ when needle EMG was conducted in MG patients. Needle EMG, combined with RNS and SFEMG can be used to diagnosis and differential diagnosis the atypical MG.