单纤维肌电图诊断眼肌型重症肌无力的敏感性分析

目的分析眼肌型重症肌无力(OMG)患者额肌单纤维肌电图(SFEMG)表现并辅助临床诊断。方法选择临床确诊为OMG患者27例,对患者行额肌SFEMG检测,同时行低频重复神经电刺激(RNS)、乙酰胆碱受体抗体(AChR-Ab)测定和新斯的明试验,比较上述检查方法的敏感性差异。结果额肌SFEMG检查结果显示,有18例患者(66.7%)异常,表现为颤抖增宽,其中6例伴有阻滞,平均颤抖值为(45.4±21.0)μs,高于正常对照组;颤抖值>55μs的电位对百分比为0%~80.0%,平均(24.2±24.5)%;阻滞百分比为0%~14%,平均(1.90±4.40)%;AchR-Ab滴度增高者8例(29.6%),其诊断OMG敏感性与额肌SFEMG敏感性存在差异;RNS异常者9例(33.3%),新斯的明试验阳性者23例(85.2%),上述2种检测方法与额肌SFEMG检查敏感性差异无统计学意义。结论额肌SFEMG检测是诊断OMG的一种敏感性较高的检测方法。

The Sensitivity Analysis of Single Fiber Electromyography in Ocular Myasthenia Gravis

Objective To study and estimate the value of SFEMG of the frontalis muscle in the diagnosis of ocular myasthenia gravis(OMG),comparing the sensitivity of the SFEMG of the frontalis muscle,repetitive nerve stimulation(RNS),blood concentration of antibody to the acetylcholine receptor(AchR-Ab) and neostigmine test.Methods In insulated room of 25 ℃,we performed SFEMG of the frontalis muscle in 27 patients with OMG who attended Beijing Tongren Hospital from August 2006 to January 2007 and 12 controls.RNS,AchR-Ab titration and neostigmine test were also performed.Results 1) Eighteen of twenty seven patients had abnormal recordings in SFEMG of the frontalis muscle,the mean jitter ranged from 20 to 97 us(average 45.4±21.0 μs),the ratio of jitter >55 μs was(24.2±24.5)% and percentage of blocks was(1.9±4.4)%,in the controls,the mean jitter ranged from 19 to 40 μs average(27.4±6.6 μs);9 of 27 patients were abnormal in low frequencies of RNS,among which 7 patients had abnormality in facial nerve,one in facial and axillary nerve and one in axillary nerve;AchR-Ab titersns were increased in 8 patients;23 of 27 patients were positive in neostigmine test.2) Sensitivities of ACh-Ab titration(29.6%) in patients with OMG were remarkably lower than SFEMG of the frontalis muscle,sensitivity of RNS(33.3%),neostigmine test(85.2%) was not different from SFEMG of the frontalis muscle.Conclusion SFEMG of the frontalis muscle shows higher sensitivity for the diagnosis of OMG than RNS and AchR-Ab titration.