Value of single fiber electromyography in diagnosis of amyotrophic lateral sclerosis / 中华神经科杂志

ABSTRACT

Objective To assess the diagnostic value of single fiber electromyography(SFEMG)in amyotrophic lateral sclerosis(ALS).Methotis SFEMG was performed in extensor digitorum communis muscles(EDC)of 165 patients with AIS and 145 patients with other neurogenetic disorders.Grade scale of the medical research council(MRC)in EDC was assessed simultaneously.The patients were divided into four groups according to the MRC scale(MRC＞4 us MRC≤4)and different disease (AIS vs other neurogenetic disorders).The parameters of SFEMG between different groups were compared.Results When the strength of EDC was normal(MRC＞4),the mean jitter was(66.1±20.1)μs in ALS and (38.0±9.2)μs in other neurogenic disorders(t=9.05,P＜0.01),median of the percentage of jitter＞ 55μs was 55%in AIS and 0 in other neurogenic disorders(Z=-7.81.P＜0.01).median of the percentage of block was 6.7%in AIS and 0 in other neurogenic disorders(Z=-6.93,P＜0.01).There was significant difference in those parameters of SFEMG between the two groups.When the strength of EDC was abnormal(MRC≤4),the mean jitter was(93.5±31.2)μs in ALS and(52.8±25.9)μs in other neurogenic disorders(t=9.37,P＜0.01),median of the percentage of jitter＞55 μs was 86%in ALS and 20%in other neurogenic disorders(Z=-8.46,P＜0.01),median of the percentage of block was 20%in ALS and 0 in other neurogenic disorders(Z=-7.25,P＜0.01).There was significant difference in those parameters of SFEMG between the two groups.When SFEMG was performed in EDC with normal muscle strength,the sensitivity and specificity of mean jitter＞55μs for diagnosis of ALS were 70.2%and 92.7% respectively.Conclusions When SFEMG is studied for diagnosis of ALS,it is recommended to perform in muscles with normal strength.The mean jitter,the percentage of jitter＞55μ s and block are of great importance in differentiating ALS from other neurogenic disorders.