Ekstedt J, Nilsson G, Stalberg E
J Neurol Neurosurg Psychiatry. 1974 May;37(5):526-39. doi: 10.1136/jnnp.37.5.526.
The electromyographic jitter is the variability at consecutive discharges in the time interval between two action potentials from two muscle fibres from the same motor unit. This paper deals with different methods of expressing the jitter. The method of choice seems to be Mean Consecutive Difference (MCD)[FORMULA: see text]where D(1), D(2) etc. are the individual time interval measurement data and n the number of discharges, preferably 50 or, if the jitter is not changing, 200. MCD can also be estimated from other measures of the jitter like Mean Range of Two (MR(2)) (giving the same estimated value as MCD), Mean Range of Five (MR(5)), Mean Range of Ten (MR(10)) and also from the Standard Deviation (SD). In a distribution without trends the following relations hold:MCD = 1·13×SDMCD = 0·49×MR(5)MCD = 0·37×MR(10)·The presence of slow variations and trends in most recordings makes SD not well suited for calculation because of the risk of getting too high estimates of the jitter.
肌电图的颤抖是指来自同一运动单位的两根肌纤维的两个动作电位之间的时间间隔内,连续放电时的变异性。本文探讨了表达颤抖的不同方法。首选方法似乎是平均连续差(MCD)[公式:见原文],其中D(1)、D(2)等是各个时间间隔测量数据,n是放电次数,最好为50次,或者如果颤抖没有变化,则为200次。MCD也可以从颤抖的其他测量指标中估算得出,如双平均范围(MR(2))(与MCD给出相同的估算值)、五平均范围(MR(5))、十平均范围(MR(10))以及标准差(SD)。在无趋势的分布中,以下关系成立:MCD = 1.13×SD;MCD = 0.49×MR(5);MCD = 0.37×MR(10)。由于大多数记录中存在缓慢变化和趋势,标准差不太适合用于计算,因为存在高估颤抖的风险。