Hughes A R, Colebatch J G
Department of Neurology, Prince of Wales Hospital, Sydney, Australia.
Muscle Nerve. 1996 Jul;19(7):836-42. doi: 10.1002/(SICI)1097-4598(199607)19:7<836::AID-MUS4>3.0.CO;2-A.
Surface electromyogram potentials were recorded from the abductor pollicis brevis, abductor digiti minimi, and extensor digitorum brevis muscles in response to finely graded nerve stimuli. Successive potentials were subtracted to obtain intermediate potentials 2%, 5%, 10%, 20%, and 50% of the maximal compound muscle action potential (mCMAP). The average latency of the onset and negative and positive peaks, and the average duration of the negative phase and whole potential were similar for all degrees of fractionation, although smaller fractionation was associated with increasing variability. An initial positivity occurred with some of the smaller fractions of the CMAP, particularly those with the lowest stimulus threshold. Submaximal CMAPs closely resembled the mCMAP once their amplitude was greater than 5-10% of the mCMAP. Our results support the common practice of expressing H-reflex amplitudes as a percentage of the M wave and may partly explain why reflexes "scale" in response to tonic activation.
记录拇短展肌、小指展肌和趾短伸肌在精细分级神经刺激下的表面肌电图电位。对连续的电位进行减法运算，以获得最大复合肌肉动作电位（mCMAP）的2%、5%、10%、20%和50%的中间电位。尽管较小的分级与变异性增加相关，但所有分级程度下起始、负峰和正峰的平均潜伏期以及负相和整个电位的平均持续时间相似。一些较小分级的CMAP会出现初始正性波，尤其是那些刺激阈值最低的情况。一旦次最大CMAP的幅度大于mCMAP的5-10%，它们就与mCMAP非常相似。我们的结果支持将H反射幅度表示为M波百分比的常见做法，并且可能部分解释了为什么反射会随着强直激活而“缩放”。
