Thilmann A F, Fellows S J, Garms E
Neurologische Klinik mit klinischer Neurophysiologie, Alfried Krupp Krankenhaus, Essen, Germany.
Brain. 1991 Feb;114 ( Pt 1A):233-44.
The electromyographic (EMG) response of the initially passive biceps brachii muscle to imposed extension applied at the elbow was studied in 19 hemiparetic and 12 normal subjects. In relaxed normal subjects, the biceps muscle was found to respond only at displacement velocities above 175 deg/s, with a single early burst of activity in the biceps EMG. In contrast, the hemiparetic subjects, in addition to the early EMG activity, also showed considerable late activity, which persisted even with stretch velocities as low as 35 deg/s. This late activity is a stretch reflex, present in fully plegic arms. It was seen in all spastic subjects in whom the tone of the biceps had been clinically assessed to be raised, but was never observed in subjects with normal muscle tone. The mean level of this EMG response was highly correlated with displacement velocity and its duration to the duration of the applied displacement. It is suggested that this reflex EMG activity is the major factor in the genesis of spastic hypertonus in the arm and that it arises not from a reduction in the threshold of the stretch reflexes of the muscle, but from a pathological increase in stretch reflex gain. It is further shown that this activity is at a high level between the first and third months after the onset of spasticity and that the reflex gain is significantly reduced when spasticity is established for a year or more. It is concluded that, while changes in passive mechanical properties may play a role when spasticity has been established for more than a year, the major cause of spastic muscle hypertonus is a pathological increase in stretch reflex activity.
在19名偏瘫患者和12名正常受试者中，研究了最初处于被动状态的肱二头肌对施加于肘部的强迫伸展的肌电图（EMG）反应。在放松的正常受试者中，发现肱二头肌仅在位移速度高于175度/秒时才有反应，肱二头肌肌电图中有一次早期的活动爆发。相比之下，偏瘫患者除了早期肌电图活动外，还表现出相当多的晚期活动，即使在拉伸速度低至35度/秒时这种晚期活动仍持续存在。这种晚期活动是一种牵张反射，存在于完全瘫痪的手臂中。在所有临床上评估肱二头肌肌张力升高的痉挛性受试者中均可见到这种牵张反射，但在肌张力正常的受试者中从未观察到。这种肌电图反应的平均水平与位移速度及其持续时间与施加位移的持续时间高度相关。有人认为，这种反射性肌电图活动是手臂痉挛性高张力产生的主要因素，它不是源于肌肉牵张反射阈值的降低，而是源于牵张反射增益的病理性增加。进一步表明，这种活动在痉挛发作后的头三个月内处于高水平，而当痉挛持续一年或更长时间时，反射增益会显著降低。得出的结论是，虽然被动力学特性的变化在痉挛持续一年以上时可能起作用，但痉挛性肌肉高张力的主要原因是牵张反射活动的病理性增加。
