Lin J P, Brown J K, Walsh E G
One Small Step Gait and Movement Laboratory, Guy's and St Thomas' Hospital Trust, London, UK.
Dev Med Child Neurol. 1999 Aug;41(8):534-48. doi: 10.1017/s0012162299001152.
The electromyographic (EMG) responses to tendon taps at the ankle and ensuing muscular twitch forces and temporal parameters were studied at varying angles across the joint range in 18 children, aged 3 to 14.9 years, with congenital hemiparetic cerebral palsy and 22 healthy (control) children, aged 3 to 13.6 years. Those subjects with hemiparesis were community ambulators without assistance. In all subjects, passive muscle stretch caused a waxing of the reflex EMG and twitch force near neutral (with the sole of the foot at right angles to the tibia) and a diminution of these with further dorsiflexion. Twitch times increased with each dorsiflexing increment, being slowest at maximum dorsiflexion and fastest at the resting plantarflexion angle. Heterogeneity of the hemiparetic-limb data is evident when compared with data of non-paretic and unaffected limbs, with clear differences in the clonic (fast twitch) as opposed to non-clonic (slow twitch) muscles. In four cases with clinical clonus, clonus frequency was reduced by passive dorsiflexion. Plaster immobilization for 1 month produced clonus which was previously absent in one subject, and caused a fast-twitch phenotype to emerge in two subjects. Follow-up after heel-cord lengthening in one subject showed that clonus frequency diminished from 9 to 3 Hz with slowing and strengthening of muscle-twitch phenotype. Short- and long-term peripheral manipulations appear to regulate neuromuscular excitability according to whether muscles are loaded or unloaded. Although damage to the nervous system provides the setting for reflex excitability, the data suggest that the muscle length (which specifies the joint angle) and the muscle-twitch phenotype of any given limb for any given case appear to dictate the actual speed and strength of reflex muscle-twitch and clonus profiles. This study illustrates how peripheral manipulations of muscles and tendons may alter the expression of what have hitherto been considered as exclusively central phenomena.
在18名年龄在3至14.9岁的先天性偏瘫型脑瘫儿童和22名年龄在3至13.6岁的健康（对照）儿童中，研究了踝关节肌腱叩击后的肌电图（EMG）反应以及随之产生的肌肉抽搐力和时间参数，这些研究是在关节活动范围内的不同角度进行的。患有偏瘫的受试者均为无需辅助的社区步行者。在所有受试者中，被动肌肉拉伸会使反射性肌电图和接近中立位（足底与胫骨成直角）时的抽搐力增强，而随着进一步背屈，这些指标会减弱。每次背屈增加时抽搐时间都会增加，在最大背屈时最慢，在静息跖屈角度时最快。与非偏瘫和未受影响肢体的数据相比，偏瘫肢体数据的异质性很明显，在阵挛性（快速抽搐）肌肉与非阵挛性（缓慢抽搐）肌肉之间存在明显差异。在4例临床阵挛病例中，被动背屈可降低阵挛频率。一名受试者进行1个月的石膏固定后出现了之前不存在的阵挛，并使两名受试者出现了快速抽搐表型。一名受试者跟腱延长后的随访显示，随着肌肉抽搐表型的减慢和增强，阵挛频率从9次/秒降至3次/秒。短期和长期的外周操作似乎根据肌肉是加载还是卸载来调节神经肌肉兴奋性。尽管神经系统损伤为反射兴奋性提供了条件，但数据表明，对于任何给定病例，任何给定肢体的肌肉长度（决定关节角度）和肌肉抽搐表型似乎决定了反射性肌肉抽搐和阵挛特征的实际速度和强度。这项研究说明了对肌肉和肌腱的外周操作如何可能改变迄今为止被认为是完全中枢性现象的表现。
