Windup of flexion reflexes in chronic human spinal cord injury: A marker for neuronal plateau potentials?
Windup of flexion reflexes in chronic human spinal cord injury: A marker for neuronal plateau potentials?
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DOI：
10.1152/jn.00979.2001
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发表时间：
2003-01-01
影响因子：
2.5
通讯作者：
Schmit, BD
中科院分区：
文献类型：
--
作者：
Hornby, TG;Rymer, WZ;Schmit, BD
脊髓损伤（SCI）后屈曲痉挛的生理基础可能涉及屈曲反射通路中脊髓神经元特性的改变。我们假设这些变化将表现为反射反应随着重复刺激应用的进行性增加（即，“卷紧”）的屈曲反射。我们研究了12例完全性慢性SCI患者的屈曲反射反应的终止。使用不同强度和刺激间隔的足底皮肤电刺激来触发足底反射。对于阈值和阈上刺激，在所有患者中，在刺激间隔小于或等于3s时，观察到踝关节和髋关节屈曲扭矩峰值以及胫骨前肌综合肌电图活动的饱和。对于阈下刺激，反射易化仅在小于或等于1s的时间间隔内发生。同样，屈曲反射的潜伏期在间隔小于或等于1s时显著降低。正在接受抗痉挛药物治疗的患者（e.例如，在一个实施例中，巴氯芬）比那些没有服用这些药物的人具有令人惊讶的更大的反射反应的终止，尽管这种差异可能与受试者组之间的痉挛频率的差异有关。结果表明，脊髓神经元兴奋性在一系列电刺激后的增加持续小于或等于3s，类似于以前的伤害性加工研究。这种长asting增加屈曲反射反应表明，细胞机制，如高原电位脊髓运动神经元，中间神经元，或两者，可能部分介导脊髓过度兴奋的下行调制输入的情况下。
The physiological basis of flexion spasms in individuals after spinal cord injury (SCI) may involve alterations in the properties of spinal neurons in the flexion reflex pathways. We hypothesize that these changes would be manifested as progressive increases in reflex response with repetitive stimulus application (i.e., "windup") of the flexion reflexes. We investigated the windup of flexion reflex responses in 12 individuals with complete chronic SCI. Flexion reflexes were triggered using trains of electrical stimulation of plantar skin at variable intensities and inter-stimulus intervals. For threshold and suprathreshold stimulation, windup of both peak ankle and hip flexion torques and of integrated tibialis anterior electromyographic activity was observed consistently in all patients at inter-stimulus intervals less than or equal to3 s. For subthreshold stimuli, facilitation of reflexes occurred only at intervals less than or equal to1 s. Similarly, the latency of flexion reflexes decreased significantly at intervals less than or equal to1 s. Patients that were receiving anti-spasticity medications (e. g., baclofen) had surprisingly larger windup of reflex responses than those who did not take such medications, although this difference may be related to differences of spasm frequency between the groups of subjects. The results indicate that the increase in spinal neuronal excitability following a train of electrical stimuli lasts for less than or equal to3 s, similar to previous studies of nociceptive processing. Such long-asting increases in flexion reflex responses suggest that cellular mechanisms such as plateau potentials in spinal motoneurons, inter-neurons, or both, may partially mediate spinal cord hyperexcitability in the absence of descending modulatory input.