Comparison of post-SCI locomotor training techniques

近年来，人们对活动依赖性可塑性在促进神经损伤后功能恢复中的作用有了越来越多的了解。人们对脊柱机制在控制行走等行为中的作用也有了新的认识。研究表明，脊髓回路的活动依赖性适应性变化可能在脊髓损伤（SCI）患者的步行功能恢复中发挥重要作用，可能在自发恢复阶段很久之后。两种有效促进功能恢复的技术是体重支持（BWS）和功能电刺激（FES）。在初步研究中，观察到在脊髓损伤患者中，使用这些干预相结合的方法进行训练，可以提高地上行走速度、腿部力量和耐力。该提案将评估慢性不完全性脊髓损伤患者在三种训练条件之一下对bws辅助跑步机训练方案的反应：1)被动（手动）辅助行走，2)主动（FES）辅助行走，或3)非辅助（自愿）行走。每种情况都有不同的优势。手动辅助步进允许援助分级为个人需要；fes辅助行走利用了脊髓反射回路，可能有助于脊髓神经生理学的有益改变；自愿踏出自己的一步可能会鼓励最大的自愿努力。这些调查将确定哪种情况最能提高地上行走的效率，并将检查与三种训练形式相关的脊髓神经生理学、力量和心肺功能的变化。基于性能的测量将包括：评估下肢协调和步态关键参数（速度、步幅和步伐节奏）的计算机运动学分析，肌肉恢复的肌电图评估和评估力量和步态效率变化的工作能力评估。神经生理学技术（如反射测试和经颅磁刺激）将用于评估脊柱上、脊柱和外周控制机制，这些机制有助于行走、自主运动和反射激活。本实验将验证以下假设：1)与被动或不给予肢体推进辅助相比，脊髓损伤受试者在主动行走时行走能力得到更大程度的改善；2)fes辅助组的受试者训练后脊髓反射活动更接近正常值；3)步行时观察到的肌电图（EMG）活动比自主运动时观察到的EMG更强。这些研究将使我们能够比较旨在改善脊髓损伤患者功能活动能力的康复策略的疗效。此外，它们将提供有关这些功能变化的神经和心肺基础的信息。

In recent years there has been an increased understanding of the role of activity-dependent plasticity in promoting functional recovery following neurologic injury. There is also an emerging appreciation for the role of spinal mechanisms in control of behaviors such as walking. Research indicates that activity-dependent adaptive changes in spinal cord circuitry may play an important part in the recovery of walking function in individuals with spinal cord injury (SCI), perhaps long after the stage of spontaneous recovery. Two technologies that appear effective in promoting functional recovery are body weight support (BWS) and functional electrical stimulation (FES). In preliminary studies, improved overground walking speed, leg strength and endurance was observed in subjects with SCI who trained using an approach combining these interventions. This proposal will assess, in individuals with chronic incomplete SCI, responses to a BWS-assisted treadmill training regimen under one of three training conditions: 1) passive (manual)-assisted stepping, 2) active (FES)-assisted stepping, or 3) non-assisted (voluntary) stepping. Each condition has distinct advantages. Manually-assisted stepping allows assistance to be graded to individual needs; FES-assisted stepping takes advantage of spinal reflex circuitry and may contribute to beneficial changes in spinal cord neurophysiology; and voluntary stepping may encourage the greatest voluntary effort. These investigations will determine which condition best promotes efficient overground walking, and will examine changes in spinal cord neurophysiology, strength and cardiorespiratory capacity associated with the three forms of training. Performance-based measures will include: computerized kinematic analysis to assess lower limb coordination and key parameters of gait (speed, stride length and step rhythm), electromyographic assessment of muscle recruitment and work capacity evaluation to assess changes in strength and gait efficiency. Neurophysiologic techniques (e.g., reflex testing and transcranial magnetic stimulation) will be used to assess supraspinal, spinal and peripheral control of mechanisms that contribute to walking, to voluntary movement and to reflex activation. The proposed experiments will test the hypotheses that: 1) walking performance in subjects with SCI improve to a greater extent when active, as opposed to passive or no assistance is given to advance the limb, 2) post-training spinal cord reflex activity will be more similar to normal values in those subjects who participate in the FES-assisted group, and 3) electromyographic (EMG) activity observed during walking will be more robust than EMG observed during voluntary movement. These studies will allow us to compare the efficacy of rehabilitation strategies aimed at improving functional mobility in individuals with SCI. In addition, they will provide information about neural and cardiorespiratory bases of these functional changes.