Comparison of post-SCI locomotor training techniques

近年来，人们越来越多地了解活动依赖性可塑性在促进神经损伤后功能恢复中的作用。人们也逐渐认识到脊柱机制在控制行走等行为中的作用。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之后很长时间。在促进功能恢复方面似乎有效的两种技术是体重支持（BWS）和功能性电刺激（FES）。在初步研究中，在使用这些干预措施相结合的方法进行训练的SCI受试者中观察到地上行走速度，腿部力量和耐力的改善。本提案将评估慢性不完全性SCI患者在以下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）辅助踏步，2）主动（FES）辅助踏步，或3）非辅助（自愿）踏步。每种条件都有明显的优势。手动辅助踏步允许根据个人需求对辅助进行分级; FES辅助踏步利用脊髓反射回路，可能有助于脊髓神经生理学的有益变化;自愿踏步可能鼓励最大的自愿努力。这些研究将确定哪种条件最能促进有效的地上行走，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。基于绩效的衡量标准将包括：计算机化运动学分析，以评估下肢协调和步态的关键参数（速度、步幅和步频）;肌电图评估肌肉招募情况;工作能力评估，以评估力量和步态效率的变化。神经生理学技术（例如，反射测试和经颅磁刺激）将用于评估有助于行走、自主运动和反射激活的机制的脊髓上、脊髓和外周控制。拟议的实验将检验以下假设：1）与被动或没有辅助来推进肢体相反，当主动时，SCI受试者的行走性能得到更大程度的改善，2）在参与FES辅助组的那些受试者中，训练后脊髓反射活动将更类似于正常值，以及3）在行走期间观察到的肌电图（EMG）活动将比在随意运动期间观察到的EMG更稳健。这些研究将使我们能够比较旨在改善SCI患者功能活动性的康复策略的有效性。此外，他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.