Degeneration of motoneurons caudal to spinal lesion

描述（由申请人提供）：拟议项目的长期目标是了解脊髓损伤（SCI）引起的肌肉轻瘫、萎缩、无力和肌肉挛缩的复杂起源，这些疾病通常导致关节活动范围有限和肌肉内在力学特性的进行性变化。特别是，我们提出的研究计划依赖于最近发展的几种新的表面肌电图（EMG）技术来研究脊髓损伤后尾侧运动神经元变性的有争议的概念。使用运动单元数指数测量和高密度表面肌电记录和处理技术，我们将确定是否可以通过三个特定目标捕获可能由于尾侧运动神经元变性而瘫痪肌肉的运动单元结构和功能变化。也就是说，我们计划通过麻痹肌肉的运动单位数（目的1）和静止麻痹肌肉的自发肌电活动记录（目的2）来评估是否有证据表明运动神经元在脊髓损伤后尾变性。此外，我们将研究运动单位动作电位传播模式和神经支配区的变化，作为瘫痪肌肉中运动神经元丢失和随后肌纤维神经再生的标志，从而为运动神经元变性脊髓损伤提供次要证据（Aim 3）。本研究中使用的方法是非侵入性的，使用起来可能很方便，并且提供了比针刺肌电图和其他常规电生理方法更有价值的信息。这些新方法的发现将增强我们对脊髓损伤中潜在运动神经元退行性变的病理生理学的理解。这将为恢复正常肌肉功能的康复策略和设备的发展提供指导。本研究的发现对脊髓损伤的诊断和治疗，改善结果测量，以及帮助评估药物或治疗的效果也具有重要的临床价值。

DESCRIPTION (provided by applicant): The long-term goals of the proposed project are to understand the complicated origins of the spinal cord injury (SCI) induced muscle paresis, atrophy, weakness, and muscle contractures that often result in a limited range of joint motion and progressive changes in intrinsic muscle mechanical properties. In particular, our proposed research plan relies on several recently developed novel surface electromygram (EMG) techniques to investigate controversial concepts about caudal motoneuron degeneration after a spinal injury. Using motor unit number index measurements and high-density surface EMG recording and processing techniques, we will determine whether motor unit structure and function changes of paralyzed muscles, potentially due to caudal motoneuron degeneration, can be captured via three specific aims. Namely, we plan to assess whether there is evidence for motoneuron degeneration caudal to spinal injury using estimates of motor unit numbers in paralyzed muscles (Aim 1), and using the recorded spontaneous EMG activities in resting paralyzed muscles (Aim 2). In addition, we will examine alterations in motor unit action potential propagation patterns and innervation zones, as a marker of motoneuron loss and subsequent muscle fiber reinnervation in paralyzed muscles, thus providing secondary evidence for motoneuron degeneration caudal to spinal injury (Aim 3). The methods used in this study are noninvasive, potentially convenient to use, and offer valuable information beyond that provided by needle-based EMG and other routine electrophysiological methods. The findings from these novel methods will enhance our understanding of the pathophysiology of potential motoneuron degeneration in SCI. This will provide guidance for the development of rehabilitation strategies and devices for restoration of normal muscle functions. The findings from this study also have important clinical value for the diagnosis and treatment of spinal injury, improve outcome measurements, and help evaluate the effects of medication or therapies. PUBLIC HEALTH RELEVANCE: The proposed examination of spinal cord injury (SCI) patients using several novel surface EMG techniques will add new knowledge for understanding the complicated origins of the SCI induced muscle paresis, atrophy, weakness, contracture and other muscle mechanical changes, thus in turn providing guidance for the development of rehabilitation strategies and devices for restoration of normal muscle functions. The findings from the project will also have important clinical value to diagnosis and treatment of motor impairments from spinal injury.