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.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Exploratory/Developmental Grants (R21)
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Motor Function, Speech and Rehabilitation Study Section (MFSR)
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Ludwig, Kip A
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Rehabilitation Institute of Chicago
United States
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Liu, Jie; Li, Xiaoyan; Li, Guanglin et al. (2014) EMG feature assessment for myoelectric pattern recognition and channel selection: a study with incomplete spinal cord injury. Med Eng Phys 36:975-80
Liu, Jie; Li, Sheng; Li, Xiaoyan et al. (2014) Suppression of stimulus artifact contaminating electrically evoked electromyography. NeuroRehabilitation 34:381-9
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Liu, Jie; Zhou, Ping (2013) A novel myoelectric pattern recognition strategy for hand function restoration after incomplete cervical spinal cord injury. IEEE Trans Neural Syst Rehabil Eng 21:96-103
Zhang, Xu; Chen, Xiang; Barkhaus, Paul E et al. (2013) Multiscale entropy analysis of different spontaneous motor unit discharge patterns. IEEE J Biomed Health Inform 17:470-6
Zhang, Xu; Zhou, Ping (2013) Filtering of surface EMG using ensemble empirical mode decomposition. Med Eng Phys 35:537-42
Zhang, Xu; Zhou, Ping (2012) Sample entropy analysis of surface EMG for improved muscle activity onset detection against spurious background spikes. J Electromyogr Kinesiol 22:901-7

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