Principal Investigator: Kevin C. McGill, PhD Project Staff: Zoia Lateva, PhD and Lisa Johanson, MS Project Category: Other Objective: The objective of this project is to develop more accurate methods for analyzing and interpreting electromyographic (EGM) signals. Such methods are useful for diagnosing neuromuscular disorders, planning aspects of curative and rehabilitation therapy, and evaluating response to treatment. They are also useful for studying the way in which muscles are organized and controlled in order to improve clinical outcomes in tendon-transfer surgeries, reconstructive surgeries, functional electrical stimulation, and therapeutic exercise. Research Plan: Our approach involves (1) developing biophysical models to understand the way in which the characteristics of the EMG signal are determined by the anatomical and physiological properties of the underlying tissue, (2) recording signals experimentally to investigate the way in which these properties are expressed in normal subjects and subjects with pathology, and (3) developing advanced signal-processing techniques to extract physiologically and clinically relevant information from EMG signals. Work Accomplished: We used EMG analysis to study the architectural organization of the brachioradialis muscle of the forearm. This muscle is a common candidate for tendon transfer in individuals with spinal cord injuries at the C5-C6 levels. It is a long, parallel-fibered muscle that is widely assumed to have a simple architecture in which all the fibers extend from origin to insertion and receive innervation in a single, centrally located endplate zone. However, our study suggests that brachioradialis actually consists of arrays of shorter fibers connected in series and has multiple endplate zones. Moreover, our results also show that some of its individual muscle fibers receive innervation from two different motoneurons at widely separated endplates. Expected Outcome: We believe that other long, parallel-fibered human muscles may also have series-fibered architectures, including several muscles of the thigh and back. A better understanding of the architecture of these muscles is important in tendon transfer and reconstructive surgeries, both for predicting biomechanical outcomes as well as for understanding issues related to the survivability of muscle fibers and intramuscular nerve branches at different proximodistal levels. The existence of doubly innervated fibers also raises a number of important questions about the development, role, and control of these fibers. We intend to investigate these issues in subsequent work. Funding Source: VA Medical Merit Review Funding Status: Funded |
