Doctor of Philosophy
Health and Rehabilitation Sciences
MacDermid, Joy C.
Alterations to the peripheral nervous system and neuromuscular physiology may impact hand function in a typical or clinical population, such as individuals with ulnar neuropathy. The mechanisms that influence these positive and negative changes are still not well understood. The three studies within my thesis aim to validate the reliability of decomposition-based quantitative electromyography (DQEMG) measurements and explore the changes in intrinsic hand neuromuscular physiology in a typical aging population and individuals recovering from a surgical intervention for severe ulnar neuropathy.
The purpose of the first study was to determine the test-retest reliability of near-fibre (NF) jiggle, a measure of motor unit stability. I found that NF jiggle had good measurement reliability with low error, especially when contrasted with traditional jiggle. The context of this reliability was specific to the intrinsic hand muscles: first dorsal interosseus (FDI), abductor digiti minimi (ADM), and fourth dorsal interosseous (4DI).
The purpose of the second study was to compare the intrinsic hand neuromuscular physiology of a typical aging population using multivariate analyses. I determined that with aging, there are decreases in motor unit number estimations (MUNE) and motor unit stability (NF jiggle) with increases to motor unit potential (MUP) area in the intrinsic hand muscles. Using a multivariate approach allowed for age-related differences and the relationship between the variables to be further elucidated.
The purpose of the third study was to describe the responses, functional outcome, and motor unit physiology of three participants following an ulnar nerve transfer surgery to treat severe ulnar neuropathy and the rehabilitation that followed. I determined that functional outcomes were associated with improvements to neuromuscular physiology and may be influenced by rehabilitation adherence. Also, factors such as comorbidities, psychosocial barriers and delay in treatment may affect functional outcomes and rehabilitation adherence.
Overall, the progression of quantitative EMG measurements and exploring mechanisms of neuromuscular changes in aging and clinical populations provide foundational knowledge that may impact rehabilitation and treatment approaches. I hope that my thesis may provide new avenues of assessment, treatment, and prognosis for persons with pathologies that influence hand function and neuromuscular physiology.
Summary for Lay Audience
Our hands are critical for achieving daily tasks like grabbing a cup of coffee or dressing ourselves. Changes to the muscles of the hand and nerves that connect to them, such as with aging or with diseases like compression of the nerve, may affect the ability of the hand to perform tasks. How these changes happen are not always well understood. The goal of the studies within my thesis are to check the stability of a measurement technique, known as electromyography (EMG), which is used to explore muscle and nerve physiology. Further, I used EMG to explore changes in the hand muscles and nerves in a healthy aging population and individuals recovering from a nerve surgery. This surgery is specifically used to treat cases of elbow nerve compression which has led to a decreased ability for the individuals to use their hand muscles.
The first study of my thesis checked the reliability of an EMG measurement in individual’s hand muscles. When we tested and retested the same EMG measurement in the hand muscles, it showed good consistency. The purpose of my second study was to compare the hand muscles and nerves of young, middle, and older aged healthy individuals. When we compared older individuals to younger ones, we found that there are less nerve connections to the muscles and the consistency of this signal transmission from the nerves to the muscles decreases in quality with age. Finally, the third study of my thesis looked at three specific patients that received a new nerve surgery procedure to treat severe nerve compression at the elbow. My study looked at the recovery process of these three patients and used EMG to explore muscle and nerves of the hand. The success of their recovery not only related to the muscles and nerves of the hands but also to when the patient received the nerve surgery, other diseases they may have had, their mental health and social situations. Overall, I hope that the studies in my thesis, which measure the hand muscle and nerves. will contribute to new ways of treating people who have difficulties with their hand muscles.
Tsang, Philemon, "Assessment of Intrinsic Hand Neuromuscular Physiology" (2020). Electronic Thesis and Dissertation Repository. 6960.
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