Date of Award
Doctor of Philosophy (PhD)
Treatment of peripheral nerve injuries depends on an accurate diagnosis of their severity to inform treatment options. Current clinical practice often necessitates delayed electrodiagnostics or surgical exploration of the injury site to determine whether surgical repair is necessary. This delays patient treatment, increases the time that muscle is denervated, and may impose an unnecessary surgery if surgical repair is not ultimately required. While imaging techniques such as diffusion tensor imaging enable visualization of healthy nerve tissue, the inflammation and axonal loss present in injured nerve obfuscates diffusion signals and confounds quantification of injury severity. Diffusion basis spectrum imaging uses multiple tensors to model the anisotropic and isotropic tissue components which address these limitations to provide highly sensitive, fiber-specific signals in the presence of injury. This dissertation examines parameter maps generated by diffusion basis spectrum imaging, including fractional anisotropy, radial diffusivity, and axial diffusivity over a 12 week recovery period following a variety of rat sciatic nerve injury models to determine the evolution of these parameters in injured and regenerated nerve and inform future studies that may use these imaging parameters as outcome metrics. Further, when surgical repair is required to treat a severe peripheral nerve injury, functional recovery remains incomplete. Therapeutic electrical stimulation has been shown to promote axonal regeneration and functional recovery following peripheral nerve repair by accelerating axonal outgrowth, yet its clinical administration is limited to the intraoperative setting. Our lab has developed implantable, thin-film wireless electrical stimulators capable of delivering therapeutic electrical stimulation wirelessly to the injured nerve over a longer period. This dissertation explores the use of therapeutic electrical stimulation for up to 12 consecutive days in rat sciatic nerve injury models including cut and repair and 40 mm isograft repair to determine the optimal time course of stimulation to enhance axonal regeneration and functional recovery.
Wilson Z. Ray
Matthew R. MacEwan, Daniel W. Moran, Sheng-Kwei Song, Matthew D. Wood,
Available for download on Thursday, January 30, 2025