UBC Theses and Dissertations
Examination of preserved motor pathways in persons with motor-complete spinal cord injury Squair, Jordan W.
Previous work has demonstrated that mobility is consistently one of the most, if not the most important function persons with a spinal cord injury (SCI) desire following their injury. By increasing functional mobility, even slightly, there may be improved independence, leading to improved quality of life. While the current clinical examination for determining the level and severity of an SCI has proven to be very reliable and useful for standardizing SCI classification, it still has significant limitations that may limit a patient’s future mobility. For example, the measures used to assess motor function in the limb following a SCI may not be sensitive enough to detect minimal levels of preserved motor function, as they are limited to manual palpation and/or visual inspection. Furthermore, the extent of preservation of trunk musculature and the vestibulospinal pathway following an SCI remains unclear. Therefore, there is a need for more sensitive measures of remaining motor activity and a need to examine the integrity of individual motor pathways. Using transcranial magnetic stimulation (TMS) and vestibular evoked myogenic potentials (VEMPs), this thesis examined the integrity of the cortico- and vestibulospinal pathways in 16 persons with a motor-complete SCI and 16 able-bodied (AB) matched controls. Despite being clinically classified as motor-complete, persons with an SCI showed some observable muscle activity to cortico- and vestibulospinal stimulation, as well as in response to voluntary contractions. In general, the corticospinal responses in the SCI group were delayed compared to their AB matched controls. The muscle activity detected using TMS related to voluntary activation; however, TMS appears to detect preserved muscle activity below that which can be voluntarily activated. Overall, the results from this thesis provide evidence for the use of TMS and VEMPs to assist in determining the neurophysiological integrity of various motor pathways in persons with a motor-complete SCI. Using these techniques may provide clinicians with more accurate information about the state of various motor pathways and may offer a method to more accurately target rehabilitation.
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