Date of Award

Fall 2018

Document Type


Degree Name

Master of Science (MS)


Biomedical Engineering

First Advisor

Schmit, Brian D.

Second Advisor

Hyngstrom, Allison S.

Third Advisor

McGuire, John R.


Functional magnetic resonance imaging (fMRI) has provided evidence of neuroplastic changes following rehabilitation in stroke survivors. Botulinum toxin (BoNT) injection therapy has become a common approach to combating spasticity—a motor disorder characterized by a velocity dependent increase in muscle tone. The neurotoxin acts to inhibit muscle contraction, relieving spasticity symptoms with peak effects occurring between 4 and 6 weeks. With decreases in muscle tone, BoNT injections could free arm movement for rehabilitation, creating the opportunity for enhanced control of the upper limb, which would have underpinnings in altered brain activity. Given evidence of cortical activation changes following other stroke rehabilitative methods, it is expected that BoNT therapy would produce similar types of changes. The aim of this study was to quantify changes in task-related activity throughout the brain in stroke survivors undergoing BoNT therapy. Understanding the changes in cortical activity resulting from BoNT injections could help improve rehabilitation methods and predict functional outcome. Changes in cortical activation in response to BoNT injections have only been documented in a handful of studies. Of these past studies, participant pools tended to include patients with moderate to high functional ability of the affected limb. Although patients receiving BoNT injections often fall within a wide range of severity, BoNT injections have been shown to provide the biggest impact on the highly impaired population. BoNT injections have also been shown to provide greatest effects during the initial injections, and the effects on long-term spasticity treatment are less prevalent in the literature. In this study, we used a voxel-based approach to quantify neuroplastic effects and capture changes in activity throughout the brain, including regions outside the primary sensorimotor cortices. We recruited a majority of participants that presented with severe spasticity, who were scheduled to receive a round of BoNT injections as part of their standard of care. By assessing the brain activation associated with repeated injections, we obtained insight into BoNT on a long-term basis, as it is traditionally prescribed.

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