Electronic Thesis and Dissertation Repository

Degree

Master of Science

Program

Neuroscience

Supervisor(s)

Dr. Mandar Jog

Abstract

Subthalamic (STN) deep brain stimulation (DBS) alleviates common appendicular PD symptoms, such as: tremor, rigidity and bradykinesia. However, the effect STN-DBS has on modulating axial gait features has not been properly quantified objectively. The purpose of the present thesis was to investigate the role STN-DBS plays in modulating specific gait features such as pace, asymmetry, variability, rhythm and postural control. It is hypothesized that axial gait function is regulated predominantly by non-dopaminergic control systems. In the acute immediate post-operative phase a surgical effect, named the microlesion effect (MLE), is thought to produce a transient improvement of appendicular and axial symptoms. It was hypothesized the MLE is a surgical effect, having a non-specific influence on both appendicular and axial symptoms. Following surgical recovery and 6 months of clinically optimized STN-DBS, it was expected that the true STN-DBS effects would be presented. It was hypothesized that STN-DBS plays an important role in the dopaminergic basal ganglia circuit and a lesser role in the non-dopaminergic system. 10 individuals with PD who were approved for STN-DBS along with 11 healthy age-matched controls were used in the study. The participants were asked to walk across a 7 metre long gait analysis carpet at a self-selected paced walk (SELF) and a fast-as-possible walk (FAST). However, in the current study we found no improvement on Unified Parkinson’s Disease Rating scale (UPDRS) appendicular scores and axial gait features at baseline, 1 week post-operation and 2 weeks post-operation. At 6 months, it was found that UPDRS scores improved for appendicular items but remained unchanged in the axial items. Furthermore, axial gait features remained unchanged in the SELF and FAST walks. Overall, axial gait function failed to improve from the MLE and STN-DBS. While the sample size was small, this finding may suggest an influence of regions outside the STN on axial function. Further analysis with more subjects should be conducted to verify the current findings.


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