An investigation of the contribution of axial rigidity to turning deficits in individuals with Parkinson’s disease
Difficulty in turning is prominent in individuals with Parkinson’s disease (PD) and the resulting postural instability increases their risk of falling. Therefore, understanding the mechanisms underpinning turning deficits in PD is highly important for rehabilitation and fall prevention. The first aim of this thesis was to clarify the mechanisms of increased fall risk during turning in PD by emulating: head and neck rigidity in healthy adults, and then observing the effects on eye movements and whole-body coordination while turning on the spot. The results revealed that experimentally inducing head and neck rigidity had multiple effects on eye movement characteristics, step amplitude, and total steps taken to complete the turn. The resultant behaviour was similar to that previously observed in individuals with PD. The second aim of this thesis was to validate the use of Inertial Measurement Units (IMUs) in combination with mobile electrooculography (EOG) for measuring eye, head and whole body coordination during turning with a view to developing a methodology that could be used to assess the effects of exercise intervention on turning characteristics of PD patients in a clinical setting. The results showed excellent reliability when compared with measures obtained using a Vicon motion analysis system suggesting that IMUs provide a viable alternative to camera-based motion capture for accurately measuring turning behaviour. The third aim of the study was to conduct a scoping review to determine whether exercise-based rehabilitation is effective in reducing axial rigidity in individuals with PD. Four out of eleven studies eligible for inclusion focused explicitly on exercise-based treatment for axial rigidity in individuals with PD. The results of the scoping review were used to design a modified exercise programme aimed at improving axial rigidity and turning dysfunction in individuals with PD. The final aim was to carry out a pilot Randomized Control Trial to study the effects of a modified exercise programme on various markers of functional mobility and turning performance in PD patients; e.g., Unified Parkinson’s Disease Rating Scale (UPDRS) functional reach test, step size, total steps and improvement in fall efficacy scale in individuals with PD. These preliminary results support the notion that targeting axial deficits may be an effective rehabilitation approach for improving mobility and reducing falls in PD.
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