Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by resting tremor, slowness of movement, rigidity as well as postural instability and gait difficulties (PIGD) motor features. Nigrostriatal dopaminergic denervation is a key pathological factor in PD. Advancing PD is associated with disabling PIGD motor features, in particular freezing of gait (FoG). This is further complicated by fear of falling resulting in pervasive sedentariness where avoidance of physical activity leads to deconditioning, thereby aggravating a downward functional spiral. The dopaminergic medication-refractory nature of PIGD motor features in advancing PD implicates non-dopaminergic brain pathologies.~The investigators have novel preliminary data showing that non-acute vestibulopathy may be another important factor contributing to PIGD motor features in PD. Unlike sporadic intermittent vestibular disorders with a more acute onset, chronic bilateral vestibular dysfunction of older age. The investigators preliminary data suggest that vestibulopathy may be a critical determinant of imbalance and gait problems in PD (scientific premise). However, these preliminary observations need to be confirmed in a larger study using more dedicated assessment methods (knowledge gap). Closing this gap is important because of the potentially high clinical translational impact if preliminary findings can be verified. The investigators will also explore whether stimulation of the vestibular system may help to improve PIGD in a small exploratory pilot biomechanistic sub-study.
Balance problems and falls are common in people with Parkinson's disease but respond poorly to dopamine stimulating medications suggesting other causes. The main goal of this study is to assess whether imbalance and gait problems in people with Parkinson's disease may be related to vestibular (inner ear balance center) changes not related to loss of dopamine in the brain.