Objective: The objective of the current study is to refine understanding of the pathophysiological mechanisms underlying freezing of gait (FOG) in Parkinson’s disease (PD) using a multimodal imaging approach.

Background: FOG is a common debilitating motor symptom of PD, affecting over 50% of the patients in the advanced stages. The underlying pathophysiology of FOG is not yet fully understood. The current study uses a multimodal imaging approach aiming to clarify the relative contributions of structural connectivity, functional connectivity and grey matter integrity to the FOG phenotype.

Methods: Thirty-five PD patients with FOG and twenty-one PD patients without FOG, matched for age, disease duration, Hoehn and Yahr stage and levodopa equivalent dose underwent diffusion tensor imaging (DTI), structural magnetic resonance imaging (MRI) and resting state MRI.

Results: Tract-based spatial statistics were applied to compare fractional anisotropy of white matter fibers across the whole brain between the two groups. Preliminary results demonstrate that patients with FOG show local reductions in FA in white matter across a range of regions that have previously been implicated in FOG including bilateral orbitofrontal cortex, right lateral occipital cortex, frontal cortex and subcortical caudate compared to patients without FOG. Extensions to the current analyses include resting state functional connectivity, voxel-based morphometry and cortical thinning assessment.

Conclusions: This study identified an association between FOG and intrahemispheric diffuse white matter damage. Combined analyses incorporating the current structural connectivity findings with measures of functional connectivity and grey matter integrity will characterise the multimodal neural changes associated with the FOG phenotype in PD. Establishing the neural correlates of FOG in PD across multiple levels of structure and function is a critical step in refining our understanding of the underlying pathophysiological mechanisms.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/multi-modal-imaging-in-parkinsons-disease-patients-with-freezing-of-gait/