Objective: To study structural Gray Matter (GM) and White Matter (WM) changes in Parkinson’s Disease (PD) patients with Freezing of Gait (FOG).

Background: FOG is a disabling disturbance experienced by many PD patients, characterized by inability to start locomotion and to move forward, mostly occurring during turning or step initiations. Although recent Magnetic Resonance Imaging (MRI) studies underlined the involvement of certain brain areas in FOG patients there is still lack of agreement between authors.

Methods: This  study included 21 PD patients with FOG, 16 PD patients without  FOG (nFOG) and 19 healthy subjects (HS). Severity of motor symptoms was evaluated by Hoen & Yahr (H&Y) and Unified Parkinson’s disease rating scale part III (UPDRS III). Cognitive impairment was excluded by using Mini Mental State Examination (MMSE) (> 26). FOG was assessed using FOG Questionnaire (FOG-Q). Participants underwent a standardized 3T MRI protocol.

Gray Matter measures Cortical volume (CV), Cortical thickness (CTh), and Surface Area (SA) were obtained by an automated surface-based analysis of T1-3D images using FreeSurfer pipeline.

White Matter measures DTI images were analyzed using two procedures: Tract-Based Spatial Statistics (TBSS) in FMRIB Software Libray (FSL) and Tracts Constrained by Underlying Anatomy (TRACULA) in FreeSurfer.

Results: Significant reduction in Cth was found in the comparison between the whole group of PD patients and HS in the left superior frontal area and in the right caudal middle frontal area. When we compared SA between groups, significantly smaller SA in the right supramarginal and superior parietal areas in FOG patients than in nFOG patients were found. Moreover, significant WM changes were observed in FOG patients in the temporal bundle of the superior longitudinal fasciculus, uncinate fasciculus and cingulum cingulate gyrus (mostly in the right hemisphere). Finally, DTI abnormalities in the uncinate fasciculus, cingulum, and corpus callosum significantly correlated with MMSE scores.

Conclusions: Structural abnormalities observed in the right frontal and posterior parietal areas in FOG patients than in nFOG and HS supports the largely accepted hypothesis of a relationship between FOG severity and executive dysfunction and suggests that FOG could result from neuronal circuitry dysfunction of the parietal areas in the right hemisphere.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/morphometric-changes-in-parkinsons-disease-manifesting-freezing-of-gait/