Objective: This study aimed at assessing structural and functional cerebellar alterations in Parkinson’s disease patients with postural instability and gait disorders (PD-PIGD).

Background: Brain structures other than basal ganglia are likely to be involved in the pathophysiological process of PD. The role of cerebellum in PD has been explored during motor tasks involving the hand, while few studies investigated its activity during gait-simulating tasks and dual-task even if gait difficulties are key features in PD-PIGD and dual-task situations can be very challenging for these patients.

Method: Twenty-one PD-PIGD patients and 23 age and sex-matched healthy controls underwent clinical, structural and functional MRI, including a motor-task (foot anti-phase movements) and a dual-task (foot anti-phase movements while counting backwards by threes). Regional grey matter cerebellar volumes were assessed automatically using an atlas propagation and label fusion strategy based on the freely available human cerebellum template and probabilistic atlas (SUIT). FMRI images were co-registered with structural images and cerebellar fMRI analysis was performed.

Results: PD-PIGD patients showed reduced volume of left cerebellum lobules VI and X, right lobule VIIIa, crus 1 and 2, bilateral lobules VIIb and vermis VIIb relative to healthy controls. During fMRI motor-task, PD-PIGD patients showed increased activity of bilateral cerebellum crus 1 and a reduced recruitment of right cerebellum lobule VIIIa relative to healthy subjects. During fMRI dual-task, PD-PIGD patients showed increased recruitment of right cerebellum crus 1 and 2 and reduced activity of left lobules I-IV relative to healthy controls.

Conclusion: PD-PIGD patients showed reduced volumes in several cerebellar motor and non-motor areas relative to controls. During both fMRI motor-task and dual-task, patients showed greater activation of cognitive cerebellar areas (crus 1-2) relative to healthy subjects and a reduced activity of motor areas (lobules I-IV and VIIIb). The increased activity of non-motor cerebellar areas might be a consequence of grey matter atrophy or an attempt to compensate the functional failure of cerebellar motor areas. Structural and functional MRI metrics focusing on cerebellum are useful to characterize brain correlates of motor and dual-task abilities in PD-PIGD patients.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/structural-and-functional-cerebellar-alterations-in-parkinsons-disease-with-postural-instability-and-gait-disorders/