Objective: To explore differences in functional connectivity of the basal ganglia in tremor dominant and non-tremor dominant Parkinson’s disease (PD) using seed-to-voxel based resting state functional MRI.

Background: PD can phenotypically be classified into tremor dominant, and non-tremor dominant PD (NTDPD). Several studies have suggested that tremor dominant PD (TDPD) has a relatively benign course in comparison to NTDPD, and displays a slower rate of progression of motor symptoms, and less cognitive impairment. This is suggestive of a possible difference in functional connectivity between NTDPD and TDPD.

Method: Fourteen patients of TDPD, and 14 patients of NTDPD underwent a 3T MRI with a 32-channel head coil, and resting state functional MRI was acquired. The CONN functional connectivity toolbox (version 18.b) was used to perform the preprocessing and analysis.  Seed-to-voxel connectivity was performed using bilateral caudate, putamen, and pallidum as seeds.  Statistical significance was set at 0.01 for uncorrected maps, and an arbitrary minimum cluster size of 100 was set for a region to be considered significant.

Results: Significantly reduced seed-to-voxel connectivity was observed in the NTDPD group involving the following regions – bilateral frontal pole, precuneus, cingulate gyrus, right orbitofrontal cortex, middle temporal gyrus, lateral occipital cortex, and angular gyrus.

Conclusion: NTDPD showed significant abnormalities in regions involved with cognition in comparison to TDPD. These results support the notion of a pathophysiological difference between TDPD and NTDPD, and provide an anatomical basis for the more prevalent cognitive impairment observed in NTDPD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/functional-connectivity-of-the-basal-ganglia-in-tremor-dominant-and-non-tremor-dominant-parkinsons-disease/