Objective: To better understand the pathophysiology of essential tremor (ET) by analysing brainstem and cerebellar neuronal circuitry activity with tailored fMRI resting state methods.

Background: ET is a highly prevalent movement disorder with a largely unknown pathophysiology. Because tremor and movement co-occur, the tremor related neuronal activity is intermingled with motor network activity and hampers task-based identification. Literature suggests changes in functional connectivity patterns of the ‘default’ or resting state network in tremor disorders. However, to investigate functional connectivity in pivotal areas relevant for tremor (cerebellum, brainstem), novel fMRI methods are needed.

Method: Fifteen ET patients with bilateral postural arm tremor were, off medication, compared to fourteen healthy controls. Resting state fMRI was acquired during eight minutes. We applied a standard normalization technique for the cortical and subcortical regions (FSL), as well as a specific normalization technique (SUIT) for the cerebellum, including a correction for the dentate nucleus position as derived from susceptibility-weighted MR imaging. For accurate brainstem signals, a masked independent component analysis (ICA) is applied which reduces physiological noise (CSF and arterial blood flow) in this area. Group analyses are derived from second-level analyses for the different regions of interest (seed-based connectivity) and ICA separately.

Results: Application of tailored techniques allowed to specifically investigate the cerebellar and brain area default network in tremor, while minimizing (physiological) noise. Preliminary results show different functional connectivity networks in the brainstem-cerebellar region between groups. Final group results will be shown at the convention.

Conclusion: Our findings show accurate identification of resting state activity in cerebellum and brainstem. By using tailored techniques focusing on cerebellum and brainstem we are able to reveal specific tremor network activations.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/functional-connectivity-within-the-cerebellum-and-brainstem-in-essential-tremor-patients-a-tailored-resting-state-fmri-approach/