Objective: To investigate the organization of functional neural networks in patients with functional (psychogenic) movement disorders (FMD).

Background: Although several task-based neuroimaging studies have pointed to abnormalities in sensorimotor and limbic connectivity in FMD, the underlying pathophysiology of this disorder remains poorly characterized. We sought to evaluate whole-brain organization of functional connections in FMD patients using a graph-theory based network analysis of resting-state fMRI data.

Methods: Resting state multi-echo BOLD fMRI and MP-RAGE images were obtained in 37 patients with clinically definite FMD and 37 age- and gender-matched healthy controls using a 3T Skyra Siemens scanner. Pre-processing was performed using the afni_proc.py script; ANATICOR was used for artifact detection and removal. Nodes used for network analysis were defined using a previously validated whole brain ROI atlas containing 200 ROIs. Graph theory measures were calculated for each node using functions from the Brain Connectivity Toolbox (MATLAB). Calculated graph theory measures included degree (the number of connections linking a given node to other nodes in the network) and betweenness centrality (the fraction of all shortest paths in a network that contain a given node), among others.

Results: As compared to controls, FMD patients demonstrated lower degree, a measure of general connectivity, in the right supplementary motor area. Patients also exhibited higher node betweenness centrality, a measure of functional integration, in the right supramarginal gyrus, left cerebellum, right medial frontal gyrus and left hippocampus. Patients exhibited reduced betweenness centrality in the right putamen, cerebellar vermis and right superior parietal lobule. Global and local network efficiency were not significantly altered in patients.

Conclusions: We propose that impaired functional organization in regions critical for sensorimotor integration and motor planning, including the SMA and cerebellum, may contribute to impairments observed in patients with FMD.

Abstract has also been submitted as an abstract to the 2016 American Academy of Neurology meeting (Vancouver, Canada).

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MDS Abstracts - https://www.mdsabstracts.org/abstract/deficits-in-sensorimotor-networks-in-functional-movement-disorders-a-graph-theory-based-network-analysis/