Session Time: 1:15pm-2:45pm
Location: Agora 3 West, Level 3
Objective: To investigate in vivobrainstem structural connectivity changes in a model of premanifest synucleinopathy, REM sleep behavior disorder (RBD), using 7 T high spatial-resolution diffusion-tensor-imaging (DTI) and a recently developed brainstem nuclei atlas [1-2].
Background: RBD patients show a loss of muscle atonia during REM sleep, and have up to a 90% risk of developing a neurodegenerative synucleinopathy 14years post RBD-diagnosis . Changes in brainstem nuclei microstructure and connectivity are expected in RBD/premanifest synucleinopathy based on animal studies and ex-vivo human studies [4-5] [figure1]. Yet, these brainstem changes underlying RBD/premanifest-synucleinopathy are understudied in living humans.
Method: Data acquisition:Under IRB-approval, we acquired at 7 T a MEMPRAGE and a spin-echo DTI[table1],in 10 idiopathic-RBD patients (age: 69.7±1.59 yrs) and 7 controls (age: 67.6±2.6 yrs). Data analysis:a) Preprocessing:see Table1. b) Definition of seed and target regions for DTI-based connectivity analysis:As seed regions, we used structural probabilistic atlas labels of 9 brainstem nuclei [1-2] and non-probabilistic labels of 5 brainstem nuclei [figure1]. As target regions, we used labels of 47 brainstem nuclei [1-2], 41 cortical/subcortical bilateral regions from Freesurfer parcellation , hypothalamus  and ventral/dorsal spinal cord.c) Single-subject and group DTI-based connectivity analysis:We run deterministic tractography propagating 10,000 streamlines from each seed and computed a structural “connectivity-index” (range: [0 1]) for each pair of seed-target masks (= fraction of streamlines propagated from seed reaching target).Then, we averaged the connectivity-index of brainstem nuclei with target-regions across subjects and displayed the group connectome with a 2D circular diagram .
Results: The structural connectome of brainstem nuclei showed overall decreased connectivity of brainstem nuclei in RBD compared to controls [figure2]. Specifically, the observeddecreased connectivity of SNR with the PTgand of sMRt [figure3-4] with contralateral brainstem nuclei in RBD is in line with animal RBD-studies and models of synucleinopathy progression .
Conclusion: The structural connectome of brainstem pathways in living humans is a promising tool to better understand and assess premanifest synucleinopathy stages.
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To cite this abstract in AMA style:MG. García-Gomar, LD. Lewis, L. Wald, B. Rosen, A. Videnovic, M. Bianciardi. Structural connectome of brainstem nuclei in REM sleep behavior disorder, a model of premanifest synucleinopathy [abstract]. Mov Disord. 2019; 34 (suppl 2). https://www.mdsabstracts.org/abstract/structural-connectome-of-brainstem-nuclei-in-rem-sleep-behavior-disorder-a-model-of-premanifest-synucleinopathy/. Accessed December 10, 2023.
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