The following article is part of conference coverage from the International Congress of Parkinson’s Disease and Movement Disorders (MDS) Virtual Annual Meeting. Neurology Advisor’s staff will be reporting breaking news associated with research conducted by leading experts in neurology. Check back for the latest news from the MDS 2021 Virtual Annual Meeting.

 

Rapid eye movement (REM)-sleep muscle atonia is linked to impaired structural connectivity between REM-on and medullary brainstem nuclei in patients with REM sleep behavior disorder (RBD), according to a study findings presented at the International Congress of Parkinson’s Disease and Movement Disorders (MDS) Virtual Congress 2021, held from September 17 to 22, 2021.


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Patients with RBD, the lack of muscle atonia during REM sleep, have a significantly higher risk (73.5%) of developing a neurodegenerative synucleinopathy 12 years postdiagnosis. Although previous studies have analyzed the brainstem pathophysiology of RBD in animals, limited research has been done among humans.

The objective of the current study was to assess brainstem structural connectivity changes in patients with RBD.

Researchers evaluated data from 12 patients with RBD (mean age, 67.9±1.7 years) and 12 control group individuals (mean age, 66.3±1.6 years), with diffusion weighted images (DWI) and a T1-weighted MEMPRAGE image obtained through 7 Tesla magnetic resonance imaging (MRI). Brainstem nuclei atlas to native DTI-space were mapped, and two-sided Wilcoxon test was used to compare the groups.

Structural connectivity changes were identified in 14 of the 32 brainstem seeds that were associated with RBD in both groups, particularly in REM-on and REM-sleep muscle-atonia medullary areas (z=2.6; P <.01). These findings matched those of animal studies, which showed that excitatory connectivity influences between REM-on regions and ventro-medullary nuclei decrease. Researchers did not observe differences in connectivity between the groups in most REM-off areas. Interconnectivity predominantly increased in meso-pontine regions.

“Interestingly, ponto-medullary brainstem nuclei, known to be involved in REM atonia, showed decreased structural inter-connectivity, possibly related to an underlying neurodegeneration process,” the researchers concluded.

Reference

Garcia-Gomar MG, Videnovic A, Singh K, et al. New insight into REM-sleep atonia circuits underlying REM sleep behavior disorder in living humans. Presented at: MDS Virtual Congress 2021. September 17-22, 2021. Abstract 1204.