A study conducted by Wei and colleagues, published in the Journal of Multiple Sclerosis and Related Disorders, showed that neuromyelitis optica spectrum disorder (NMOSD) patients had decreased degree centrality (DC) in comparison to healthy controls. Furthermore, the decrease of DC had a statistically significant relationship to a reduction in visual acuity and optic neuritis (ON), suggesting that neural network dysfunction may play a role in clinical presentations of NMOSD patients.

NMOSD is an autoimmune disease that involves visual impairment and brain connectivity modifications. DC portrays the quantity of immediate functional connections between a brain area and the remainder of the brain within the total connectivity matrix. Consequently, it can assess how much a node affects the entire brain and merges information across functionally segregated brain regions.

“The reduced DC values indicate that the number of direct connections within the brain networks decreases during the disease mechanism in NMOSD patients,” authors expressed.


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Authors calculated DC by the graph method with functional magnetic resonance imaging (fMRI) of the brain, firstly identifying voxels with changes in whole-brain functional connectivity to compare with other voxels.

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Overall, a decrease in DC number was statistically significant in the superior orbital gyrus (ORBsup), left angular gyrus (ANG), and right parietal superior gyrus (SPG) in comparison to healthy controls. 

SPG and ANG play a substantial part in the dorsal visual pathway responsible for spatial awareness and visual function. DC numbers in the SPG area significantly correlate to reduced visual acuity, whereas DC numbers in the ANG area significantly correlate with ON’s frequency. Notably, spatial awareness and visual function loss are frequent manifestations in NMOSD patients, and specific brain areas were related to distinct clinical aspects. 

The authors saw the study sample size and brain-only fMRI analysis as limitations of their study; hence, further studies must have a greater sample size and optic nerve and spinal cord assessment to increase the results’ validation.

Nonetheless, the authors are confident that these results provide a meaningful understanding of the neural process and clinical manifestations in NMOSD patients. “This is the first study to assess the intrinsic dysconnectivity pattern of brain functional networks in NMOSD patients by using DC analysis,” the authors said. 

Reference

Wei R, Yan J, Wu H, et al. Irregular degree centrality in neuromyelitis optica spectrum disorder patients with optic neuritis: A resting-state functional magnetic resonance imaging studyMult Scler Relat Disord. Published online January 21, 2022. doi:10.1016/j.msard.2022.103542