title: Abnormal organization of white matter network in patients with no dementia after ischemic stroke.
abstract: Structural changes after ischemic stroke could affect information communication extensively in the brain network. It is likely that the defects in the white matter (WM) network play a key role in information interchange. In this study, we used graph theoretical analysis to examine potential organization alteration in the WM network architecture derived from diffusion tensor images from subjects with no dementia and experienced stroke in the past 5.4-14.8 months (N = 47, Mini-Mental Screening Examination, MMSE range 18-30), compared with a normal control group with 44 age and gender-matched healthy volunteers (MMSE range 26-30). Region-wise connectivity was derived from fiber connection density of 90 different cortical and subcortical parcellations across the whole brain. Both normal controls and patients with chronic stroke exhibited efficient small-world properties in their WM structural networks. Compared with normal controls, topological efficiency was basically unaltered in the patients with chronic stroke, as reflected by unchanged local and global clustering coefficient, characteristic path length, and regional efficiency. No significant difference in hub distribution was found between normal control and patient groups. Patients with chronic stroke, however, were found to have reduced betweenness centrality and predominantly located in the orbitofrontal cortex, whereas increased betweenness centrality and vulnerability were observed in parietal-occipital cortex. The National Institutes of Health Stroke Scale (NIHSS) score of patient is correlated with the betweenness centrality of right pallidum and local clustering coefficient of left superior occipital gyrus. Our findings suggest that patients with chronic stroke still exhibit efficient small-world organization and unaltered topological efficiency, with altered topology at orbitofrontal cortex and parietal-occipital cortex in the overall structural network. Findings from this study could help in understanding the mechanism of cognitive impairment and functional compensation occurred in patients with chronic stroke.
authors.affiliation: Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China ; Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Shi
authors.affiliation: Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China ; CUHK Shenzhen Research Institute, Shenzhen, China.
authors.forename: Defeng
authors.initials: D
authors.lastname: Wang
authors.affiliation: Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Winnie C W
authors.initials: WC
authors.lastname: Chu
authors.affiliation: Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Shangping
authors.initials: S
authors.lastname: Liu
authors.affiliation: Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Yunyun
authors.initials: Y
authors.lastname: Xiong
authors.affiliation: Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.
authors.forename: Yilong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Lawrence K S
authors.initials: LK
authors.lastname: Wong
authors.affiliation: Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Vincent C T
authors.initials: VC
authors.lastname: Mok
mesh_terms: D000368:Aged; D003704:Dementia / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009413:Nerve Fibers, Myelinated / Q000473:pathology / Q000502:physiology; D020521:Stroke / Q000473:pathology* / Q000503:physiopathology