Abnormal organization of white matter network in patients with no dementia after ischemic stroke

PLoS One. 2013 Dec 13;8(12):e81388. doi: 10.1371/journal.pone.0081388. eCollection 2013.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Dementia / pathology*
  • Dementia / physiopathology
  • Female
  • Humans
  • Magnetic Resonance Imaging
  • Male
  • Middle Aged
  • Nerve Fibers, Myelinated / pathology
  • Nerve Fibers, Myelinated / physiology
  • Stroke / pathology*
  • Stroke / physiopathology

Grants and funding

The work described in this paper was supported by grants from the Research Grants Council of the Hong Kong Special Administrative Region, China (Project No. CUHK 411811, 475711, 416712, 473012), grants from Shenzhen Science and Technology Innovation Committee (Project No. JC201005250030A and JCYJ20120619152326449), and grants from the National Natural Science Foundation of China (Project No. 81101111, 81201157, 81271653). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.