Impaired small-world network efficiency and dynamic functional distribution in patients with cirrhosis

Tun-Wei Hsu, Changwei W Wu, Yu-Fan Cheng, Hsiu-Ling Chen, Cheng-Hsien Lu, Kuan-Hung Cho, Wei-Che Lin, Ching-Po Lin

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)

Abstract

Hepatic encephalopathy (HE) is a complex neuropsychiatric syndrome and a major complication of liver cirrhosis. Dysmetabolism of the brain, related to elevated ammonia levels, interferes with intercortical connectivity and cognitive function. For evaluation of network efficiency, a 'small-world' network model can quantify the effectiveness of information transfer within brain networks. This study aimed to use small-world topology to investigate abnormalities of neuronal connectivity among widely distributed brain regions in patients with liver cirrhosis using resting-state functional magnetic resonance imaging (rs-fMRI). Seventeen cirrhotic patients without HE, 9 with minimal HE, 9 with overt HE, and 35 healthy controls were compared. The interregional correlation matrix was obtained by averaging the rs-fMRI time series over all voxels in each of the 90 regions using the automated anatomical labeling model. Cost and correlation threshold values were then applied to construct the functional brain network. The absolute and relative network efficiencies were calculated; quantifying distinct aspects of the local and global topological network organization. Correlations between network topology parameters, ammonia levels, and the severity of HE were determined using linear regression and ANOVA. The local and global topological efficiencies of the functional connectivity network were significantly disrupted in HE patients; showing abnormal small-world properties. Alterations in regional characteristics, including nodal efficiency and nodal strength, occurred predominantly in the association, primary, and limbic/paralimbic regions. The degree of network organization disruption depended on the severity of HE. Ammonia levels were also significantly associated with the alterations in local network properties. Results indicated that alterations in the rs-fMRI network topology of the brain were associated with HE grade; and that focal or diffuse lesions disturbed the functional network to further alter the global topology and efficiency of the whole brain network. These findings provide insights into the functional changes in the human brain in HE.

Original languageEnglish
Pages (from-to)e35266
JournalPLoS One
Volume7
Issue number5
DOIs
Publication statusPublished - 2012
Externally publishedYes

Keywords

  • Adult
  • Aged
  • Ammonia
  • Brain
  • Brain Mapping
  • Female
  • Humans
  • Linear Models
  • Liver Cirrhosis
  • Magnetic Resonance Imaging
  • Male
  • Middle Aged
  • Models, Neurological
  • Nerve Net
  • Neural Pathways
  • Journal Article
  • Research Support, Non-U.S. Gov't

Fingerprint Dive into the research topics of 'Impaired small-world network efficiency and dynamic functional distribution in patients with cirrhosis'. Together they form a unique fingerprint.

Cite this