Small world properties changes in mild traumatic brain injury

Abstract

Purpose To investigate local and global efficiency changes characterized by small-world properties based on resting-state functional MRI, such as centrality and clustering coefficient, in mild traumatic brain injury (MTBI) patients; and to associate these findings with axonal injury as measured by diffusion tensor imaging (DTI) as well as with post-concussive symptom (PCS). Materials and Methods Thirty patients (mean age 35 ± 13 years) with clinically defined MTBI and 45 age-matched healthy controls (mean age 37 ± 10 years) participated in the experiments. Resting-state functional MRI was performed using gradient echo planar imaging sequence with 3 Tesla MRI scanner to obtain functional small-world networks. Out of all participants, 20 MTBI patients and 20 controls had available DTI data with three b-values (0, 500, 1000) s/mm2 and 30 directions for diffuse axonal injury analyses. Results Compared with controls, MTBI patients showed lower relative betweenness centrality (P = 0.01), but significantly higher clustering coefficient (P = 0.04), and these two metrics correlated negatively in patients (r = −0.77; P < 0.001). Regions with lower betweenness centrality (e.g., frontal and occipital) corresponded with the regions of reduced FA in patients, while global FA reduction correlated with betweenness centrality (r = 0.48; P = 0.03) and clustering coefficient (r = −0.46; P = 0.04) in MTBI patients. In addition, there was significantly higher thalamocortical connectivity that correlated with clustering coefficient (r = 0.39; P = 0.03) in patients. Also, patients with higher clustering coefficient tended to have less PCS score with negative correlation (r = −0.4; P = 0.04). Conclusion Our results demonstrated significant functional small-world properties changes in patients with MTBI, and suggest decreased global efficiency, possibly due to diffuse axonal injury and local network upregulation including increased thalamo-cortical connectivity.

Understanding white matter structural connectivity differences between cognitively impaired and nonimpaired active professional fighters

“…To the best of our knowledge, there have been no studies comparing the change in the brain topological organization between participants who are cognitively impaired and nonimpaired where the participants in both groups are exposed to RHI. Nevertheless, when compared to healthy controls, Zhou () showed that graph‐theoretical measures in participants with mild TBI showed a decreased betweenness‐centrality but a higher clustering coefficient. However, no significant difference in any graph‐theoretical measures was observed in our cohort of impaired and nonimpaired professional fighters.…”

Altered Functional Brain Networks in Patients with Traumatic Anosmia: Resting-State Functional MRI Based on Graph Theoretical Analysis

“…The reported results of these invisible changes, however, are inconsistent in terms of functional connectivity. Some studies reported decreased global efficiency and increased modularity in patients with mild traumatic brain injury and posttraumatic stress disorder (4748). Conversely, several recent studies reported an increase in the resting functional connectivity after traumatic concussion relative to the controls (4950), which is in line with our findings.…”

Graph-theoretical Analysis of EEG Functional Connectivity during Balance Perturbation in Traumatic Brain Injury: A Pilot Study

“…Graph theory can help identify alterations in the global brain connectivity organization [64]. Previous studies have shown that TBI disrupts the optimal 'small-world' architecture of the network (as often observed in the healthy population), affecting the optimal balance between local segregation within and global integration between specialized independent subnetworks [64]; [65]; [66]. We seek to evaluate how TBI impairs this optimal integration/segregation balance at baseline and during balance perturbation.…”