Functional Adaptation of Brain Network Topology in Individuals with Chronic Ankle Instability: A Graph-Theoretical Study

Objectives: This study aims to understand the supraspinal regulation of balance control in chronic ankle instability (CAI) by characterizing the large-scale communication and interaction via brain functional network topology in CAI and establish the association between topological properties and dynamic balance performance. Methods: In this cross-sectional design study, 40 CAI individuals and 39 healthy control (HC) individuals were enrolled. To assess the dynamic balance, the Y-balance test was utilised. To explore the topological structure of brain networks, graph theory was used to analyse resting-state functional MRI data. Results: The CAI group had lower normalized reach distances in the Y-balance test than HC. Compared to HC, CAI exhibited remarkably lower nodal degree centrality (Dc) and higher nodal shortest path length (NLp) within the sensorimotor network (SMN), particularly in the precentral gyrus, temporal cortex, and pre-supplementary motor area of the right hemisphere. CAI showed reduced NLp and increased nodal efficiency in the posterior cingulate cortex of the left hemisphere, a hub region of the default mode subnetwork (DMN). In CAI, high Dc and low NLp in the precentral gyrus of the right hemisphere were substantially correlated to poor performance of the Y-balance test, but not in HC. Conclusions: CAI individuals demonstrated diminished regional processing capability within the SMN and a potential compensatory increase in nodal efficiency within the DMN, which are critical to maintain safe balance in this cohort. These alterations in supraspinal networks could be an effective target for rehabilitation and management in CAI.