Distinct brain network patterns in complete and incomplete spinal cord injury patients based on graph theory analysis

To compare the changes in brain network topological properties and structure-function coupling in patients with complete spinal cord injury (CSCI) and incomplete spinal cord injury (ICSCI), to unveil the potential neurobiological mechanisms underlying the different effects of CSCI and ICSCI on brain networks and identify objective neurobiological markers to differentiate between CSCI and ICSCI patients.

Thirty-five SCI patients (20 CSCI and 15 ICSCI) and 32 healthy controls (HCs) were included in the study. Here, networks were constructed using resting-state functional magnetic resonance imaging to analyze functional connectivity (FC) and diffusion tensor imaging for structural connectivity (SC). Then, graph theory analysis was used to examine SC and FC networks, as well as to estimate SC-FC coupling values.

Compared with HCs, CSCI patients showed increased path length (Lp), decreased global efficiency (E_g), and local efficiency (E_loc) in SC. For FC, ICSCI patients exhibited increased small-worldness, clustering coefficient (C_p), normalized clustering coefficient, and E_loc. Also, ICSCI patients showed increased C_p and E_loc than CSCI patients. Additionally, ICSCI patients had reduced SC-FC coupling values compared to HCs. Moreover, in CSCI patients, the SC network's Lp and E_g values were significantly correlated with motor scores, while in ICSCI patients, the FC network's C_p, E_loc, and SC-FC coupling values were related to sensory/motor scores.

These results suggest that CSCI patients are characterized by decreased efficiency in the SC network, while ICSCI patients are distinguished by increased local connections and SC-FC decoupling. Moreover, the differences in network metrics between CSCI and ICSCI patients could serve as objective biological markers, providing a basis for diagnosis and treatment strategies.