Differential brain reorganization in chronic cervical spinal cord injury and its relation to motor versus sensory impairments: a preliminary investigation

Spinal cord injury (SCI) disrupts the communication between the brain and the rest of the body, triggering widespread spinal and supraspinal changes resulting in a cascade of functional impairments. MRI has proved useful to investigate neural circuits reorganization, offering insights into the neuroplastic changes underlying specific impairments and deficits. However, it remains unclear whether different impairments are associated with differential patterns of structural and functional brain reorganization, a knowledge gap addressed in this study. Anatomical and resting-state functional MRI data from 12 participants with complete and incomplete chronic cervical SCI and 12 age- and sex-matched able-bodied individuals were acquired. SCI participants' arm and hand sensory and motor functions were assessed using the Graded Redefined Assessment of Strength Sensibility and Prehension scale. Cortical thickness, gray matter volume and resting-state functional connectivity (rs-FC) were measured and compared between groups while also considering changes in clinical scores in SCI. Widespread structural and functional changes in various cortical and subcortical regions were highlighted in individuals with chronic cervical SCI as compared to the able-bodied controls. Specific alterations were seen in cortical thickness, gray matter volume and rs-FC of the sensorimotor, and visuospatial processing networks. Mainly rs-FC of sensorimotor cortical and subcortical areas showed changes differentially associated to only-motor versus sensory deficits in the SCI group. Motor and sensory impairments at the chronic stage appears associated with differential patterns of brain reorganization in individuals with chronic cervical SCI, prominently involving regions of the visual and visuospatial networks. Some of the regions with altered rs-FC, notably the thalamus and putamen, showed also changes in their anatomy in SCI. The findings confirm the value of multimodal brain MRI for characterizing neural correlates of specific impairments following SCI and informing personalized therapeutic strategies. Our results support the consideration of interventions that engage visual and visuospatial networks to promote function recovery after SCI.