Alterations in Cortical Sensorimotor Connectivity following Complete Cervical Spinal Cord Injury: A Prospective Resting-State fMRI Study

Abstract

Functional magnetic resonance imaging (fMRI) studies have demonstrated alterations during task-induced brain activation in spinal cord injury (SCI) patients. The interruption to structural integrity of the spinal cord and the resultant disrupted flow of bidirectional communication between the brain and the spinal cord might contribute to the observed dynamic reorganization (neural plasticity). However, the effect of SCI on brain resting-state connectivity patterns remains unclear. We undertook a prospective resting-state fMRI (rs-fMRI) study to explore changes to cortical activation patterns following SCI. With institutional review board approval, rs-fMRI data was obtained in eleven patients with complete cervical SCI (>2 years post injury) and nine age-matched controls. The data was processed using the Analysis of Functional Neuroimages software. Region of interest (ROI) based analysis was performed to study changes in the sensorimotor network using pre- and post-central gyri as seed regions. Two-sampled t-test was carried out to check for significant differences between the two groups. SCI patients showed decreased functional connectivity in motor and sensory cortical regions when compared to controls. The decrease was noted in ipsilateral, contralateral, and interhemispheric regions for left and right precentral ROIs. Additionally, the left postcentral ROI demonstrated increased connectivity with the thalamus bilaterally in SCI patients. Our results suggest that cortical activation patterns in the sensorimotor network undergo dynamic reorganization following SCI. The presence of these changes in chronic spinal cord injury patients is suggestive of the inherent neural plasticity within the central nervous system.

Fig 1. Overview of Data Process.

Top to bottom: Data acquisition, preprocessing to obtain individual sensorimotor network maps, and statistical analysis for group-level comparisons. SCI, spinal cord injury; con, control; SPGR, spoiled gradient-recalled echo sequence; fmri, functional magnetic resonance imaging; rsFMRI, resting state functional magnetic resonance imaging; WM, white matter; CSF, cerebrospinal fluid; SMN, sensory motor network.

Fig 2. Changes in resting-state functional connectivity of sensorimotor network between SCI patients and controls with each row corresponding to a specific ROI.

Left column, Location of ROIs. Remaining columns, Clusters showing significant difference in functional connectivity. Color-coded statistical t-value maps (corrected p<0.05) showing positive and negative correlation (coded in yellow to light blue). Blue colors signifying negative t-values indicating SCI patients have lower connectivity to corresponding ROI compared to controls and vice versa (z-coordinates of cross sections are reported in Talairach space). SCI, spinal cord injury; ROI, region of interest.