A MRI Study Of Brain Functional And Structural Changes In Patients With Spinal Cord Injury

Part I Altered spontaneous brain activity in patients with acute spinal cord injury revealed by resting state functional MRIObjective Previous neuroimaging studies have provided evidence of structural and functional reorganization in patients with spinal cord injury (SCI) in the subaute and chronic stage. However, it remains unknown whether the spontaneous brain activity changes in acute SCI. In this study, we investigated intrinsic brain activity in acute SCI patients using a regional homogeneity (ReHo) analysis based on resting state functional magnetic resonance imaging.Methods A total of 15 male patients with acute SCI (<30 days) and 16 healthy male controls participated in the study. The ReHo value was used to evaluate spontaneous brain activity, and voxel-wise comparisons of ReHo were performed to identify brain regions with altered spontaneous brain activity between groups. Correlation analyses were carried out to explore relationships between the clinical variables and ReHo by regions showing changed brain activity in acute SCI patients.Results Compared with the controls, the acute SCI patients showed decreased ReHo in the bilateral primary motor cortex/primary somatosensory cortex, bilateral supplementary motor area/dorsal lateral prefrontal cortex, right inferior frontal gyrus, bilateral dorsal anterior cingulate cortex and bilateral caudate; and increased ReHo in bilateral precuneus, the left inferior parietal lobe, the left brainstem/hippocampus, the left cingulate motor area, bilateral insula, bilateral cerebellum and bilateral thalamus. The average ReHo values of the left thalamus and right insula were negatively correlated with the international standards for the neurological classification of spinal cord injury motor scores.Conclusion Our findings indicate that acute distant neuronal damage has an immediate impact on spontaneous brain activity. In acute SCI patients, the ReHo was prominently altered in brain regions involved in motor execution and cognitive control, default mode network and in which are associated with sensorimotor compensatory reorganization. Abnormal ReHo values in the left thalamus and right insula could serve as potential biomarkers for the assessment of the extent of neural damage and the prediction of clinical outcomes in acute SCI.Part II Altered brain activation during sequential finger-to-thumb opposition in paraplegic patients with spinal cord injury:a functional MRI studyObjective To investigate the pattern of brain reorganization during sequential finger-to-thumb opposition in paraplegic patients with spinal cord injury (SCI) using blood oxygen level dependent functional magnetic resonance imaging.Methods A total of 12 paraplegic patients with SCI and 12 healthy male controls participated in the study. All subjects underwent BOLD-fMRI during sequential finger-to-thumb opposition. The BOLD-fMRI scans using a block design. The activation experiment consisted of 30s periods of rest alternating with 30s periods of movement. The total data collection lasted 240s. The data were analysed using Statistical Parametric Mapping 8 to show the activation of brain within groups and between groups. The contralateral maximum t value and the volumes of activation in the contralateral M1 were calculated for each subject. Correlation analyses were carried out in SCI group to explore relationships between the contralateral maximum t value, the volumes of activation in the contralateral M1 and the level of injury, the time since SCI, the international standards for the neurological classification of spinal cord injury motor scores of SCI patients.Results Statistical comparisons of the contralateral maximum t value and the volumes of activation in the contralateral Ml did not reveal any significant differences between the SCI patients and the controls. The volumes of activation in the contralateral Ml were negatively correlated with the level of the spinal cord injury. Compared with the controls, the maximum activation of the SCI patients showed a posterior shift during sequential finger-to-thumb opposition, whereas without shift of activation towards the deefferented and deafferented limb representation. Increased activation was found in the bilateral primary motor cortex, supplementary motor area, inferior parietal lobe and insula in patients with SCI.Conclusion The SCI patients showed a posterior shift for hand motor representation and increased activation in motor associated areas suggesting that SCI has impact upon the reorganization of brain function, which maybe correlate with the level of the injury.Part III Gray and white matter changes in patients with acute spinal cord injury: a voxel-based morphometry studyObjective We aimed to use voxel-based morphometry (VBM) to evaluate the volume changes of gray and white matter in patients with acute spinal cord injury (SCI). To determine if acute SCI results in anatomical changes in human brain.Methods A total of 16 patients with acute SCI (<30 days) and 20 healthy controls participated in the study. We assessed the volume changes of gray matter and white matter in patients with acute SCI by VBM analysis of T1-weighted MRI data.Results VBM analysis revealed smaller gray matter and white matter volume in subjects with SCI compared with controls. In particular, lower gray matter volume was detected in the bilateral inferior frontal gyrus, insula, medial prefrontal cortex, anterior cingulate cortex and cerebellum and smaller white matter volume of the bilateral cranial corticospinal tracts at the internal capsule.Conclusion Acute SCI leads to atrophy of the cortices associated with emotional processing and the corticospinal tracts, which may provide a better understanding of the mechanisms of the acute SCI impact on brain.