MRI investigation of the sensorimotor cortex and the corticospinal tract after acute spinal cord injury: a prospective longitudinal study

Abstract

SummaryBackgroundIn patients with chronic spinal cord injury, imaging of the spinal cord and brain above the level of the lesion provides evidence of neural degeneration; however, the spatial and temporal patterns of progression and their relation to clinical outcomes are uncertain. New interventions targeting acute spinal cord injury have entered clinical trials but neuroimaging outcomes as responsive markers of treatment have yet to be established. We aimed to use MRI to assess neuronal degeneration above the level of the lesion after acute spinal cord injury.MethodsIn our prospective longitudinal study, we enrolled patients with acute traumatic spinal cord injury and healthy controls. We assessed patients clinically and by MRI at baseline, 2 months, 6 months, and 12 months, and controls by MRI at the same timepoints. We assessed atrophy in white matter in the cranial corticospinal tracts and grey matter in sensorimotor cortices by tensor-based analyses of T1-weighted MRI data. We used cross-sectional spinal cord area measurements to assess atrophy at cervical level C2/C3. We used myelin-sensitive magnetisation transfer (MT) and longitudinal relaxation rate (R1) maps to assess microstructural changes associated with myelin. We also assessed associations between MRI parameters and clinical improvement. All analyses of brain scans done with statistical parametric mapping were corrected for family-wise error.FindingsBetween Sept 17, 2010, and Dec 31, 2012, we recruited 13 patients and 18 controls. In the 12 months from baseline, patients recovered by a mean of 5·27 points per log month (95% CI 1·91–8·63) on the international standards for the neurological classification of spinal cord injury (ISNCSCI) motor score (p=0·002) and by 10·93 points per log month (6·20–15·66) on the spinal cord independence measure (SCIM) score (p<0·0001). Compared with controls, patients showed a rapid decline in cross-sectional spinal cord area (patients declined by 0·46 mm per month compared with a stable cord area in controls; p<0·0001). Patients had faster rates than controls of volume decline of white matter in the cranial corticospinal tracts at the level of the internal capsule (right Z score 5·21, p=0·0081; left Z score 4·12, p=0·0004) and right cerebral peduncle (Z score 3·89, p=0·0302) and of grey matter in the left primary motor cortex (Z score 4·23, p=0·041). Volume changes were paralleled by significant reductions of MT and R1 in the same areas and beyond. Improvements in SCIM scores at 12 months were associated with a reduced loss in cross-sectional spinal cord area over 12 months (Pearson's correlation 0·77, p=0·004) and reduced white matter volume of the corticospinal tracts at the level of the right internal capsule (Z score 4·30, p=0·0021), the left internal capsule (Z score 4·27, p=0·0278), and left cerebral peduncle (Z score 4·05, p=0·0316). Improvements in ISNCSCI motor scores were associated with less white matter volume change encompassing the corticospinal tract at the level of the right internal capsule (Z score...

Tracking sensory system atrophy and outcome prediction in spinal cord injury

“…These changes are likely to involve changes at the level of cellular metabolism, blood flow, and functional depression, inducing a state of hypoactivity and shrinkage of sensory neurons and their axons 57. In accordance with motor system atrophy during the first year after injury,9 the magnitude of atrophy within the sensory system was evident in both incomplete and complete paraplegic and tetraplegic patients. This finding is of interest, as patients with a very chronic SCI show level‐dependent spinal atrophy, with more pronounced atrophic changes in those patients with higher lesion levels 12.…”

Characterizing the Location of Spinal and Vertebral Levels in the Human Cervical Spinal Cord

“…12,18 The development of methods to manage the hostile imaging environment and to account for cardiorespiratory-related motion has allowed improved applications to detect structural (such as diffusion and magnetization transfer imaging) and functional anomalies that occur in relation to traumatic injury of the spinal cord. 1,2,19,20 Other disorders, such as multiple sclerosis, have also benefited from spinal cord imaging. 21 Degenerative spinal disease, such as cervical spondylosis, is an increasing health burden due to the aging population.…”

Clinically Feasible Microstructural MRI to Quantify Cervical Spinal Cord Tissue Injury Using DTI, MT, and T2*-Weighted Imaging: Assessment of Normative Data and Reliability

“…27,34,35 However, such techniques are inherently complex and require specialized pulse sequences, while typically requiring lengthy scan times. Furthermore, these methods face challenges in achieving acceptable SNR and reliability, particularly in the SC, which is considerably more difficult to image than the brain due to magnetic field inhomogeneity and physiologic motion.…”