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. 2013 Sep;12(9):873-881.
doi: 10.1016/S1474-4422(13)70146-7. Epub 2013 Jul 2.

MRI Investigation of the Sensorimotor Cortex and the Corticospinal Tract After Acute Spinal Cord Injury: A Prospective Longitudinal Study

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Free PMC article

MRI Investigation of the Sensorimotor Cortex and the Corticospinal Tract After Acute Spinal Cord Injury: A Prospective Longitudinal Study

Patrick Freund et al. Lancet Neurol. .
Free PMC article

Erratum in

  • Lancet Neurol. 2013 Sep;12(9):846

Abstract

Background: In 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.

Methods: In 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.

Findings: Between 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 4·01, p<0·0001).

Interpretation: Extensive upstream atrophic and microstructural changes of corticospinal axons and sensorimotor cortical areas occur in the first months after spinal cord injury, with faster degenerative changes relating to poorer recovery. Structural volumetric and microstructural MRI protocols remote from the site of spinal cord injury could serve as neuroimaging biomarkers in acute spinal cord injury.

Funding: SRH Holding, Swiss National Science Foundation, Clinical Research Priority Program "NeuroRehab" University of Zurich, Wellcome Trust.

Figures

Figure 1
Figure 1
Longitudinal changes in spinal cord area (A) Change in cross-sectional spinal cord area at the C2/C3 level after injury in patients with spinal cord injury and in healthy controls. (B) Change in cross-sectional spinal cord area differed significantly between patients and controls. Horizontal error bars show SE of the scan intervals and vertical error bars show SE for percentage change in cross-sectional spinal cord area.
Figure 2
Figure 2
Longitudinal changes in grey and white matter volume shown by tensor-based morphometry (A) Overlay of statistical parametric maps (uncorrected p<0·001, shown for descriptive purposes, masked by the union of the cranial corticospinal tract and the bilateral sensorimotor cortex) showing regions of volume changes in grey matter (in blue) and white matter (in red). (B) Illustration showing changes in white matter volume in the corticospinal tracts, at the level of the left internal capsule, in patients and healthy controls. Horizontal error bars show SE of the scan intervals and vertical error bars show SE for percentage change in spinal cord area.
Figure 3
Figure 3
Changes at 12 months shown by voxel-wise analysis of microstructure and volume Overlay of statistical parametric maps (uncorrected p<0·001, shown for descriptive purposes, masked by the union of the cranial corticospinal tract and the bilateral sensorimotor cortex) showing regions of reduced volume of grey and white matter (blue) in patients compared with controls at 12 month follow-up. The reductions in longitudinal relaxation rate R1 (yellow) and magnetisation transfer MT (red) in patients compared with controls at 12 month follow-up suggest changes in myelination.
Figure 4
Figure 4
Correlation between spinal cord atrophy and clinical outcome SCIM=spinal cord independence measure.
Figure 5
Figure 5
Correlation between brain atrophy and clinical outcome (A) Overlay of statistical parametric maps (uncorrected p<0·001, shown for descriptive purposes; masked by the union of the cranial corticospinal tract) showing associations of volume changes with ISNCSCI motor score (blue) and SCIM score (red). (B) Rates of change in atrophy in patients with a SCIM score <50 and ≥50 at 12 months. Horizontal error bars show SE of the scan intervals and vertical error bars show SE for percentage change in white matter volume change of the corticospinal tract at the level of the internal capsule relative to baseline. SCIM=spinal cord independence measure. ISNCSCI=international standards for the neurological classification of spinal cord injury.

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