This study compares remote neurodegenerative changes caudal to a cervical injury in degenerative cervical myelopathy (DCM; i.e., non-traumatic) and incomplete traumatic spinal cord injury (tSCI) patients, using magnetic resonance imaging (MRI)-based tissue area measurements and diffusion tensor imaging (DTI). Eighteen mild-to-moderate DCM patients with sensory impairments (modified Japanese Orthopedic score: 16.2 ± 1.9), 14 incomplete tetraplegic tSCI patients (American Spinal Injury Association Impairment Scale C and D), and 20 healthy controls were recruited. All participants received DTI and T2*-weighted scans in the lumbosacral enlargement (caudal to injury) and at C2/C3 (rostral to injury). MRI readouts included DTI metrics in the white matter (WM) columns and cross-sectional WM and gray matter area. One-way analysis of variance with Tukey's post hoc comparison (p < 0.05) was used to assess group differences. In the lumbosacral enlargement, compared with DCM, tSCI patients exhibited decreased fractional anisotropy in the lateral (tSCI vs. DCM, -11.9%, p = 0.007) and ventral WM column (-8.0%, p = 0.021), and showed a trend toward lower values in the dorsal column (-8.9%, p = 0.068). At C2/C3, compared with controls, fractional anisotropy was lower in both groups in the dorsal (DCM vs. controls, -7.9%, p = 0.024; tSCI vs. controls, -10.0%, p = 0.007) and in the lateral column (DCM: -6.2%, p = 0.039; tSCI: -13.3%, p < 0.001), while tSCI patients had lower fractional anisotropy than DCM patients in the lateral column (-7.6%, p = 0.029). WM areas were not different between patient groups but were lower compared with controls in the lumbosacral enlargement (DCM: -16.9%, p < 0.001; tSCI: -10.5%, p = 0.043) and at C2/C3 (DCM: -16.0%, p < 0.001; tSCI: -18.1%, p < 0.001). In conclusion, mild-to-moderate DCM and incomplete tSCI lead to similar degree of degeneration of the dorsal and lateral columns at C2/C3, but tSCI results in more widespread white matter damage in the lumbosacral enlargement. These remote changes are likely to contribute to the patients' impairment and recovery. DTI is a sensitive tool to assess remote pathological changes in DCM and tSCI patients.
Keywords: degenerative cervical myelopathy; diffusion tensor imaging; magnetic resonance imaging; neurodegeneration; traumatic spinal cord injury.