Neurodegeneration in the spinal ventral horn prior to motor impairment in cervical spondylotic myelopathy

Remote grey matter pathology has been suggested rostral to the compression site in cervical spondylotic myelopathy (CSM). We used computational neuroimaging to assess in-vivo the extent and functional relevance of neurodegeneration in ventral and dorsal horns above the site of compression in the cervical cord of CSM patients. Twenty patients with CSM and eighteen healthy subjects underwent a high-resolution structural and diffusion MRI protocol at vertebra C2/C3. Patients received comprehensive clinical assessments. T2*-weighted data were used to segment the cross-sectional area of the grey matter into the ventral and dorsal horns. Within the ventral and dorsal horns mean diffusivity (MD) and fractional anisotropy (FA) derived from diffusion tensor imaging data determined the underlying microstructural integrity. Finally, the relationships between neurodegeneration occurring in the grey and white matter and clinical impairment were investigated. Patients suffered from mild to moderate CSM with mainly sensory impairment. The cross-sectional area of the ventral horns was not reduced (p=0.863) when compared to controls, but MD was increased (p=0.045). Greater increases in MD within the ventral horn were associated with white matter diffusivity changes (increased MD: p=0.013; decreased FA: p=0.028) within the lateral corticospinal tract. In contrast, dorsal horn cross-sectional area was reduced by 16.0% (p