Directional Diffusivities in Human Spinal Cord Correlate with Functional Outcome

Junqian Xu¹, Eric C. Klawiter¹, Tammie L.S. Benzinger², Robert T. Naismith¹, Sheng-Kwei Song², Anne H. Cross¹

Axial and radial diffusivities were quantified in the spinal cord white matter tracts of six stable multiple sclerosis (MS) patients with good recovery and two stable neuromyelitis optica patients with poor recover. Results were compared with that from seventeen healthy volunteers. Between the good recovery MS group and the normal control group, no significant differences in axial diffusivity were observed, suggesting little permanent axonal damage in these MS patients; while radial diffusivity increased moderately in the MS group compared to control, suggesting incomplete remyelination. In the two NMO patients with poor recovery, dramatically increased radial diffusivity in the center of the lesion (both located in posterior column) indicates severe tissue demyelination correlating with loss of vibration perception; while decreased axial diffusivity and increased radial diffusivity in the normal appearing cortical spinal tracts correlated with motor function measures, such as, muscle test, 9-hole peg test, and 25-foot timed walk.