Magnetic resonance outcome measures in multiple sclerosis trials: time to rethink?

Spinal cord atrophy in multiple sclerosis and relationship with disability across clinical phenotypes

BACKGROUND

Several studies have shown a relationship between spinal cord atrophy and clinical disability in patients with multiple sclerosis (MS).

OBJECTIVES

We examined the correlation between cervical cord cross-sectional area at the C2 vertebral level (CSA-C2) and the expanded disability status scale (EDSS) in patients with relapsing-remitting and progressive forms of MS. The latter included both secondary and primary progressive MS patients.

METHODS

A total of 150 patients with MS were recruited from the Wayne State University MS clinic. Ninety-three had relapsing-remitting MS and 57 patients had progressive MS. MRI scan of the cervical cord was obtained for each patient. Correlation studies and multivariate regression analysis was performed, blinded to clinical status.

RESULTS

The mean age was 41.3 year old, 64.6% were women, mean disease duration was 11.2 years, CSA-C2 was 80.2mm(2) and mean EDSS was 3.8. There was significant correlation between CSA-C2 and EDSS (r -0.75, p<0.0001). Sub-group analysis showed CSA-C2 was 68.6mm(2) and 87.3mm(2) in the progressive and relapsing-remitting groups, respectively (p<0.0001). Multivariable regression showed that CSA-C2 was a significant predictor of disability independent of disease duration, and phenotype.

CONCLUSIONS

Our study demonstrates that CSA-C2 has a strong correlation with clinical disability in both RRMS and progressive MS. Greater spinal cord atrophy was seen in patients with progressive than relapsing-remitting MS. CSA-C2, disease duration, and phenotype are independent predictors of disability.