Normalized upper cervical spinal cord atrophy in multiple sclerosis.

BACKGROUND AND PURPOSE To find an optimal normalizing factor for upper cervical spinal cord area (UCCA) and to establish whether, in a cross-sectional study, the normalized UCCA correlates better with the neurological disability than the absolute measurement in multiple sclerosis patients. METHODS UCCA and three potential normalizing factors were estimated from magnetic resonance imaging data in 51 control subjects. Their reliability was assessed and the linear relationships between UCCA and three potential correction factors were investigated. UCCA was then normalized by these factors respectively. On the basis of these results, an optimal factor was selected and applied to 29 MS subjects. RESULTS An extremely strong correlation between UCCA and LECA was seen (r = .88, P < .01). The coefficient of variation (COV) of UCCA was reduced to 4.4% from 9.3% after correction by LECA. The normalized measurement of UCCA correlated better with the expanded disability status scale (EDSS) than the absolute measurement especially in relapsing-remitting multiple sclerosis patients. Moreover, more spinal cord atrophy was identified in corrected data than uncorrected data. CONCLUSION Our findings suggest that LECA is an optimal correction factor for UCCA and normalized UCCA is preferable to absolute measurement in cross-sectional study.