Spinal cord atrophy in multiple sclerosis caused by white matter volume loss.

OBJECTIVE To assess the relative contributions of white matter (WM) and gray matter (GM) volume loss to spinal cord atrophy in multiple sclerosis (MS). DESIGN Postmortem study of transverse sections obtained from 5 levels of the spinal cord, with measurement of the cross-sectional GM and WM areas. SETTING Department of Neuropathology, University of Nottingham, Nottingham, England. PATIENTS Fifty-five MS cases and 33 controls. MAIN OUTCOME MEASURES Size of the WM and GM areas. RESULTS The WM area was significantly reduced in MS cases in the upper but not the lower cord levels. The GM area was not significantly different between MS and control cases. CONCLUSION Spinal cord atrophy in MS is due to WM rather than GM volume loss.