Disability in patients with multiple sclerosis was independently linked to microstructural abnormalities of spinal cord grey matter on diffusion tensor imaging study in a prospective study of healthy controls and patients at various stages of disease.
Spinal cord atrophy and abnormal grey matter radial diffusivity explained 77% of variance in scores on the Expanded Disability Status Scale (EDSS), said Dr. Hugh Kearney of the Queen Square MS Centre at the University College London Institute of Neurology and his associates. Grey matter involvement was already present in patients with relapsing-remitting multiple sclerosis (MS) but was more pronounced in those with secondary progressive disease, the investigators said.
The researchers performed 3 T spinal cord magnetic resonance imaging and diffusion tensor imaging on 113 subjects – 30 healthy controls, 21 individuals with a clinically isolated syndrome, 33 who had relapsing-remitting MS and 29 who had secondary progressive MS (J. Neurol. Neurosurg. Psychiatry 2014 Aug. 5 [doi:10.1136/jnnp-2014-308241]).
Compared with controls and subjects with relapsing-remitting MS, those with secondary progressive disease had significantly worse abnormalities in measures of spinal cord radial diffusivity, fractional anisotropy, and mean diffusivity in the grey matter and posterior columns, the investigators said.
Furthermore, spinal cord grey matter radial diffusivity and cord area were independently associated with EDSS disability scores (beta = 0.33 and P less than .01; beta = –0.45 and P less than .01, respectively), and radial diffusivity was independently linked to scores on a 9-hole peg test (beta = –0.33; P less than .01) and timed walk (beta = –0.20, P = .04), the researchers said.
Based on the findings, grey matter pathology in the spinal cord may underlie physical disability in MS, including the irreversible disability that characterizes secondary progressive disease, Dr. Kearney and his associates said. Investigators should next examine longitudinal changes in diffusion tensor imaging measures of spinal cord grey matter and how these changes relate to clinical progression, they said.
The research was funded by the MS Society of Great Britain and Northern Ireland, UCLH-UCL Biomedical Research Centre, the International Spinal Research Trust, and the Engineering and Physical Sciences Research Council. The authors reported no competing interests.