Gray matter atrophy in longstanding multiple sclerosis

The aim of this study is to identify the measures of focal and diffuse white matter (WM) abnormalities that are related to whole-brain, deep, and cortical gray matter (GM) atrophy in long-standing multiple sclerosis (MS).

A total of 208 patients with MS of long-standing duration (disease duration ≥ 10 years) and 60 healthy control subjects were enrolled. The MS group was relatively old, had a mean disease duration of 20 years, and consisted of 130 patients with relapsing-remitting (RR) MS, 53 patients with SP MS and 25 patients with primary-progressive (PP) MS. Patients with PP MS and SP MS had higher Expanded Disability Status Scale scores than those with RR MS.

Magnetic resonance (MR) imaging was performed at 3 T. normalized GM volume (NGMV), normalized WM volume (NWMV), normalized deep GM volume (NDGMV), cortical thickness, and normalized lesion volume (NLV) were quantified. Patients had a median lesion volume of 11.24 mL, which is consistent with moderate to advanced disease. Tissue integrity of normal-appearing WM (NAWM) and lesions was measured by using diffusion-tensor MR imaging. NGMV, NDGMV, and cortical thickness were reduced in patients with MS. NWMV, NLV, and patient sex were the explanatory variables for NDGMV. The model for cortical thickness consisted of fractional anisotropy of NAWM, NLV, and patient age and sex.

The relationship between GM atrophy and WM abnormalities was weaker in primary and secondary progressive disease than in relapsing-remitting disease. Whole-brain and deep GM atrophy were particularly explained by WM atrophy and lesion volume, while cortical atrophy was associated with NAWM integrity loss. The weaker relationship between GM atrophy and WM abnormalities in patients with progressive disease might indicate a more independent neurodegenerative disease process in these patients. GM atrophy was most pronounced in patients with SP MS and correlated with Expanded Disability Status Scale scores. WM abnormalities were not restricted to focal lesions but included widespread damage to the NAWM. The degree of GM atrophy showed strong correlations with measures of WM abnormalities.

Authors: Steenwijk MD, Daams M.
Source: Radiology. 2014 Apr 23:132708. [Epub ahead of print]
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