Abstract
BackgroundBrain atrophy is a well-accepted imaging biomarker of multiple sclerosis (MS) that partially correlates with both physical disability and cognitive impairment.Methodology/Principal FindingsBased on MRI scans of 60 MS cases and 37 healthy volunteers, we measured the volumes of white matter (WM) lesions, cortical gray matter (GM), cerebral WM, caudate nucleus, putamen, thalamus, ventricles, and brainstem using a validated and completely automated segmentation method. We correlated these volumes with the Expanded Disability Status Scale (EDSS), MS Severity Scale (MSSS), MS Functional Composite (MSFC), and quantitative measures of ankle strength and toe sensation. Normalized volumes of both cortical and subcortical GM structures were abnormally low in the MS group, whereas no abnormality was found in the volume of the cerebral WM. High physical disability was associated with low cerebral WM, thalamus, and brainstem volumes (partial correlation coefficients ∼0.3–0.4) but not with low cortical GM volume. Thalamus volumes were inversely correlated with lesion load (r = −0.36, p<0.005).ConclusionThe GM is atrophic in MS. Although lower WM volume is associated with greater disability, as might be expected, WM volume was on average in the normal range. This paradoxical result might be explained by the presence of coexisting pathological processes, such as tissue damage and repair, that cause both atrophy and hypertrophy and that underlie the observed disability.
Highlights
Multiple sclerosis (MS) causes multifocal white matter (WM) lesions that are visible on MRI and that are characterized by a varied array of pathologic processes, including inflammation, demyelination, remyelination, edema, axonal damage, and gliosis [1]
Lower WM volume is associated with greater disability, as might be expected, WM volume was on average in the normal range
Brainstem volume trended toward smaller values in multiple sclerosis (MS), whereas ventricle volume trended towards larger values in MS; the latter had the largest relative volume change (38% larger in MS)
Summary
Multiple sclerosis (MS) causes multifocal white matter (WM) lesions that are visible on MRI and that are characterized by a varied array of pathologic processes, including inflammation, demyelination, remyelination, edema, axonal damage, and gliosis [1]. All of these processes can cause substantial changes in tissue volume. The relationships between each of these measures and volumes of lesions and/or individual brain structures have been studied previously. Brain atrophy is a well-accepted imaging biomarker of multiple sclerosis (MS) that partially correlates with both physical disability and cognitive impairment
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