In MS, neurodegenerative processes involve several cortical and subcortical structures of the central nervous system.
To perform a multiparametric assessment of cortical, deep grey matter (DGM), cerebellar and cervical cord atrophy to characterize MS phenotypes and to explain patients’ disability.
3T brain and cervical cord T2- and 3D T1-weigthed images were acquired from 198 MS patients (139 relapsing-remitting [RR] MS, 59 progressive [P] MS) and 67 healthy controls (HC) at three European sites. Cortical thickness (CTh), DGM volumes, cerebellar volumes and cervical cord cross-sectional area (CSA) were compared between MS patients and HC and across clinical phenotypes. In patients, sex-, age-, and site-corrected stepwise linear regression models investigated the association of brain and cord lesion burden and cortical, DGM, cerebellar and cervical cord atrophy with clinical disability.
Compared to HC, MS patients had widespread atrophy in all cortical lobes, DGM nuclei and cerebellar lobules, as well as reduced cord CSA. Similar results were observed in RRMS patients vs HC, except for the left superior parietal lobule and left frontal pole (p=range from <0.001 to 0.04). In PMS patients, additional cortical atrophy vs RRMS was identified in all investigated lobes (p=range from <0.001 to 0.03), except for selected cingulate, parietal and occipital regions. At the univariate analysis, in MS patients higher disability was associated with more severe cortical, DGM, cerebellar and cervical cord atrophy (p=range<0.00-0.047). The multivariate model retained cerebellar and cervical cord atrophy as significant predictors of higher EDSS score (R2=0.45, p<0.001) as well as of pyramidal (R2=0.42, p<0.001), sensory (R2=0.28, p<0.001) and cerebellar (R2=0.50, p<0.001) functional system scores.
Abnormalities of regional CTh, DGM volume, volume of the cerebellar lobules and cervical cord CSA characterized the main MS clinical phenotypes. Atrophy within the cerebellum and cervical cord was crucial for explaining clinical disability, mainly within sensorimotor domains.