Objective: We previously reported that voxel-based morphometry (VBM) is effective for classifying the disease types causing cerebellar atrophy. In the present study, with the objective of examining the progression of atrophic lesions in the cerebellar variant of multiple system atrophy (MSA-C), VBM images were classified according to disease stage.

Methods: Twenty-nine patients with MSA-C were examined with VBM (46 sessions in total) during or after 2007. The onset ages ranged from 48 to 77 years (median, 59 years). There were 10 men and 19 women. The disease durations at the time of VBM ranged from 6 to 129 months (median, 37 months). VSRAD advance was used for analyzing VBM images, and the gray matter (GM) and white matter (WM) on brain magnetic resonance images were separated and extracted. On the basis of the resultant Z-score images, GM and WM were classified into 4 and 5 grades, respectively. Voxel-based analysis stereotactic extraction estimation (vbSEE) was performed to construct an average image for each grade. The number of voxels showing atrophy with a Z-score of 2 or higher and mean Z-scores were determined in each field of the brainstem, cerebellum, and cerebrum.

Results: Disease duration correlated highly with grades of GM and WM, Z-scores, and SARA scores. The GM of each cerebellar hemisphere showed areas with a Z-score of 2 (hereinafter described as Z2) to Z3 (GM1). Atrophy of these areas spread and progressed to Z4 (GM2). One of the hemispheres was then affected at Z5 to Z6 (GM3). Ultimately, both hemispheres were severely affected at Z6 (GM4). Disease duration correlated highly with the Z-scores for cerebellar GM. As for WM, atrophy started in the middle cerebellar peduncles (WM1) and spread to the pons (WM2). Atrophy affecting one of the middle cerebellar peduncles became severe at Z5 to Z6 (WM3) and subsequently spread to both middle cerebellar peduncles (WM4). Ultimately, the pons and both middle cerebellar peduncles were severely affected at Z6 (WM5). Disease duration correlated highly with the Z-scores for WM of the cerebellum and brainstem. For WM grading, the mode of progression was readily ascertained visually, while GM grading correlated highly with disease duration and the ability to walk.

Conclusions: Disease stage classification using VBM was useful for assessing the mode and stage of progression of MSA-C and also facilitated early diagnosis of MSA-C.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/disease-stage-classification-of-the-cerebellar-variant-of-multiple-system-atrophy-based-on-voxel-based-morphometry/