Reduced fractional anisotropy in early-stage cerebellar variant of multiple system atrophy

BACKGROUND: In patients with the cerebellar variant of multiple system atrophy (MSA-C), reduced fractional anisotropy (FA) has been reported in several brain areas. However, since previous studies have employed predetermined regions of interest (ROI), the brain areas showing the earliest alterations in FA are unknown. The sensitivity of detecting early-stage MSA-C and the time course of the FA reduction are also unknown. The purpose was to address these issues to determine the diagnostic value of FA for early diagnosis. METHODS: Twenty-one patients with MSA-C were investigated. Voxel-based FA analysis and morphometry were used to detect the differences between early-stage MSA-C and normal controls. An ROI-based FA analysis was also used to clarify the temporal profile. RESULTS: From the early-stage, MSA-C patients exhibited reduced FA and white matter atrophy in the middle cerebellar peduncle, the inferior cerebellar peduncle, and the ventral pons. The FA of these areas decreased rapidly during the first few years after onset, after which a rather gradual reduction occurred. The receiver operating characteristics analysis revealed a high sensitivity and specificity for discriminating early MSA-C from normal controls. CONCLUSIONS: FA measurement could potentially be used to make an early diagnosis and monitor progression in MSA-C patients.