White Matter Microstructure of the Cerebellar Peduncles Is Associated with Balance Performance during Sensory Re-Weighting in People with Multiple Sclerosis.

People with multiple sclerosis (PwMS) exhibit impaired balance during different sensory environments and poor cerebellar peduncle microstructure. We aimed to examine associations between microstructures of the superior, middle and inferior cerebellar peduncles (CP) with visual, vestibular, and proprioceptive-based balance in PwMS. Twenty-seven PwMS and twenty-nine healthy controls (HC) underwent MRI and balance assessments. We assessed CP microstructure with radial diffusivity (RD) and fractional anisotropy (FA) and balance with center of pressure-derived measures of path length and root mean square of sway during proprioceptive (C2), visual (C3), and vestibular (C4) balance conditions of the modified clinical test of sensory integration on balance (mCTSIB). PwMS exhibited significantly lower FA (p < 0.001) and greater RD (p < 0.001) across all CP and greater path length (p < 0.05) in the mCTSIB compared with HC. In PwMS, significant associations were detected between inferior CP white matter microstructure and proprioceptive-based balance control (rho = -0.43, p < 0.05) and middle CP white matter microstructure and visual-based balance control (rho = 0.39, p < 0.05). PwMS may rely more on cerebellar-regulated proprioceptive- and visual-based balance control than HC.