Pontocerebellar imaging abnormalities in multiple system atrophy

Brain MRI in a patient with multiple system atrophy (MSA) with predominant cerebellar ataxia (MSA-C). Transverse axial T2-weighted images (A through C) show pontine atrophy, cruciform hyperintensity in the mid-pons ("hot cross bun sign," most apparent in A within the circle), hyperintense signal abnormality and atrophy of both middle cerebellar peduncles (B, arrowheads), and atrophy of both cerebellar hemispheres. On sagittal T1-weighted MRI (D), there is striking pontocerebellar atrophy (circle).