Thinning of the brainstem (mainly pons and medulla oblongata) with prominence of the prepontine cistern and fourth ventricle. The hot cross bun sign is present in the pons on T2-weighted images.
Diffuse widening of folia in both cerebellar hemispheres and the vermis, and thinning of both middle cerebellar peduncles. Widened subarachnoid spaces and sulci in both cerebral hemispheres.