Fig. 2.

Brain MRI without IV contrast (obtained 2 days after the initial brain CT): sagital (a), coronal (b), and axial (c) T2 weighted sequences of the brain demonstrate interval development of extensive gyral swelling (double head arrows), diffuse cerebral sulcal effacement (yellow arrow), downward cerebellar tonsillar herniation (blue arrow), and compression and ventral displacement of the brainstem and fourth ventricle (red arrows). Axial DWI sequences (d, e, f) demonstrate no evidence of restricted diffusion to suggest acute ischemia. Axial T2 gradient-echo sequence (g, h) demonstrates prominent collateral tortuous superficial cortical veins and prominent engorged collateral deep medullary veins coursing through the centrum semiovale bilaterally (green arrows).