Diffusion-weighted imaging in acute hyperammonemic encephalopathy.

Magnetic resonance imaging (MRI) findings associated with chronic liver disease are characterized by cerebral atrophy and bilateral, symmetric hyperintensities of the globus pallidus on T1-weighted images without corresponding signal intensities in T2-weighted images. Recently, distinct MRI changes of acute hepatic encephalopathy have been described which may be misinterpreted given their resemblance to hypoxic-ischemic injury imaging changes as well as their limited description in the neurologic literature. We describe 3 cases of acute hyperammonemic encephalopathy primarily characterized by restricted diffusion involving the insular and cingulate cortices and thalamus bilaterally.