Influenza A Encephalopathy, Cerebral Vasculopathy, and Posterior Reversible Encephalopathy Syndrome: Combined Occurrence in a 3-Year-Old Child

MR images obtained immediately on transfer (A–F) and on follow-up at 5 days (G–H). A–D, Axial FLAIR MR images obtained immediately on transfer demonstrate signal-intensity abnormality in the thalami bilaterally (arrowheads), characteristic of influenza-associated encephalopathy. Also present is abnormal signal intensity in the cortex and subcortical white matter of the occipital poles (open arrows), occipital-parietal junction (curved arrows), and posterior frontal lobes (arrows) bilaterally, left inferior temporal-occipital junction (short arrow), and midposterior cerebellar hemispheres (not shown), consistent with PRES vasogenic edema. The edema is greatest in the occipital-parietal region (curved arrows). Additional focal lesions are present in the midbrain (open arrowhead), pons, and middle cerebellar peduncle. E, Axial diffusion-weighted MR image demonstrates small foci of restricted diffusion in the thalami bilaterally (arrows) consistent with early necrosis of influenza-associated ANE. A small focus of restricted diffusion is present in the medial left occipital-parietal junction (small curved arrow) with a second likely present more peripherally in areas of PRES vasogenic edema (arrowhead). These regions demonstrate true restricted diffusion on the accompanying apparent diffusion coefficient map. F, Axial gradient-echo T2* MR image demonstrates the small focus of petechial hemorrhage in the left thalamus (arrow) just lateral to the left thalamic restricted diffusion. G–H, Follow-up T2-weighted MR images obtained on day 5 demonstrate the more typical features of PRES vasogenic edema in the cortex and white matter of the occipital-parietal and frontal-parietal junctions (curved arrows) and frontal lobes (arrows), along with continued demonstration of the bilateral thalamic lesions (arrowheads).