Acute necrotizing encephalopathy during novel influenza A (H1N1) virus infection

MRI: Axial (A) and sagittal (B) T2-weighted MRI shows confluent hyperintensity involving the cortical–subcortical regions of the occipital and parietal lobes. There are also several small areas in internal and external capsula, insular cortex, and bilaterally in the thalamus and in the left superior cerebral peduncle (A, B). Axial diffusion-weighted image map shows restricted water diffusion in the corresponding areas mimicking acute ischemic infarction with cytotoxic edema. The lesions are not confined to a certain arterial territory (C). The spectroscopic study (echo time = 144 msec) shows high peaks for lactate (arrow), with normal values for choline, creatine, and NAA (D).