Influenza A (H1N1)-Associated Acute Necrotizing Encephalopathy with Unusual Posterior Reversible Encephalopathy Syndrome in a Child.

Other than respiratory symptoms, influenza A (H1N1) can rarely cause neurological complications in children and adults. In this article, we aimed to present H1N1-associated acute necrotizing encephalopathy (ANE) and asymmetrical involvement of posterior reversible encephalopathy syndrome (PRES) in a 30-month-old male patient with clinical and radiological imaging findings. The patient who presented to the hospital with febrile convulsion and lethargy had elevated liver enzymes and coagulopathy. The magnetic resonance (MR) examination revealed diffusion restriction in bilateral cerebellar white matter, thalami, and periventricular white matter which was consistent with ANE. Susceptibility-weighted imaging (SWI) sequence showed hemorrhage in bilateral thalami and cerebellar white matter. There was high signal on fluid-attenuated inversion recovery (FLAIR) sequences in right temporooccipital cortical, subcortical, and periventricular white matter suggestive of PRES. MR angiography showed vasculopathy which is supportive for PRES. This is the second case of H1N1-associated pediatric PRES reported in the literature.