Influenza-associated encephalitis/encephalopathy with a reversible lesion in the splenium of the corpus callosum: a case report and literature review.

We report the cases of two patients with influenza-associated encephalitis/encephalopathy (IAEE) who presented with mild CNS manifestations and complete recovery within a few days. Initial MR imaging at days 4 and 5 revealed a lesion in the central portion of the splenium of the corpus callosum with a reduced apparent diffusion coefficient (ADC) value, which completely resolved on follow-up studies at day 10. We postulate two possible mechanisms for decreased ADC; namely, intramyelinic edema and an inflammatory infiltrate.