A Neonatal Case of Mild Encephalopathy/Encephalitis with a Reversible Splenial Lesion.

The neurological symptoms of pediatric mild encephalopathy/encephalitis with a reversible splenial lesion (MERS) are mild and have a good prognosis. However, some aspects of neonatal MERS are unclear due to a lack of clinical knowledge. We present a neonatal case of MERS with features of poor activity and prolonged poor oxygenation after birth without asphyxia. He was diagnosed with MERS by brain magnetic resonance imaging (MRI) on day10, because the diffusion restriction of the splenium of the corpus callosum (SCC) seen on diffusion-weighted MRI on day 5 was attenuating. He was discharged due to good progress on day 26, but growth issues and developmental delay were observed in the follow up from 1-10 months. In rare neonatal cases, many aspects of the clinical course and prognosis are thus unclear. MERS should be considered in newborns who show unexplained non-neural or other encephalopathic symptoms.