Retrospective evaluation of mild encephalitis/encephalopathy with a reversible splenial lesion in children

BACKGROUND: Comprehensive documentation on consecutive years of mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) in children is lacking. This study aims to provide an in-depth analysis of the clinical profiles of MERS in children across different age groups, focusing on pathogens and recovery time. METHODS: In this retrospective study, 43 patients diagnosed with MERS were enrolled between December 2017 and November 2021. Due to different clinical manifestations at different ages, we categorized them into two age groups: the 6-year-old or younger group and the over 6-year-old group. Clinical data were described and compared for these age cohorts. RESULTS: Sixty percent of the cases occurred during winter, with two distinct peaks in onset age, at 1-3 years of age and 7-8 years of age. Intestinal infections were prevalent among children aged below 6 years, mainly caused by rotavirus; convulsion was the most common symptom (92.6% vs. 50%, p = 0.005). Conversely, respiratory tract infections were often observed in children older than 6 years of age, which were mainly attributed to mycoplasma pneumonia; headache and dizziness were characteristic symptoms (62.5% vs. 18.5%, p = 0.003). No significant differences were found in treatment outcomes between the two age groups. Nonetheless, MERS type II exhibited a notably longer clinical recovery time than type I (4.8 ± 1.7 vs. 8.2 ± 5.5). CONCLUSION: Mild encephalitis/encephalopathy with a reversible splenial lesion exhibits a distinct seasonal pattern with varied clinical manifestations across different age groups. Although the prognosis was favorable, discernible differences in clinical symptoms and pathogens were observed between the two age cohorts. It was noted that the clinical recovery time for MERS type II was comparatively protracted in comparison with type I.