Prospective Evaluation of Childhood Encephalitis: Predisposing Factors, Prevention and Outcome.

Background: Acute encephalitis in childhood is a serious condition. The severity varies between studies, partly reflecting differences in study design where only severe cases from referral centers often are reported. The aim of this study was to prospectively study the clinical picture and etiology of acute encephalitis in childhood at a primary and tertiary pediatric hospital in Sweden.

Methods: All children with acute encephalitis were prospectively included from 2011 to 2016. Laboratory tests, investigations and follow-up were performed according to standardized study protocols.

Results: Eighty-nine children were included (46 female and 43 male) with a median age of 53 months. An etiology was established in 61/89. Tick-borne encephalitis virus, enterovirus and rotavirus dominated and 34% were caused by a virus preventable by vaccination. Immune-mediated encephalitis was seen in 7 children. An abnormal electroencephalography picture was seen in 77/86, pathologic findings on neuroimaging in 13/49, and 38/89 children had seizures. Sequelae were reported by 49%. A high prevalence of previous contact with child and adolescent psychiatry was seen and, although not statistically significant, the need for extra support at school before encephalitis and the presence of central nervous system disease in the family seemed to predispose for a longer hospital stay.

Conclusion: Encephalitis is a condition with long-term consequences. Most children need admission to hospital, and many need surveillance in the intensive care unit. The etiology can be determined in a majority of cases, and 1/3 could have been prevented by vaccination. This study corroborates electroencephalography as a cornerstone in diagnosis.