Publication date: Jun 25, 2025
Previous national studies of acute encephalopathy in Japan were conducted in 2007-2010 and 2014-2017. In this third study (April 1, 2020-October 31, 2023), spanning the coronavirus disease 2019 (COVID-19) outbreak, we compared results to assess trends in pediatric viral infections and therapeutic practices. Questionnaires were sent to 430 hospitals of the Japanese Pediatric Society, yielding 241 responses and 1197 cases. A secondary survey to 151 facilities received 110 responses (72. 8 %), identifying 622 eligible patients (604 for treatment, 544 for outcome analysis). Data on patient background, syndrome classification, causative virus, treatment, and prognosis were collected. Among 622 cases (54. 6 % boys), the highest incidence was in 1-year-olds, with case numbers peaking during COVID-19 and influenza outbreaks. The frequency of clinical syndromes was: acute encephalopathy with biphasic seizures and late reduced diffusion, 35. 1 %; clinically mild encephalitis/encephalopathy with a reversible splenial lesion, 17. 8 %; hemorrhagic shock and encephalopathy syndrome (HSES), 6. 9 %; acute encephalitis with refractory, repetitive partial seizures, 3. 7 %; acute fulminant cerebral edema (AFCE), 2. 2 %; acute necrotizing encephalopathy, 1. 6 %; and unclassifiable, 31. 4 %. Notably, the combined HSES/AFCE rate increased from 1. 9 % in the 2014-2017 survey to 9. 1 %, likely due to enhanced diagnosis and COVID-19 impact. Pathogens were exanthem subitum (16. 1 %), severe acute respiratory syndrome coronavirus 2 (15. 9 %), and influenza (7. 7 %). Treatments included steroid pulse therapy (68. 9 %), mitochondrial cocktails (42. 5 %), and targeted temperature management (31. 0 %). This study provides a comprehensive overview of pediatric acute encephalopathy during COVID-19 outbreaks, shows increases in the incidence of HSES/AFCE, and presents current treatment.
| Concepts | Keywords |
|---|---|
| Influenza | Acute encephalopathy |
| Japanese | Clinical syndromes |
| Therapy | COVID-19 |
| Pediatric neurology | |
| SARS-CoV-2 |
Semantics
| Type | Source | Name |
|---|---|---|
| disease | MESH | coronavirus disease 2019 |
| disease | MESH | viral infections |
| disease | MESH | syndrome |
| disease | MESH | influenza |
| disease | MESH | seizures |
| disease | MESH | encephalitis |
| disease | MESH | encephalopathy |
| disease | MESH | hemorrhagic shock and encephalopathy syndrome |
| disease | MESH | cerebral edema |
| disease | MESH | Long Covid |