Mortality and Neurologic Sequelae in Influenza-Associated Encephalopathy: Retrospective Multicenter PICU Cohort in France

OBJECTIVES: To describe and estimate the mortality rate of severe influenza-associated encephalopathy/encephalitis among children admitted to PICUs. DESIGN: Multicenter retrospective study. SETTING: Twelve French PICUs. PATIENTS: All children admitted for influenza-associated encephalopathy/encephalitis between 2010 and 2018 with no severe preexisting chronic neurologic disorders and no coinfection potentially responsible for the disease. INTERVENTION: None. MEASUREMENTS AND MAIN RESULTS: We collected the clinical presentation; laboratory, electroencephalographic, and MRI findings; and treatments used in the PICU. The primary outcome was mortality. The secondary outcomes included sequelae at discharge and last follow-up. We included 41 patients with a median (interquartile range) age of 4.7 years (2.5-8.2 yr). The main reasons for admission were altered consciousness (59%) and status epilepticus (34%); 48% of patients had meningitis, and one third had acute necrotizing encephalopathy on MRI. Mechanical ventilation was required in 73% of patients and hemodynamic support in 24%. The use of specific treatments was variable; steroids were given to 49% of patients. Seven patients (17%) died in the PICU. Median (interquartile range) PICU stay length was 7 days (2-13 d), and total hospital length of stay was 23 days (7-33 d). On hospital discharge, 49% (n = 20) had neurologic sequelae, with 27% (n = 11) having severe disabilities defined by modified Rankin Score greater than or equal to 4. CONCLUSIONS: Children requiring PICU admission for influenza-associated encephalopathy/encephalitis have high mortality and morbidity rates. The management remains highly variable due to the lack of guidelines.