NEW RESEARCH has found that around half of critically ill adults with severe encephalitis face death or long-term disability within three months of intensive care admission. While overall outcomes remained stable at one year, patients with autoimmune encephalitis demonstrated notably better recovery.
Encephalitis, an acute inflammation of the brain caused by infection, autoimmunity, or other triggers, is a serious neurological emergency with high mortality and morbidity. Prognosis in severe cases has remained uncertain, particularly for patients requiring intensive care. To address this, researchers conducted a large multicentre study across France, closely tracking survival and functional outcomes in patients hospitalised with confirmed or probable encephalitis.
The prospective cohort included 310 adults admitted to 31 intensive care units between October 2017 and April 2021. Patients had clear cerebrospinal fluid findings and required critical care support. At three months, 161 patients (51.9%) had unfavourable outcomes, of whom 84 (27.1%) had died. Advanced age and immunocompromised status independently predicted worse results, while early administration of intravenous acyclovir was linked to better survival and functional outcomes (odds ratio 0.38). Across all patients, levels of disability showed little change between the three-month and one-year follow-up points, with only 1.1% difference in functional independence. However, outcome trajectories varied by cause. In the autoimmune encephalitis group, functional improvement of nearly 9% was recorded at one year, whereas no significant progress was observed among those with infectious, unknown, or other forms.
For clinicians, these findings underline the urgency of early diagnosis and treatment in encephalitis care, as well as the need for ongoing follow-up in survivors. The data suggest that targeted long-term support may be especially beneficial for patients with autoimmune encephalitis, who show greater scope for recovery beyond the acute phase.
Reference
Sonneville R et al. Outcomes of critically ill adult patients with acute encephalitis. JAMA Netw Open. 2025;8(9):e2532478.
