Abstract

Viral encephalitis is a serious neurological condition associated with high morbidity and mortality. Acute neurological severity, including coma, seizures, and need for intensive care, might influence outcomes and the development of post-encephalitic epilepsy; however, data remain inconsistent. A systematic review and meta-analysis were conducted in accordance with PRISMA guidelines. PubMed, Embase, Web of Science, and Scopus were searched from inception to January 2026. Observational studies of adult patients with viral encephalitis that reported mortality, functional outcomes, or neurological severity markers were included. A random-effects model with Freeman–Tukey transformation was used to pool proportions. Four studies comprising 1,193 patients were included. The pooled mortality rate was 16.6% (95% CI: 14.5–18.8; I² = 0%). Poor functional outcomes were observed in 67.3% (95% CI: 52.0–80.9; I² = 95.7%). The pooled proportions of coma and mechanical ventilation were 21.9% and 76.6%, respectively, both with high heterogeneity. Acute seizures occurred in 30.7%, while seizures as an ICU indication were reported in 33.6%, with consistent estimates. Adult viral encephalitis was found to be associated with substantial mortality and a high burden of neurological complications. Acute severity markers were common and might have prognostic relevance, although variability across studies remains significant. Further standardized prospective research is needed to clarify outcomes and long-term risks, including post-encephalitic epilepsy.

Key words: Viral encephalitis, epilepsy, neurological severity, seizures, meta-analysis