Prognostic Outcomes in Seropositive and Seronegative Autoimmune Encephalitis.

Objectives: Autoimmune Encephalitis (AE) is an immune-mediated inflammatory disorder of the central nervous system with heterogeneous clinical manifestations and variable outcomes. The prognostic significance of antibody status (seropositive vs. seronegative) remains incompletely understood, particularly in Iranian populations. This study aimed to compare clinical characteristics, therapeutic interventions, and prognostic outcomes between seropositive and seronegative patients with AE (≤ 18 years) admitted to two tertiary referral hospitals in Tehran, Iran. Material & Methods: In this study, medical records of 58 patients diagnosed with AE between 2019 and 2024 at Ali Asghar and Hazrat Rasool Hospitals were reviewed. Patients were classified as seropositive or seronegative based on antibody testing. Results: Of the 58 patients, 31 (53.4%) were seropositive and 27 (46.6%) were seronegative. The mean age was 41.94 ± 24.87 months, and 72.4% were male. Seizures were the most common clinical manifestation. No significant differences were observed between seropositive and seronegative groups in initial disease severity, functional outcomes, neurological complications, treatment allocation (all p > 0.05). In multivariable analysis, initial disease severity (OR = 13.3, p = 0.032) and the presence of underlying diseases (OR = 31.4, p = 0.007) were independently associated with poor prognosis, whereas serologic status was not. Conclusion: Serologic status does not significantly influence disease severity, treatment response, or prognosis in patients with AE. Initial clinical severity and comorbidities are the primary determinants of poor outcome. Management strategies should prioritize early recognition, assessment of disease severity, and timely immunotherapy regardless of antibody status.