Exploring seizure characteristics in individuals with autoimmune encephalitis: A comprehensive retrospective study in a low-middle-income country setting☆

Introduction: Seizures and epilepsy are well-documented in association with autoimmune encephalitis. Despite this, a notable gap exists in understanding the persistence of seizures beyond the acute phase, particularly within the context of low- and low-middle-income settings. Objective: To evaluate the frequency, clinical characteristics, diagnosis, and potential factors associated with the occurrence and persistence of seizures in autoimmune encephalitis patients. Methods: This was a retrospective, cross-sectional study. Patients diagnosed with possible, probable or confirmed autoimmune encephalitis according to the Graus criteria at the "Instituto Nacional de Ciencias Neurolo<acute accent>gicas" in Lima, Peru, were included between January 2018 and April 2023. Demographic, clinical, diagnosis, and management information was recorded. A bivariate analysis was performed considering the persistence of seizures at one-year follow-up and a second analysis was performed to compare the groups according to the anti N-methylD-aspartate receptor (NMDAR) antibody results. Results: Sixty patients predominantly male (40; 66.7 %) were included. Only 36 (60 %) patients were tested for antibodies, 16 (44.4 %) were NMDAR positive. 46 (76.7 %) patients had at least one seizure and 13 (37.1 %) had seizures after 1 year of follow-up. Patients with seizure relapse were younger, 20 (IQR: 18-28) versus 29.5 years (IQR: 21-48), p=0.049. Four (44.4 %) patients with persistent seizures had positive NMDAR results. Similar sex distributions, no differences in seizure characteristics, and higher CSF cell count in the NMDAR-positive group were observed. Neuroimaging, EEG findings, and follow-up times were comparable between the groups. Conclusions: We found a 37.1 % seizures rate after one year of follow-up, predominantly in younger patients.