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 Neurológicas” 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-methyl-D-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.