Seizures as Initial Presentation and Enduring Predisposition to Seizures in Autoimmune Encephalitis

Abstract

Purpose. This retrospective study is aimed at investigating the clinical characteristics of autoimmune encephalitis (AE) and long-term prognosis of patients who initially present with seizures as well as risk factors for enduring predisposition to seizures in AE. Methods. From January 1, 2013, to October 31, 2021, a total of 343 AE patients from a single center diagnosed with autoimmune encephalitis (AE) were enrolled in this study, including 198 antibody-positive AE and 145 antibody-negative but probable AE. According to initial symptoms, AE patients were divided into two groups: onset with seizure group and onset with nonseizure group. The clinical characteristics were retrospectively reviewed. Patients were clinically evaluated at onset and at 6, 12, and 24 months of follow-up. Modified Rankin Scale (MRS) score, Clinical Assessment Scale in Autoimmune Encephalitis (CASE) score, and seizure-related information were assessed. Results. In AE, patients with seizures as the first presentation were younger, with a median-onset age of 28 years old. Compared with other types of antibody-positive AE, anti-GABABR AE more frequently began with seizures, while anti-CASPR2, anti-AMPAR, and anti-DPPX encephalitis usually began with symptoms other than seizures. The most common type of initial seizures in AE was focal to bilateral seizure (67.6%), with a significant prevalence in antibody-positive AE ($P=0.001$). In addition, compared with nonseizure group, patients with seizures as an initial presentation had higher MRS and CASE scores at 24 months of follow-up. Older age at onset and focal nonmotor seizure type were independent risk factors for an enduring predisposition to seizures in AE patients. Conclusion. The younger and anti-GABABR-positive AE patients are more prone to onset with seizures. AE patients who initially presented with seizures had worse long-term neurological recovery. Onset age and seizure type should be highly appreciated when formulating the strategy for therapy at post-AE status.