The clinical, diagnostic and treatment spectrum of seropositive and seronegative autoimmune encephalitis: Single-center cohort study of 51 cases and review of the literature

Objective: Autoimmune encephalitis (AE) comprises a spectrum of inflammatory neurological syndromes characterized by immune responses to neuronal autoantigens, leading to diverse clinical manifestations, particularly behavioral and cognitive decline. Methods: This single-center retrospective study included 51 patients diagnosed with AE from 2013 to 2019 in a southeast Michigan tertiary care hospital. Patients were then divided into two groups, seropositive AE (AE+) and seronegative AE (AE−), based on antibody detection in the serum, cerebrospinal fluid or both when available. The study compares AE+ and AE− subtypes across clinical, diagnostic, and therapeutic parameters. Results: A total of 34 patients were classified as AE+, and 17 as AE−. Demographic analysis showed no significant differences in age, sex or race between the two groups. Clinical presentations varied widely, encompassing psychiatric symptoms, movement disorders, seizures and confusion; 24% patients had a prior malignancy. Laboratory assessments found diverse autoantibodies in AE+ patients' serum. Radiological and electrophysiological assessments showed no significant differences between the groups. AE− patients had higher rates of confusion compared with AE+ patients (59% vs. 18%, P = 0.004). Conclusions: This study focuses on the complexities associated with diagnosing AE, emphasizing the challenges posed by the heterogeneity of symptoms and often negative antibody test results. Rapid identification of AE, regardless of seropositivity or seronegativity, emerges as a critical factor for clinicians, facilitating the prompt initiation of immunotherapy and/or tumor removal if needed. These insights contribute to a better understanding of the landscape of this condition, offering clinicians the tools to refine their diagnostic and treatment strategies. Ultimately, the study aimed to enhance the management of AE, empowering healthcare professionals to make accurate and timely interventions for patients.