Antibody-Negative Autoimmune Encephalitis: A Single-Center Retrospective Analysis

Area of Science:

• Neurology
• Immunology
• Neuroinflammation

Background:

• Autoimmune encephalitis (AE) encompasses heterogeneous inflammatory central nervous system (CNS) diseases.
• Patients without detectable neural autoantibodies are classified as antibody-negative AE.
• Understanding antibody-negative AE is vital for accurate diagnosis and treatment.

Purpose of the Study:

• To characterize the clinical features, triggers, treatments, and outcomes of antibody-negative AE patients.
• To evaluate the diagnostic yield of comprehensive antibody testing in suspected antibody-negative AE cases.
• To highlight the importance of thorough investigation in this patient group.

Main Methods:

• Retrospective monocentric study of adult patients tested for neural antibodies between 2011-2020.
• Inclusion criteria: probable antibody-negative AE, definite antibody-negative ADEM, or definite autoimmune LE.
• Re-analysis of serum/CSF samples using comprehensive cell-based and tissue-based assays.

Main Results:

• 1.5% (33/2250) of tested patients were classified as possible antibody-negative AE.
• Of 10 probable/definite AE/LE/ADEM cases, one had malignancy; none received alternative diagnoses.
• 80% received immunotherapy, 60% received specific treatments (e.g., rituximab, IVIg); 50% improved, 30% died.

Conclusions:

• Antibody-negative AE diagnosis requires comprehensive antibody testing.
• Diagnostic efforts are warranted due to potential benefits from immunotherapy.
• Identifying antibody-negative AE can reveal underlying malignancies.