AEs are severe inflammatory disorders of central nervous system. The diagnosis remain challenging and relies on the clinical manifestations, finding biomarkers and therapy response. However, this can be problematic given that antibody testing results are not readily available and negative testing does not exclude the diagnosis.

In our cohort psychiatric manifestations and autonomic dysfunction at onset were more frequently seen in AE+. Positive oligoclonal bands in AE- patients may represent immunological response and guide clinicians to consider immunotherapy when clinical suspicion for AE is high. Early recognition of highly suggestive presentation despite negative autoantibodies is important for this potentially treatable disorders.