Coexistence of anti-NMDAR and anti-IgLON5 antibodies in an autoimmune encephalitis patient: The first case report

Background: The coexistence of autoimmune encephalitis (AE) with multiple neural autoantibodies is of great clinical significance because overlying antibodies may cause superposition or variation of clinical syndrome, which increases the difficulty of diagnosis and treatment of the disease. To the best of our knowledge, the coexistence of anti-N-methyl D-aspartate Receptor (NMDAR) and anti-IgLON5 antibodies in AE has not been published previously. Case presentation: A 38-year-old female patient presented to our hospital due to headache and abnormal psychiatric behavior. Based on her clinical manifestations (psychiatric and behavioral abnormalities, involuntary limb movements, and sleep disorders) and laboratory assessment results (positive human leukocyte antigen (HLA)-DQB1*05:01 haplotype, anti-NMDAR, and antiIgLON5 antibodies), she was diagnosed as AE with coexisting anti-NMDAR and anti-IgLON5 antibodies. After treatment with intravenous methylprednisolone and immunoglobulin, as well as plasmapheresis, her symptoms gradually improved with exception for the sleep disorders. Although oral prednisone acetate and mycophenolate mofetil were continued after discharge, her symptoms of sleep disorders did not improve at 6-month follow-up. Conclusion: This is the first case of AE co-existing with anti-NMDAR and anti-IgLON5 antibodies. Co-existence of neural auto-antibodies should be considered when patients present with overlapping or atypical symptoms. Special attention should be paid to the treatment of these patients as some anti-IgLON5 encephalitis patients may not benefit from immunotherapy treatment.