To present a patient demonstrating clinical and radiologic evidence of brainstem and limbic encephalitis with multiple neuronal autoantibodies

Brainstem, diencephalic, and/or limbic encephalitis is characteristic of anti-Ma1/Ma2 antibody-mediated encephalitis, while brainstem involvement is atypical for anti-NMDA-R encephalitis.  Although coexisting autoantibody syndromes are rare, a systematic diagnostic approach with autoantibody testing and malignancy screening is essential in suspected autoimmune/paraneoplastic encephalitis.

His presentation is most consistent with anti-Ma1/Ma2 mediated encephalitis, with coexisting CSF anti-NMDA-R antibodies producing an overlapping clinical syndrome, likely in response to a lung neoplasm. Initial diagnostic testing for suspected autoimmune encephalitis should include a panel of autoantibodies, as there can be significant overlap in clinical symptoms associated with each neural autoantibody. Individual antibody testing should be informed by the clinical presentation. Anti-Ma1/Ma2 antibodies are not part of standard autoimmune panels but were tested in this scenario, in addition to a standard panel, given the pattern of encephalitis and neoplastic risk factors. A broader autoantibody evaluation is required if a mismatch occurs between clinical features and discovered antibodies, or else the diagnosis may be missed. In the setting of multiple autoantibodies, a careful evaluation for malignancy or systemic autoimmunity is warranted, with malignancy screening informed by the antibodies present.