Autoimmune encephalitis with anti-IgLON5 and anti-GABAB-receptor antibodies: A case report.

Rationale: Anti-IgLON5 disease is a complex neurological illness which is characterized by progressive sleep and movement disorders and defined by specific autoantibodies to IgLON5. We here describe the first case of a patient with coexisting anti-IgLON5 as well as anti-γ-aminobutyric acid B (GABAB)-receptor antibodies and predominant clinical features of anti-IgLON5 disease.

Patient Concerns: The patient initially presented with subacute symptoms of severe sleep disorder, gait stability, dysarthria, cognitive impairment, depressive episode and hallucinations.

Diagnoses: The patient was diagnosed with autoimmune encephalitis, based on clinical features and positive anti-IgLON5 antibodies in serum as well as in cerebrospinal fluid and anti-GABAB-receptor antibodies in serum only.

Interventions: Initially, the patient was treated with high dosages of methylprednisolone and subsequently with plasmapheresis. Due to the lack of clinical improvement immunosuppressive treatment with intravenous cyclophosphamide was initiated.

Outcomes: Following the first year of cyclophosphamide treatment, neurological examination revealed an improvement in gait instability, visual and acoustic hallucinations and sleep disorder.

Lessons: The case report demonstrates that anti-IgLON5 and anti-GABAB-receptor antibodies can coexist in the same patient whereas clinical leading symptoms are determined by those antibodies that were tested positive in cerebrospinal fluid.