Autoimmune encephalitis with coexisting antibodies to GABABR, GAD65, SOX1 and Ma2

Abstract Background Autoimmune encephalitis (AE) refers to a heterogeneous group of CNS autoimmune disorders characterized by the production of different anti-neuronal surface synaptic protein-associated antibodies. In recent years, autoimmune encephalitis that is positive for multiple anti-neuronal antibodies has been gradually recognized in the clinic, with complex and varied clinical manifestations, especially in combination with malignant tumours, which have worse treatment and prognosis. Current clinical studies on the coexistence of multiple anti-neuronal antibodies in patients with AE are mainly disseminated case reports. Patients with AE in which four anti-neuronal antibodies coexist are even rarer. Case presentation: We report a patient who initially presented with small cell lung cancer and hyponatraemia, followed by seizures and progressive deterioration of consciousness, cognition and psychiatric abnormalities. A cell-based assay (CBA) method was used to detect serum and cerebrospinal fluid anti-neuronal surface or prominent protein antibodies. Patients with AE diagnosed with co-existing anti-GABABR, GAD65, SOX1 and Ma2 antibodies and receiving gammaglobulin, steroid shock therapy, and chemotherapy for small cell lung cancer. Conclusions The coexistence or overlap of multiple anti-neuronal surface antibodies with anti-neuronal intracellular antibodies is rare and increases the likelihood of underlying malignancy. Elucidating the impact of individualised immunotherapy and coexisting antibodies on the clinical presentation of patients has the potential to improve long-term prognosis.