AQP4 and autoimmune encephalitis: Routine cerebrospinal fluid testing, autoimmune encephalitis-related antibodies, paraneoplastic syndrome-related antibodies, oligoclonal bands, aquaporin-4, myelin oligodendrocyte glycoprotein, glial fibrillary acidic protein, autoantibodies, thyroid-related antibodies, cardiolipin antibodies, antineutrophil cytoplasmic antibodies, metabolic screening, and other screening results were all negative.