Several autoantibodies are associated with autoimmune encephalitis. Some of these antibodies are directed against intracellular neuronal antigens such as Hu and Ma2, which are strongly associated with paraneoplatic syndrome. In the past 10 years, various antibodies were identified that recognize neuronal cell–surface or synaptic proteins in patients associated with or without malignancy. Some of these antibodies are able to directly access receptors of neurotransmitters or channels and are responsible for causing neurological syndromes. Autoimmune encephalopathy with these antibodies generally responds to immunotherapies, such as steroids, plasmapheresis, and intravenous immunoglobulin as well as immunosuppressant and anti–cancer treatments in cases of paraneoplastic syndrome.
Patients with N–methyl–D–aspartate (NMDA) receptor antibodies, which are the most common in autoimmune encephalopathy, often cause psychiatric manifestation, memory impairment, seizures, dyskinesia, catatonia, autonomic instability and respiratory failures. Although 86% of patients become worse at the stage of mRS5, almost 80% of all patients recover to the stage of less than mRS2 with immunomodulatory therapy and careful management for their general condition. Detection of those antibodies in both serum and CSF using cell–based assays is important for definite diagnosis. Availability of screening systems of antibodies and covering health insurance for immunomodulatory therapy for autoimmune encephalitis are highly expected.