Autoimmune encephalitides are uncommon diseases encompassing a wide clinical spectrum, and have many differential diagnoses. By contrast with the first descriptions of these diseases, not only acute or subacute presentations are observed; instead many patients have a progressive course mimicking neurodegenerative disorders. Fortunately, accurate and easy-to-use diagnostic criteria are available since 2016, facilitating the identification of possible cases. The diagnosis is mainly based on clinical findings, supported by brain imaging and cerebrospinal fluid analysis. Detection of autoantibodies specifically targeting neuronal antigens then allows the establishment of diagnosis. Herein, we briefly review the clinical presentation and the ancillary tests leading to a probable or definite diagnosis, which is the first step towards adequate management of these patients.
