[The diagnostic challenge of autoimmune encephalitis].

Autoimmune encephalitis encompasses a spectrum of neurological disorders characterized by an autoimmune response directed against neurons and glia. Around two-thirds of cases exhibit autoantibodies targeting neuronal or glial antigens in the cerebrospinal fluid and/or serum. The diagnosis is based on specific criteria combining a subacute clinical presentation and complementary test results. However, approximately one-quarter of patients do not present any paraclinical abnormalities, making the diagnosis complex. Testing for anti-antibodies is pivotal for diagnosis, and their interpretation should be contextual. Best practices for anti-neural antibody detection involve appropriate sample collection and confirmation of positive results in relation to the clinical picture.