Autoimmune Encephalitis

Autoimmune encephalitides (AE) associated with antibodies against neural (neuronal or glial) surface antigens yields a new category of diseases for which there is compelling evidence that the antibodies have direct pathogenic effects. Antibody-mediated AE occurs in persons of all ages, with some types affecting predominantly children and young adults. The diversity of clinical manifestations varies according to the type of autoantibody. The most common types are the encephalitis associated with NMDAR antibodies (which mainly affects children and young women, ~40% of the latter associated with ovarian teratoma), acute disseminated encephalomyelitis (ADEM, the most frequent in children, with white matter involvement and MOG antibodies in ~60% of cases), and limbic encephalitis, particularly a subtype that associates with LGI1 antibodies and predominantly occurs in patients older than 50 years). AE can be suspected on clinical grounds. However, in most instances, the definitive diagnosis requires the detection of neural antibodies in the cerebrospinal fluid (CSF), with the exception of MOG antibodies in ADEM, which are predominantly detected in serum. The importance of recognizing these clinical-immunological associations is that they inform about treatment, potential comorbidities (e.g., tumors), and prognosis. Despite the severity of symptoms, prompt diagnosis and treatment lead to improvement or good recovery in most cases.