The number of acute encephalitides diagnosed each year is gradually increasing, reaching approximately 5 to 10/100,000 per year; more than 50% of etiologies currently remain unknown. The majority of them are acute encephalitis of infectious origin, but it is estimated that 20% of encephalitis in northern Europe is related to an autoimmune mechanism with the majority of encephalitis with anti-NMDA Ac discovered recently in 2007. The study of a large American encephalitis cohort showed a death rate of 3% to 7% in cases of autoimmune encephalitis. Furthermore, delay in the initiation of effective treatment (tumor removal or immunotherapy) beyond 4 weeks is associated with a poor prognosis at 1 year.

It is therefore necessary to better understand the signs of autoimmune encephalitis in order to recognize the disease quickly and to start a treatment quickly; in order to improve the management and the prognosis of these children.

Inclusion criteria:

• Age between 0 and 17 years at diagnosis
• Patient diagnosed between 01/01/2006 and 31/12/2018 with autoimmune encephalitis in one of the participating university hospitals (Besançon, Nancy, Strasbourg, Reims and Dijon)
• Presence of clinical criteria of clinical and/or radiographic encephalitis
• Presence of one or more antibodies in the blood or CSF
• Parental authority holders and their child of childbearing age having given their consent for the use of the child's data for this research

Exclusion criteria:

• Refusal to participate in the study
• Absence of consultation at any of the study centers
• Absence of clinical and/or radiographic criteria for encephalitis.
• Absence of antibodies found in blood or CSF

Minor subject (≤17 years) diagnosed between 01/01/2006 and 31/12/2018 with autoimmune encephalitis