Immunoadsorption Therapy in Managing NMDAR Antibodies Encephalitis

Inclusion Criteria: * Age: 0-18 years inclusive * Autoimmune encephalitis with positive anti-NMDAR antibodies in CSF (definite anti-NMDAR encephalitis according to Graus's criteria (Graus et al., 2016). * PCPCS and mRS at 4 or over at the inclusion after first line therapy (steroids and/or IgIV) when Rituximab therapy is warranted * Parents or legal guardians signed the Informed consent form * Social insurance affiliation Exclusion Criteria: * Autoimmune encephalitis without NMDAR antibodies * PCPCS and mRS scores under 4 after first-line therapy * Contraindication to perform central vascular access * Pregnancy, breastfeeding or absence of effective contraception (including abstinence) in a pubertal patient. * Contraindication to perform IA therapy : * Clinical conditions that prohibit transitory volume changes * Indications that prohibit anticoagulation using Heparin and/or ACD-A solutions * History of hypercoagulability * Generalized viral, bacterial and/or mycotic infections * Severe immune deficiencies (e.g. AIDS) * Suspected allergies against sheep antibodies or agarose