The Role of Plasmapheresis In Pediatric Antibody- Negative Autoimmune Encephalitis

Objective We show the efficacy and relative safety of plasmapheresis as a treatment option for antibody negative AIE in children. Background Plasmapheresis is well established therapy for antibody mediated autoimmune encephalitis (AIE). In patients with no identified antibody, the role of plasmapheresis is unclear. Starting plasmapheresis becomes even more controversial in children with antibody negative AIE Design/Methods An IRB approved chart review was conducted on patients <18 years diagnosed with autoimmune encephalitis. A retrospective analysis of response to plasmapheresis and long term follow up was conducted on patients that did not have an identified antibody. Results 52 patients <18 years were diagnosed with autoimmune encephalitis, 14 (26.9%) of these tested negative for antibodies. 2 (14%) patients received only steroids, while all others received Steroids plus IVIG. 7 (58%) patients received rituximab for poor response/relapse following Steroids plus IVIG. Of these, 3 (43%) patients further underwent plasmapheresis for presumed refractory AIE. All patients had improvement after plasmapheresis and remained symptom free, including seizure freedom, at 2 year follow up. One patient needed repeat plasmapheresis for presumed relapse. No adverse effects reported. Conclusions Several studies have shown that timely delivery of immunotherapies is crucial and delay in treatment due to negative autoantibodies can lead to poorer outcomes. Plasmapheresis is safe and should be considered for refractory/relapsing AIE in children, even in the absence of an identified antibody. Larger studies in future can help solidify the findings from our cohort.