Reversal of profound cortical atrophy with immunotherapy in pediatric anti-NMDA receptor encephalitis

Anti-NMDA receptor (NMDAr) encephalitis is an autoimmune condition marked by neuropsychiatric symptoms and NMDAr IgG autoantibodies in the serum and/or cerebrospinal fluid. While MRI findings are often nonspecific or normal, the reversibility of imaging abnormalities with immunotherapy remains underexplored. We report a 3-year-old girl who presented with seizures, altered mental status, and encephalopathy diagnosed with medically refractory anti-NMDAR encephalitis. Initial neuroimaging was unremarkable, but subsequent MRIs revealed T2 hyperintensities and leptomeningeal enhancement. After delayed treatment with IVIG, methylprednisolone, Rituximab, and plasmapheresis, the patient showed clinical improvement. Observational MRI scans after treatment demonstrated reduced parenchymal volume loss and stabilization of T2 changes over 4.5 years. This case highlights the potential for clinical and radiographic improvement after treatment in anti-NMDAR encephalitis and the benefit of immunomodulatory therapy even years after presentation.