Child Neurology: Parainfectious Anti-NMDAR Encephalitis With Anti-MOG and Anti-AQP4 Seropositivity in an Infant

Overlap syndromes of anti-N-methyl-d-aspartate (NMDA) receptor encephalitis and myelin oligodendrocyte glycoprotein (MOG) or aquaporin-4 (AQP4)-mediated demyelination, either concurrently or sequentially, have been increasingly recognized. We report a 7-month-old infant who presented with 7 days of fever, seizures, irritability, and signs of meningeal irritation. Initial workup suggested acute meningoencephalitis; therefore, the child was treated with antibiotics, antivirals, empirical antitubercular therapy, and steroids. After transient improvement, the child's condition deteriorated including the development of new-onset choreo-ballistic-dystonic movements, encephalopathy, sleep disturbances, and dysautonomia. CSF analysis revealed positivity for parvovirus B19 and Epstein-Barr virus, along with autoantibodies against the NMDA receptor. In addition, serum testing was positive for anti-MOG and anti-AQP4 antibodies. Despite prompt immunotherapy with methylprednisolone, intravenous immunoglobulin, rituximab, and cyclophosphamide, the child showed only moderate improvement and later developed drug-refractory infantile epileptic spasm syndrome. The coexistence of multiple autoantibodies for immune-mediated encephalitis in this case illustrates potential links to underlying disease mechanisms as well as underscores the therapeutic challenges posed by triple seropositivity (anti-NMDA receptor, anti-MOG, and anti-AQP4 IgG autoantibodies) in an infant.