MOG-AD and CASPR2 Encephalitis (Overlap Syndrome) in an Adolescent Girl: A Case Report

Abstract Background: Although myelin oligodendrocytes glycoprotein antibody-associated disease (MOG-AD) and anti-contactin-associated protein-like 2 (CASPR2) antibody-mediated encephalitis are distinct neurological disorders, combined existence has rarely been reported in adults. We report this rare overlap syndrome in the pediatric age group. Clinical Description: A 14-year-old girl presented with insidious onset of behavioral changes, insomnia and mental apathy worsening over 1 month, with progressive difficulty in walking, tremors of limbs, vision impairment and bladder/bowel symptoms. Bilateral ophthalmoplegia, cerebellar, and pyramidal tract signs were noted on examination. Management and Outcome: Neuroimaging and comprehensive autoimmune workup with serological testing for multiple antibodies showed features of MOG antibody-associated disease and CASPR2 encephalitis. First-line immunotherapy (pulse steroids and intravenous immunoglobulin) was initiated with marked improvement in the child. Mycophenolate mofetil was started as maintenance immunotherapy, and there was near complete resolution of the lesions at follow-up. Conclusion: This is perhaps the first report of overlap of MOG-AD and CASPR2 encephalitis in the pediatric age group, emphasizing the importance of comprehensive serological testing, including autoimmune encephalitis panel and workup for demyelinating diseases in children with multineuraxial involvement and atypical presentations.