Case Report: Overlap syndrome of anti-NMDA receptor encephalitis and MOG-associated disease in a pediatric patient-literature insights.

Myelin oligodendrocyte glycoprotein antibody disease (MOGAD) and anti-N-methyl-D- aspartate receptor (NMDAR) encephalitis pediatric cases are especially challenging due to phenotypic variability, limited literature, and the absence of standardized treatment protocols. We present the first documented African case of pediatric MOG and NMDAR overlapping syndrome (MNOS), with a review of all pediatric MNOS cases reported thus far in the literature. A previously healthy seven-year-old boy developed rapid-onset sleep disturbances, neuropsychiatric symptoms, multiple cranial nerve palsies, and hyperkinetic movements. Serological and cerebrospinal fluid (CSF) analyses confirmed dual positivity for anti- MOG and anti- NMDAR antibodies. The patient responded favorably to first line immunotherapy with intravenous immunoglobulin and corticosteroids, showing marked clinical improvement by the six-month follow-up. A corticosteroid taper was initiated thereafter. At fourteen-month follow-up, he had a second episode with a MOGAD- associated cerebral cortical encephalitis phenotype. Antibody screening confirmed persistent dual positivity for both anti-NMDAR and anti-MOG antibodies. The clinical outcome was favorable following first-line immunotherapy combined with oral immunosuppressants. This case highlights the uniqueness of this entity, where antibody dynamics are closely tied to the clinical course.