Clinical characteristics of children with anti-N-methyl-D-aspartate receptor encephalitis with and without anti-myelin oligodendrocyte glycoprotein antibody.

To analyze the clinical characteristics of an overlapping syndrome, MNOS, of anti-myelin oligodendrocyte glycoprotein antibody (MOG-Ab) coexisting with anti-N-methyl-D-aspartate receptor encephalitis (NMDARE) in children. We included patients with NMDARE at Children's Hospital of Chongqing Medical University between 2018 and 2022 and conducted a comparison between NMDARE with and without MOG-Ab. Among 163 patients with NMDARE, 15 individuals tested positive for MOG-Ab. The median age of MNOS was 11 years (IQR 8-13). Furthermore, 10 out of 15 were female. More than half of MNOS experienced a prior history of encephalitis or demyelinating disorders. Among ten patients with low MOG-Ab titers, two met the diagnostic criteria for MOGAD. All five patients with high MOG-Ab titers satisfied the criteria for MOGAD. A total of seven patients diagnosed with MOGAD presented with acute disseminated encephalomyelitis. The proportion of prodromal symptoms and brain lesions, the neutrophil counts, and the frequency of mycophenolate mofetil administration were significantly higher in MNOS compared to NMDARE patients without MOG-Ab (p < 0.05). The outcomes of MNOS were favorable and comparable to those observed in NMDARE. Nevertheless, MNOS demonstrated a higher tendency to relapse, with rates of 60.0% compared to 3.1% (p < 0.001).

Conclusion: Pediatric MNOS exhibited a high prevalence among females, particularly those with a prior history of MOGAD or encephalitis. MNOS had a favorable prognosis but with a high relapse rate. Coexisting MOG-Ab in pediatric MNOS may be pathogenic or a bystander, potentially correlating with antibody titers.

What is known: • Pediatric anti-N-methyl-D-aspartate receptor encephalitis (NMDARE) coexisting with anti-myelin oligodendrocyte glycoprotein antibody (MOG-Ab) generally has a favorable prognosis, albeit with a tendency to relapse. • Pediatric NMDARE coexisting with MOG-Ab may exhibit imaging features indicative of demyelination.

What is new: • Pediatric patients of MOG-Ab coexisting with NMDARE overlapping syndrome (MNOS) were predominantly observed in females, particularly those with a history of MOG-Ab-associated disorder (MOGAD) or encephalitis. • Compared with NMDARE patients, pediatric MNOS patients had higher neutrophil counts and more frequently exhibited abnormal MRI findings in the basal ganglia, insular lobe, temporal lobe, thalamus, and cerebellum.