Myelin oligodendrocyte glycoprotein antibody-associated meningoencephalitis without cerebral parenchyma involvement on MRI: A single-centre paediatric cohort study.

Since meningoencephalitis with prominent meningeal involvement was first described as a rare phenotype of myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), sporadic cases have been reported. However, most of the reports were case reports and small sample cohorts. We conducted a retrospective analysis of paediatric patients with MOG antibody-associated meningoencephalitis without cerebral parenchyma involvement on imaging at Beijing Children's Hospital between 2017 and 2024. Upon reviewing the records of 320 MOG antibody-positive paediatric patients in our centre, we identified 18 (6%) patients (median age, 7.2 years; female, 10) with disease onset. The common clinical symptoms were fever (94%), headache (56%), seizure (44%) and vomiting (44%). Most patients had leukocytosis (78%) and elevated ESR and CRP levels (61%). Cerebrospinal fluid analysis revealed intracranial hypertension (28%), leukocytosis (100%) and elevated protein levels (33%). Negative cranial magnetic resonance images were observed in 4 patients, and meningeal enhancement was observed in 14 patients. Fourteen patients showed no improvement with antibiotic therapy but responded effectively to immunotherapy. After a median follow-up of 22 months, 4 (22%) of the 18 patients experienced relapse. At the time of the last follow-up, all patients had a good prognosis (mRS < 2). Conclusion: Meningoencephalitis without parenchymal involvement on MRI represents an underrecognized MOGAD phenotype. The incorporation of this entity into diagnostic criteria and the initiation of early immunotherapy could increase diagnostic sensitivity and reduce relapse risk in children.