Objective:

To describe a pediatric case of Myelin Oligodendrocyte Glycoprotein Antibody–associated Disease (MOGAD) presenting with FLAIR-hyperintense Lesions in Anti-MOG–associated Encephalitis with Seizures (FLAMES) and evolving hemispheric involvement.

Background:

MOGAD encompasses a spectrum of demyelinating syndromes that can include encephalitic presentations such as FLAMES. Pediatric FLAMES is rarely reported and can mimic infectious or autoimmune meningoencephalitis. Recognition is essential, as early immunotherapy can alter the disease course.

Design/Methods:

NA

Results:

A 10-year-old girl presented with new-onset generalized convulsions and left hemiparesis. Initial temperature was 38.2°C and labs demonstrated leukocytosis (21K WBCs/µl) with neutrophilic predominance. EEG revealed right-sided focal slowing with epileptiform discharges. MRI brain showed right hemispheric cortical and leptomeningeal T2/FLAIR hyperintensity and enhancement. CSF revealed 165 cells/µl with lymphocytic predominance; comprehensive infectious and autoimmune panels were negative. She was treated empirically for infectious meningoencephalitis and started antiseizure medication. Autoimmune panels were pending at discharge. She returned the following day with recurrent seizures. MRI brain showed progressive leptomeningeal enhancement. MOG IgG antibodies returned positive (FACS titer 1:100, CBA titer 1:80–1:40) and CSF had one oligoclonal band. She received IVIG and her symptoms gradually resolved. She returned to the hospital 10 weeks later for new right-sided weakness, aphasia, and suspected focal seizure. MRI brain demonstrated new left hemispheric cortical–leptomeningeal hyperintensities with enhancement; prior right-cerebral changes had resolved. Findings were consistent with relapsing FLAMES. She received IV steroids and IVIG over five days with improvement and was discharged with a steroid taper.

Conclusions:

This case illustrates a relapsing, bilateral-sequential FLAMES phenotype of pediatric MOGAD. Recognition of evolving hemispheric involvement is key, as relapses may occur despite first-line immunotherapy and antiseizure control. Additionally, this case illustrates the diagnostic value of the MOG titer, but the limitations in its prognostic value for potential relapses and/or disease severity. Early identification, immunotherapy initiation, and adequate follow up are critical for improved outcomes.