FLAIR-hyperintense lesions in anti-MOG-associated encephalitis with seizures overlaying anti-N-methyl-D-aspartate receptor encephalitis: A case report

Rationale: FLAIR-hyperintense lesions in anti-myelin oligodendrocyte glycoprotein (MOG)-associated encephalitis with seizures (FLAMES) is a rare clinical phenotype of anti-MOG; immunoglobulin G-associated disease is often misdiagnosed as viral encephalitis in the early stages. Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is an autoimmune encephalitis caused by antibodies targeting the GluN1 subunit of the NMDAR. The coexistence of anti-NMDAR encephalitis and FLAMES is very rare. Patient concerns: A 20-year-old female patient initially presented with seizures accompanied by daytime sleepiness. Diagnoses: Magnetic resonance imaging revealed FLAIR-hyperintense lesions in unilateral cerebral cortex. NMDAR antibodies was positive in the cerebrospinal fluid and MOG antibodies in the serum. Interventions: Steroid therapy was administrated. Outcomes: The symptoms completely relieved. At 6-month follow-up, the patient's condition remained stable. Magnetic resonance imaging showed no abnormalities in the unilateral cerebral cortex. Conclusion: When a patient with anti-NMDAR encephalitis or FLAMES is encountered in clinical practice, the coexistence of these diseases with double-positive anti-NMDAR and MOG antibodies should be considered and adopt appropriate evaluation and treatment.