It is not clear how additional anti-CNS IgG should be interpreted in the disease course and treatment of patients with myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD).

We present an unusual patient with IgG to MOG, NMDA Receptor, and Glial Fibrillary Acid Protein (GFAP). Her disease course was most consistent with MOGAD.

This 37-year-old right-handed female initially presented four years prior with headache and right-handed weakness with paresthesias. MRI brain demonstrated a left tumefactive lesion involving the hypothalamus, amygdala, basal ganglia and mesial temporal lobe with subtle mass effect. Whole body PET scan did not demonstrate malignancy. Transvaginal ultrasound was negative for an ovarian teratoma. CSF was positive for IgG to NMDA-R and GFAP using cell-based assays (2017). Over the next four years, there were five relapses with bilateral internuclear ophthalmoplegia, right sided hemiparesis and hemianesthesia, horizontal diplopia, vertigo with mild left sided ataxia on finger-to-nose, and right optic neuritis. Brain MRI demonstrated progression of disease to the pons, midbrain, and cerebellum. Patient had symptom resolution with five days of methylprednisolone plus IVIG for each relapse. In 2021, the patient had positive serum MOG Ab (twice) (titer 1:40 and 1:160; negative <1:10) and CSF MOG ab (titer 1:4; negative <1:2). She was now seronegative for NMDA-R-IgG and GFAP-IgG in serum and CSF. After starting rituximab, MRI demonstrated decreased T2 FLAIR hyperintensity.

It is known that IgG to NMDA receptor can coexist with IgG to MOG. They share features of encephalopathy, seizures, and leptomeningeal enhancement which are consistent with NMDA encephalitis. We describe a rare patient with positive IgG to MOG, NMDA receptor, and GFAP. She ultimately presented with characteristics of MOGAD (optic neuritis/perineuritis and T2 FLAIR hyperintensities in the brainstem and deep white matter). We will compare characteristics of GFAP astrocytopathy, MOGAD, and NMDA encephalitis through a literature review.