A Case of Optic Neuritis in a Patient with Anti-Aquaporin 4 and Anti-Myelin Oligodendrocyte Glycoprotein Antibody Double-Seropositive Neuromyelitis Optica Spectrum Disorder

Purpose: To report a case of optic neuritis caused by anti-aquaporin 4 (AQP4) and anti-myelin oligodendrocyte glycoprotein (MOG) antibody double-seropositive neuromyelitis optica spectrum disorder (NMOSD).Case summary: An 86-year-old female presented with a 10-day history of blurred vision in her right eye. The initial best-corrected visual acuity in the right eye was limited to hand motion, while the left eye had a visual acuity of 0.9; a relative afferent pupillary defect was observed in the right eye. Fundus examination showed normal optic disc appearance, and optical coherence tomography (OCT) indicated normal retinal nerve fiber layer thickness. Magnetic resonance imaging revealed enhancement and swelling of the right optic nerve, and signs of myelitis. The patient tested positive for anti-AQP4 and anti-MOG antibodies, leading to a diagnosis of NMOSD, and high-dose intravenous steroids and immunoglobulins were administered. Two months after the initial visit, fundus examination and OCT revealed optic disc atrophy in the right eye, with no improvement in visual acuity. After additional immunosuppressive treatment for 2 months, the anti-MOG antibody test returned negative. The patient continued on oral steroids and immunosuppressive agents for 12 months, during which no improvement in visual acuity was observed, with no recurrence of optic neuritis. The left eye remained unaffected throughout the 2-year follow-up period.Conclusions: Cases of double-seropositive NMOSD are rare, with unclear treatment protocols and prognosis. In this case, despite treatment with steroids and immunosuppressants, the patient's optic nerve atrophy did not improve, with no recurrence of optic neuritis during the 2-year follow-up period.