Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease Onset in Pregnancy: A Case Report.

Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is an autoimmune demyelinating disorder of the central nervous system in which optic neuritis is a frequent manifestation. Its presentation during pregnancy may pose a diagnostic challenge because bilateral optic disc edema and headache can mimic idiopathic intracranial hypertension or hypertensive disorders of pregnancy. We report a 39-year-old primigravid woman at 31 weeks of gestation with gestational diabetes and class III obesity who presented with progressive bifrontal headache followed by transient bilateral blurred vision, dyschromatopsia, and sudden severe visual loss in the right eye. Ophthalmologic examination showed bilateral papilledema, a relative afferent pupillary defect in the right eye, and reduced visual acuity. Ultrasound demonstrated an enlarged optic nerve sheath diameter, while brain and spine magnetic resonance imaging showed no major abnormalities. Visual evoked potentials revealed bilateral conduction delay, more severe in the right eye. Lumbar puncture showed a normal opening pressure (19.5 cmH2O) and normal cerebrospinal fluid cytochemistry, but cerebrospinal fluid-restricted oligoclonal bands were detected. Given the clinical suspicion of inflammatory optic neuropathy, serum testing for demyelinating disorders was performed and was positive for anti-myelin oligodendrocyte glycoprotein (MOG) antibodies, whereas aquaporin-4 and systemic autoimmune antibodies were negative. The patient was treated with intravenous methylprednisolone followed by therapeutic plasma exchange because of limited initial response, with progressive visual recovery and no maternal or fetal complications. This case highlights that MOG-associated optic neuritis should be considered in pregnant patients with acute visual loss and bilateral optic disc edema. Intracranial hypertension was ruled out, and paraclinical studies concluded bilateral inflammatory optic neuritis. Early recognition, serologic confirmation, and timely immunotherapy are essential to improve visual outcomes. Careful postpartum follow-up is warranted because relapse risk may increase after delivery.