Pearls & Oy-sters: Optic Neuritis as First Demyelinating Event During Pregnancy in 2 Young Hispanic Women: MS vs MOGAD.

Optic neuritis (ON) can present as the first demyelinating attack in both multiple sclerosis (MS) and myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD), which may require different treatment depending on the final diagnosis. We present 2 young Hispanic women who presented with ON during pregnancy, one of whom was diagnosed with MS and the other with MOGAD. We describe key clinical features to help differentiate between MS and MOGAD including ON features, brain and spinal MRI, CSF profiles, and serum MOG and aquaporin-4 (AQP-4) antibodies, which all can help guide clinicians to an ultimate diagnosis. Pregnancy is usually considered an immunotolerant state because complex immunologic shifts arising to support tolerance of the developing fetus seem to decrease the risk of relapses. However, relapses may still occur during pregnancy, and relapse rates increase immediately postpartum. Our cases raise the possibility that young Hispanic patients may face increased risk of demyelinating disease activity even during the relatively immunotolerant state of pregnancy. A high index of suspicion for demyelinating disease should be maintained to accelerate diagnosis and prevent disability.