Abstract
Optic neuritis associated with anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis poses a novel challenge and is recognised as being part of overlapping antibody-associated demyelinating syndromes. We report a case of a 10-year-old girl who first presented with anti-NMDAR encephalitis and later developed four episodes of left optic neuritis. Blurring of vision, pain on eye movement, and headache were the striking features in all episodes of optic neuritis. For each recurrent episode of optic neuritis she was treated with intravenous methylprednisolone, following which visual acuity, colour vision, and visual field improved to normal. Neuroimaging was unremarkable. Myelin oligodendrocyte glycoprotein and aquaporin-4 antibody tests were negative. She developed a relapse of anti-NMDAR encephalitis after recurrent episodes of optic neuritis despite being on azathioprine. Intravenous immunoglobulin and cycles of cyclophosphamide were started, and she has been free from optic neuritis and encephalitis for more than one year since. Optic neuritis and anti-NMDAR encephalitis are reversible with intensive immunotherapy. Early and accurate diagnosis can lead to better management of this condition.