A Case of AQP4-IgG Neuromyelitis Optica Presenting with Orbital Inflammatory Syndrome.

A 45-year-old healthy African-American man experienced 2 months of right-eye soreness followed by acute onset of right painful vision loss with binocular, oblique diplopia. Visual acuity was count fingers OD and 20/20 OS. He had a partial, right, pupil-involving cranial nerve III palsy with a right relative afferent pupillary defect and optic disc edema with tortuous vessels. Magnetic resonance imaging showed increased T2 signal with tortuosity and thickening of the retrobulbar right optic nerve with associated restricted diffusion and enhancement, enhancement of orbital fat adjacent to the optic nerve sheath, and relative right proptosis. Workup was positive for aquaporin-4 antibody (AQP4-IgG) consistent with neuromyelitis optica spectrum disease (NMOSD). Our patient presented with signs and symptoms of orbital inflammation with optic neuritis and, to our knowledge, this is the first reported case of AQP4-IgG NMOSD presenting with orbital inflammatory syndrome.