Orbital Apex Syndrome Associated with Myelin Oligodendrocyte Glycoprotein Positivity: A Case Report

Purpose: To report a case of orbital apex syndrome presenting with optic perineuritis and oculomotor nerve palsy in myelin oligodendrocyte glycoprotein-associated disease (MOGAD).Case summary: A 31-year-old male presented to the clinic with sudden onset of diplopia and visual disturbance in the right eye, lasting for 8 days. He experienced ocular pain with eye movement and had ptosis in the right eye. Visual acuity was 1.0 in both eyes. The pupil of the right eye was dilated and exhibited a relative afferent pupillary defect. An extraocular examination revealed 6 PD hypotropia of the right eye, with limited ocular movement except for abduction. The right eye also showed mild optic disc swelling. MRI revealed enhancement of the optic nerve sheath in the right eye. He tested positive for anti-MOG antibody in his serum. Steroid pulse treatment with methylprednisolone (1 g/day IV for 5 days) was initiated, leading to improvement in ocular symptoms.Conclusions: MOG-associated disease can present as orbital apex syndrome with optic perineuritis and oculomotor nerve palsy. Clinicians should consider the possibility of MOGAD in patients with optic neuritis and ocular motility disorders.