We report a patient with myelin oligodendrocyte glycoprotein (MOG) antibody positivity who manifested myelitis with right optic perineuritis (OPN) 6 years following left OPN. A 45-year-old man treated 6 years previously for left OPN developed ascending numbness in both legs, urinary dysfunctions, and constipation. Neurologic examination disclosed bilateral hypesthesia extending downward over the chest from the T8 level. No motor weakness was evident. Visual field testing showed dense peripheral constriction with intact central vision on the right and a smaller superior scotoma on the left. Visual acuity and funduscopic findings were normal. Results of routine serologic investigations and autoimmune antibody titers, including those of anti-aquaporin 4 antibody, were within normal limits, except that both serum and cerebrospinal fluid were positive for anti-MOG antibody. MRI displayed a longitudinal cord lesion extending from T2 to T9, as well as optic nerve sheath enhancement characteristic of OPN. The patient was diagnosed with myelitis in addition to OPN, both resulting from MOG antibody-associated demyelination. Patients with myelitis, require careful assessment of visual acuity and visual fields to detect possible accompanying OPN and ON. We suspect that OPN in some other patients may likewise be caused by anti-MOG antibody.
Keywords: anti-MOG antibody; anti-MOG antibody associated disorder (MOGAD); myelin oligodendrocyte glycoprotein (MOG); myelitis; optic perineuritis (OPN).