Sequential Optic Neuritis: A Neuromyelitis Optica Spectrum Disorder.

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune relapsing demyelinating disorder which often leads to severe disability typically targeting spinal cord, optic nerves, and brainstem. Around 75% of NMOSD patients have serum immunoglobulin-G (IgG) autoantibodies to the aquaporin-4 channel (AQP4-IgG). AQP4-IgG antibodies have a central role in new diagnostic criteria of NMOSD. These antibodies have a critical role in long-term management after the first attack. The prevalence of this disorder is lower than multiple sclerosis in European countries. However, NMO makes a substantial proportion of the demyelinating diseases of the central nervous system in countries like Pakistan, where it can be mistaken for multiple sclerosis. Accurate diagnosis is essential as some of the drugs for multiple sclerosis can potentially worsen NMOSD. We present a case of sequential optic neuritis with positive aquaporin 4 antibodies. We have discussed the history, examination findings, diagnostic workups, and treatment of the patient.