Neuromyelitis optica spectrum disorder is an autoimmune astrocytopathy that primarily affects the optic nerves and spinal cord. Its association with rheumatoid arthritis is remarkably rare, with only 15 documented cases reported globally to date. This report describes the unique case of a 34-years-old woman with rheumatoid arthritis who developed concurrent aquaporin 4-immunoglobulin G-positive relapsing neuromyelitis optica spectrum disorder. The case underscores the substantial risk of initial...