Acute myelitis and optic neuritis are the main clinical features of patients with neuromyelitis optica (NMO), which usually appears as a relapsing-remitting course of disease that worsens over days and improves over weeks. We present a patient with chronic progressive myelitis over a 4-month period without remission as having a limited form of NMO that improved after plasmapheresis. Plasmapheresis may benefit patients with chronic progressive myelitis, which may be a manifestation of NMO, as well as those with a relapsing-remitting course of NMO.