In Devic neuromyelitis optica (NMO), a severe myelopathy is associated with acute or subacute optic neuropathy, with or without recovery. For more than a century, neurologists have debated the precise nosologic classification of NMO among inflammatory demyelinating diseases in general, and multiple sclerosis (MS) in particular. Recently, new criteria have been proposed for both NMO and MS, allowing the 2 entities to be differentiated in most cases. Because a small proportion of cases nevertheless fulfill the criteria for both NMO and MS, challenges persist for clear definitions, especially concerning the roles of immunomodulatory and immunosuppressive treatment.
de Seze J. Neuromyelitis Optica. Arch Neurol. 2003;60(9):1336-1338. doi:10.1001/archneur.60.9.1336