Neuromyelitis optica (NMO) is a controversial entity that has been periodically redefined. Initially, the condition was coined by Devic1 as an acute monophasic process characterized by severe bilateral optic neuritis and myelitis. In 1999, the disorder was defined to include patients with relapsing-remitting disease, and new criteria were proposed that included clinical findings, magnetic resonance imaging (MRI), and spinal fluid pleocytosis.2 The recent detection of antibodies in some patients with NMO has been used to further extend the diagnostic criteria of this entity.3- 5 While the recent amendments have attempted further differentiation of patient populations with multiple sclerosis (MS) and NMO, there remain no definitive clinical criteria, laboratory testing, neuroimaging, or histopathologic features that separate these 2 disorders as individual nosologic entities.
Galetta SL, Bennett J. Neuromyelitis Optica Is a Variant of Multiple Sclerosis. Arch Neurol. 2007;64(6):901-903. doi:10.1001/archneur.64.6.901