Neuromyelitis optica (NMO), previously known as Devic's disease, is a central nervous system disorder that primarily affects the eye nerves (optic neuritis) and the spinal cord (myelitis). Now known in broader terms as neuromyelitis optica spectrum disorder, NMO occurs when your body's immune system reacts against its own cells in the central nervous system, mainly in the optic nerves and spinal cord, but sometimes in the brain.

The cause of neuromyelitis optica is usually unknown, although it may sometimes appear after an infection, or it may be associated with another autoimmune condition. Neuromyelitis optica is often misdiagnosed as multiple sclerosis (MS) or perceived as a type of MS, but NMO is a distinct condition.

Neuromyelitis optica may cause blindness in one or both eyes, weakness or paralysis in the legs or arms, painful spasms, loss of sensation, uncontrollable vomiting and hiccups, and bladder or bowel dysfunction from spinal cord damage. NMO attacks may be reversible, but can be severe enough to cause permanent visual loss and problems with walking.

Children may develop confusion, seizures or coma as a manifestation of NMO.

Sept. 19, 2015