Neuromyelitis Optica

Neuromyelitis optica causes attacks of optic neuritis and transverse myelitis, as can multiple sclerosis (MS).

• In MS, optic neuritis typically causes visual impairment in one eye at a time, while both eyes may be affected simultaneously in NMO.
• Transverse myelitis — which refers to inflammation across both sides of the spinal cord at a single level — causes weakness and loss of sensation in the legs and — depending how high on the spinal cord the inflammation occurs — occasionally in the arms. Transverse myelitis can also affect bowel and bladder function. Transverse myelitis attacks tend to be more severe in NMO than in MS, causing more severe symptoms — although that is not always the case.

A new blood test that measures antibodies to aquaporin-4 detects NMO in about 70 percent of cases. This test may identify that a person has NMO even before he or she experiences all the symptoms that lead to a confident diagnosis.