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.