Neuromyelitis Optica

Neuromyelitis optica (NMO) is a rare inflammatory disease of the central nervous system affecting the optic nerves and spinal cord that can cause temporary or permanent blindness and paralysis.

NMO is believed to affect up to 10 in 100,000 persons worldwide. It is more common in those of African, Asian, Pacific Island, Polynesian, or Caribbean descent. Approximately 4% of cases of NMO appear in childhood. NMO is more common in women, but among children there is no difference between the sexes.

There are two types of NMO. The most common form is called “relapsing” NMO in which an initial attack is followed by periodic flare-ups of disease. The first relapse generally occurs within six months of the initial attack, but in some patients, years may pass between attacks. NMO relapses in 80% to 90% of cases. When no further attacks occur after the initial attack, NMO is considered “monophasic.”

The most common presenting symptom of NMO is optic neuritis, in which patients experience pain inside one or both eyes particularly with eye movements, and loss of vision. Other symptoms may include:

• Weakness or paralysis in the legs or arms
• Difficulty walking
• Numbness or tingling
• Painful spasms
• Uncontrollable nausea, vomiting, or hiccups
• Bladder or bowel control problems

In some attacks, dangerous complications can include unregulated changes in vital signs like heart rate and blood pressure, or even respiratory failure. An NMO attack is a medical emergency and needs to be treated promptly.

Neuromyelitis optica is an autoimmune disorder, which means the body mistakenly attacks its own healthy tissue. In NMO, the immune system targets the optic nerves and spinal cord, causing inflammation and swelling that results in injury and loss of function. As with other autoimmune diseases, the cause of NMO remains unknown. About 10% to 20% of patients with NMO have another autoimmune disorder, such as systemic lupus erythematosus, Sjogren syndrome, myasthenia gravis, or systemic sclerosis.

Most patients with NMO have elevated levels of an antibody called aquaporin-4 (anti-AQP4, or NMO-IgG) which is believed to play a direct role in the cause of the disease. Some NMO syndromes are associated with anti-myelin oligodendrocyte glycoprotein (MOG) antibodies instead of anti-AQP4 antibodies, and these patients may have clinically less severe disease with fewer relapses.

To diagnose NMO, your doctor will take a detailed medical history and give your child a thorough neurological physical exam. Your doctor will also order diagnostic tests to help rule out other conditions with similar symptoms, such as multiple sclerosis (MS) or other autoimmune diseases.

Diagnostic tests may include:

• An MRI to look for damaged areas in the brain, optic nerves and spinal cord.
• Blood tests to look for autoantibodies such as anti-AQP4 and anti-MOG. The presence of these antibodies will help doctors diagnose NMO and rule out MS.
• A lumbar puncture (spinal tap), which may show elevated white blood cells and protein, indicators of inflammation in the spinal fluid.

There is no cure for NMO. Treatment for neuromyelitis optica aims to control inflammation during attacks and prevent future relapses.

Your child may be given intravenous corticosteroids to decrease swelling and inflammation during an attack. Another NMO treatment that can reduce symptoms is called plasmapheresis, a process in which the blood is filtered through a machine to remove the antibodies causing the autoimmune response. Further attacks may be prevented with maintenance medication to suppress the immune system.

The outlook for people with NMO varies widely and depends on the severity and frequency of attacks, as well as how quickly attacks are treated. People with NMO may develop permanent vision loss, paralysis, and breathing problems due to muscle weakness. When NMO is severe, some patients ultimately require a ventilator for breathing support. A multidisciplinary team of neurologists, physical and occupational therapists, social workers, and other health professionals can help patients with NMO adapt to life changes.

At Children’s Hospital of Philadelphia (CHOP), your child will see a team of experts who specialize in neuroinflammatory diseases like NMO. Your child’s care team will include a neurologist, nurse practitioner, nurse, occupational therapist, physical therapist and social worker. We partner with other specialties within CHOP such as ophthalmology, urology, pain management, and neuropsychiatry to coordinate your child’s care.