Neuromyelitis optica is a rare chronic condition that causes eye pain and even vision loss. This disease happens when your own immune system attacks your nervous system.

In this article, we look at the symptoms and causes of this condition, who’s at risk of getting it, and how it’s treated.

Neuromyelitis optica (NMO) is disease that’s caused by an autoimmune attack on your optic nerve and spinal cord.

Symptoms can mimic those of multiple sclerosis (MS), but these are two different conditions. NMO used to be considered a type of MS, but the antibody that causes the majority of NMO cases can’t be found in people with MS.

NMO may called by a number of other names too, according to the National Organization for Rare Disorders. These include:

  • (Asian, Japanese) opticospinal multiple sclerosis
  • Devic disease or Devic syndrome
  • optic neuromyelitis
  • opticomyelitis

The main symptoms of neuromyelitis optica (NMO) fall into two categories: optic neuritis or myelitis.

Optic neuritis is an inflammation of the optic nerve. This is the nerve that sends signals between your eyes and your brain. As NMO antibodies create inflammation in this nerve, you may feel pain in both eyes — or more commonly just one eye. This pain is quickly followed by blurred vision.

Myelitis can take many forms, but in NMO it causes transverse myelitis — inflammation of the spinal cord. When the spinal cord becomes swollen or inflamed, it can cause all kinds of symptoms, like:

  • a loss of motor functions or movement
  • loss of sensation or numbness
  • weakness in the legs
  • pain in the spine or limbs
  • urinary or bowel incontinence
  • loss of autonomic functions
  • reduced reflex responses
  • stiff neck
  • headache

These symptoms are usually more severe after an NMO flare than an MS flare. Where MS episodes are usually mild but progress over time, NMO has severe episodes that come and go.

If untreated, NMO episodes can cause severe complications like permanent loss of function. However, the disease doesn’t usually get worse over time on its own.

NMO usually strikes after a period of relapse where you may feel at least partially recovered. Some people do develop a form of the disease where symptoms become permanent or last for months at a time.

In some cases, an episode might resolve, but the disease has caused lasting nerve damage. Unlike MS however, NMO affects only your nerves and does not impact your brain directly.

Neuromyelitis optica (NMO) is caused by the malfunction of your immune system. Your body creates antibodies that attack a type of protein that moves water through your cells, called an anti-AQP4 antibody.

In some people, anti-MOG antibodies may also be present. These are the antibodies common in MS that strip the insulating layer of nerves and exposes them to damage.

Unlike other autoimmune diseases, NMO rarely has a genetic connection. Less than 3 percent of people with NMO have an affected relative. The disease affects fewer than 5 per 100,000 people and more than 80 percent of cases develop in women in their 30s and 40s, per 2018 research.

It’s been suggested that NMO affects people from some ethnic backgrounds — like Indian, Asian, and Black — more than others, but a 2018 study found no real difference in prevalence between ethnic groups.

Some risk factors that have been identified in people with NMO include:

Your doctor or specialist may suspect neuromyelitis optica (NMO) based on your condition and symptoms alone, but blood testing is key to receiving an accurate diagnosis. If you’re experiencing symptoms of NMO, your doctor will want to rule out other neurological conditions like MS.

Your examination will include:

  • a detailed family and personal medical history
  • a review of your symptoms
  • blood or cerebrospinal fluid (CSF) testing for antibodies
  • imaging studies like X-rays and MRI scans

Doctors today don’t believe that neuromyelitis optica (NMO) is curable. However, medications and therapies can help reduce the effects of the disease and relieve symptoms.

Clinical trials are underway and new medications are being investigated, but treatment typically focuses on controlling acute flare-ups and preventing recurrences rather than curing the disease.

The following list includes a number of common treatments used for NMO:

  • Biologics. Soliris (eculizumab) was approved by the Food and Drug Administration (FDA) in 2019 to treat people with NMO who have the AQP4 antibodies. Two more medication options, Uplinza (inebilizumab-cdon) and Enspryng (satralizumab-mwge), were approved by the FDA in 2020.
  • Steroids. Severe, acute attacks of NMO are usually treated with high dose intravenous corticosteroids. This type of medication can decrease the response of your immune system and help to reduce inflammation. Methylprednisone is a common choice of medication in this class.
  • Plasma exchange. People with severe NMO attacks that don’t respond to medication may need plasma exchange (plasmapheresis). With this therapy, you’re connected to a machine that operates similarly to those used in kidney dialysis. The machine takes blood from your body and filters it to remove the antibodies that cause NMO. After filtration, a plasma substitute is mixed with your blood and it is returned to your body. This treatment usually requires a stay in the hospital for observation.
  • Immunosuppression. Suppressing your immune system is the go-to strategy for long-term management of NMO. Some choices for medications can include corticosteroids, Imuran (azathioprine), mycophenolate mofetil, and Rituxan (rituximab).
  • Symptom management. A number of medications may be prescribed to help you manage the symptoms of NMO. These medications don’t treat the disease itself but can be used to help control or relieve problems like pain or spasticity.

Autoimmune diseases can be difficult to diagnose and treat. Neuromyelitis optica (NMO) is a condition that shares many symptoms with multiple sclerosis, but this rare version attacks only the optic nerve and spine.

You can control the condition to some extent by suppressing your immune system, reducing inflammation, and decreasing antibody levels, but there is no cure for NMO.

NMO comes in periods of flares and remissions. A doctor can help you manage these cycles and treat your symptoms.