Neuromyelitis Optica Spectrum Disorder (NMOSD)

Neuromyelitis optica spectrum disorder (NMOSD) shares some symptoms with multiple sclerosis and may be misdiagnosed as MS. It is also known as neuromyelitis optica (NMO) or Devic’s disease. It’s a rare autoimmune disorder of the central nervous system (CNS). The CNS consists of the optic nerves, brain and spinal cord.

In autoimmune disorders, the immune system thinks healthy tissues are a threat and attacks them. In NMOSD, the body produces antibodies (anti-AQP4) that attack Aquaporin-4 (AQP4) in the CNS. AQP4 is a protein on astrocytes, a type of cell that helps the nerves in the CNS work properly. This attack leads to inflammation and damage to the astrocytes, as well as to the nerve cells and their myelin insulation. This damage disrupts the messages from the brain and spinal cord to the rest of the body, causing weakness, worsened vision or other symptoms.

NMOSD is a relapsing disease where relapses (flare-ups, attacks or exacerbations) are followed by periods of some recovery. Relapses in NMOSD are often very severe and cause permanent damage, so preventing attacks through early and ongoing treatment is important to prevent long-term disability.

Changes in vision (optic neuritis) and symptoms caused by spinal cord inflammation (transverse myelitis) are common in NMOSD.

Symptoms caused by optic neuritis include:

• Loss or blurring of vision in one or both eyes
• Loss of color vision
• Eye pain

Symptoms caused by transverse myelitis include:

• Weakness, numbness or loss of sensation
• Paralysis
• Loss of bowel or bladder control or difficulty emptying the bladder
• Spasticity (increased muscle tone or stiffness in the arms or legs)
• Shooting pain or tingling in the neck, back or abdomen

Other symptoms that commonly occur with an NMOSD attack include uncontrollable hiccups, nausea, and/or vomiting.

Diagnosis requires symptoms of NMOSD and results from other tests. The process of diagnosis may include:

• Medical history to identify any past or present symptoms that might be caused by NMOSD, MS or another disorder.
• Neurologic exam of your thinking, vision, hearing, sensations, strength, swallowing, reflexes, coordination, walking and balance
• MRI of your brain, optic nerves and spinal cord.
• Spinal tap (lumbar puncture) to examine cerebrospinal fluid.
• Eye scans and vision tests.
• Blood tests including anti-AQP4 antibody testing. Some people who test negative for anti-AQP4 may have a related condition called myelin oligodendrocyte glycoprotein antibody disorders (MOGAD). 

There are an estimated 4,000 to 8,000 people with NMOSD in the United States and a quarter-million people worldwide.

• NMOSD is more common in women (> 80 percent) than men.
• NMOSD occurs in all parts of the world. It is more common among people of African and Eastern Asian descent than in people who are white. NMOSD may be the most common form of demyelinating disease within the African and Eastern Asian communities.
• NMOSD can occur at any age — in children as young as 3 and adults as old as 90 — but appears most often between ages 30 and 50.

• NMOSD attacks may affect both eyes at the same time. MS usually affects one at a time.
• NMOSD usually affects only the optic nerve and spinal cord although there may be lesions in specific areas of the brain (such as the brainstem). MS typically affects multiple areas of the brain as well as the spinal cord and optic nerve.
• Due to the effects on the brain, people with MS experience cognitive changes over time, such as changes in memory, reasoning and problem solving. Cognitive changes are not typically a symptom of NMOSD.
• Disability from NMOSD results from relapses and is rarely progressive. MS can start off as or develop into a progressive disease.
• NMOSD attacks are generally more severe than MS attacks.

Read about other diseases with symptoms similar to NMOSD and MS.

There is no cure for neuromyelitis optica (NMOSD) at this time, but there are effective treatments. The standard of care for an attack of NMOSD includes the following:

• Intravenous (into the vein) high-dose corticosteroids (methylprednisolone) to reduce the inflammation of the nervous system.
• Plasma exchange (PLEX) for severe attacks or if no improvement occurs with corticosteroids. The goal of PLEX is to lower the level of anti-AQP4 antibodies in the blood. PLEX involves removing blood from the body through a needle and tubing. Through a series of steps, the plasma (the liquid part of the blood) is separated from blood cells and replaced with an artificial plasma substitute. The plasma substitute and blood cells are combined and returned to the body intravenously. The procedure lasts several hours and may be repeated multiple times over a number of days.

Because the likelihood of recurrence is very high and attacks are generally severe and often result in permanent disability, ongoing treatment to suppress the immune system is necessary. Three drugs have been approved by the U.S. Food and Drug Administration (FDA) specifically for treatment of anti-AQP4 positive NMOSD:

• Eculizumab (Soliris®)
  • View the medication guide.
• Inebilizumab-cdon (Uplizna®)
  • View the medication guide.
• Satralizumab-mwge (Enspryng®)
  • View the medication guide.

Other drugs that are used off-label to prevent attacks include:

• Azathioprine (Azasan® and Imuran®)
  • Azasan medication guide
  • Imuran medication guide
• Mycophenolate mofetil (Cellcept®)
  • Cellcept medication guide
• Prednisone
• Rituximab (Rituxan®) and biosimilars
  • Rituxan medication guide

• The Siegel Rare Neuroimmune Association (SRNA) is a nonprofit organization dedicated to the support of people with Acute Disseminated Encephalomyelitis (ADEM), MOGAD, NMOSD, optic neuritis and transverse myelitis. They support individuals living with these diseases and their families, maintain a clinical care network and fund research.
• The Sumaira Foundation is dedicated to generating global awareness of NMOSD and MOGAD, supporting research to find cures and creating a community of support for those affected by these diseases.
• Guthy-Jackson Charitable Foundation funds research to accelerate solutions for NMOSD, spreads awareness, and runs support groups for those living with NMOSD and their loved ones.
• Ask an MS Navigator — While the organizations above are the best resources for information and research on NMOSD, our MS Navigator team can provide help with understanding health insurance, resources for facing financial challenges and assessments for personalized case management

Reviewed by Shuvro Roy, MD, and Elias Sotirchos, MD, August 2022.