Myths and Facts: What to Know About NMOSD

by Lexi Krupp Health Writer

Twenty years ago, if you developed neuromyelitis optica spectrum disorder (NMOSD), there’s a good chance your physician might have diagnosed you with multiple sclerosis instead. It’s easy to see why: Both are caused by impairments to the central nervous system—the part of your brain and spinal cord that coordinates movement and sensory information. But there are some pretty big differences, too, and doctors now recognize NMOSD as an entirely separate disease. Get ready to learn more about this lesser-known condition.

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Fact: NMOSD Is Not MS

If you head to the doctor’s office with concerns about sudden numbness or weakness, it’s natural for your M.D. to wonder about MS. After all, as far as diseases go, MS is fairly common, affecting more than one in 1,000 people. Meanwhile, NMSOD is far rarer, with one person in every 100,000 diagnosed. But despite the two conditions sharing certain similarities, NMOSD and MS differ in significant ways, including specific symptoms, how the disease progresses, and what treatments work best.

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Myth: NMOSD Is a Progressive Condition

Unlike MS, where neurological damage often accumulates over time and successive attacks get worse, NMOSD symptoms do not typically “progress.” Instead, people experience isolated attacks of severe nervous system inflammation. These attacks can happen at any time—50% of people experience a second attack within a year of the first while others recur years later. “Because of the lack of predictability, we treat everyone as though they are going to be recurrent,” says Jeffrey Bennett, M.D., Ph.D., a neurologist at University of Colorado Denver School of Medicine.

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Fact: Attacks Can Leave Lasting Damage

NMOSD attacks usually affect the optic nerve, spinal cord, or part of the brainstem. These severe assaults can lead to vision loss or impairment (often in one eye), extreme weakness in the arms or legs, paralysis, loss of bladder control, and painful itching or spasms. NMOSD attacks can cause irreversible damage, especially if untreated. Because of the unforgiving nature of this disease, doctors stress “early recognition, aggressive preventive therapy, and rapid institution of acute treatment for attacks,” says Dr. Bennett.

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Myth: Vision Loss Is Always Temporary

The nerves connecting your eyes to your brain are one of the most common targets of NMOSD. When these nerves become inflamed it’s referred to as “optic neuritis,” a condition that can cause painful loss of vision, blurry spots, and a decreased ability to distinguish colors in one or both eyes. These symptoms are typically more severe than in an MS attack, and NMOSD patients often won’t make a full recovery to normal vision, especially without treatment.

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Fact: Vomiting and Hiccups Are Symptoms

Hiccups may not sound like a particular hardship, but when you imagine uncontrollable bouts, accompanied by vomiting and nausea, for days or weeks, it can be pretty miserable. And it’s not because NMOSD gives you indigestion or a bad stomach bug—instead, the disease damages part of the brainstem (the back of the brain that continues down into the spinal cord) that controls these involuntary reflexes, causing the behaviors to go on autopilot. Vomiting and hiccups often occur in the first attack, or in the beginning stages of the disease.

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Myth: The Cause of NMOSD Is a Mystery

Scientists now know that about 75% of people with NMOSD make an antibody against a protein called aquaporin-4 (AQP4), which helps transport water in the cells of the body. These antibodies are particularly fixated on attacking AQP4 in the brain, spinal cord, and optic nerves, resulting in inflammation, which then triggers symptoms of the disease. As for the 25% of people who do not test positive for this antibody, experts believe there may be other antibodies at play with NMOSD, including one for a protein called myelin oligodendrocyte glycoprotein (MOG) that helps protect the nerves.

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Fact: Spinal Cord Inflammation Is Common

Inflammation of a long tract of the spinal cord is one of the key ways doctors distinguish NMOSD from MS. Typically, damage from NMOSD extends over at least three vertebrae (a good chunk of the spinal cord), which is why people often have such severe symptoms. Depending on exactly where the damage occurs, people might experience weakness and numbness, paralysis of their limbs (loss of both movement and sensation), or loss of bladder control during an attack.

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Myth: NMOSD Is an Isolated Disease

Not true! Many people with NMOSD have other autoimmune conditions, like myasthenia gravis, systemic lupus erythematosus, Sjögren syndrome, or Celiac disease. About one in four NMOSD patients with aquaporin-4 antibodies have another autoimmune disorder; MS patients, on the other hand, rarely have a secondary autoimmune disease. Additionally, women are more likely to have NMOSD, and though it’s possible for people of any age to have NMOSD, the disease often doesn’t cause problems until middle age.

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Fact: Effective Treatments Exist

In the past year, multiple NMOSD-specific drugs have become available that reduce the risk of future attacks. “It has become a very treatable disease,” says Ilya Kister, M.D., a neurologist at New York University Langone Medical Center. To treat an attack, doctors give patients high doses of steroids, while immunosuppressants are used to manage the situation longer-term. The result: Once potentially fatal, NMOSD is now considered a chronic condition that is highly manageable, allowing those diagnosed to live healthy and active lives.

Lexi Krupp
Meet Our Writer
Lexi Krupp

Lexi Krupp is a journalist who covers health and science stories for audio and print. Before moving to New York City, she taught ecology in Wisconsin and Maine.