Neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis (MS) might seem alike at first, but they’re distinct conditions. Both autoimmune conditions affect the central nervous system (CNS), which includes the brain, optic nerve, and spinal cord, and they share similar symptoms. Because of this overlap, doctors sometimes misdiagnose one for the other.
“After 22 years of being told I had MS, my doctor told me I actually have NMO,” shared one member of MyMSTeam. “I’m having a hard time wrapping my head around a new diagnosis and having to start from scratch again.” NMOSD is commonly called neuromyelitis optica (NMO) and was formerly known as Devic’s disease.
Thanks to modern medical advances, misdiagnoses of NMOSD and MS are less common. Researchers have identified specific biomarkers (proteins or other signs of a disease found during testing) that help distinguish between the two conditions. Still, recognizing differences in their symptoms remains key to accurate diagnosis and treatment. This article breaks down the similarities and differences between NMOSD and MS symptoms.
NMOSD is a rare disease that typically appears between ages 30 and 50, although it can begin at any age. Researchers estimate that 250,000 people worldwide are living with NMOSD, including 4,000 to 8,000 in the United States.
If left untreated, NMOSD attacks can lead to paralysis and blindness. Like MS and most other autoimmune diseases, NMOSD is more commonly found in women than men, according to the National Multiple Sclerosis Society.
The exact cause of NMOSD remains unknown. However, research shows that about 50 percent of people with the condition have a family history of autoimmune diseases or an existing autoimmune condition such as Sjögren’s syndrome, celiac disease, or systemic lupus erythematosus (SLE). Additionally, about 75 percent of people with NMOSD have a specific antibody biomarker called aquaporin 4 immunoglobulin G (AQP4-IgG).
One key difference between MS and NMOSD is how episodes occur and how severe they are. MS usually starts with a mild episode that isn’t life-threatening. In contrast, NMOSD often begins abruptly with severe symptoms that may have long-term effects.
Because both NMOSD and MS are autoimmune diseases, they share several symptoms. Both conditions damage the CNS, including the optic nerves, which are responsible for vision.
Vision problems are often among the first noticeable symptoms in both NMOSD and MS. More than 17,200 MyMSTeam members report having vision problems as a symptom of MS. “The first sign of getting sick was failing a vision test in the military,” one member wrote.
Both NMOSD and MS can cause vision-related problems, including:
However, the severity and pattern of vision loss often differ between the two conditions. Read on for more details about these differences.
Think of your spinal cord as a highway connecting your brain to the rest of your body. Signals travel in two directions — ascending and descending. Ascending signals carry sensory information (like touch, pain, and temperature) from the body to the brain. At the same time, descending signals carry motor (movement) commands from the brain to the muscles. Spinal cord damage can disrupt one or both pathways, leading to symptoms such as:
Both NMOSD and MS cause relapses — times when symptoms suddenly worsen, followed by partial or full recovery — also known as episodes or attacks. Although they affect the body in different ways, both conditions can lead to long-term damage and disability if left untreated.
While NMOSD and MS share some symptoms, understanding their differences can help ensure the right diagnosis from the start.
In NMOSD, vision loss is often severe and may affect both eyes at once. This is because optic neuritis (inflammation of the optic nerve) tends to be worse in NMOSD. In MS, vision loss from optic neuritis tends to be milder and usually affects just one eye at a time.
Inflammation in the spinal cord can lead to paralysis or sensory changes in both conditions. However, in NMOSD, spinal cord lesions (injuries) are typically bigger and more severe, leading to weakness and loss of sensation in the arms or legs. This symptom is often linked to longitudinally extensive transverse myelitis, a condition in which inflammation spans a large section of the spinal cord. In MS, transverse myelitis tends to be more common and severe, and the characteristic long spinal cord lesions seen in NMOSD rarely show up in MS.
Some symptoms are common in NMOSD but rarely occur in MS. These symptoms originate in a specific area of the brainstem and include:
Compared with NMOSD, MS affects the brain more broadly, leading to cognitive (thinking) challenges such as:
Reduced speed of information processing
Because some NMOSD and MS symptoms overlap, it’s important to get an accurate diagnosis as soon as possible. A misdiagnosis can delay proper treatment, increasing the risk of long-term disability.
Both NMOSD and MS are autoimmune diseases that damage myelin, the protective coating around nerves that helps transmit sensory and motor signals between the brain and the body. However, neurological exams and MRI scans of the brain and spinal cord can help doctors distinguish between the two conditions.
In MS, MRI scans typically show small, scattered brain lesions that follow a specific pattern. Researchers have found that brain lesions are less common in NMOSD. Also, about 80 percent of people with NMOSD who have myelitis (spinal cord inflammation) develop long, continuous spinal cord lesions. This finding is rare in MS.
To confirm a diagnosis, doctors may use additional tests, such as:
For both NMOSD and MS, early and accurate diagnosis is crucial for finding the best therapies and starting treatment as soon as possible. If you have doubts about your diagnosis, talk to your neurologist (a specialist in nervous system disorders) or seek a second opinion. With recent advances in diagnosis and treatment strategies, the outlook for people with NMOSD is brighter than ever before.
On MyMSTeam, the social network for people with MS and their loved ones, more than 218,000 members come together to ask questions, give advice, and share their stories with others who understand life with MS.
Are you living with NMOSD or MS? Did your symptoms lead to an initial misdiagnosis? Share your experience in the comments below, or start a conversation by posting on your Activities page.
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I needed to read this Carolyn thank you
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