Do Factors Like Race and Age of Onset Predict Long-Term NMO Effects in Kids?

Experts have been working hard to learn more about the progression of neuromyelitis optica spectrum disorder (NMOSD or NMO).

In adults, some research has suggested that the age of the first attack of NMO symptoms may predict long-term effects. For example, adults with NMO may be more likely to have severe vision problems if their first NMO symptoms occurred before age 21 compared to symptoms occurring later in life.¹

As we find out more about NMO in kids, the same questions have sprung up.

NMO in kids

About 3 to 5 percent of all cases of NMO are in kids. Learning more about specific markers in the blood, including the AQP4-IgG (aquaportin-4) and MOG-IgG antibodies, has helped experts better diagnose and understand NMO in kids.²

Kids can have both AQP4-IgG- or MOG-positive NMO. The age of first symptoms is usually in the pre-teen to early teen years. In addition, girls are more likely to have NMO than boys, especially later in childhood.²

The first symptoms of NMO in kids are similar to those in adults. Optic neuritis (inflammation of the optic nerve which controls vision) and transverse myelitis (inflammation in the spinal cord) are common.²

Like adults, kids can also have area postrema syndrome (excessive vomiting and hiccups) with NMO. It is also possible to have acute brainstem syndrome. This includes symptoms like double vision, hearing loss, facial pain or paralysis, dizziness, and trouble speaking.²

The treatment of NMO in kids is similar to that of adults. The main focus is on slowing down the immune system to decrease inflammation and damage.²

Predicting NMO outcomes in kids

Finding ways to predict how a child’s NMO will behave can be important for treatment and long-term expectations.

One team of researchers in the United Kingdom reviewed records from 49 people diagnosed with NMO as children. They were diagnosed between 1980 and 2020. All the people tested positive for AQP4-IgG antibodies either at diagnosis or in the years following if they were diagnosed before antibody testing was available.³

The average age of first NMO symptoms (age of onset) for all people was 12 years old. Of all the people in the study:³

• More than 80 percent were female
• 39 percent were white
• 35 percent were Black
• 20 percent were Asian
• 6 percent were mixed race

Long-term symptoms

Around 6.5 years after the age of onset, many people in the study still had symptoms. Data shows:³

• 34 percent had permanent visual problems
• 26 percent had cognitive impairment (trouble thinking or processing information)
• About 21 percent had an Expanded Disability Status Score (EDSS) of 4, which means they had a relatively severe disability as a result of NMO

Age of onset and relapses

Overall, nearly 84 percent had at least one relapse of NMO after initial symptoms. About 50 percent had their first relapse within the first year.³

Although the time until treatment was started was similar for all kids in the study, there was a difference in time to first relapse.³

Earlier relapses were more common for kids with an NMO onset before 12 years old. Older children tended to have a longer time until first relapse. Younger kids were also more likely to develop permanent vision problems sooner than older kids.³

Race and NMO experience

There were several trends between race and NMO outcomes among the cases reviewed:³

Non-Asian children were more likely to reach an EDSS score of 4 sooner than their Asian peers
White children seemed to be most affected by vision issues, including permanent visual issues or optic neuritis
White children tended to have an earlier age of onset than Black children, who were often impacted later

Race also seemed to play a role in treatment outcomes. Specifically, Black children were more likely to have no response to high-dose steroid treatment and need a second treatment option.³

Treatment and outcomes

The specific treatments used had an impact on overall outcomes. For example, having an episode of optic neuritis increased the risk of developing permanent vision problems. However, kids who received both steroids and a second-line treatment did not have long-term vision issues.³

On the other hand, more than 40 percent of kids with optic neuritis treated with steroids only had long-term vision issues. The immune-system-impacting drug Rituxan® (rituximab) seemed to have the biggest impact on NMO symptoms. It had the lowest rate of discontinuation (stopping the drug for any reason). Plus, those who took it had zero relapses over a follow-up period of 4.5 years.³

Overall, more research is needed to understand the relationships between demographics and NMO experience. However, some early research suggests that factors like race, age of symptom onset, and treatment experience may all play a role in long-term outcomes.