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Outlining the Clinical and Radiological Features of NMOSD, MOGAD

Disease Spotlight | <b>Disease Spotlight: NMOSD</b>

Amy Kunchok, MD, staff neurologist at the Mellen Center for Multiple Sclerosis and Research at Cleveland Clinic, discussed a recent talk she gave that highlighted the different phenotypes of AQP-IgG NMOSD and MOGAD.

Both aquaporin-4 antibody (AQP4) neuromyelitis optica spectrum disorder (NMSOD) and myelin oligodendrocyte glycoprotein antibody disease (MOGAD) are neurologic diseases that necessitate additional research, as components of a developing field. However, experts do have a general understanding of the clinical and radiological features of each condition, informing a diagnostic approach for this patient population. 

Amy Kunchok, MD, staff neurologist, Mellen Center for Multiple Sclerosis Treatment and Research, Cleveland Clinic, spoke on both AQP4-IgG NMOSD and MOGAD with NeurologyLive®, following her talk at a recent Institutional Perspectives in Neurology: Multiple Sclerosis event. Comparing the 2 conditions, Kunchok highlighted demographic differences, as AQP4-IgG NMOSD affects adult women more often, whereas MOGAD is more common in younger patients, with a lower female sex predominance. 

Kunchok provided an overview of the different phenotypes for each disease, highlighting key points, as well as directions for future research. While both conditions still have questions regarding clinical outcomes, MOGAD raises more concerns as experts consider how to best treat patients, particularly if they have a relapsing or monophasic disease course, she said.

NeurologyLive®: Can you provide an overview of the different phenotypes of AQP4-IgG NMOSD and MOGAD discussed in your talk?

Amy Kunchok, MD: In the talk, we discussed a little bit about the clinical phenotype of aquaporin-4 NMOSD, and we went through the clinical features and radiological features, and then compared also, the clinical and radiological features of MOGAD.

For NMO, we covered a little bit about the optic neuritis features for NMOs—often it's posterior optic nerve involvement, sometimes chiasmal, and often these patients have poor recovery. We went through briefly about peri-ependymal lesions in NMOSD, and that these are often found in the very highly vascular regions that are devoid of the blood brain barrier, so the third and fourth ventricles. Then we went through some characteristics of myelitis—clinical and radiological features—but in particular, we talked a bit about longitudinally extensive myelitis, ring enhancing lesions, and bright spotty lesions for myelitis in NMOSD. Finally, we talked about the less common presentations of diencephalic lesions that can be seen, and some of the brain lesions. They were the main clinical features that we discussed for aquaporin-4 NMOSD. 

We talked a little bit about the most common phenotype for my MOGAD, optic neuritis, and this is often a bilateral optic neuritis that often can involve the anterior optic nerve. We also talked about some interesting features of perineal enhancement that we can see an optic disc edema in optic neuritis in MOGAD.

For myelitis, we discussed that can also have short segments as well as longitudinally extensive lesions, and the “H” pattern is a common radiological feature that can be seen where the gray matter is—there's a hyperintense signal that of the gray matter. Also, we talked about the conus lesions that are fairly commonly observed in MOGAD myelitis. We talked a little bit about the brain lesions and brainstem lesions—these large, fluffy ADEM-type lesions, as well as sometimes cerebellar peduncle lesions that can occur in MOGAD. More rarely or less commonly seen, we talked a little bit about the cortical encephalitis lesions that we can see with cortical FLAIR lesions, and sometimes that leptomeningeal enhancement.

What are the key takeaways for the clinical community?

We talked about how even though these disorders are a little bit similar clinically, in that they can involve lesions in the optic nerve and spinal cords—optic neuritis and myelitis are common phenotypes of both—there were some clinical features and radiological features that can distinguish the 2. We did also talk about demographic [differences], as some adult females affected by aquaporin-4 often have coexistent autoimmunity. For MOGAD, we don't see as much coexistent autoimmunity, we see it in younger patients, [and there is] not as much of a female predominance. 

Clinically, we talked about some of these features. The optic neuritis, there can be some clinical differences with more posterior optic nerve involvement for aquaporin-4, less for MOGAD, some different myelitis features on the MRI that can distinguish between the 2 and pathognomonic features for aquaporin-4 and some differences that you might see in MOGAD. So, there are clinical and radiological features, even though they can be as a group affecting the same regions in a central nervous system, there are some distinguishing features. 

We also talked a little bit about the NMOSD criteria and how the seronegative NMOSD criteria is sometimes applied to patients with MOGAD, and there are a small proportion of patients—probably about 20 to 30%—that can fulfill those criteria. But the majority of MOGAD patients actually don't fulfill the seronegative NMOSD criteria, so that's another important take home message.

What are the next steps in phenotyping for these patients? What do clinicians still need to understand?

I think there are a lot of questions for both disorders, but for MOGAD, that is a less developed field, particularly about clinical outcomes. What sort of treatment should we use in these patients? Which patients should be treated? Which patients are going to have a relapsing course versus a monophasic course, which then might have an impact on which patients we select for immune treatments? These are some of the questions I think that we need to further research.

Transcript edited for clarity.