Scott Zamvil, MD, phD – Mayo Clinic:
Is NMO a form of multiple sclerosis? And it’s a very interesting question, but they are separate entities. This is a very exciting area right now because we know that NMO is really much less common than MS, but they do share some commonalities. They’re both inflammatory or autoimmune diseases affecting the central nervous system. And one, MS, attacks the myelin so we call that a de myelinating disease. Whereas an NMO, we have an attack on a different cell type, not the one that makes the myelin, but the astrocyte. And NMO is much less common. And NMO is mediated or caused by an antibody, MS not so much, but we know that they have different causes and yet we need to distinguish them. Why? Because of therapies.
A therapy for one may not be the therapy for the other, that’s important. Both can cause optic neuritis, and they do, and both can cause transverse myelopathy. In one case it may be a partial, a different type of a transverse myelitis, but they both occur. Clinically, they overlap. And that’s the challenge right now for physicians. And as we learn more, we’re also have found that not everyone who has NMO has the antibody to that protein, the water channel, aquaporin four. And in the next few years we’re going to learn more about those patients that do have NMO or NMO spectrum disorder, but they don’t have that antibody, because we’re learning so much about the other proteins that may be mimics or maybe other forms of NMO. NMO, in a sense, the spectrum disorder, is actually maybe evolving in some way.