Management of Optic Neuritis - Episode 3
Robert C. Sergott, MD:As far as choice of what medications to use for optic neuritis and MS [multiple sclerosis], our choices now are robust. Some patients are still treated with injectable therapy, like glatiramer acetate or the interferons, but many are also treated with oral medications as well as intravenous infusions. While we can prevent a lot of relapses now, where MS therapy needs to move to—and we’ll talk about this a little later in the program—is how we repair damage. That’s really going to be the focus of the next decade in this therapy.
Rod, you mentioned earlier a neuromyelitis optica, NMO. Bring our audience up to date on how this has changed what happens with the management of acute optic neuritis. And you also mentioned something about how the optic nerve looks on MRI [magnetic resonance imaging].
Rod Foroozan, MD: Yeah. It used to be we would lump all inflammatory optic neuropathy together that looked somewhat like MS. We now know that there are some variants, and there’s a spectrum of disease. Around the early to mid-2000s there became a blood test available for neuromyelitis optica, which is an antibody to aquaporin 4, and that was a game changer because we could now define—by pathophysiology and identify with a blood test—those patients who were going to be at risk for a more progressive disease. And that really started to split up NMO from MS with more certainty. Because before that, if you looked at the literature, there were lumpers and splitters. Some people just felt that NMO was a sort of variant of MS, and that’s clearly been shown not to be the case, not only diagnostically but also therapeutically. Some patients who are treated for NMO will respond poorly to the traditional MS medications.
The availability of this antibody to aquaporin 4 was a game changer for us. And what was noticed relatively early on was that patients who had more severe optic nerve involvement, poor vision, bilaterality, simultaneous involvement, or what I mentioned before with the degree of enhancement of the optic nerve, longer stretches of enhancement, extending into the optic chiasma, for example, those were patients who were somehow different immunologically in how their inflammation occurred and were at risk for having a positive NMO blood test. We’ve identified those as candidates to go ahead and get those blood tests straightaway and not wait for a clinical response.
Robert C. Sergott, MD: I cannot emphasize the importance of what Rod just said to the daily practice of neurology, ophthalmology, and neuro-ophthalmology. NMO is a vicious disease. It’s just not a little worse demyelination. Beautiful work by Claudia Lucchinetti from Mayo Clinic has shown that this is a vasculitis that has special preference for the optic nerve, the retina, an area of the brain near the start of the spinal cord called the medulla, the area postrema, and for long segments of the spinal cord. Rod also mentioned that we were taught that you need to think about NMO, which was also called Devic’s disease, only if both optic nerves were involved. Completely false.
Every patient who comes to see us, either at the Wills Eye Hospital emergency department or to us in clinic, gets an NMO titer and something called an anti-MOG titer that we’ll have Rod talk about a little more in a few minutes. Other things as clinicians you want to ask about is whether patients in the past ever had a couple of weeks of uncontrollable hiccups, and that’s because this inflammation affects the area postrema in the medulla. Another rare symptom is itching, and it’s now well documented that an attack of itching lasting for weeks or a month can be a sign of neuromyelitis optica before we have vision loss. We used to sometimes image the spinal cord in optic neuritis patients, but now we do it in everybody, the cervical and thoracic cord.
Rod mentioned how long the area of optic nerve inflammation is in NMO. What we do now is image the cord in everyone because you’ll see asymptomatic lesions that stretch over several segments of the cord. And there are patients who will have what’s called seronegative NMO. That is, the blood test will be negative, but they’ll have these clinical features or the neuroradiological features, and that’s still NMO.
Anybody who doesn’t get better with steroids, I am very suspicious of NMO and now we have a very low threshold to move to a technique called plasmapheresis to wash out their blood, and that’s something we’ve had some dramatic success with.