Once in a while a patient with apparent MS receives a surpise diagnosis - it is not MS at all, but rather NMO. NMO stands for neuromyelitis optica, and it used to be called Devic’s disease. It is quite similar to MS, and used to be considered a subtype of MS, but in the past decade we have learned that it is in fact a distinct disease and it requires different treatment entirely. There is now a blood test called an NMO-IgG test, which accurately diagnoses NMO in most cases.
NMO is like MS but the attacks are usually limited to the spinal cord (neuromyelitis) and to the optic nerves (optica) and only rarely affect the rest of the brain. The attacks are often quite severe, however, and the recovery that we often see in MS patients is usually less pronounced in NMO. In other words, NMO patients with optic neuritis may not recover as much vision, and those with spinal cord attacks (myelitis) may be more likely to have permanent paralysis.
We treat the acute attacks in a similar fashion to MS attacks, that is, with high dose steroids. We may then go to plasmapheresis, which replaces the body’s plasma with artificial plasma, if steroids don’t work.
Long term, the drugs for MS, Avonex, Rebif, Tysabri etc do not work in NMO patients. We usually have to rely on immunosupressant drugs such as Imuran and CellCept. If those do not work we then use Rituxan, an intravenous medication which is a monoclonal antibody which depletes certain types of white blood cells. Rituxan is usually given every 6-8 months or so depending on blood counts. It may cause significant infusion reactions, and there are very rare reports of PML, the viral infection also seen as a complication of therapy with Tysabri.
To sum up, NMO is a serious disease which is now understood to be similar to, but distinct from MS. It requires aggressive treatment in order to prevent disability. There is a lot of current research interest in NMO, and I suspect that new therapies will be developed before long.
For those of you who want to learn more, the Guthy-Jackson Foundation is devoted to the cause and cure of NMO and can be reached at www.guthyjacksonfoundation.org or by phone at 858-638-7638.