Perspectives in MS
Perspectives in MS

Neuromyelitis Optica, Part 1

TEXT SIZE: A A A

Multiple sclerosis is by far the most common demyelinating disease of the central nervous system, but certainly not the only or even the most severe such illness. In this post, I would like to discuss a much rarer illness known as either neuromyelitis optica (NMO) or Devic’s disease. There is some controversy about whether or not NMO is simply a variant of MS or a different disease entirely.  Most neurologists today believe that NMO is a different disease from MS, but the debate is ongoing.

The diagnostic criteria for NMO were established only in 2006.  According to these criteria, to be diagnosed with NMO patient must have:

  1. Optic neuritis,
  2. Spinal cord inflammation(termed myelitis)

And at least two of three supportive criteria:

  1. MRI evidence of a contiguous spinal cord lesion 3 or more segments in length,
  2. Brain MRI at onset nondiagnostic for multiple sclerosis,
  3. NMO-IgG antibody detected in the blood.

The main features of NMO are recurrent episodes of optic neuritis combined with inflammation of the spinal cord that is 3 or more segments in length, much longer than spinal inflammation in MS.  The optic neuritis in NMO is often in both eyes.  Additionally, while the brain MRI in NMO may show some lesions, it typically shows many fewer lesions than in MS and the lesions are not in the same location in the brain.  According to the guidelines, the MRI for NMO patients would not meet the diagnostic criteria for MS at the time the illness is diagnosed. Finally, unlike MS, there is a blood test for and antibody in NMO. The NMO antibody is directed against a water channel on certain cells in the nervous system known as astrocytes. It is positive in about 75% of patients with NMO.

Because the test is negative in about 25% of patients with NMO, it is a far from perfect test. If the blood test comes back positive for NMO, it almost certainly means that the person has this illness. However, it is still possible for a person to have NMO, yet not have this antibody in detected in their blood. It may not be possible to differentiate MS from NMO early in the disease course, especially if a patient presents with a symptom such as unilateral optic neuritis that could be a feature of either disease.  Since MS is much more common than NMO, it is the illness that should be thought of first. However doctors must always have an open mind and be willing to reconsider this diagnosis if new evidence emerges. In my next post, I will further compare and contrast MS and NMO.

  • 1

Tags: Living With

Was this article helpful? Yes No

Recommended for You

  • Goodbye!

    By: Jonathan Howard, MD
    Feb 28, 2012

    Goodbye!!! Unfortunately, this is going to be my last column for now. Let me take this chance to thank the folks at Healthline for giving me the opportunity to write as much as I did. The one requirement I made when I started writing is that n...

    Read more »

  • Vitamin D, Part 2

    By: Jonathan Howard, MD
    Jan 31, 2012

    While the role of a low vitamin D level is a becoming an established risk factor for MS, it is not universally accepted as such. Even less clear is the role for vitamin D supplementation once the diagnosis of MS has been made is less clear. A s...

    Read more »

  • Secondary Progressive MS vs Relapsing-Remitting MS

    By: Jonathan Howard, MD
    Jan 05, 2012

    One of the most common questions I am asked by patients is whether they are in the relapsing-remitting phase of MS or in the progressive phase of the illness. Lets again review what these terms mean. About 85% of patients start the illness wit...

    Read more »

  • Relapses and Disability, Part 2

    By: Jonathan Howard, MD
    Dec 27, 2011

    In my last post I briefly summarized two papers that showed that relapses in MS were only very rarely sources of permanent disability. But does this mean that relapses don’t matter? Does this mean that by using medications to prevent relapses ...

    Read more »

Advertisement

About the Author

Dr. Howard is a neurologist & psychiatrist, and an expert in multiple sclerosis.

Recent Blog Posts

Advertisement
Advertisement