The worldwide prevalence of neuromyelitis optica is thought to be approximately 1 to 3 individuals per 100, 000. Some believe that the prevalence can be as high as 5 per 100, 000. According to worldwide reports, female to male ratios range from 2:1 to 10:1. Moreover, up to 90% of relapsing NMO patients are women. However, men are more commonly affected by the rarer monophasic form of the disease.

The exact causes of Neuromyelitis optica are unknown. The immune system – specifically NMO-IgG antibodies and immune cells targeting AQP4 – attack the supportive cells in the brain called astrocytes. This immune response is distinct from MS, in which the immune response targets the myelin sheath. When antibodies bind to the aquaporin-4 protein, they trigger a cascade of immune processes ultimately leading to damage (such as the loss of the myelin sheath) which can be permanent. 

Up to 50% of individuals with the disease have a family history of many different types of autoimmune disease, but less than 3% of individuals who have a family history of Neuromyelitis optica specifically.

The median age of onset is 39 years, however, the disease may also occur in children and in the elderly.

Optic neuritis, or myelitis may present themselves as the first symptom.

The optic neuritis may occur in only one eye, but quite often it occurs in both. Pain and loss of vision are usually the first symptoms of optic neuritis.

The myelitis affects sensory, autonomic, and motor functions below a certain point on an individual’s body. This usually results in pain in limbs, paralysis, diminished reflexes, loss of bowel/bladder control, and sensory loss.  

The main symptoms of Devic's disease are due to loss of vision and spinal cord function. Optic neuritis may manifest as visual impairment with decreased visual acuity, although visual field defects, or loss of color vision may occur in isolation or prior to formal loss of acuity. Spinal cord dysfunction can lead to muscle weakness, reduced sensation, or loss of bladder and bowel control.

Neuromyelitis optica can cause spastic weakness, and individuals suffering can often experience recurrent relapses.

Diagnosis is made using a set of clinical criteria that starts with presence of the AQP4 antibody. Patients who test positive for this antibody in the context of either ON or TM are diagnosed with NMO. Those who test negative for the antibody have to meet a more rigorous set of criteria to make sure seronegative (a negative result based on a test of blood serum) NMO is the correct diagnosis.

It is important to distinguish Neuromyelitis optica from MS during the diagnostic process as the two may present very similar symptoms. This can be done using MRI and finding long lesions on the spinal chord over several vertebral segments. Also, the AQP4 antibody is not found in NMO.

It is advised to request a test for neuromyelitis optica if an individual believes that are displaying symptoms as there are tests – such as the blood test described in the next section – which can be positive when the first symptoms appear.

There are many tests used for diagnosis. These include: blood tests, spinal taps, examination of cerebrospinal fluid, MRI imaging, and CAT scans. 

Specifically for blood tests which are testing the NMO-IgG levels in the blood (which is the most sensitive and specific blood test) can detect antibodies that are specific for the aquaporin-4 protein (AQP-4) and can give a positive result in 80% of patients by the time the first symptoms appear; however, it should be underlined, that 10%±25% of NMO patients are seronegative for AQP4-IgG.

There is no cure for neuromyelitis optica, and as a result the only possibility is to treat the symptoms. Attacks specifically are treated with high doses of intravenous corticosteroids – i.e. methylprednisolone IV – for a short period of time. If the corticosteroids do not have an effect then plasmapherisis may be used, however, this is only supported by small and unregulated clinical trials – although they do report high levels of success.

For long term prevention immune suppressive drugs are sometimes used, such as azathioprine, azathioprine with oral prednisone, mitoxantrone, immunoglobulin IV, rituximab and mycophenolate mofetil. However no controlled clinical trials exist for the use of immune suppressing drugs, but there are currently 3 worldwide phase III trials underway. More research will be needed to determine the effect of immunosuppressing drugs.

The prognosis varies. Some individuals recover from specific relapse – although some do not – but the neurological effects build up, and can have a severe effect. 85% of individuals with the disease have recurring relapses.

The five-year survival is 90% in monophasic patients and 68% in relapsing ones. In the second group, deaths are typically due to respiratory failure.

Many individuals will have sight problems, and may be left blind in one or both eyes. Recurrent relapses may lead to permanent paralysis.

The effects of early intervention are not fully known, but it is believed that the amount of attacks an individual experiences will be reduced by 50%.

Take all medications prescribed, and continuously monitor your health. Find support groups where individuals with the disease can talk about their experiences. 

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http://www.malacards.org/card/neuromyelitis_optica?search=Neuromyelitis+optica.

Wikipedia Foundation. (16 March 2016). Neuromyelitis optica. Retrieved form https://en.wikipedia.org/wiki/Neuromyelitis_optica.

Mayo Clinic Staff. (19 Sept 2015). Neuromyelitis optica. Retrieved from http://www.mayoclinic.org/diseases-conditions/neuromyelitis-optica/basics/definition/con-20036360.

Weinshenker. B., Wingerchuk. D. (February 2009). Neuromyelitis optica. Retrieved from 

http://www.orpha.net/consor/cgi-bin/OC_Exp.php?Expert=71211.

NIH. (February 23, 2016). NINDS Neuromyelitis Optica Information Page. Retrieved from 

http://www.ninds.nih.gov/disorders/neuromyelitis_optica/neuromyelitis_optica.htm

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http://rarediseases.org/rare-diseases/neuromyelitis-optica/.