Devic's disease: symptoms, causes and treatment

Autoimmune diseases are those in which the body itself attacks itself. One of the best known is multiple sclerosis. In this article, however, we will talk about another one, which is related to it: Devic's disease or neuromyelitis optica (NMO).

This disease is inflammatory and demyelinating; It affects the nerve fibers of the Central Nervous System, especially those of the optic nerve and the spinal cord. In this article we will know what it consists of, its fundamental characteristics, its symptoms, causes and treatment.

• Related article: "The 15 most common nervous system diseases"

What is Devic's disease?

Devic's disease, also called neuromyelitis optica (NMO) (or NMO spectrum disorders), is a neurological disorder considered rare, affecting between 1 and 9 people in 100,000. Is about an autoimmune and demyelinating inflammatory disease, primarily affecting the myelin of the optic nerve and spinal cord.

Myelin is a layer that protects the axons of nerve cells, and that has the function of increasing the speed of transmission of the nerve impulse.

• You may be interested in: "Myelin: definition, functions and characteristics"

Characteristics

The main affectation in Devic's disease is a demyelination of the nerve fibers of the Central Nervous System (CNS), which includes the optic nerve (it becomes inflamed) and causes degeneration axonal. On the other hand, spinal symptoms also appear due to inflammation of the spinal cord (motor and sensory disturbances in the extremities).

In relation to its course, it can vary from one person to another; in women, for example, there is usually a course of recurrent attacks. However, although more rarely, a monophasic course can also occur, with episodes of optic neuritis (ON). (inflammation of the optic nerve) and myelitis isolated over time, but simultaneous (later we will see in what consist).

This second type of course it appears more typically in young people, both in men and women. Regarding its distribution by sex, 90% of people affected by Devic's disease are women. The average age of onset is around 50-55 years, although it can appear at any age.

Symptoms

The main symptoms of Devic's disease are the following:

1. Optic neuritis (ON) attacks

Optic neuritis is an inflammation of the optic nerve. These attacks can be unilateral or bilateral. Basically, in these episodes the cells of our immune system attack the structures of the organism; in this case, to the myelin sheaths of the optic nerve(s). This symptom is also typical of multiple sclerosis.

• You may be interested in: "Multiple sclerosis: types, symptoms and possible causes"

2. acute myelitis

Also called acute transverse myelitis, it is an inflammation of the white and gray matter of the CNS, in one or more adjacent medullary segments. Generally the segments of the thorax are inflamed. Myelitis can appear due to Devic's disease, but also due to multiple sclerosis, infections, certain drugs, etc.

3. blindness attacks

These attacks are usually sharp and very severe. It is common for them to appear separated in time (every "X" months or even years). After them, the patient presents a partial recovery thereof.

Blindness attacks usually appear simultaneously with attacks of optic neuritis and myelitis.

4. paraparesis or quadriparesis

Paraparesis involves reduced motor strength in two of the extremities (generally the lower ones); It can also cause paralysis in them. Quadriparesis is the same but with involvement of all four limbs.

5. sensory impairment

The senses of the patient with Devic's disease may deteriorate as the disease progresses, due to the different attacks produced. This will imply difficulties or alterations in your visual and auditory system, mainly..

6. sphincter impairment

The sphincters, as they depend on the spinal cord and therefore the CNS, will also be affected in this disease. This can cause, for example, urine loss due to weakness and loss of sphincter control..

7. other symptoms

Devic's disease can also involve other symptoms, although they are rarer. These can be vomiting, nausea (caused by inflammation of the bone marrow), sleep or endocrine disorders (caused by a disturbance in the hypothalamus) and attacks of cerebral edema. The latter can cause some confusion in the patient, even induce a coma.

8. Associated disorders

It is common for people with Devic's disease to also manifest other types of disorders, these being systemic and autoimmune. Examples of them are: ed Sjögren syndrome and systemic lupus erythematosus (SLE).

Causes

The cause of Devic's disease is unknown. However, its etiology has been linked to autoantibodies against aquaporin-4 (a type of antibody). That is to say, it is known to have an autoimmune origin, just like multiple sclerosis.

As there is still no well-defined and easy-to-determine cause of this disease, its diagnosis is basically clinical, made from the observation of the symptoms manifested by the patient. On the other hand, although the diagnosis is mostly clinical, NMR (Nuclear Magnetic Resonance) tests are normally performed to detect possible spinal cord injuries.

In acute attacks of myelitis, spinal cord lesions usually involve 3 or more vertebral segments. This technique (MRI) can be used to differentiate Devic's disease from other autoimmune disorders, such as Multiple Sclerosis (MS). A difference between these pathologies, and which also helps to establish a diagnosis, is a normal brain MRI in the early stages of Devic's disease.

Sometimes it happens, however, that the patient has had atypical brain lesions, or that he has only had a first episode of myelitis; in these cases, finding autoantibodies against aquaporin-4 helps to diagnose Devic's disease with a little more certainty.

Treatment

Drug treatment used for Devic's disease includes intravenous corticosteroids; these drugs often decrease the duration of symptoms that cause attacks of blindness and optic neuritis. In addition, they have the advantage of accelerating the visual recovery of the patient.

However, the use of corticosteroids has no influence on the functional recovery of the patient or on his prognosis. It also does not decrease the risk of developing multiple sclerosis in the future (since these two diseases are closely related).

Devic's disease prevention is very important, and any minimal symptoms should be taken into account. A good preventive strategy is to perform a magnetic resonance imaging (MRI) of the brain in case of any suspicion of suffering from the disease. On the other hand, once the disease is diagnosed, it will be of great importance go to specialized ophthalmologists and neurologists who can recommend an appropriate treatment for each case.

Forecast

Devic's disease has a good prognosis, although certain visual disturbances may sometimes remain. In more serious cases, the patient can go blind..

Bibliographic references:

• Alvarez, J.C. et al. (2014). Monographs in Multiple Sclerosis. Demyelinating diseases with optic and medullary involvement in MS: 9-96.
• Arias-González, N.P., Valencia-Paredes, D. (2014). Neuromyelitis optica, anti-aquaporin antibodies 4. Medical Journal MD, 6(1): 58-61.
• Wingerchuk, D., Lennon, V., Lucchinetti, C., Pittock, S. & Weinshenker, B. (2007). The spectrum of neuromyelitis optica. The Lancet Neurology, 6: 805-815.