Autoimmune diseases are those in which the body 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 in 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.
What is Devic’s disease?
Devic’s disease, also called neuromyelitis optica (NMO) (or spectrum of NMO disorders), is a neurological disorder considered rare, affecting between 1 and 9 people out of 100,000. It is an autoimmune and demyelinating inflammatory disease, which mainly affects the myelin of the optic nerve and the spinal cord .
Myelin is a layer that protects the axons of the nerve cells and has the function of increasing the speed of transmission of the nerve impulse.
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 (this becomes inflamed) and which produces axonal degeneration. On the other hand, , spinal symptoms also appear due to inflammation of the spine (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, there can also be a monophasic course, with episodes of optic neuritis (ON) (inflammation of the optic nerve) and myelitis isolated in time but simultaneous (we will see what these consist of later on).
This second type of course appears more typically in young men and women . In terms of 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.
The main symptoms of Devic’s disease are as follows:
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, the myelin sheaths of the optic nerve(s). This symptom is also typical for multiple sclerosis.
2. Acute myelitis
Also called acute transverse myelitis, this is an inflammation of the white and grey substance of the CNS, in one or more adjacent spinal segments. Usually the segments of the chest are inflamed. Myelitis can be caused by Devic’s disease, but also by multiple sclerosis, infections, certain drugs, etc.
3. Blindness attacks
These attacks are usually acute and very serious. It is common for them to appear separately in time (every “X” months or even years). After them, the patient presents a partial recovery of them.
Attacks of blindness usually occur simultaneously with attacks of optic neuritis and myelitis.
4. Paraparesis or quadriparesis
Paraparesis involves the reduction of the motor strength of two of the limbs (usually the lower ones); it can also cause paralysis in the limbs. Quadriparesis is the same but affects all four limbs.
5. Sensory impairment
The senses of the Devic’s disease patient may deteriorate as the disease progresses, due to the different attacks produced. This will imply difficulties or alterations in their visual and auditory system, mainly..
6. Deterioration of the sphincters
The sphincters, because they depend on the spinal cord and therefore the CNS, will also be affected in this disease. This can lead, for example, to urine loss through weakening and loss of sphincter control .
7. Other symptoms
Devic’s disease may also involve other symptoms, although these are more rare. These may include vomiting, nausea (caused by inflammation of the spine), sleep or endocrine disorders (caused by a disturbance in the hypothalamus), and strokes of brain swelling. The latter can cause some confusion in the patient, even inducing a state of coma.
8. Associated disorders
It is common for people with Devic’s disease to have other types of disorders as well, both systemic and autoimmune. Examples are: Sjögren’s syndrome and systemic lupus erythematosus (SLE) .
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, is known to have an autoimmune origin, just like multiple sclerosis .
As there is not yet a well-defined and easy to determine cause for 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, MRI (Magnetic Resonance Imaging) tests are normally performed to detect possible spinal cord injuries.
In acute attacks of myelitis, spinal cord injuries usually involve three or more vertebral segments. This technique (MRI) can be used to differentiate Devic’s disease from other autoimmune disorders, such as Multiple Sclerosis (MS). One difference between these pathologies, which also helps establish a diagnosis, is a normal brain MRI in the early stages of Devic’s disease .
Sometimes it occurs, however, that the patient has had atypical brain lesions, or has only had a first episode of myelitis; in these cases, finding autoantibodies to aquaporin-4 helps diagnose Devic’s disease with a little more certainty.
The drug treatment used for Devic’s disease includes intravenous corticosteroids ; these drugs usually decrease the duration of the symptoms that cause the attacks of blindness and optic neuritis. In addition, they have the advantage of speeding up the patient’s visual recovery.
However, the use of steroids has no influence on the patient’s functional recovery or prognosis. Nor does it decrease the risk of developing multiple sclerosis in the future (as these two diseases are closely related).
Prevention of Devic’s disease is very important, and any minimal symptoms should be taken into account. A good preventive strategy is to perform a brain magnetic resonance imaging (MRI) on any suspicion of the disease. On the other hand, once the disease is diagnosed, it will be of great importance to go to specialized ophthalmologists and neurologists who can recommend an appropriate treatment for each case.
Devic’s disease has a good prognosis, although sometimes certain visual disturbances may remain. In more severe cases, the patient may go blind .
- Álvarez, J.C. et al. (2014). Monographs in Multiple Sclerosis. Demyelinating diseases with optical and spinal cord involvement in MS: 9-96.
- Arias-González, N.P., Valencia-Paredes, D. (2014). Optical neuromyelitis, 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 optic neuromyelitis. The Lancet Neurology, 6: 805-815.