Neuromyelitis optica

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at August 25, 2016
StartDiseasesNeuromyelitis optica

Neuromyelitis optica, which is also known as Devic's disease or Devic's syndrome, is a medical condition that causes damage to several nerves throughout the body. It has many causes and a variety of symptoms, so discovering and diagnosing the condition can be somewhat difficult. 

Contents

Definition & Facts

Neuromyelitis optica is a type of heterogenous condition which means that the symptoms vary wildly among patients. In general, it is somewhat similar to multiple sclerosis, but neuromyelitis optica focuses on a few areas of the body. Patients with neuromyelitis optica tend to have issues with damage to their optic nerve and spinal cord.

There are many variants outside of the standard version of Devic's syndrome, such as the variant associated with brain lesions or the variant associated with autoimmune diseases. Altogether, these various versions are categorized under the broad umbrella of neuromyelitis optica spectrum diseases. Only about 1 out of 100,000 people worldwide develop neuromyelitis optica.

Symptoms & Complaints

Depending on how severe the damage to the optic nerve and spinal cord is, people with neuromyelitis optica may suffer from a variety of symptoms. Over time, almost every person with neuromyelitis optica deals with limited optic nerve and spinal cord function.

As the optic nerve degrades, optic neuritis sets in. This causes eye pain and decreased vision, and the vision loss associated with neuromyelitis optica can cause a loss of color, increasing blurriness, or a decreased range of vision.

The damage to the spinal cord also causes transverse myelitis. At first, patients may just feel temporary weakness or numbness in the limbs, but this can gradually turn into paralysis.

Spinal cord damage can also result in difficulty controlling bladder and difficulty controlling bowel movements. If a person has the type of neuromyelitis optica that results in lesions of the brain, they can deal with nausea, vomiting, and hiccups because the area of the brain that controls these functions is damaged.

Not all of the symptoms of neuromyelitis optica occur at once. Instead, the condition is associated with a gradual loss of function due to neuromyelitis optica attacks. These attacks may occur every few days, or they can be years apart.

Between attacks, a patient will go into remission and improve slightly, regaining some sight or limb usage. However, they tend to gradually deteriorate after several successive attacks. 

Causes

Neuromyelitis optica is caused by malfunctioning antibodies called NMO-IgG which is a form of immunoglobulin. In most cases, these NMO-IgG antibodies mistakenly start to target the aquaporin 4, a protein that is in cells surrounding the nerves. When this happens, the coating that is supposed to protect the optic and spinal nerves develops inflammation and slowly wears away over time if the neuromyelitis optica attacks are not halted.

The precise reason that these harmful antibodies are triggered is still not entirely understood, but when they get to very high levels, a neuromyelitis optica attack occurs. It often happens if a patient is suffering from another disease, such as HIV, lupus, or the varicella zoster virus.

Though it is not strictly an inherited condition, having a family history of neuromyelitis optica increases a person's risk of developing the disease. This seems to happen because certain genes increase a person's susceptibility to NMO-IgG antibody attacks.

Diagnosis & Tests

In order to be diagnosed with neuromyelitis optica, a patient must meet a certain set of criteria. First of all, doctors will check for inflammation of the optic nerve, which is called optic neuritis, and the spinal cord which is called myelitis. Normally, optic neuritis can be diagnosed through a simple ophthalmoscopic examination.

Myelitis can only be diagnosed with a magnetic resonance imaging (MRI) scan of the spinal cord and the brain. Lumbar punctures (spinal taps) can also be used to determine the degree of inflammation. If the diagnosis is confirmed for inflammation in these two areas, a doctor will begin to suspect that a patient may have neuromyelitis optica. It is then necessary to rule out other similar diseases, like multiple sclerosis that also cause inflammation but occur in other places within the body.

Once other conditions are ruled out, the final step is testing the blood to see if a patient has elevated levels of the NMO-IgG antibodies that cause neuromyelitis optica. This normally requires blood samples to be taken and sent to a laboratory for examination. The diagnosis process for neuromyelitis optica can be somewhat lengthy, since it requires so many steps and takes a while for symptoms to be obvious enough that doctors suspect neuromyelitis optica.

Treatment & Therapy

Since the underlying causes of this condition are still not completely understood, it is currently impossible to completely cure a patient of this condition. However, prompt medical treatment can alleviate symptoms and brighten a patient's prognosis. Injections of high dosage corticosteroids can greatly reduce the length of an attack, and this prevents the inflammation from becoming strong enough to cause damage.

It is also somewhat beneficial to remove blood plasma and replace it with donated plasma. This seems to work because it lowers the overall levels of NMO-IgG in the bloodstream. By reducing the duration of neuromyelitis optica attacks, most patients can retain some use in their limbs and some eyesight. Further dosage of immunosuppressive drugs may possibly help to prevent more attacks from happening.

Other medications and physical therapies can be used to manage the cramping, pain, tingling, bladder problems, and stomach pain that often happens to people with neuromyelitis optica. Though they are still in clinical trial stages, some researchers also hope to reverse the damage done during neuromyelitis optica by replacing the nerve coating damaged during neuromyelitis optica attacks with cell transplantation.

Prevention & Prophylaxis

Unfortunately, there is no method of entirely preventing neuromyelitis optica from occurring. Patients who already have the condition may benefit from genetic counseling to avoid passing any susceptibility for neuromyelitis optica on to their offspring.

Since the onset of this condition often occurs after catching a virus, practicing good hygiene may theoretically help to slightly reduce a person's chances of triggering neuromyelitis optica.