Neuromyelitis Optica (NMO) is an autoimmune disease that affects the neurons of the brain and spinal cord. It causes symptoms that come on quickly and can go away entirely. However, over time these episodes can lead to problems with walking, vision, or coordination.
NMO is also called neuromyelitis optica spectrum disorder (NMO-SD).
The immune system is made up of immune cells. Immune cells usually fight off threats from the outside, such as viruses, bacteria, and fungi. In autoimmune diseases, immune cells attack the healthy cells of the body.
The nerves of the body are like electrical wires. They have a coating on the outside called myelin. In NMO, immune cells attack the myelin coating on the nerves in the brain and spinal cord. The myelin is broken down. The brain can make some repairs, but over time, scars develop. Scarring prevents the nerves from conducting electricity. This is why NMO is called a demyelinating disease.
The immune cells that NMO is most commonly associated with is a pathogenic antibody specific for the aquaporin-4 (AQP4) water channel. Physicians will typically draw blood to look for the presence of this antibody when they suspect NMO.
SIGNS AND SYMPTOMS
The breakdown of myelin can cause different symptoms in NMO depending on the part of the nervous system affected.
Most Common Areas Affected
Three specific areas of the brain and spine are commonly affected in NMO. When they are inflamed, symptoms appear.
Transverse myelitis: This is inflammation in the spinal cord.
It can cause:
- Weakness, numbness, cramping, or tingling of one part of the body
- Tremor in one part of the body
- Problems with urination or stooling (accidents)
Optic neuritis: This is inflammation of the nerves that connect the eyes to the brain.
It can cause:
- Loss of vision
- Blank spots in the visual field
- Blurry vision in one or both eyes
- Loss of color vision (colors may look pale or “washed out” in one or both eyes)
- Pain, especially with eye movement
Area postrema syndrome: Inflammation in this area of the brain (the “emetic reflex center” at the floor of the fourth ventricle deep inside the brain) can cause:
- Nausea or vomiting
- Long episodes of hiccupping
The area postrema syndrome will often occur prior to the other symptoms associated with NMO.
The hypothalamus, an area deep in the brain, can sometimes be affected by NMO. When it is, this can cause:
- Excessive sleepiness
- Difficulty controlling breathing, heart rate, or blood pressure
Inflammation Without NMO
None of the symptoms listed above are specific to neuromyelitis optica. Transverse myelitis or optic neuritis can happen sometimes without other symptoms. They can happen without an obvious cause. They may never even occur again. In these cases, the symptoms would not be considered NMO.
Generally, NMO symptoms will last for weeks. Sometimes symptoms go away entirely, and sometimes the damage is permanent.
No single factor has been shown to cause neuromyelitis optica. We know less about its risk factors than we do about risk factors for other autoimmune demyelinating diseases like multiple sclerosis. We do know that:
- Some infections can trigger NMO
- Smoking and exposure to cigarette smoke increases the risk of NMO
DIAGNOSIS AND LABORATORY INVESTIGATIONS
A doctor may be concerned about NMO when a picture of the brain or spinal cord looks abnormal. These pictures are created with magnetic resonance imaging, or MRI. MRI can show areas where myelin has been damaged. The damaged areas are called lesions. A medicine called contrast may be used to help see lesions.
Once a child is receiving treatment for NMO, a doctor may order an MRI, especially if new symptoms develop. This can show whether there are new lesions in the brain. It can show lesions even if there are no new symptoms.
Sometimes, the doctor will do more tests to confirm a diagnosis.
These may include:
If a child has been diagnosed with either transverse myelitis or optic neuritis, doctors will probably look for certain types of antibodies in the blood, such as aquaporin 4 (AQP4).
A lumbar puncture
This can test the cerebrospinal fluid that surrounds the brain and spine. For example, the cerebral spinal fluid may demonstrate inflammation or increased protein.
Transverse myelitis and optic neuritis can be caused by other conditions besides NMO.
- Extreme vitamin deficiencies
- A rheumatologic disease like lupus
- Multiple sclerosis or another demyelinating disease
If a child has transverse myelitis, a doctor may send them to an ophthalmologist (eye doctor) or neuro-ophthalmologist (brain-eye-doctor). These specialists can look for subtle signs of optic neuritis. This is important because the combination of transverse myelitis and optic neuritis points to the diagnosis of neuromyelitis optica. This can change treatment and prognosis. It may also indicate to the physician to monitor the patient more closely.
TREATMENT AND THERAPIES
Treatments for an Acute Attack
If a child has an attack of transverse myelitis or optic neuritis, a doctor may offer medications that change the way the immune system works. These can include:
- Therapeutic plasma exchange, or plasmapheresis
- Immunoglobulin G, or antibodies from other people, also called IVIG (this is rare)
Treatments for Chronic Neuromyelitis Optica
Medicines that treat NMO change the way the immune system works. They prevent flares of symptoms. These medicines cannot repair damage to the brain and spinal cord. However, they are very important for preventing new damage.
Medications for NMO include:
These medications are taken daily to decrease the immune response. They reduce the risk of recurrence in NMO.
Infusions that reduce B cells
Infusions can get rid of the immune system’s B cells or antibodies. B cells or antibodies can specifically trigger attacks on the myelin. Infusions are given intravenously (by IV). They are given about once every 6-12 months.
Infusions that reduce other immune system cells
These are used less commonly in children. They reduce other kinds of cells that play a role in the immune system.
Families will need to discuss the risks and benefits of the above medications with a doctor to determine which is best.
Other medications may help with symptoms of NMO, such as:
- Problems with urination
Children with NMO should also:
- Eat a healthy diet
- Take vitamin D every day
These are safe, healthy, and natural ways to prevent relapses of NMO. However, in many cases, medication will still be necessary.
Some people with NMO will only have one attack. Others will have many. Attacks of NMO can cause serious problems with:
- Urination and stooling
In some rare cases, NMO can cause death.
It is hard to predict which children will need treatment. It is hard to predict if they will need treatment for months or years. It is important to discuss this with a doctor.
The brain and spinal cord cannot be repaired once damaged. Children with transverse myelitis (inflammation in the spinal cord) may need physical therapy or occupational therapy. This can improve walking and movement.
NMO does not usually affect the way children think or process information. However, having a chronic illness can be stressful. Children may need counseling or psychological therapy to cope with the stress.
The Sumaira Foundation for NMO
The Sumaira Foundation for NMO is a 501(c)(3) organization dedicated to generating global awareness of Neuromyelitis Optica Spectrum Disorder (NMOSD), fundraising to help find a cure, and creating a community of support for patients and their caregivers.
Siegel Rare Neuroimmune Association
The Siegel Rare Neuroimmune Association (SRNA) is a not-for-profit international organization dedicated to the support of children, adolescents, and adults with a spectrum of rare neuroimmune disorders including: Acute Disseminated Encephalomyelitis (ADEM), Acute Flaccid Myelitis (AFM), MOG Antibody Disease (MOGAD), Neuromyelitis Optica Spectrum Disorder (NMOSD), Optic Neuritis (ON) and Transverse Myelitis (TM).
Their mission is to support individuals living with rare neuroimmune diagnoses and their families, promote awareness to empower patients, families, clinicians, and scientists, through education programs (such as the SRNA Quality of Life Family Camp for children and their families diagnosed with a rare neuroimmune disorder) and publications and, to build a collaborative and dedicated clinical care network and help advance scientific understanding and research.
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