Complications and Comorbidities
Neuromyelitis optica spectrum disorder (NMO) is a rare demyelinating disorder. Myelin is the protective coating around the nerve fibers in your brain, spinal cord, and eye. Damage to the myelin layer is called demyelination. Demyelination leads to brain and nerve problems because the nerve signals can slow or stop.1,2
NMO is also an autoimmune disorder. This means that the immune system cannot tell the difference between healthy cells and invaders like viruses, fungi, or bacteria. Because the body cannot tell the difference, it begins to attack and damage healthy cells.
NMO occurs alongside other conditions and may lead to added comorbidities and complications. “Comorbidity” describes a condition that occurs at the same time as another condition. Comorbid conditions can interact in ways that make both worse.
Mental health problems
Along with damage to the brain, eye, and spinal cord, NMO can coexist with mental health problems. The most common problems include:3,4
Doctors think mental health problems occur more often in NMO for a variety of reasons, including:3,4
- Decrease in quality of life due to symptoms of NMO
- Inflammatory changes in the brain
Longer disease duration is linked to the lowered quality of life reported by those with NMO. It is difficult for doctors to know whether some mental health disorders are underlying (were there before the diagnosis of NMO) or caused by NMO. This means there is an association but not causation. Studies have been limited, and more research is needed.3,4
Memory and attention problems
Up to 70 percent of people with NMO have memory or attention problems. Those with more damage to the brain fibers have more problems with memory and attention.Specific problems include issues with:5
- Sustained attention
- Verbal memory
- Speed of information processing
Studies of these complications and why they happen more often in those with NMO are limited. Doctors think they may happen due to changes to the structure of the brain that can occur in NMO.5
Other autoimmune conditions
NMO and other autoimmune conditions often occur together. The reason they occur together is unclear. It may be due to complex interactions between genes and immunity.6
Autoimmune conditions that are common with NMO include:6-9
- Lupus – The immune system attacks healthy tissue, such as the skin, joints, kidneys, brain, and other organs. The symptoms and severity of the disease can vary widely among people.
- Sjogren’s syndrome – The immune system attacks certain healthy parts of the body, most commonly the tear and saliva glands. Other fluid-producing areas, like the nose, throat, skin, or vagina, can also be impacted.
- Autoimmune thyroid disorder (Hashimoto's disease) – Your immune system creates antibodies that damage your thyroid gland.
Fatigue is the lack of mental or physical energy. Fatigue can directly result from a disease process (primary) or an indirect effect (secondary). In NMO, fatigue is usually thought to be a result of a secondary process. Causes of secondary fatigue may include:10
- Side effects from NMO drugs
- Sleep problems
- Problems with walking (increased energy needed)
The exact reason why sleep problems occur more commonly in NMO is not known. Doctors think it is a combination of several factors, including:11
- Structural damage to the brain and spinal cord
- Weakness of the diaphragm, which is an important muscle for breathing
- Side effects from drugs used to treat NMO
- Chronic (long-term) pain
Some people with NMO develop breathing problems. Symptoms range from mild shortness of breath to respiratory failure, requiring the use of a ventilator to breathe. Doctors think this may be due to factors including:12,13
- Weakness of the breathing muscles
- Brain stem disease involvement
Rapid weight loss
Between 15 to roughly 50 percent of those with NMO have brain stem involvement. This involves damage to the nerve fibers in a specific area of the brain stem known as the area postrema (AP). The AP region is rich in aquaporin-4 (AQP4). AQP4 is the target of a specific antibody found in NMO. This AQP4 antibody (AQP4-IgG) causes a condition known as area postrema syndrome (APS). Symptoms of APS include:12,14
APS is more common in Asian and Black populations.14
Rapid weight loss may occur with APS because of nausea and vomiting. Those who have severe symptoms may require additional treatment to help with nutrition and weight gain.14