Neuromyelitis optica spectrum disorder (NMO) is a rare inflammatory disease that affects the spinal cord, eye, and brain.
The symptoms of NMO can be different depending on which part of the body is affected. Symptoms also vary in severity and how long they last. However, NMO is most commonly associated with optic neuritis symptoms, which affect eye function, and transverse myelitis, which affects arm and leg function.1
NMO and demyelination
Nerve fibers in your brain, spinal cord, and eye have a protective coating called myelin. Damage to this layer is called demyelination. Some conditions, including NMO, are demyelinating because they damage this protective layer.2
When myelin is damaged, nerve signals can slow or stop. This leads to brain and nerve problems. In NMO, damage to the nerve fibers occurs in the:2
- Eye nerves, called optic neuritis
- Spinal cord, called transverse myelitis
- Brain stem, causing several different syndromes
What is optic neuritis?
The optic nerve is the bundle of nerve fibers acting as the communication cable between your eyes and your brain. Optic neuritis occurs when inflammation damages the optic nerve.3
Symptoms of optic neuritis may include:1,3
- Sudden eye pain or headache – This is usually made worse with eye movement.
- Problems with vision or complete loss of vision – This usually occurs in 1 eye but can affect both eyes. It can include partial or complete blindness, problems seeing different colors, blurred or tunnel vision, or poor depth perception.
What is transverse myelitis?
Transverse myelitis occurs when inflammation damages the spinal cord. It is defined by symptoms and signs of nerve problems in the motor (movement) and sensory (sensation) tracts on both sides of the spinal cord.4,5
Symptoms of transverse myelitis include:1,4,5
- Neck or back pain
- Arm or leg weakness, ranging from mild to complete paralysis in 1 or multiple limbs
- Tightness or a band-like feeling in the belly, chest, arms, or legs
- Sensitivity to touch, cold, or heat
- Feeling of numbness, tingling, coldness, itching, or burning
- Urgent need to urinate or difficulty urinating
- Urinary incontinence (unintentional passing of urine)
- Constipation leading to vomiting (throwing up), belly bloating, pain, or inability to pass stool or gas
- Bowel incontinence (unintentional passing of stools)
- Painful muscle spasms
- Fever
Brain stem syndromes
Some people with NMO may develop brain inflammation. Vomiting, nausea, and hiccups that are hard to control (intractable) may occur. This is known as area postrema syndrome (APS). Between 16 and 43 percent of people with NMO have APS. Outcomes vary depending on the amount of damage to the brain.6
Course of symptoms
Generally, NMO symptoms begin suddenly. After the first attack, NMO follows an unpredictable path, and remission can vary. Episodes of optic neuritis or transverse myelitis can last weeks to months, and in some cases can last years. However, these symptoms are usually temporary and resolve fully or partially, most often after a course of treatment. Damage from attacks may accumulate, with symptoms worsening over time depending on how often and how severe the attacks are.1
How will the symptoms develop over time?
The chance of recurrence of disease activity is greater than 90 percent. Attacks in NMO can be devastating. Outcomes vary widely with each person. If the disease is left untreated, early and severe disability is common.6,7
Disability from NMO may include:6,7
- Vision loss or blindness
- Problems moving, walking, or standing
- Complete paralysis
- Bladder problems