Neuromyelitis optica

Overview

Neuromyelitis optica, also known as NMO, is a central nervous system disorder that causes inflammation in nerves of the eye and the spinal cord.

NMO also is called neuromyelitis optica spectrum disorder (NMOSD) and Devic disease. It occurs when the immune system reacts against the body's own cells. This happens mainly in the spinal cord and in the optic nerves that connect the retina of the eye with the brain. But it sometimes happens in the brain.

The condition may appear after an infection, or it can be linked with another autoimmune condition. Altered antibodies bind to proteins in the central nervous system and cause damage.

Neuromyelitis optica is often misdiagnosed as multiple sclerosis, also known as MS, or is seen as a type of MS. But NMO is a different condition.

Neuromyelitis optica can cause blindness, weakness in the legs or arms, and painful spasms. It also can cause loss of sensation, vomiting and hiccups, and bladder or bowel symptoms.

Symptoms can get better and then worse again, known as a relapse. Treatment to prevent relapses is important to help prevent disability. NMO can cause permanent vision loss and trouble walking.

Symptoms

Symptoms of neuromyelitis optica are related to the inflammation that occurs in the nerves of the eye and spinal cord.

Vision changes caused by NMO are called optic neuritis. These may include:

• Blurred vision or loss of vision in one or both eyes.
• Not being able to see color.
• Eye pain.

Symptoms related to the spinal cord are called transverse myelitis. These may include:

• Stiffness, weakness or numbness in the legs and sometimes in the arms.
• Loss of feeling in the arms or legs.
• Not being able to empty the bladder or trouble managing bowel or bladder function.
• A tingling feeling or shooting pain in the neck, back or stomach.

Other symptoms of NMO may include:

• Hiccups.
• Nausea and vomiting.

Children can have confusion, seizures or coma. However, these symptoms in children are more common in a related condition known as myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD).

Symptoms may get better and then worse again. When they get worse, it's known as a relapse. Relapses can happen after weeks, months or years. Over time, relapses can lead to total blindness or loss of feeling, known as paralysis.

Causes

Experts don't know exactly what causes neuromyelitis optica. In people who have the disease, the immune system attacks healthy tissues in the central nervous system. The central nervous system includes the spinal cord, brain and optic nerves that connect the retina of the eye with the brain. The attack occurs because altered antibodies bind to proteins in the central nervous system and cause damage.

This immune system reaction causes swelling, known as inflammation, and leads to the damage of nerve cells.

Risk factors

Neuromyelitis optica is rare. Some factors that may raise the risk of getting NMO include:

• Sex assigned at birth. Women have NMO more often than do men.
• Age. Most often, NMO affects adults. The average age of diagnosis is 40. However, children and older adults also can have neuromyelitis optica.
• Race or ethnicity. People of Hispanic, Asian, or African or Afro-Caribbean descent have NMO at higher rates than do people who are white.

Some research suggests that not having enough vitamin D in the body, smoking and having few infections early in life also may raise the risk of neuromyelitis optica.