Neuromyelitis optica

Symptoms and causes

Neuromyelitis optica (NMO) is a rare central nervous system condition. It causes inflammation in nerves of the eye and the spinal cord.

NMO also is called neuromyelitis optica spectrum disorder (NMOSD) or Devic disease. It happens when the immune system reacts to the body's own cells. That type of condition is called an autoimmune disease. NMO typically affects the spinal cord and the optic nerves that connect the retinas of the eyes to the brain. Sometimes it also can happen within the brain.

NMO may appear after an infection. Or it may be linked to another autoimmune condition. Neuromyelitis optica used to be considered a form of multiple sclerosis (MS), and it still sometimes may be diagnosed incorrectly as MS. But NMO is a condition separate from MS.

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

Symptoms may get better and then get worse again. This is called a relapse. Treatment to prevent relapses is important to help prevent long-term health issues related to NMO.

Symptoms of neuromyelitis optica are caused by inflammation in the nerves of the eye and spinal cord.

Together, symptoms that affect the eye due to inflammation of the optic nerves are called optic neuritis. They 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 collectively 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 with NMO can have confusion, seizures or coma. But these symptoms in children are more common in a related condition called myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD).

Symptoms may get better and then get worse again. This is called a relapse. Relapses can happen after weeks, months or years. Over time, relapses can lead to total blindness or loss of feeling and mobility, known as paralysis.

Experts don't know exactly what causes neuromyelitis optica. In people who have this condition, the immune system attacks healthy tissues in the central nervous system. The central nervous system includes the spinal cord and brain, as well as the optic nerves that connect the retinas of the eyes to the brain. The immune system attack happens when an antibody called aquaporin-4-immunoglobulin G (AQP4-IgG) binds to proteins in the central nervous system. That causes swelling and inflammation. The inflammation then damages nerve cells.

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

• Sex assigned at birth. Those assigned female at birth have NMO more often than those assigned male at birth.
• Age. The average age at diagnosis is 40. But children and older adults also can have neuromyelitis optica.
• Race or ethnicity. People of Hispanic, Asian, African or Afro Caribbean descent have NMO at higher rates than do other people.

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.