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Wednesday, May 3, 2017

Neuromyelitis Optica: The Basics

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In the June/July issue we profile Christine Ha, winner of the 2012 title of MasterChef, Fox TV's popular amateur chef cook-off competition hosted by Gordon Ramsay. Ha is the first and only blind contestant and winner. While a student at the University of Texas at Austin in 1999, she started losing her vision due to neuromyelitis optica, a rare autoimmune disorder of the central nervous system. In this online exclusive, our experts explain the disorder, describe the symptoms, and list the treatments.

BY ROBERT-FIRPO-CAPPIELLO

What Is Neuromyelitis?

Neuromyelitis optica (NMO) is a rare inflammatory autoimmune disease of the central nervous system in which the immune system attacks myelin, the fatty substance that surrounds nerve fibers and promotes the movement of nerve signals from cell to cell, in the optic nerves and the spinal cord. Unlike multiple sclerosis (MS), NMO is not a progressive disease; clusters of attacks commonly occur months or even years apart, with periods of remission during which affected areas can recover to some degree, according to the National Institute of Neurological Disorders and Stroke.

How Common Is It?

Recent research suggests that NMO affects fewer than 20,000 people in the United States. It disproportionately affects women; 70 to 90 percent of people with NMO are female. Onset typically occurs during childhood or middle age, most commonly affecting non-white middle-aged women.

What Are the Symptoms?

NMO is characterized by two major conditions: optic neuritis, which causes eye pain and vision loss, and transverse myelitis, which causes tingling, numbness, and sometimes paralysis of the arms and legs, and may be accompanied by loss of bladder and bowel control. The period between initial optic neuritis and ensuing transverse myelitis can vary from a few days to several years. Less severe recurring symptoms include sensory disturbances such as a "pins and needles" feeling in the limbs and temporary blurred vision.

What Are the Risk Factors?

Other than the fact that NMO disproportionately affects women, few risk factors have been identified. Classic risk factors for MS, such as smoking and infectious mononucleosis, do not increase the risk of NMO, according to a 2015 study in Multiple Sclerosis Journal. A 2014 study in PLoS One suggests a correlation between low levels of vitamin D and NMO (as is common in other autoimmune disorders), but no clear cause and effect has been established.

How Is It Diagnosed?

Doctors order blood tests to look for biomarkers associated with autoimmune disorders. Brain and spinal MRIs are used to look for lesions that can confirm NMO. If NMO is suspected, a doctor will draw spinal fluid to see if an NMO-specific antibody, which appears in about 80 percent of people with the disorder, is present.

What Treatments Are Available?

No cure exists and no therapies have been approved by the US Food and Drug Administration to treat NMO. However, the use of intravenous steroids and plasma exchange as well as immune-suppressing therapy, in particular the anti-cancer drug rituximab, has proved effective in treating attacks.