Overview

Neuromyelitis Optica Spectrum Disorder

Neuromyelitis optica spectrum disorder (NMOSD) is a rare autoimmune disease of the central nervous system (CNS). Autoimmune disease describes a disease in which the immune system is accidentally attacking the body instead of bacteria, viruses and other pathogens. The CNS includes the brain, spinal cord and optic nerves.

NMOSD includes the condition once called neuromyelitis optica (NMO). The name was changed because the disease can present itself in a number of different ways.

Understanding NMOSD vs. multiple sclerosis

NMOSD is distinct from multiple sclerosis (MS) although both diseases can appear similar to begin with. In some cases, an initial diagnosis of MS may later be diagnosed as NMOSD. They have different causes and treatments. Some MS medications do not work for NMOSD and may worsen the condition.

How NMOSD affects the nervous system

In most people with NMOSD, the immune system mistakenly makes proteins called antibodies that attack a normal protein in the nervous system called aquaporin-4 (AQP4). AQP4 is a protein found on cells in the brain, spinal cord and optic nerves.

When the antibody attaches to AQP4, it can cause inflammation and injury. This often leads to some degree of blindness and/or muscle weakness. Some people with NMOSD do not have AQP4 antibodies, so doctors also use symptoms, imaging and other tests to diagnose the condition.

How NMOSD can affect you

NMOSD usually occurs in attacks with varying degrees of improvement following. Most often it affects:

  • The optic nerves that supply vision
  • Long sections of the spinal cord, leading to weakness in one or more limbs, and bladder/bowel dysfunction
  • A part of the brainstem (area postrema) that, when affected, leads to nausea, vomiting and hiccups

Attacks may be severe and can cause lasting disability. Early diagnosis and treatment are important, and treatment is centered around putting a break on the immune system. NMOSD can affect adults and children, and it may occur along with other autoimmune diseases.