Rapid Weight Loss

Reviewed by: HU Medical Review Board

Neuromyelitis optica spectrum disorder (NMO) is a rare inflammatory disease of the central nervous system (eye nerves, spinal cord, and brain). NMO may also be called neuromyelitis optica or NMO.1

NMO is a demyelinating disorder. Myelin is the protective coating that surrounds the nerve fibers in your brain, spinal cord, and eye. Damage to the myelin layer is called demyelination. Demyelination causes nerve signals to slow or stop, leading to brain and nerve problems.1,2

NMO is also an autoimmune disorder. This means that the immune system cannot tell the difference between healthy cells and invaders like viruses, fungi, or bacteria. Because the body cannot tell the difference, it begins to attack and damage healthy cells.

The symptoms of NMO can vary depending on which part of the body is affected. Symptoms also vary in severity and how long they last. Rapid weight loss may occur with NMO for a variety of reasons.3

AQP4 and NMO

Antibodies are chemicals the immune system makes to kill germs. In some diseases, antibodies can also be harmful. One antibody that attacks a protein called aquaporin-4 (AQP4) causes inflammation and damage to the brain, spinal cord, and eye nerve (optic nerve).4,5

AQP4 is found on brain cells called astrocytes and helps control water balance in the brain. The brain, spinal cord, and eye nerve (optic nerve) have AQP4. AQP4 antibodies (AQP4-IGg) damage the myelin of the brain cells and cause inflammation.4,5

Brain stem syndromes

Some people with NMO have nerve fiber damage in the brain. Most of these people have AQP4 antibodies (AQP4-IgG).3,5

Area postrema syndrome

Some people with NMO have brain stem involvement. This may involve damage to the nerve fibers in a specific area of the brain stem known as the area postrema (AP). The AP region is rich in AQP4. AQP4 antibodies (AQP4-IgG) bind to AQP4 in this region of the brain, causing a condition known as area postrema syndrome (APS). Symptoms of APS include:3,5,6

  • Nausea
  • Loss of appetite or aversion to food (anorexia)
  • Vomiting
  • Hiccups

APS symptoms may last weeks or even months and may lead to rapid weight loss. Depending on the severity and length of time a person has APS, treatment can vary. Sometimes, a feeding tube may be needed to maintain body weight and ensure proper nutrition.3,5,6

Cranial nerve weakness

Cranial nerves relay information between the body and the brain. Damage to these nerves (also known as lower motor neurons) can lead to bulbar weakness (palsy).7

Bulbar palsy can have a wide variety of symptoms depending on the nerve that is damaged. Some of these symptoms may include:7

  • Problems chewing or swallowing (dysphagia)
  • Slurred speech (dysarthria)
  • Decreased gag reflex
  • Weak jaw and facial muscles

Bulbar palsy can make it difficult to chew and swallow food. This may lead to weight loss and require additional treatment. Also, those with difficulty swallowing are at an increased risk of food entering the lungs (aspiration). This can lead to lung infection (pneumonia), which can be serious or life-threatening.7


Some people with NMO who have weight loss or difficulty chewing and swallowing will need help getting the nutrition their body needs. One method that may be used is tube feeding (enteral nutrition). Tube feeding uses a special liquid food mixture. This liquid contains all the nutrition the body needs:8

  • Protein
  • Carbohydrates (sugar)
  • Fats
  • Vitamins
  • Minerals

Tube feeding uses a tube into the stomach or small intestine. It may need to be a permanent therapy for those with NMO.8

By providing your email address, you are agreeing to our privacy policy.