Neuromyelitis Optica – Symptoms and Causes
What Is Neuromyelitis Optica?
Neuromyelitis optica (NMO) is a disorder that affects the central nervous system, causing inflammation in the optic nerves and spinal cord. This condition is also called neuromyelitis optica spectrum disorder (NMOSD) or Devic disease. It happens when the body’s immune system mistakenly attacks its own cells.
The immune response primarily targets the optic nerves and the spinal cord, though brain involvement can occur in some cases. NMO may develop after an infection or alongside other autoimmune conditions.
Damaged antibodies attach to proteins in the central nervous system, leading to injury. People often confuse NMO with multiple sclerosis (MS), but they are separate conditions with different treatments and outcomes.
Common symptoms include:
- Vision loss (potentially permanent)
- Arm or leg weakness
- Painful muscle spasms
- Reduced sensation
- Vomiting and hiccups
- Bladder and bowel problems
NMO typically follows a relapsing pattern where symptoms improve and then worsen again. Proper treatment to prevent these relapses is crucial to avoid permanent disability, such as vision loss or difficulty walking.
Symptoms
Neuromyelitis optica (NMO) causes inflammation in the nerves of the eye and spinal cord, leading to various symptoms. The eye-related symptoms, known as optic neuritis, include:
- Vision problems in one or both eyes, from blurriness to complete vision loss
- Color blindness or difficulty distinguishing colors
- Pain in the eyes
When NMO affects the spinal cord, it causes transverse myelitis with symptoms such as:
- Muscle problems including stiffness and weakness in legs and sometimes arms
- Sensory loss in arms or legs
- Bladder and bowel difficulties including inability to empty the bladder
- Pain sensations that may feel like tingling or shooting pains in the neck, back, or stomach
NMO can also cause less common symptoms like hiccups, nausea, and vomiting.
In children with NMO, confusion, seizures, or coma may occur, though these symptoms appear more frequently in a related condition called myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD).
The disease typically follows a pattern of remission and relapse, where symptoms improve and then worsen again. Relapses can happen after weeks, months, or years. With repeated relapses, patients may develop permanent blindness or paralysis over time.
Causes
The exact cause of neuromyelitis optica remains unknown. Scientists believe this condition occurs when the immune system mistakenly attacks healthy tissues within the central nervous system, which includes the brain, spinal cord, and optic nerves.
In this autoimmune process, modified antibodies incorrectly bind to proteins found in central nervous system tissues. This binding triggers inflammation—swelling that damages nerve cells and disrupts normal function.
Unlike regular immune responses that protect the body, this abnormal reaction harms the very tissues it should protect. The damage particularly affects the optic nerves and the spinal cord.
Risk Factors
Several factors may increase the chance of developing neuromyelitis optica (NMO):
- Gender: Women develop this condition more frequently than men.
- Age: The average diagnosis occurs around age 40. However, NMO can affect people of any age, including children and older adults.
- Racial and Ethnic Background: Higher rates appear in Hispanic, Asian, and African or Afro-Caribbean populations compared to white individuals.
Some studies suggest additional possible risk factors, including:
- Low vitamin D levels
- Smoking
- Limited exposure to infections during childhood
