Demyelination

Demyelination occurs when the protective covering around your nerve cells becomes damaged, disrupting the way your nerves send messages throughout your body and potentially affecting movement, vision, sensation, and other vital functions.

Table of contents

• What is demyelination?
• Types of demyelinating diseases
• Associated anatomy
• Symptoms of demyelinating diseases
• What causes demyelination?
• How are demyelinating diseases diagnosed?
• Treatment options
• How common are demyelinating diseases?

What is demyelination?

Demyelination refers to damage to a protective covering called myelin that wraps around many of your nerves^[1]. Think of myelin like the insulation on an electrical wire. It covers the long part of nerve cells, called the axon, helping messages from your brain travel quickly and smoothly through your body, much like electricity flows through a wire^[4].

Myelin is made of fatty white substances and protein layers. It strengthens, protects, and insulates your nerve cells, allowing electrical signals to travel between cells^[1]. In nerves that have myelin, signals can travel up to 150 meters per second. Without it, signals may only travel at 0.5 to 10 meters per second^[6].

When myelin becomes damaged or worn away, it disrupts the transmission of signals through the affected nerves. This reduction in the nerves’ ability to conduct messages can lead to problems with sensation, movement, thinking, or other body functions, depending on which nerves are affected^[3]. When demyelination occurs, scar tissue often forms in place of the damaged myelin. Brain signals cannot move across scar tissue as quickly, so your nerves don’t work as well as they should^[4].

Types of demyelinating diseases

Demyelinating diseases can be grouped based on which part of your nervous system they affect. Your central nervous system includes your brain and spinal cord, while your peripheral nervous system includes nerves outside of your brain and spinal cord^[1].

Common demyelinating diseases affecting the central nervous system include^[1]:

• Multiple sclerosis (MS)
• Neuromyelitis optica spectrum disorder (NMOSD)
• Transverse myelitis (TM)
• Acute disseminated encephalomyelitis (ADEM)
• Progressive multifocal leukoencephalopathy (PML)
• Central pontine myelinolysis

Common demyelinating diseases affecting the peripheral nervous system include^[1]:

• Guillain-Barré syndrome (GBS)
• Charcot-Marie-Tooth disease (CMT)
• Chronic inflammatory demyelinating polyneuropathy (CIDP)

Multiple sclerosis is the most common demyelinating disorder. About one in 500 people have it^[4]. It is an autoimmune condition, meaning the body’s immune system mistakenly attacks its own tissues—in this case, the myelin sheath or the cells that produce it^[2].

Associated anatomy

• Brain
• Spinal cord
• Optic nerves
• Peripheral nerves

Symptoms of demyelinating diseases

Signs and symptoms of demyelinating diseases vary based on the type and which nerves are affected. You might experience symptoms that affect only one part of your body, or you may have several symptoms at the same time. Symptoms can also change in intensity, sometimes getting worse before improving for a period of time^[1].

Common symptoms of central nervous system demyelinating diseases include^[1]:

• Vision changes, including blurry vision, impaired color vision, pain with eye movement, or double vision
• Tingling or numbness in various parts of your body
• A squeezing sensation around your chest or abdomen
• Fatigue
• Bladder or bowel problems
• Electrical tingling or shocks down your back, arms, or legs when you bend your neck forward
• Difficulty walking
• Muscle weakness or stiffness

Additional symptoms that may appear with various demyelinating diseases include^[3]:

• Clumsiness and trouble with coordination
• Slurred speech
• Loss of sensation
• Unsteady gait
• Hearing problems

What causes demyelination?

Damage to myelin and the cells that form it causes demyelinating diseases. This damage happens when your immune system mistakenly attacks healthy myelin. Your immune system normally protects your body from bacteria and viruses that can make you sick. Sometimes, however, it doesn’t get the correct instructions and confuses your myelin cells for harmful invaders. When this happens, it causes inflammation, which is swelling and irritation that leads to the symptoms of demyelinating diseases^[1].

A demyelinating disease can develop due to multiple factors, including^[1]:

• A viral or bacterial infection
• Genetic changes in your DNA that make you more likely to develop the condition
• Autoimmune reactions where the body attacks its own tissues
• Damage to blood vessels in your brain
• Lack of oxygen to the brain
• Vitamin deficiencies

In many cases, doctors aren’t certain what causes these conditions^[4]. Proposed causes include genetic predisposition, environmental factors such as viral infections, or exposure to certain chemicals^[3].

How are demyelinating diseases diagnosed?

A diagnosis is important for managing a demyelinating disease. Your doctor will first review your medical history and discuss any potential symptoms you’re experiencing. If a demyelinating disease is suspected, you’ll likely be referred to a neurologist, a doctor who specializes in conditions affecting the nervous system, who will perform a neurological exam^[13].

Several tests may be recommended to rule out other possible conditions and confirm a diagnosis. These tests might include^[13]:

• An MRI (magnetic resonance imaging scan) to create detailed images of your brain and spinal cord
• A CT scan (computed tomography scan) for cross-sectional images of your body
• Electromyography (EMG) test to check nerve and muscle function
• Lumbar puncture (also known as a spinal tap) to examine the fluid around your brain and spinal cord
• Blood tests to check for various conditions

Treatment options

There is no cure for demyelinating diseases, so early treatment is important^[4]. Once you have a diagnosis, you’ll work closely with your doctor to create a treatment plan unique to you. Treatment focuses on managing the condition that caused your demyelinating disease and managing your symptoms^[13].

Your doctor will work with you to^[4]:

• Lessen the effects of symptom flare-ups
• Control the course of the disease
• Manage your symptoms

Treatment options may include:

Medications can help ease pain, fatigue, and stiff muscles^[4]. For multiple sclerosis, there are medications called disease-modifying therapies (DMTs) that can reduce the number of symptom flare-ups^[4]. Physical therapy can help with muscles that don’t work the way they used to^[4].

The specific treatment varies based on which type of demyelinating disease affects you. Your healthcare team will tailor the approach to your individual needs and circumstances.

How common are demyelinating diseases?

Multiple sclerosis is one of the most common demyelinating diseases. A study in 2019 estimated that there were nearly 1 million people in the United States living with MS^[1]. The condition usually starts between ages 20 and 40^[4]. MS is more likely to affect women and has a genetic link. It may also be triggered by something in a person’s environment^[4].