Autoimmune demyelinating disease

What is autoimmune demyelinating disease?

Autoimmune demyelinating disease is a condition where your body's immune system (the system that normally protects you from illness) mistakenly attacks the myelin sheath in your brain, spinal cord, and nerves. The myelin sheath is a protective covering around nerve cells that works like insulation on electrical wires. It helps messages from your brain move quickly and smoothly through your body.1

When this protective covering is damaged or destroyed, a process called demyelination, your nerves can't communicate as they should. Brain signals can't move across damaged areas as quickly, so your nerves don't work as well as they should. Scar tissue often forms in place of the damaged myelin.12

In autoimmune demyelination, myelin breaks down in areas where immune cells have gathered. The myelin layers themselves are the target of the allergic reaction. The damaged myelin sheaths are then removed by cells called macrophages that strip the myelin off the nerve fibers.3

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Autoimmune Demyelinating Diseases, CNS, CNS Autoimmune Demyelinating Disorders, Demyelinating Autoimmune Diseases, Central Nervous System, Autoimmune Demyelinating Disorders, CNS

Types of autoimmune demyelinating diseases

Autoimmune demyelinating diseases can affect either your central nervous system (brain and spinal cord) or your peripheral nervous system (nerves outside of your brain and spinal cord).1

Central nervous system autoimmune demyelinating diseases include:

• Multiple sclerosis (MS): This is the most common demyelinating disease. In MS, the immune system attacks the myelin sheath or the cells that produce and maintain it. The attack causes swelling and injury to the myelin. This can result in areas of scarring. A study in 2019 estimated that there were nearly 1 million people in the United States living with MS.12
• Neuromyelitis optica spectrum disorder (NMOSD): This involves inflammation and demyelination of the central nervous system, especially affecting the optic nerve and spinal cord.2
• Transverse myelitis (TM): This causes inflammation of the spinal cord.1
• Acute disseminated encephalomyelitis (ADEM): Children are more likely to get this brief but widespread bout of inflammation that damages myelin in the brain and spinal cord. Sometimes it affects the optic nerve. You get ADEM when your body attacks its own tissues in response to an infection with a virus or bacteria.14
• Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD): An inflammatory disease of the central nervous system that affects the optic nerve and spinal cord.2
• Optic neuritis: Inflammation of the optic nerve in one or both eyes.2

Peripheral nervous system autoimmune demyelinating diseases include:

• Chronic inflammatory demyelinating polyneuropathy (CIDP): This is a rare type of autoimmune disorder where the body attacks the myelin sheaths around nerve cells in the peripheral nervous system. CIDP slowly develops over at least eight weeks. People in their 50s and 60s seem more likely to develop it than people in other age groups. Men are twice as likely as women to get the disease.56
• Guillain-Barré syndrome (GBS): Healthcare providers consider CIDP to be the long-term form of GBS. GBS is a rare autoimmune condition in which your immune system attacks your peripheral nerves. The most severe stage of GBS is usually around two to three weeks after symptoms start, but most people then start improving.16

Associated anatomy

• Brain
• Spinal cord
• Optic nerves
• Peripheral nerves
• Myelin sheath
• Central nervous system
• Peripheral nervous system

Symptoms

Signs and symptoms of autoimmune demyelinating diseases vary based on the specific type and which parts of your nervous system are affected. You might experience symptoms that affect only one part of your body or many at the same time. Symptoms can fluctuate in severity, meaning they can get worse before improving for a period of time.1

Common symptoms affecting the central nervous system include:

• 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 or extreme tiredness
• Bladder or bowel problems, including difficulty when trying to urinate or a feeling of urgency
• Electrical tingling or shocks down your back, arms, or legs when you bend your neck forward
• Difficulty walking
• Muscle weakness or stiffness1

Symptoms specific to CIDP (affecting peripheral nerves) include:

• Tingling in the arms and legs
• Gradual weakening of the arms and legs
• Loss of reflexes
• Loss of balance and ability to walk
• Loss of feeling in the arms and legs, which often starts with not being able to feel a pinprick5

Symptoms of ADEM usually come on quickly and include:

• Fever
• Low energy
• Headache
• Nausea and vomiting
• Confusion
• Irritation
• Eyesight problems
• Trouble with coordination4

Causes and risk factors

The destruction of myelin and myelin-forming cells causes autoimmune demyelinating diseases. Damage to your myelin happens when your immune system mistakenly attacks healthy myelin. Your immune system protects your body from things that can make you sick, like bacteria and viruses. Sometimes, your immune system doesn't get the correct instructions and confuses your myelin cells for cells of something that can harm your body. When this happens, it causes inflammation (swelling and irritation), which leads to symptoms of demyelinating diseases.1

An autoimmune demyelinating disease can happen due to multiple factors, which can include:

• A viral or bacterial infection
• Genetic predisposition (changes in your DNA) that make someone more likely to develop an autoimmune disorder
• Other medical conditions1

Unlike Guillain-Barré syndrome, there usually isn't an infection that comes before CIDP. There doesn't seem to be a genetic link to CIDP. However, CIDP can occur in anyone, though people in their 50s and 60s seem more likely to develop it. Men are twice as likely as women to get CIDP.5

For ADEM, the condition develops when your body attacks its own tissues in response to an infection with a virus or bacteria. It's rare, but it can also be a reaction to a vaccine. Sometimes the cause is unknown.4

Diagnosis

Diagnosing autoimmune demyelinating diseases requires a comprehensive approach. Because some of these conditions are rare, it can be hard to correctly diagnose the disease at first.5

A healthcare provider will first review your medical history and discuss any symptoms you're experiencing. Most often, you'll be referred to a neurologist (a doctor who specializes in nervous system disorders), who will perform a neurological exam (a physical examination that tests how your nervous system is working).5

Diagnostic tests may include:

• Blood tests: To identify specific antibodies (proteins your immune system makes) or rule out other conditions5
• Magnetic resonance imaging (MRI): To detect inflammation, lesions (damaged areas), and demyelination in the brain or spinal cord5
• Nerve conduction study and electromyogram (EMG): To look for myelin damage in peripheral nerves. This involves using mild electrical currents to test nerve and muscle function and response5
• Lumbar puncture (spinal tap): To see if levels of certain proteins related to the disease are higher than normal. A small needle is inserted into the back and a small amount of the fluid that surrounds the spinal cord is withdrawn5
• Nerve biopsy: To look at microscopic changes in nerve tissue5

For CIDP specifically, if symptoms last longer than 8 weeks, a provider may suspect CIDP rather than Guillain-Barré syndrome.5

Treatment

There's no cure for autoimmune demyelinating diseases, so early treatment is important. Your doctor will work with you to develop a treatment plan that addresses your specific condition and symptoms. Treatment focuses on managing the disease and its symptoms.4

Treatment goals include:

• Lessening the effects of attacks
• Controlling the disease course
• Managing your symptoms4

Common treatment approaches include:

• Medications to fight inflammation: Drugs that reduce inflammation can stop damage to myelin. These are particularly important in treating acute episodes.4
• Disease-modifying therapies: For conditions like multiple sclerosis, there are over 20 drugs available that can change the course of the disease and lower the number of relapses.4
• Symptom management: Medications can ease pain, fatigue, and stiff muscles. Physical therapy can help with muscles that don't work the way they used to.4
• Immunosuppression: Treatments that reduce immune system activity may be used to prevent further attacks on myelin.7

For CIDP specifically, treatment is particularly important because appropriate treatments can improve the outcome. CIDP is treatable, but it can come back, which may require ongoing treatment.6

Related diseases

Several conditions are related to or can be confused with autoimmune demyelinating diseases:

Multiple sclerosis, Neuromyelitis optica spectrum disorder, Transverse myelitis, Acute disseminated encephalomyelitis, Myelin oligodendrocyte glycoprotein antibody-associated disease, Optic neuritis, Chronic inflammatory demyelinating polyneuropathy, Guillain-Barré syndrome, Progressive multifocal leukoencephalopathy, and Charcot-Marie-Tooth disease.