MS causes white blood cells to attack or injure myelin and other parts of the CNS (central nervous system). The resulting damage and scar tissue on your neurons can slow communication between your brain and body.

You know about the symptoms if you or a loved one has MS. They may include muscle weakness, trouble with coordination and balance, vision problems, thinking and memory issues, and sensations such as numbness, prickling, or “pins and needles.”

What you may not know is how this autoimmune disease affects the body. How does it interfere with the messaging system that helps your brain control your actions?

Nerve damage can occur anywhere in the spinal cord, the brain, or both. This is why MS symptoms may vary from person to person. Depending on the location and severity of the white blood cell attack, symptoms may include:

  • loss of balance
  • muscle spasms
  • weakness
  • tremors
  • bowel and bladder problems
  • eye problems
  • hearing loss
  • facial pain
  • brain issues such as memory loss
  • sexual issues
  • problems with speech and swallowing

MS attacks the brain and spinal cord tissues, known as the central nervous system (CNS). This system includes the complex network of nerve cells responsible for sending, receiving, and interpreting information from all parts of the body.

During daily life, the spinal cord sends information to the brain via these nerve cells. The brain then interprets the information and controls how you react to it. You can think of the brain as the central computer and the spinal cord as a cable between the brain and the rest of the body.

Nerve cells (neurons) carry messages from one part of the body to another through electrical and chemical impulses. Each has a cell body, dendrites, and an axon. The dendrites are thin, web-like structures that branch out from the cell body. They act like receptors, receiving signals from other nerve cells and transmitting them to the cell body.

The axon, also called a nerve fiber, is a tail-like projection that serves the opposite function of the dendrites: It sends electrical impulses out to other nerve cells.

A fatty material known as myelin covers the axon of the nerve cell. This covering protects and insulates the axon, much like the rubber shell that protects and insulates an electric cord.

Myelin is composed of lipids (fatty substances) and proteins. In addition to protecting the axon, it helps nerve signals travel quickly from one part of the body to another or the brain. MS attacks myelin, breaking it down and interrupting nerve signals.

Scientists believe that MS begins with inflammation. Infection-fighting white blood cells enter the CNS and attack the nerve cells.

Scientists speculate that a latent virus, when activated, may cause the inflammation. A genetic trigger or an immune system malfunction may also be to blame.

When inflammation spikes, MS is activated. Attacking white blood cells damage the myelin that protects the nerve fiber (axon). Imagine a damaged electrical cord with wires visible, and you’ll have a picture of how the nerve fibers appear without myelin. This process is called demyelination.

Just like a damaged electrical cord may short out or create intermittent surges of power, a damaged nerve fiber will be less efficient at transmitting nerve impulses. This can trigger the symptoms of MS.

If you get a cut on your arm, the body forms a scab over time as the cut heals. Nerve fibers also form scar tissue in areas of myelin damage. This tissue is stiff and hard and blocks or obstructs the flow of messages between nerves and muscles.

These areas of damage are typically called plaques or lesions and are a significant signal of the presence of MS. In fact, the words “multiple sclerosis” mean “multiple scars.”

During inflammation, attacking white blood cells can also kill glial cells. Glial cells surround nerve cells and provide support and insulation. They keep nerve cells healthy and produce new myelin when it’s damaged.

However, if glial cells are killed, they’re less able to keep up with repair. Some of the new research for an MS cure is focused on transporting new glial cells to the site of myelin damage to help encourage reconstruction.

An MS episode or period of inflammatory activity can last from a few days to several months. In relapsing/remitting types of MS, the person usually experiences remission with no symptoms. During this time, the nerves will try to repair themselves and may form new pathways to get around the damaged nerve cells. Remission can last from months to years.

However, progressive forms of MS do not show as much inflammation and may not show any remission of symptoms, or at best, will only plateau and then continue to cause damage.

There is no known cure for MS. However, therapies can slow the disease and help control symptoms.