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Myelin and the Central Nervous System (cont.)


What is myelin?

Myelin is a fatty material that coats, protects, and insulates nerves, enabling them to quickly conduct impulses between the brain and different parts of the body. Myelin also contains proteins that can be targeted by the immune system. Myelin coats the nerves of both the central nervous system and the peripheral nervous system; the destruction of the myelin in the central nervous system is what triggers many of the symptoms of multiple sclerosis (MS).

Nerve cells are coated with sections of myelin, and the tiny spaces between the sections are called nodes. As the brain sends messages through the nerves of the spinal cord, the impulses jump from node to node. Myelin prevents these impulses from escaping from the nerve at the wrong point.

T cells from the body's own immune system attack and destroy the myelin sheath
T cells from the body's own immune system attack and destroy the myelin sheath Click to view larger image.

In multiple sclerosis, T cells from the body's own immune system attack and destroy the myelin sheath, leaving the nerve cell fibers unprotected.

How is myelin destroyed?

In multiple sclerosis (MS), the body's immune system T cells attack the myelin sheath that protects the nerve fibers. The T cells either partially or completely strip the myelin off the fibers, leaving the nerves unprotected and uninsulated. The nerves are not as able to pass messages from the brain to the other body parts. The messages the nerves try to send are delayed or distorted and the messages the brain receives may be misinterpreted.

Myelin is lost in multiple areas, leaving scar tissue that due to its hardened characteristics is called sclerosis. These damaged areas where the myelin has been destroyed and further disrupt the ability for the nerves to pass messages are also called plaques. These plaques can be identified by magnetic resonance imaging (MRI), a technique that helps doctors assess and monitor the progression of multiple sclerosis.

What happens when myelin is destroyed?

Patient Comments

When myelin is destroyed, the transmission of nerve impulses is impaired. Messages do not get through quickly and clearly from the brain to the correct body part. The more myelin is destroyed, the slower and less efficient the nerve impulses are. Depending on the severity of the immune system attack, the nerve fibers themselves may be damaged or destroyed. (See Multimedia file 1). Damage to nerve fibers may play an important role in determining how severe disability in multiple sclerosis may become.

When the brain nerves do not communicate well with nerves from other areas of the central nervous system (brainstem or spinal cord) or cannot relay information to nerves that exit these structures (peripheral nervous system), the symptoms of multiple sclerosis can occur.

For More Information

The Myelin Project

Myelin Repair Foundation

Medically reviewed by Joseph Carcione, DO; American Board of Psychiatry and Neurology


1. Adams R, Victor M, Ropper A. Multiple Sclerosis and Allied Demyelinative Diseases. In: Principles of Neurology. 6th ed. NY: McGraw-Hill; 1997:902-927.
2. Dangond F. Multiple Sclerosis: A Prototypical Human Demyelinating Disease. In: Dangond F. Disorders of Myelin in the Central and Peripheral Nervous Systems. Butterworth-Heinemann: 2002:103-138.
3. Dangond F. Repair and Neuroprotective Strategies in MS. In: Olek MJ. Multiple Sclerosis. Etiology, Diagnosis, and New Treatment Strategies. Totowa, NJ: Humana Press; 2004:193-207.

Medically Reviewed by a Doctor on 4/22/2016
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Myelin and the Central Nervous System - Symptoms

How did you first experience symptoms of multiple sclerosis as myelin was destroyed?

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