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.