Multiple sclerosis (MS) is a degenerative disease that affects the nervous system. Symptoms like an inability to move muscles correctly and even complete paralysis arise because of the degeneration of a substance called myelin that coats much of the nerves of the body. In healthy people, the myelin acts as an insulator around nerves, helping the electrical impulses pass through the nerves move efficiently. When the myelin breaks down, these impulses slow down or stop altogether, and the areas of the body that the nerves normally send signals to do not receive the appropriate messages, resulting in the symptoms of MS.
In a healthy person, the brain receives signals from the rest of the body from sensations, and it also sends signals to other parts of the body to stimulate movement. The peripheral nervous system (PNS) is the arrangement of nerves around the body, and the central nervous system (CNS) is the collection of nerves inside the brain and the spinal cord. Myelin is a white and fatty substance that covers the nerves of the CNS.
Brain and spinal cord cells collect sensations and instruct the rest of the body to move muscles. Each nerve transmits a signal through a system of electrical impulses and chemical signals. Myelin protects the outside of the nerve cell, and keeps the electrical impulses inside the cells so they do not dissipate their energy outside the cells, but rather keep all the electricity in the right place and direction. The link between myelin and multiple sclerosis occurs in MS patients because the myelin of the CNS that helps the nerves pass signals efficiently is damaged.
When the myelin is damaged, or broken down altogether, the nerve cell underneath cannot hold its electrical signals properly. The signals slow down dramatically, or may even be lost altogether. Nerve cells that are supposed to pass on sensation messages to the brain may then produce abnormal sensations that feel like pinpricks or numbness.
Nerve cells that normally send signals to muscles and produce an almost instantaneous movement may only be able to stimulate weak movement or none at all. This can show itself in symptoms like paralysis, double vision or muscular weakness. Doctors do not yet know, as of 2011, what causes the damage to myelin and multiple sclerosis development, although particular genetics and triggers like viruses are suspected. One explanation for the damage to myelin is that the condition is an autoimmune disease, which means that the body's own immune system is attacking the myelin for an unknown reason.
Despite the lack of information about the cause of problems with myelin and multiple sclerosis, some medications can have positive effects on the symptoms of the disease, although MS is not yet curable. These medicines include steroids, interferons and antibodies. Artificial myelin protein is another option. Physical activity can also potentially improve the rate of degeneration of myelin and multiple sclerosis.