What is MS (Multiple Sclerosis)?

The term "multiple sclerosis" means "many scars." This is because multiple sclerosis is a chronic condition characterized by scars or lesions in the spinal cord and the brain.

• Over 400,000 people in the United State and as many as 2.5 million people worldwide have been diagnosed with multiple sclerosis.
• Multiple sclerosis affects almost twice as many women as men.
• MS hits most often in people between the ages of 20 and 50 years.

People with multiple sclerosis are diagnosed in the prime of their lives, which adds to the fear and anxiety often felt in the wake of a diagnosis.

Multiple sclerosis is a central nervous system disease, meaning it affects the brain, the spinal cord and the optic nerve. Multiple sclerosis symptoms occur because the connections between the brain and the body's nerves are damaged. The effects of MS are often compared to the way faulty electrical wiring can lead lights to flicker. In a similar way, multiple sclerosis causes problems in signaling throughout the nervous system, which lead to symptoms such as tingling, numbness, blurred vision, and walking problems.

• Multiple sclerosis is considered an autoimmune disease
• Triggered by infection or virus
• Genetics play a role
• Geography
• Types of MS
• Nerve Damage and Demyelination
• Multiple sclerosis symptoms are unpredictable

Multiple sclerosis is considered an autoimmune disease

The immune system is a complex network of cells that helps our bodies fight off infection. Crucial to the normal functioning of the immune system is the ability of immune system cells to recognize the difference between healthy cells that are part of the body and unhealthy invaders such as bacteria and viruses. In autoimmune diseases, the immune system loses this ability to distinguish between host and invader. Certain cells in the immune system start attacking healthy tissue as if it were an infection. This is what scientists believe happens in multiple sclerosis. Cells that normally fight infection start attacking the myelin around nerve fibers as if it were an invader. One of the indicators of multiple sclerosis is an abnormally high level of certain immune cells in the spinal fluid.

Though multiple sclerosis has been recognized as a disease since the mid 1800's, its cause still remains a mystery. Scientists are working with several theories about the cause of multiple sclerosis as their foundation for efforts toward a cure.

Response to infection or virus

Scientists suspect that multiple sclerosis may be indirectly linked to a virus or bacteria. Researchers are currently studying if genetically predisposed individuals have a hyperactive immune response to a virus or bacteria, and this immune response leads to MS. As of yet, no virus or bacteria has been identified, and there is no evidence that MS is contagious. However, the clear involvement of the immune system in multiple sclerosis indicates this path of research may be promising.

Genetics play a role

Multiple sclerosis is not directly inherited, but it is clear that genetic factors play a role in who gets the disease. Children and siblings of people with MS are at higher risk of getting the disease. Non-identical twins have the same risk as that of any other sibling, but the identical twin of a patient with MS has a much higher risk of getting the disease. Even though genetics are clearly involved, the fact that the identical twin of a person with MS does not always get the disease tells us that more than genetics is involved.

Geography

The place where you grew up also plays a role in determining who is more likely to get multiple sclerosis. Multiple sclerosis is more common in cooler areas of the globe. In the United States, Northern states have higher rates of MS than Southern states, and Canada has a rate of MS double that of the US. However, the geographical effect only seems to apply to the first fifteen years of life. If you grew up in Minnesota and then moved to Louisiana at 25 years old, your risk of MS would be the same as for anyone who never left Minnesota. Moving to a warmer climate after age 15 confers no protection.

Types of MS

While multiple sclerosis symptoms and course of illness can vary from person to person, there are three forms of the disease-relapsing-remitting MS, secondary progressive MS, and primary progressive MS.

• Relapsing-remitting MS: This type shows clearly defined flare-ups or relapses with some amount of recovery in between. It affects about 80% of all people with MS.
• Secondary progressive MS: While technically a form of progressive MS, this type acts more like a relapsing form of MS in its early-to-mid stage, with relapses and remissions being quite common. But then a more continuous loss of physical and cognitive functions starts to take over, and flare-ups or relapses become less common. Fifty percent of people with relapsing-remitting MS will develop secondary progressive MS within 10 years of their initial diagnosis.
• Primary progressive MS: In this type of multiple sclerosis, there are no flare-ups or relapses, but over a period of years, there is gradual loss of physical and cognitive functions. This form of MS affects about 10% of all people with MS.

Nerve Damage and Demyelination

You may have heard that multiple sclerosis involves something called demyelination. Demyelination is damage that occurs to the protective sheath, called myelin, which surrounds nerve fibers.

Nerve fibers, called axons, connect the muscles and sensory fibers to the brain and the spinal cord. Electrical impulses travel along these axons, bringing information back and forth across the brain, the spinal cord and the nerves. This communication over the axons enables movement, speech, thinking, vision and the other senses.

Surrounding these axons at regular intervals is a sheath made of fat and protein called myelin. Myelin protects the axons and also helps speed up the signals traveling along the spinal cord and in the brain. For example, when you decide to take a walk, myelin helps ensure that the signal from your brain that tells your leg to move gets there immediately and intact.

Multiple sclerosis occurs when this myelin is damaged, which slows down and interrupts the electrical impulses traveling to and from the brain and the spinal cord. When these electrical impulses can't get to their destination efficiently or can't get there at all, symptoms develop.

Multiple sclerosis can damage the myelin in many places throughout the central nervous system. This is why people with MS have symptoms in various places throughout their bodies.

Multiple sclerosis symptoms are unpredictable

Many people with multiple sclerosis wonder why their symptoms may suddenly appear, last a few weeks, and then clear up completely. The reason for this is that damaged myelin can often heal itself. However, with multiple sclerosis, though the myelin may heal enough to alleviate symptoms, scars and lesions are often left behind indicating where the damage was done. These scars can build up and themselves interfere with the electrical impulses traveling across the central nervous system. In addition, in places where the myelin does not heal, the axon itself can become damaged.

When working with your healthcare provider to choose the best multiple sclerosis treatment for you, consider AVONEX. AVONEX is the only once-weekly MS treatment that delays progression of disability and reduces the number of flare-ups.

1-22107-01