What is multiple sclerosis (MS)?
Multiple sclerosis (MS) is thought to be an autoimmune disease, which means that your own immune system mistakenly attacks normal tissues in your body. In MS, these attacks are aimed at the myelin in the central nervous system.
The central nervous system, which includes the brain and spinal cord, is made up of nerves that act as the body's messenger system. Each nerve is covered by a fatty substance called myelin, which insulates the nerves and helps in the transmission of nerve impulses, or messages between the brain and other parts of the body.
MS gets its name from the buildup of scar tissue (sclerosis) located in more than one area (multiple) of the brain and/or spinal cord. Plaques form when the protective myelin sheath is destroyed, a process called demyelination. Without the myelin, signals transmitted throughout the central nervous system are disrupted or halted. The brain then becomes unable to send and receive messages.
Although the nerves can regain myelin, this process is not fast enough to outpace the deterioration that occurs. The types of symptoms, severity of symptoms, and the course of MS vary widely, partly due to the location of the scar tissue and the extent of demyelination.
What causes multiple sclerosis?
There is no known cause of MS. The disease is probably related to a number of factors, including heredity, environmental factors, and problems with the immune system.
A likelihood for developing the disease might be inherited. This is called hereditary predisposition. If you have a relative with MS, you have a 10 percent to 15 percent higher risk of developing MS.
Environmental factors, such as common viral infections, also seem to trigger MS in people who have a hereditary predisposition.
The ultimate consequence of MS is that immune cells enter the brain and spinal cord, attack the myelin, and eventually cause myelin loss and scarring. The entire process results in the failure of nerve impulses to be sent or received properly.
The nature of the genetic susceptibility, the precise environmental triggers of MS, and the cause of the autoimmune attack on the brain tissue require further research.
Who is affected by MS?
In the United States, about 1 in 1000 people has MS. Multiple sclerosis symptoms generally appear between the ages of 20 and 40. Women are more likely than men to have the disease. In fact, about two-thirds of people with MS are women.
How does MS progress?
The course of multiple sclerosis varies for each person. Because of this, people are told by their doctors that they "probably" or "possibly" have MS. Your diagnosis is based on the combination of problems, patterns of recurrence, which systems are impaired, and your lab results. There is no way to predict how each person's condition will progress.
Four basic types of MS have been defined:
- Relapsing-remitting — This is characterized by acute attacks, called exacerbations, followed by full recovery or some neurological symptoms after recovery. The disease does not worsen in the periods between relapses.
- Primary progressive — This is characterized by a gradual but steady progression of disability, without any obvious relapses and remissions.
- Secondary progressive — This initially begins with a relapsing-remitting course, but later evolves into progression at a variable rate.
- Progressive relapsing — This is characterized by a steady progression in disability with acute attacks that might or might not be followed by some recovery.
What does my future hold?
One of the greatest challenges of MS is the unpredictability and uncertainty of what is to come. A good plan for coping with your concerns about the future is to:
- Educate yourself about possible changes.
- Work with your doctor and other health care professionals to manage your symptoms.
- Communicate openly with your family and others.
- Keep your life satisfying and fulfilling.
Although there’s currently no cure for MS, the disease is rarely fatal. Up to two-thirds of people with MS are still able to walk unassisted 25 years after diagnosis.
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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 4/15/2005
