What is Multiple Sclerosis?

Multiple sclerosis (or MS) is a chronic, often disabling disease that attacks the central nervous system (CNS), which is made up of the brain, spinal cord, and optic nerves. Symptoms may be mild, such as numbness in the limbs, or severe, such as paralysis or loss of vision. The progress, severity, and specific symptoms of MS are unpredictable and vary from one person to another.

MS is Thought to be an Autoimmune Disease

The body’s own defense system attacks myelin, the fatty substance that surrounds and protects the nerve fibers in the central nervous system. The nerve fibers themselves can also be damaged. The damaged myelin forms scar tissue (sclerosis), which gives the disease its name. When any part of the myelin sheath or nerve fiber is damaged or destroyed, nerve impulses traveling to and from the brain and spinal cord are distorted or interrupted, producing the variety of symptoms that can occur.

Most people with MS learn to cope with the disease and continue to lead satisfying, productive lives.

The Four Courses of MS

People with MS can typically experience one of four disease courses, each of which might be mild, moderate, or severe.

Relapsing-Remitting MS
People with this type of MS experience clearly defined attacks of worsening neurologic function. These attacks—which are called relapses, flare-ups, or exacerbations —are followed by partial or complete recovery periods (remissions), during which no disease progression occurs. Approximately 85% of people are initially diagnosed with relapsing-remitting MS.
Primary-Progressive MS
This disease course is characterized by slowly worsening neurologic function from the beginning—with no distinct relapses or remissions. The rate of progression may vary over time, with occasional plateaus and temporary minor improvements. Approximately 10% of people are diagnosed with primary-progressive MS.
Secondary-Progressive MS
Following an initial period of relapsing-remitting MS, many people develop a secondary-progressive disease course in which the disease worsens more steadily, with or without occasional flare-ups, minor recoveries (remissions), or plateaus. Before the disease-modifying medications became available, approximately 50% of people with relapsing-remitting MS developed this form of the disease within 10 years. Long-term data are not yet available to determine if treatment significantly delays this transition.
Progressive-Relapsing MS
In this relatively rare course of MS (5%), people experience steadily worsening disease from the beginning, but with clear attacks of worsening neurologic function along the way. They may or may not experience some recovery following these relapses, but the disease continues to progress without remissions.
Since no two people have exactly the same experience of MS, the disease course may look very different from one person to another. And, it may not always be clear to the physician—at least right away—which course a person is experiencing.


Some Important Facts

MS is a chronic, unpredictable neurological disease that affects the central nervous system.
Different people are likely to experience very different symptoms.
MS is different from muscular dystrophy (MD), which is a group of disorders that cause progressive and irreversible wasting away of muscle tissue. Although MD has some symptoms in common with MS—such as weakness and problems with walking—MD affects the muscles directly while MS affects the central nervous system.
MS is not contagious and is not directly inherited
Most people with MS have a normal or near-normal life expectancy.
The majority of people with MS do not become severely disabled.
There are now FDA-approved medications that have been shown to reduce the number of relapses and "modify" or slow down the underlying course of MS.
People who are diagnosed with a clinically isolated syndrome (CIS) have had one episode of neurologic damage that is similar to the damage that occurs in MS, but they have not yet met the criteria for a definite diagnosis of MS.

For more information please visit the National MS Society http://www.nationalmssociety.org