To Benefit MS Families and the National MS Society, Connecticut Chapter

What is Multiple Sclerosis?


MS is a Disease of the Immune System

MS is a disease that involves an immune system attack against the central nervous system (brain, spinal cord, and optic nerves). The disease is thought to be triggered in a genetically susceptible individual by a combination of one or more environmental factors. Although MS is thought by some scientists to be an autoimmine disease, others disagree strongly because the specific target of the immune attack in MS has not yet been identified. For this reason, MS is referred to as animmune-mediated disease.


As part of the immune attack on the central nervous system, myelin (the fatty substance that surrounds and protects the nerve fibers in the central nervous system) is damaged, as well as the nerve fibers themselves. 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.