Multiple sclerosis (MS) is a neurological disorder that is typically characterized by symptoms that grow progressively more severe with time. Some patients may experience only one or a few attacks of symptoms. Others will have life-changing symptoms as they cope with increasing debilitation and paralysis.

The National Multiple Sclerosis Society estimates that 400,000 Americans and 2.5 million people worldwide have the disease.

MS is believed to be an autoimmune disorder, in which the body’s immune system attacks the myelin that surrounds nerves in the brain and spinal cord. Normally the myelin helps conduct signals along the length of the neurons (nerve cells). In patients with MS, the myelin degrades and is replaced with scar tissue, a process termed sclerosis. The loss of myelin causes the nerve signals to move more slowly or become distorted or blocked.

Scientists do not completely understand why the immune system begins to attack the body’s nerves. There is some evidence of a genetic link that may make some people more susceptible to an unknown environmental trigger. Many researchers believe the trigger is a virus or bacteria, but other factors are also suspected.

There are four types of MS that are generally recognized. They differ in how the symptoms progress. Relapsing-remitting MS patients experience attacks of symptoms that may last weeks or months before a period of remission. After several years, it may develop into secondary-progressive MS with constant symptoms that become more severe and lack significant periods of remission. Primary-progressive MS is similar to secondary-progressive MS, but is not preceded by a period of relapse and remission. Patients with progressive-relapsing MS experience symptoms that continually get worse, as well as periodic attacks of more severe symptoms.

A physician may suspect that a patient has MS based on the patient’s symptoms and the results of a neurological examination. To confirm the diagnosis, a combination of tests are required. These are likely to include imaging tests (e.g., MRI), an analysis of cerebrospinal fluid (spinal tap) and an evoked potential study.

There is a great deal of ongoing research concerning MS. Much of it is focused on trying to discover the causes of the disease. It is hoped that finding the cause will lead to ways to prevent and cure the disabling disease.