What is Multiple Sclerosis (MS)? 
MS is a disease of the central nervous system. In it, myelin (a fatty tissue that surrounds and protects the nerve fibers of the central nervous system) is lost in multiple areas, leaving scar tissue called sclerosis. These damaged areas are also known as plaques or lesions. Sometimes the underlying nerve fiber (or axon) is also damaged or broken. When myelin or the nerve fiber is destroyed or damaged, the ability of the nerves to conduct electrical impulses to and from the brain is disrupted, and this produces the various symptoms of MS. MS is not contagious. No one can catch MS from another person.

What Causes MS?
While the exact cause of MS is un-known, most researchers believe that the damage to myelin results from an abnormal response by the body’s immune system. Normally, the immune system defends the body against foreign invaders such as viruses or bacteria. In autoimmune diseases, the body attacks its own tissue. MS is probably an autoimmune disease in which myelin is the major target of an immune attack.

How Is MS Detected?
The diagnosis of MS can be very difficult. Because there is no single test that can be used to confirm MS, the process of diagnosis typically involves:

• evidence from the person’s history
• a clinical examination,
• and one or more laboratory tests

A physician often requires all three in order to rule out other possible causes for symptoms and to gather facts consistent with a diagnosis of MS.

Symptoms
The range of symptoms experienced by people with MS varies dramatically from person to person. Symptoms are problems that are reported by the person him- or herself. MS symptoms can include reduced or abnormal sensations, weakness, vision changes, clumsiness, sudden loss of bladder control, and so on. Symptoms might appear in any combination and be mild or severe. They are usually experienced for unpredictable periods of time. But symptoms alone don’t indicate MS. Any one or combination of these symptoms might have causes unrelated to MS.

Signs
After taking a careful medical history, including all of a person’s symptoms, past and present, the physician will do a series of tests to check for signs that can explain the symptoms or point to disease activity of which a person may not be aware.

Common signs that can be detected by the doctor during a physical examination include:

• altered eye movements and abnormal responses of the pupils
• subtle changes in speech patterns
• altered reflex responses
• impaired coordination
• sensory disturbances
• evidence of spasticity and/or weakness in the arms or legs.

Tests
Magnetic Resonance Imaging. The preferred test, which detects plaques or scarring possibly caused by MS, is magnetic resonance imaging (MRI). The MRI scan is a diagnostic tool that currently offers the most sensitive non-invasive way of imaging the brain.