Multiple Sclerosis (MS) is a disease of the brain and spinal cord (central nervous system), usually diagnosed between the ages of 20 and 50. In MS, the covering of the nerves (myelin sheath) is destroyed (demyelination). The underlying nerve fiber may also be damaged or severed. Like insulation on electrical wires, myelin insures rapid transmission of nerve impulses. 

When myelin or nerve fibers are damaged, the messages from the brain, for example, to move a body part, and messages to the brain, for example, to interpret sensations, are not transmitted effectively. Body movement may be slow or uncoordinated and body sensations may be altered. 

While at first there may be healing and return to normal function (remission) later, a scar (called a plaque) may form which permanently interferes with motor and sensory control. Damage to the myelin sheath can occur at any time and affect any part of the brain or spinal cord. The disease is called multiple sclerosis because there are multiple areas of scarring (sclerosis). 

Each person with MS has a unique set of symptoms depending on where in the central nervous system the demyelination occurs. Common symptoms include weakness, numbness, incoordination, loss of balance, visual problems, loss of bladder or bowel control, mood swings, cognitive problems, difficulty speaking, and fatigue. MS is not fatal or contagious. However, a small number of people have a severe type of MS, which may shorten life expectancy. 

Diagnosis

The diagnosis of MS can be very difficult. There is no single laboratory test that proves someone does or does not have MS. Tests such as magnetic resonance imaging (MRI), evoked potentials, and analysis of cerebrospinal fluid may strongly suggest MS. A neurologist or other physician will make the diagnosis when there are definite signs of MS in multiple parts of the central nervous system. This usually means that there has been more than one episode of neurologic impairment and more than one symptom; for example, weakness in one arm and the other leg, weakness and numbness or weakness and bladder problems. Because some people have only a single episode, or mild symptoms that come and go, long periods of uncertainty before the diagnosis is made are not uncommon. 

What causes MS?

We don't yet know what causes MS. Destruction of myelin seems to be due to an abnormal response of the immune system in which cells that normally protect against illness react against the body's own tissues (an autoimmune response). A virus or other agent to which someone is exposed in childhood might trigger this abnormal immune response in later life.

The disease is not directly inherited. However, there appears to be some genetic susceptibility to MS, as evidenced by a slightly increased incidence of MS in close relatives. 

What happens to people with MS?

This depends on how often episodes of demyelination occur and how much of the brain and spinal cord is affected. The most common form of MS is relapsing-remitting MS, in which people have clearly defined flare-ups or relapses when their symptoms become dramatically worse. These are followed by recovery or remission, when symptoms go away completely or partially. Seventy to 75% percent of people with MS begin with relapsing-remitting MS. About 15% of people with MS have a progressive course from the start. Their symptoms generally do not remit and may become worse. This is called primary-progressive MS. Some 6%–10% have a progressive course with acute attacks. This is called progressive-relapsing MS and is quite rare. Finally, about half of all the people who begin with relapsing-remitting MS develop secondary-progressive MS within 10 years. They may continue to have attacks and partial recovery but their symptoms and disabilities slowly become worse.

However, all these forms of MS may stabilize or become worse at any time.

We believe that two out of three people with MS remain ambulatory over their lifetimes, but many of them need a cane or other assistive device for walking, and some of them will choose a scooter or wheelchair to conserve energy.

Are there any treatments for MS?

Yes. Traditionally, steroids and ACTH have been used to shorten acute exacerbations, also called relapses or flare-ups.

There are also many treatments and medications that can give some relief for specific symptoms such as muscle spasms, pain, or incontinence. Appropriate vigorous exercise has a proven positive effect in mild to moderate MS. Adequate rest and a nutritious diet are also very important. Today, there are new, federally approved medications that "modify" the course of MS. These drugs slow the rate of relapses, slow the onset of disability, and limit MS activity in the brain, as seen on MRI scans.