What are the symptoms of MS ?
Symptoms of
MS include loss of coordination, tremor, numbness, weakness,
loss of vision and double vision. A single attack or
exacerbation may include symptoms that have occurred
previously or entirely new symptoms. Severe fatigue is a
common problem in MS. Since there are many different causes
of fatigue, however, this one symptom alone is not adequate
to diagnose MS.
In people
under 40, MS most often occurs as attacks or exacerbations
of symptoms that appear and worsen over a few hours or days.
These acute attacks are usually followed by periods of
improvement or stability, referred to as remissions. Not all
people with MS have acute attacks, however. In people age 40
or older, the disease tends to progress slowly, with few or
no acute exacerbations or remissions.
How does MS affect the nervous system?
MS is
characterized as an autoimmune disease. In an autoimmune
disease, cells of the body's immune system that normally
attack foreign bacteria or viruses misidentify certain body
tissues as foreign and proceed to attack and destroy them.
MS is one of a
group of diseases called demyelinating diseases. In MS the
immune cells attack and destroy the myelin surrounding
certain nerve fibers. Myelin, a fatty sheath composed of
many layers, is wrapped around the larger nerve fibers in
the brain and spinal cord. The presence of myelin enables
these fibers to conduct nerve impulses faster and more
efficiently than fibers without myelin. Damage to the myelin
results in partial or complete failure of the nerve fiber's
ability to conduct impulses.
Depending
upon which fibers of the brain or spinal cord are affected,
a variety of symptoms such as numbness, weakness, loss of
vision or incoordination may result. The term "multiple"
comes from the tendency of the disease to involve many
different parts of the brain and spinal cord. The term
"sclerosis"
means hardening, referring to the hardening of tissue or
scar formation in areas where the myelin has been damaged.
What causes MS?
The cause of
MS is unknown. The major theories are:
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1
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It is
a viral infection. |
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2
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It is
an autoimmune disease. |
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3
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It is
an autoimmune disease brought on by a viral
infection. |
Although a
number of viruses have been isolated from people with MS,
none has ever been proven to cause the disease. Despite a
great deal of research, both in the laboratory and with
animals that develop diseases similar to MS, the cause of MS
remains uncertain.
What is the risk of developing MS? Primary risk factors are:
Hereditary factors: Although MS is not
hereditary, there are hereditary risk factors. If one of
your parents, a brother or sister has MS, your risk of
developing the disease is about ten times greater than
average for your community. In the Pacific Northwest, the
risk of developing MS for first-order relatives (parent,
child, brother or sister) of a person with MS is one or two
chances out of 100, whereas in the general population the
risk of developing MS is about one chance out of 1,000.
Geographic distribution:
MS is much more common in temperate climates, both north and
south of the equator, than in the tropics. This holds true
in North America, Europe, Australia and New Zealand. It is
not known why this is so. It is clear, however, that both
genetic factors and environmental factors are important in
assessing a person's risk of developing MS.
A reported epidemic:
At least one epidemic of MS has been identified. It occurred
in the Faroe Islands in the North Sea, beginning around
1943, with the last case in the primary epidemic occurring
around 1959. The epidemic was attributed to something
brought in by British troops who occupied the islands during
World War II. Whether this was a virus, some other
infectious agent or an environmental element is not known.
Sex ratio:
MS, along with other autoimmune diseases such as lupus, is
more common in women than men. About two-thirds of people
diagnosed with MS are women. The reason for this is
uncertain.
Do all people with MS become disabled?
Development of disability in MS is highly variable. Most
individuals with MS continue to work for many years with the
disease. While memory and mental abilities may be affected
by the disease, these effects are usually not severe. Many
people with MS are able to continue as effective employees
despite some physical handicap.
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