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AGING.TXT
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1992-12-04
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AGING AND HORMONAL CHANGES
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All living things grow old. The spine is not immune to the
process and in fact ages more rapidly than other parts of the
body.
One of the trademarks of the aging process is the gradual
dessication or drying out of body tissues. It seems odd that a
man or woman will live comfortably to an age of 80 yet begin to
show signs of spinal aging in the early twenties. However, at
that early age it can be demonstrated that the intervertebral
discs are starting to lose their flexibility and moisture
content. Aging has begun.
This may be due to our genetic makeup as well as the relentless
force of gravity constantly pressing on the unstable upright
spinal column.
The discs, as we learned from an earlier chapter, comprise about
25% of the length of the spinal column. As aging takes place
they gradually become compressed, lose moisture and shrink.
Joint motion, flexibility and all-important shock absorbing
qualities gradually diminish. Chronic spinal strain thus begins.
These mechanical stresses are transferred to the vertebrae,
supporting muscles and ligaments. The ligaments holding the
structure together may be pulled or lifted from the vertebral
surfaces which in turn attempt to minimize the instability by
creating bony spurs or growth projections to fill the missing
spaces. This can eventually lead to osteoarthritis as the spine
shrinks in overall length. A classic and for the most part
inescapable fact of aging.
However if the supporting muscles and structures of the spine
are kept in good shape with judicious exercise habits, the pain
and loss of flexibility is minimized to a certain extent. In the
back and spine, as no other site of the body, the truism "use it
or lose it" has clear and absolute meaning.
Osteoporosis or osteopoenia can be a side effect of aging.
Gradually the bones can become brittle and spongy, thus losing
critical bone tissue mass. Normal bone tissue is not a static,
dead tissue. It may seem dead and brittle, but it is definitely
not dead. A constant turnover of bone calcium and other tissue
takes place at all times within bones. One perspective is that
every bone in your body is replaced, molecule for molecule,
every 6.5 years.
Bones also react to stress and fractures - healing and bonding
together to reproduce the original load bearing characteristics
and also enlarging slightly along the axis of stress. Put a bone
under pressure and, within limits, it will attempt to grow
stronger and deposit additional calcium to counteract the
stress. Astronauts in the gravity free environment gradually
lose calcium. In a sense gravity is both friend and foe: it
provides the stress which keeps bones strong yet it eventually
collapses and compresses our upright spinal column. A biological
paradox at best.
Bone has two primary anatomic structures: 1) matrix, the protein
"sponge" into which calcium is deposited and hardened. 2) An
intercellular tissue which fills the hollow pores of the matrix
with solid calcium salts - a sort of glue which binds the tissue
and calcium together.
The matrix onto which calcium is deposited is produced by
osteoblast cells. Meanwhile another variety of cell, the
osteoclast, reabsorbs bone which has aged and must be removed.
Thus two opposing forces are at work governed by different
cells: one deposits bone mass, the other removes it. Usually the
chemical and cellular forces are in balance. However when the
osteoclasts gain the upper hand, more bone is removed than is
replaced. This is the mysterious mechanism which is the basis of
the disease osteoporosis.
However we need to go a little further to learn about the
specific dynamics of this process and how it affects the spine.
The outer portion of bone is hard and is called the cortical
layer. The inner core is softer and spongy and is known as the
cancellous layer. The inner cancellous layer is the region where
dynamic chemical and cellular activity takes place. Calcium
salts are moved around, primary blood cells are generated and a
host of other process occur within this bone core area.
And this is the central clue why the vertebrae of the spine seem
to be uniquely prone to osteoporosis, certain infections and
some tumors. It is because a LARGER region of the vertebrae is
CANCELLOUS (soft tissue - dynamic cell reactions) than cortical
(relatively stable - slow chemical turnover). Because of this
important difference, the bones of the spine are much more
easily disturbed by chemical, hormonal or metabolic imbalances
in other parts of the body.
In this respect, the structure of the vertebrae of the spine are
dramatically different from bones in the other parts of the
body. Why do these vertebral bones have this unique structure?
Some anthropologists speculate that our own evolution is to
blame. Our rapid adoption of an upright posture REQUIRED the
bones of the spine to become more cancellous and dynamic in
cellular activity to allow for an unstable and inherently risky
upright spinal posture. Nature and evolution simply did the best
it could given the short time frame needed to adopt an upright
posture!
A particular hormonal imbalance, usually associated with the
menopause of women, has been linked statistically to
osteoporosis. Apparently the shifting tides of hormones produced
at menopause can lead to gradual thinning and spongy weakening
of the vertebral bones whose uniquely dynamic and chemically
sensitive cancellous core is susceptible to the hormone
triggered event we call osteoporosis.
X rays conclusively reveal the weakening of the vertebral bodies
in osteoporosis. The attempted treatment, although by no means
conclusively successful, is hormone replacement therapy.
Frequently this means administration of both male (testosterone)
and female (estrogen) hormones. Calcium tablets and vitamin D
may also be prescribed. The benefit of this method of therapy is
open to debate among members of the medical community, although
it is usually attempted as the the best available treatment for
now. Hip fractures in elderly patients have also been reduced by
providing vitamin D and calcium within an enriched dietary plan.
In the case of senile osteoporosis, a variation not related to
menopause, different hormones are usually administered along
with calcium and vitamin D tablets. The results are also not
clearly demonstrated, but are nonetheless frequently attempted.
Once vertebral collapse occurs, back braces or surgery may be
required. Bed rest is not always the treatment to use in this
situation because once bed rest or disuse sets in, the spongy
vertebrae begin to deteriorate rapidly. Lack of use tends to
accelerate the process of bone loss in most conditions involving
osteoporosis. Bones need a certain amount of use and exposure to
gravity to keep calcium deposits in place. Bed rest can
accelerate calcium loss.
One malady related to osteoporosis is the gradual expansion of
the intervertebral discs into the upper and lower plates - the
roof and floor - of the bony vertebrae themselves. However, if
the vertebrae have already lost most of their elasticity, this
likelihood is diminished. Unlike a disc rupture which takes
place either into the spinal canal or outwards towards the
lateral side of the spinal column, disc expansion can take place
directly into the weakened mass of the vertebral body itself in
cases of osteoporosis.
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INFECTIONS
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Infections and tumors of the spine are rare indeed, but worth
mentioning in any discussion of maladies which affect the spine.
The advent of modern antibiotics has erradicated many spinal
infections, but nonetheless prudent physicians consider and test
for the presence of spinal infections when other causes cannot
be assigned.
Tuberculosis is usually associated with a severe infection of
the lungs but has been reported in medical literature to also
infect the vertebrae of the spinal column. The bacteria which
causes tuberculosis is easily carried in the blood stream and
can take up residence in the spongy core of the vertebrae. Since
the bacteria cause slow growing abscesses and eventual formation
of scar tissue, patients may eventually report loss of motor or
other nerve function as the spine is compressed or pinched by
the encroaching scar tissue and gradually collapsing vertebral
bone mass.
In severe cases of tuberculosis of the spine, partial or
complete paralysis of the lower body has been reported if spinal
nerves are severely affected. A low grade fever, common with
most bacterial infections, is an early manifestation. Profuse
sweating at night, back pain, vomiting and a limit in the range
of motion of the back may follow. A chest X ray may show no
evidence of lung involvement. A biopsy with a hypodermic syringe
is the conclusive laboratory test for presence of infection.
This procedure removes a small quantity of fluid from a
suspected spinal abscess which is sent to a medical laboratory
for positive identification of the tuberculosis bacillus.
Surgery and spinal fusion is the corrective method of choice in
advanced stages of the disease. The bacteria which infects the
spine selectively attacks the bone mass of the vertebrae and
seldom involves the flexible discs since they do not contain
oxygen and blood which the bacteria requires for growth.
A serious outbreak of antibiotic-resistant tuberculosis began to
surface in early 1992 and was reportedly seen in New York and
regions of Florida. Although initial reports suggest it is
primarily linked to tuberculosis of the lungs, spinal
involvement may evolve as the bacteria spreads into the general
population. New antibiotic compounds are currently under
investigation to treat this unusually virulent form of
tuberculosis which could eventually cause a new pandemic and
reversion to earlier methods of treatment such as sanitorium
care and strict isolation.
Meningitis refers to an infection of the spinal cord. A variety
of bacteria and virus organisms have been implicated as causing
this serious disease. Symptoms include, but are not limited to,
stiffness of the neck and spine and painful spasms. The
meningoccocus bacteria, a common cause of meningitis, may also
cause fever. However, viral organisms causing meningitis may not
always produce fever. The early stages of meningitis may begin
as simple back pain. A common diagnostic test is for the
physician to test muscle reflexes in the lower extremities. If
specific lower body reflex sites are hyperactive (overly
reactive to touch), meningitis is a strong suspect.
Polio, or more properly poliomyelitis, involves similar viral
infection of the spinal cord. However, common anti-polio
vaccines have almost erradicated this disease in the United
States, but it does continue to surface in parts of Africa and
remote regions of the World.
Spondylitis is a bacterial infection of the spine usually
involving the common staphylococcus bacteria which may be
carried to the site of the spine by the bloodstream. The
vertebral bones are usually infected and the bacteria may spread
from one vertebrae to the next. Back pain, fever and loss of
appetite may be present in spondylitis victims. X rays of the
vertebrae in early stages of the disease may show little
evidence of infection, but as the bacteria grow, X rays and
biopsy (drawing infected fluid from the vertebra with a
hypodermic needle) provide conclusive identification of this
bacteria. Antibiotics are usually able to halt the spread of the
infection. Surgery may be required if the vertebrae have been
severely damaged or contain large abscesses.
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TUMORS
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Discussing tumors immediately brings to mind a sinister word:
cancer.
However it is important to note that cancer applies to malignant
or spreading tumors which invade and destroy healthy tissue and
bone. Benign tumors generally do not spread throughout the body,
can be removed by surgery and may present little actual tissue
damage.
Thankfully, tumors both benign and malignant of the spine are
relatively rare.
Malignant tumors are generally divided into two classes: Primary
and secondary. Primary tumors originate in a specific tissue or
bone. Secondary tumors, also known as metastatic tumors, have
spread to a specific tissue from another primary site of origin.
The most common sites where primary malignant tumors begin are
the prostate gland, breast, lung, kidney and thyroid. These are
the classic sites where the majority of cancers originate.
Primary malignant tumors may eventually involve bone, especially
the large bones of the spinal column and lumbar vertebrae
because of their spongy, blood rich cancellous core which was
discussed earlier.
Diagnostic methods to determine the primary or original site of
the cancer are frequently undertaken by a physician and may
involve tests such as X rays of the lung, thyroid studies with
radioactive materials, pyelograms of the kidney, mamograms of
the breast, ultrasound studies of the prostate and biopsy of the
spine. Treatment may involve a combination of radiation,
chemotherapy and hormones which is directed at the primary or
original site of cancer growth. Treatment of the secondary site
may involve a similar or modified treatment with radiation and
chemotherapy as well.
Malignant tumors can involve areas other than the bones of the
spine. Liposarcomas and fibrosarcomas are malignant tumors of
fatty tissues and muscles of the back respectively. Schwannoma
is a malignant cancerous invasion of the spinal cord.
Malignant tumors of the spine are usually secondary - they have
spread to that location from another part of the body. In fact
the first sign of cancer in another part of the body, the
prostate or kidneys for example, is the presence of back pain
which results from the invasion of the cancer to the bones of
the spine or soft tissue of the back from its primary site. Some
physicians note that if back pain increases when the patient
lies down, a tumor may be a probable culprit - although this
simple clinical observation must be corroborated with additional
tests.
Other than the secondary tumors we have discussed, a few primary
tumors of the spine have also been detailed in medical
literature. Several rare types have been reported: 1) Osteogenic
sarcoma, a rare and extremely deadly form of cancer which grows
rapidly. 2) Multiple myeloma which reflects an abnormal rapid
growth of bone marrow cells. 3) Chordoma which is usually slower
growing and may confine itself to localized areas of the spine.
Chordomas can be surgically removed with moderate success, but
can recur with time although their growth and reappearance is
slow. Sarcomas are usually fast growing and more resistant to
surgery, radiation and chemotherapy - and thus among the
deadliest of tumors.
This tutorial is merely a starting point! For further
information on back care and back pain, be sure to register this
software ($25.00) which brings by prompt postal delivery a
printed, illustrated guide to back pain written by a physician
plus two software disks. From the main menu select "Print
Registration Form." Or from the DOS prompt type the command
ORDER. Mail to Seattle Scientific Photography (Dept. BRN), PO
Box 1506, Mercer Island, WA 98040. If you cannot print the order
form, send $25.00 to the above address and a short letter
requesting these materials. End of chapter.