The disc
is made up of connective tissue, which wears normally
as we age. However, many of the problems that cause neck
pain are from abnormal wear and tear. This process is
called degeneration of the intervertebral
disc. Degeneration often results from small injuries that
may not cause pain at the time the injuries actually occur.
Over time, these injuries add up and the abnormal wear
and tear can weaken the connective tissue that makes up
the disc. Once the connective tissue is weak, sudden stress,
such as a whiplash type movement, may injure the disc
more easily. The entire process of disc degeneration is
sometimes referred to as spondylolysis. You may hear your
doctor refer to your neck problem as spondylolysis of
the cervical spine.
To really understand neck pain, you need an understanding
of the wear and tear process, called disc degeneration.
This will also help you later understand what can happen
to the neck when a sudden injury can cause immediate pain
and dysfunction. The next section will explain both the
process of degeneration and the most common causes of
pain in the neck. Degenerative
Disc Disease
To help you
understand disc degeneration, compare a spinal segment
to two vanilla wafers (the "vertebrae") and
a marshmallow (the "disc"). Imagine a fresh
marshmallow between the two wafers. When you press the
wafers close together, the marshmallow gives or "squishes
out". Suppose you leave the marshmallow out for
a week and it starts to dry out. When you press it between
the wafers, it is not quite as spongy. If you press
hard enough, the outside of the marshmallow may even
tear or split. Suppose you left the marshmallow out
for a month. It would probably be so dried out it would
be hard and very thin and would not have any "shock
absorbing" ability.
As we age, the disc
loses some of its water content and, as a result, some
of its shock absorbing ability. Like the marshmallow,
the first changes that occur in the disc are tears in
the outer ring of the disc, called the annulus. Tears
in the annulus may occur without symptoms. Therefore,
you may not notice when they occur or what caused them.
These tears heal by forming scar tissue. Scar tissue
is weaker than normal tissue. Repeated injuries and
tears cause more wear and tear to the disc. As the disc
wears, it loses more of its water content. It becomes
less and less "spongy", eventually no longer
able to act as a shock absorber.
As the disc continues
to wear, it begins to collapse. The space between each
vertebra becomes smaller. The collapse also affects
the way that the facet joints in the back of the spine
"line up". Like any other joint in the body,
the change in the way the bones fit together causes
abnormal pressure on the articular cartilage. Articular
cartilage is the smooth shiny material that covers the
end of the bones in any joint. Over time, this abnormal
pressure causes wear and tear arthritis (osteoarthritis)
of the facet joints.
Bone spurs may form
around the disc and facet joints. It is thought that
too much motion in a spinal segment causes the bone
spurs to form. Eventually, bone spurs can form around
the nerves of the spine, causing a condition called
spinal stenosis.
Spinal
Conditions
Degeneration
of the disc and spinal segment can result in several
different spinal conditions that cause problems. These
include: mechanical neck pain, cervical radiculopathy,
and spinal stenosis. Sometimes we may injure our neck
with a relatively minor injury. These minor injuries
may cause neck pain for a few days and then go away.
This is commonly referred to as a neck, or muscle strain.
Actually, we may never fully understand what has been
injured in one of these episodes.
Muscle
Strain Of Neck
A "muscle
strain" of the neck is a common diagnosis given
when a patient presents a stiff neck. In some cases,
this may represent a true "muscle strain",
or "pulled muscle" involving the muscles around
the spine of the neck. However, muscle spasm is a common
symptom that can result when other areas of the neck
are injured. Problems that are commonly referred to
as a muscle strain may also involve injury of other
soft tissues of the neck including: the disc, the ligaments
around the spinal segment, and the muscles. Injury to
any, or all, of these structures may cause similar symptoms.
Mechanical Neck Pain
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