Cervical Disc Herniation
Introduction to cervical disc herniation
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The seven cervical (neck) vertebrae support the
head, allowing rotation and movement and providing pathways
for the spinal cord and the cervical nerves. Besides the vertebral
foramen (the spinal canal through which the spinal cord passes),
the cervical vertebra have smaller foramina (canals) through
which a large artery and the cervical nerves pass. |
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| Photo of an extended neck |
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X-ray of implanted artificial cervical disc in
an extended neck. |
The cervical nerves are responsible for controlling the neck, arms
and upper body. The portion of the cervical nerve as it exits the
spinal column is called the nerve root. The functions of the cervical
vertebrae– spinal cord and artery pathways, support, and movement
– make them especially significant for spinal health.
What is a cervical disc herniation?
 The
discs between the cervical vertebrae are much smaller than the
other discs in the back. They can become weakened, causing some
of the disc material to protrude. This generally occurs at the
lower level of the neck, at the fifth or sixth vertebra (C-5
or C-6 or C-7). In a cervical disc herniation, the herniated
disc generally pushes outward rather than inward on the spinal
nerve. This outward protrusion places pressure on the cervical
nerve roots, resulting in dysfunction and pain in the neck,
arms, and upper body.
What causes cervical disc herniation?
Accidents, especially those with an abrupt change in speed, are
one cause of cervical disc herniation. The weight of the head, when
whipped rapidly or violently, exerts tremendous force on the neck
muscles and structures. This force can weaken the wall (annulus
fibrosus) of the disc, causing the disc material to bulge outward.
Disc degeneration related to repetitive minor trauma can also lead
to disc herniation.
Because the discs between the cervical vertebrae are much smaller
and generally bear a lesser load than discs in the lumbar region,
herniations occur less often than in other areas of the spine. Posture
or position problems, when chronic, may also weaken the muscles
and structures of the spinal column.
Can cervical disc herniation be prevented?
The best way to prevent cervical disc herniation is to prevent
accidents and reduce the severity of injuries. Seat belts and air
bags in cars are designed especially for this purpose. Ergonomic
working positions and appropriate exercise and rest all help to
prevent injuries and achieve good neck health.
What treatment options are there for cervical disc herniation?
Surgical treatment
If conservative treatment fails to relieve the pain after 2 or
3 months, surgery may be necessary to relieve the pressure on the
cervical nerves. After using an MRI or CT scan to determine the
exact presence of the herniation, the herniated disc may be surgically
removed either from the front (anterior) or the back (posterior)
of the neck. Surgery may also be urgently recommended for progressive
weakness, numbness or severe neck and arm pain.
Most cervical herniated discs are removed from the front as this
procedure allows the surgeon to more easily place bone graft in
the disc space. This results in a wider opening for the nerve root.
The posterior route may be more appropriate if the disc is large
and soft and protrudes to the side of the canal. In either case,
most patients are able to return home after one night in the hospital.
The use of advanced microscopic imaging, computers, software and
tracking technology allow the surgeon to clearly visualize structures,
make decisions based upon precise measurements and information,
and maneuver in exacting detail.
Types of Surgery
Microscopic posterior cervical
foraminotomy
The foramen, the small canal within or between the vertebra, provides
the passageway for a nerve. If the disc has ruptured or the body
of a vertebra has collapsed, the foramen is distorted or made smaller,
pressing on the nerve. Using advanced microscopic imaging, computers,
software and tracking technology the surgeon is able to clearly
see and maneuver at the same time within a very limited area, reducing
injury to surrounding tissues. Tiny portions of the bone surrounding
the foramen are removed, leaving a larger canal for the nerve to
occupy without pressure. The new technologies help the surgeon avoid
injury to the nerve during the procedure.
Anterior cervical discectomy
and fusion
Removal of a cervical herniated disc (cervical discectomy) is necessary
when the disc has ruptured and lost its ability to retain its form,
thereby placing pressure on the nerves. From an incision on the
front of the neck, the disc is carefully and precisely removed and
the two bordering vertebrae are joined to create stability. Very
small sections of bone may be used from another part of the body
to bridge the gap left from the removed herniated disc (fusion).
Cervical Laminaplasty
The lamina is a flat portion of bone that is the back portion of
the vertebra. When the spinal canal has become too small due to
injury or disease, it may be made larger by use of laminaplasty.
An incision is made down the back of the neck to expose the cervical
vertebrae. On one side of the vertebral column, the lamina are cut
through just far enough to create a hinge-like movement, much like
a door. Then the lamina on the other side are cut all the way through
to, in effect, open the door. The back portion of the vertebrae,
the spinous processes (bumps you feel on the back) are removed to
make more room for the "door" to open. After gently opening
the "door" of each vertebra to create more room for the
spinal cord and nerve roots behind it, bone wedges are inserted
to keep the "door" from totally closing. Then the "door"
is closed securely onto the wedges, resulting in an expanded "doorway"
for the nerves.
By increasing the space for the spinal cord and nerve roots, laminaplasty
reduces the cause of pain and may help prevent progression of spinal
deformity. It preserves the stability of the neck, but may result
in loss of the ability to extend the neck backwards and may reduce
other cervical motion. A relapse of pain may occur if excessive
bone growth occurs as the bone heals.
Cervical instrumentation
Advanced imaging equipment also provides the surgeon with the ability
to precisely determine what the final position of the vertebrae,
and subsequently the nerve canals, should be. Thorough and accurate
measurements of positions of the vertebral structures assure the
surgeon that both bone and manufactured implants precisely align
the spine and the nerve canals. The correct sizing of the implant,
using interactive templating, is critical in obtaining an ideal
outcome. This precision is possible using microscopic imaging, computers,
software and tracking technology.
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John
J. Regan, M.D.