Posterior Cervical Decompression and Fusion
Dr. Sekhon has performed over 500 posterior
cervical fusions. For an appointment call 775-657-8844
 See:
1. Poster on a series of
decompressions
2. Poster on a series of
sequential screws
3. Publication on 1026 screws
4.
Publication on 50
consecutive decompressions
Definition
A posterior approach to the
cervical spine is generally reserved for patients with
myelopathy. Myelopathy literally means
"sick spinal cord" and can be caused by
many things, some of which are not reversible.
Compression of the cord can cause myelopathy and is the commonest
reason for surgical intervention. The
approach is also gaining popularity for the management of trauma and tumor
conditions but it is really in the management of myelopathy secondary to
degenerative disease (so -called "wear and tear") that a posterior
decompression and fusion is most frequently utilized.
Cervical myelopathy does not
typically cause pain. Myelopathy can be asymptomatic or can cause
dysfunction in the upper or lower extremities. Typical symptoms include
the loss of hand control, a feeling of heaviness in the hands or legs,
stiffness in walking and unsteadiness in walking. In the degenerative
spine, it is typically caused by pressure on the spinal cord. This can
occur because wear and tear leads to bulging of the discs, facet joints
become larger and intrude into the space for the spinal cord, and also,
some people are borne with a narrow space for their spinal cord.
Anatomy
The spinal cord lives in a bony hole, the spinal
canal. A posterior cervical laminectomy involves an incision on the back
of the neck and bone is taken away over the spinal cord to its widest
diameter. After that, a fusion is performed across the facet joints at
these levels using local bone from the laminectomy, screws and plates or
rods.
This
is the extent of bone removal and decompression from a posterior
approach (yellow) allowing for excellent spinal cord decompression. Note
that this is greater than that achieved by an anterior approach (orange
arrows) where the position of the vertebral arteries limits lateral
exposure.
Reason For Operation
The main reason this form of surgery is performed is
to try and reduce the risk of deterioration in spinal cord function.
At
the extreme end, bad myelopathy patients are wheelchair bound. Coupled
with this, even patients with little in the way of symptoms are
more at
risk of spinal cord injury. This is because the space for the spinal
cord is reduced and an accident as trivial as a minor car accident can
transiently narrow this space via ligamentous buckling, injuring the
cord. Consequently, this surgery is primarily performed as a
prophylactic procedure to stop deterioration in the future.
The added fusion has several benefits:
-
it allows for a much wider decompression
-
it prevents
the spine falling into kyphosis, which is literally a reversal of the
normal curve of the spine, a situation which leaves the spine more prone
to injury.
Technique
The procedure is performed under
a general anesthetic and is performed on a special table called an
Jackson Operating Table which allows safe positioning of the patient as
well x-ray to be used throughout the procedure. Typically it takes 2-4
hours.
The head is held in a special
device the keep the neck still. This is shown below:
A cut is made in the back of the
neck and the thick muscles in the back of the neck are stripped away but
reattached again at the end of the operation. The most important part of
the case is now removal of the bone and ligaments
overlying the spinal cord. This is done very carefully with
drills and fine bone-biting instruments.
Once
the bone is removed along with the ligaments,
screws are placed through plates ( or else connected via titanium
rods). X-ray guidance allows for precise screw placement. The screws,
rods or plates (so-called "hardware") holds the bones still whilst the
fusion occurs. The bone removed in the laminectomy is crunched up and
placed in around the facet joints which have been roughened up and form
the bed of the future fusion.
This operation does not typically
require a blood transfusion. A typical fusion is shown below.
Risks
The most disastrous complication that can occur from
a posterior cervical decompression and fusion is injury to the spinal
cord or death. This risk is approximately 1%. Every spinal operation has
a risk of leakage of spinal fluid, infection, bleeding, hardware related
problems etc. etc. and these would sit at approximately 5%. There are
also general risks of clots in the legs or lungs, pneumonia, heart
attack etc which is again at about 5%. All in all 90-95% do well from
surgery with no complications, but no surgery can be done with zero
complications.
Unlike anterior cervical fusions, posterior fusions
have not been shown to be associated with as much
adjacent segment wear and tear. It may be jus that this technique
is new. Nevertheless the joints above and below the fusion are prone to
wear and tear and may require further surgery in the future. This is
uncommon.
Expectations
The aim of surgery is typically to stop progression of myelopathy and any gains
are a bonus. Typically:
The operation is best performed before the myelopathy has progressed too
far. The patient who starts in a wheelchair will probably stay there.
Most patients do note some improvement.
The main advantage of doing a posterior decompression with a fusion is
that a wide laminectomy can be performed and consequently the
compression is relieved via a single-stage procedure and a further
anterior approach is not required.
Recovery
A collar is placed and this is
worn for 6 weeks. I let my patients take the collar off for showers
and meals as
long as they hold their head still. There is marked
muscle spasm in the
first 1-2 weeks after surgery and so headaches and neck pain are common.
These are usually management by the use of muscle relaxants and
analgesia and in almost all cases, the neck pain resolves in a few
weeks. Typically 2-5 nights are required in hospital to allow the pain
to settle.
Typical x-rays are shown below:
At discharge, the collar is worn for a total of 6
weeks. At that time flexion/extension x-rays of the cervical spine are
taken and if these are satisfactory, the collar is discontinued over a
period of 1-2 weeks. Initially, the neck is very stiff at this point,
but with physiotherapy much of the movement returns. Because the
operation is a fusion, there will always be some restriction in
movement, when compared to an earlier date, but most patients do not
find this restriction interferes with day to day life (see below).
(Above):
This woman underwent a C3-7 fusion and decompression and is photographed
6 weeks after surgery, showing an excellent range of movement.
Repeat MR scanning
if performed on the
cervical spinal cord will show an adequate decompression of the spinal cord
(see below):
BEFORE SURGERY (note compression)
AFTER SURGERY (note there is
space around the cord)
I will typically follow my patients for 12 months with
repeat x-rays to ensure no hardware-related complications. After that
time, investigations are only performed if problems occur.
Non-Surgical Options
There are very few non-surgical
options in terms of the management of cervical myelopathy. The only real
option is to defer surgery if the patient feels the risks outweigh the
benefits. There is no guarantee that they will deteriorate if they
decide not to have surgery. Because the compression of the spinal cord
is structural lesion, no physiotherapy, diet or alternative therapy will
relieve the compression. Chiropracty is contraindicated as spinal
manipulation can lead to spinal cord injury.
Other
Points
Myelopathy is common and become more so as the
population ages. Cervical laminectomy with lateral mass fusion is the
most recent operation available to the spinal surgeon in the management
of multilevel spinal cord compression. Because the compression is from
the back as well as the front, artificial disc surgery may not be
adequate to deal with this pathology is some patients, and here a
laminectomy and fusion may indicated.
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