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Thoracoscopic,
laparoscopic, endoscopic, “through the scope”, minimally
invasive? These terms describe recently popularized approaches
to spine surgery. In order to understand how these approaches
may have a role in your spinal surgery, the terminology
must be understood.
Endoscope
An endoscope
is an instrument used for the examination of a hollow viscus
such as the bladder or a cavity such as the chest. The endoscope
is basically a camera mounted on a long thin lens with a
cable and a light source. The light source is mounted onto
the lens and provides light to illuminate the field to be
visualized. The cable mounted on the camera connects to
a TV screen, which displays the camera’s field of focus.
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Figure
1: Endoscope with Camera and Light Source
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Figure
2: Endoscope and TV Monitor
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Endoscopy,
Thoracoscopy, Laparoscopy
Endoscopy
is the visual inspection of any cavity or hollow viscus
by means of an endoscope. Thoracoscopy is the visualization
of the thoracic cavity or the chest. Thoracoscopy is used
to assist in procedures on the heart and lungs. Laparoscopy
is the visualization of the abdominal cavity. Laparoscopy
is used to assist in procedures on the intestines, stomach,
or removal of the gallbladder.
What
is the purpose of utilizing the endoscope? The endoscope allows the surgeon to have an
illuminated and magnified view of the operating field without
having to make a large incision. With the assistance of
the endoscope surgeons can utilize several small incisions
to perform the same procedure they would otherwise perform
using a single large incision.
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Figure
3: Postoperative Endoscopic Incisions
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Laparoscopic
and thoracoscopic surgery are not new techniques. Dr. Jacobaeus
was the first to publish his work in 1910 on both of these
topics. In the 1980’s laparoscopic cholescystectomy or removal
of the gallbladder became very wide spread. However, it
was not until the early 1990’s when the application of these
techniques became utilized in the field of spinal surgery.
Early uses were for biopsy, removal of thoracic disc herniations
and releasing or mobilizing the anterior spine for scoliosis
and kyphosis. The applications rapidly expanded to many
aspects of spinal surgery.
Instrument Availability
Unfortunately just the existence
of the endoscope does not automatically allow the spine
surgeon to perform surgery endoscopically. First, the surgeon
must first recognize if the surgery can be performed without
a formal incision. Currently only a small number of spinal
surgeries can be performed utilizing an endoscopic approach.
Once deciding to perform the surgery endoscopically, the
surgeon must determine if all of the instruments and implants
(screws, rods, and cages) are available to perform the surgery.
You may ask, if the surgery is now being performed with
a formal incision, are not all of the tools and implants
needed to perform the surgery already available?
The answer to this is unfortunately no. Instruments
used for endoscopic surgery differ from the instruments
used to perform surgery through a formal incision.
Endoscopic
Instruments
When a surgery is performed
with a large incision the dissection leads the surgeon directly
to the spine. The approach enables the surgeon to touch
the spine and manipulate the spine manually as is often
necessary. Instruments for performing open surgery are traditionally
made short allowing the surgeon better control and tactile
feel. The implants and the tools used to insert the implants
are often very large and bulky, because the incision size
allows a large access.
Figures
4 & 5: Endoscopic Instrumentation
In developing the endoscopic
approach for spinal surgery, the first task was to develop
longer streamlined instruments. New and different instruments
needed to be developed to perform tasks that were normally
done with the surgeon’s hands on the spine, but now must
be performed at a significant distance from the spine. As
these instruments were developed basic procedures could
now be performed endoscopically. As the technique progressed
the desire to instrument the spine became the next step.
We needed to develop implants that could fit through small
incisions and the instruments to insert and manipulate the
implants that would fit through the same portals.
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Figure
6: Endoscopic Instrument for Compression of Scoliosis
Instrumentation
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Endoscopic Portals
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Figure
7: Thoracoscopic Portal
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Portals are
devices that provide a passage through which the surgeon
operates. The incisions
for endoscopic surgery are usually a centimeter in length.
Once the skin incision is made an instrument is used to
continue the dissection into the cavity, usually the chest
or abdomen, depending the incision location and the patient’s
body this can be a fairly long distance. When the instrument
is removed all the tissue falls back into place and the
opening into the cavity can be very difficult to find. In
order to avoid damaging the tissue by moving instruments
in and out of the passage, a portal is placed into the incision
to hold the tissue apart.
There are
two main designs of portals, open or sealed. The open portal
is an open tube that allows for the passage of air from
outside of the body to inside the cavity and acts only as
a spacer. The sealed portal limits the passage of air or
gas into or out of the cavity. This type of portal is often
used in the abdominal cavity, this allows for the cavity
to be expanded allowing the surgeon space to operate. The
portals used in the thoracic spine tend to be 11 to 12mm,
while portals used in the abdominal cavity tend to be larger.
All of the instruments and implants had to be made to not
only fit through these small passages, but also perform
their function once inside the cavity.
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Figure
8: Thoracoscopic Portal View in the Chest Cavity
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Operating
Space
In the thoracic
spine the space to operate through is provided by deflating
the lung. The anesthesiologist performs this by placing
a special breathing tube down the trachea into the large
airway of each lung. Once in place the patient is asleep
and breathing with only one lung, which is very safe and
commonly done. This allows the opposite lung to deflate
and falls out of the way of the spine. The portals are placed
and the procedure to be performed on the spine is begun.
While in the thoracic cavity the lung is collapsed for space,
in the abdomen the cavity is filled with CO2 gas creating
the operating space.
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Figure
9: Thoracic Cavity View with the Lung Deflated
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Figure
10: Abdominal Laparoscopic View of L5-S1 Disc Space
and the Middle Sacral Vein
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The goal of
endoscopic surgery must be the same as surgery performed
with a formal open procedure. The incision and tissue dissection
to the spine may be less, but the surgical procedure cannot
be less. Advantages of endoscopic surgery include:
improved postoperative recovery, decreased pain,
and faster return to activities. These findings have been
demonstrated in many, but not all endoscopic procedures.
Even today only a small percentage of spinal conditions
are suitable for endoscopic surgery. Do not hesitate to
discuss with your spine surgeon if your particular condition
is amenable to an endoscopic approach.
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Figure
11: Thoracoscopic View of Endoscopic Scoliosis Correction
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