Thoracic Disc Herniation
Introduction 
The spine is composed of 33 vertebrae, uniquely aligned to support
the body and provide a passageway for the spinal cord and nerves.
At the top of the spine are seven cervical (neck) vertebrae, followed
by 12 thoracic vertebrae from which the 12 pairs of ribs originate.
Next are 5 lumbar vertebrae, followed by the 5 fused sacral bones
(the back of the pelvis) and 4 fused bones of the coccyx (tailbone).
What is thoracic disc herniation?
 The
cervical, thoracic and lumbar vertebrae are separated from each
other by intervertebral discs which cushion and separate the
vertebra, providing space for the nerves roots to exit the spinal
canal. Discs are composed of cartilage that lies between the
bony vertebral bodies of the spine. The disc and vertebral bodies
are considered joints since there is motion. The discs are composed
of an outer wall of tough fibrous tissue called the annulus
fibrosus, and a softer, inner substance called the nucleus pulposus.
The nucleus pulposa contains water, which like a water filled
balloon, gives cushioning to the disc. If a disc degenerates
(a herniated disc), it flattens and puts pressure on the spinal
cord. Because the space between the vertebrae is shorter, the
bones may put pressure on the nerves also.
What causes thoracic disc herniation?
The natural curvature of the spine provides the skeleton strength
and stability. The curves act like a coiled spring to distribute
the mechanical stress as the body moves. As discs age, they lose
their water content and begin to degenerate. The annulus fibrosis
(outer ring), may also be damaged through general wear and tear
or by injury in which the nucleus, under extreme pressure, bulges
out through the annulus fibrosis ring.
Can thoracic disc herniation be prevented?
Like other discs in the spine, the thoracic discs are vulnerable
to injury when the person practices poor posture. Sensible exercises,
designed to strengthen the upper back, help to improve posture and
prevent injury. Maintaining a healthy lifestyle with good nutrition
is key, as well as preventing accidents. The spine, designed for
flexibility, will perform best if cared for properly.
What treatment options are there for thoracic disc herniation?
VATS – Video Assisted Thoracic
Surgery
The standard open surgical approaches to the thoracic spine usually
involve creating a large opening in the chest wall. Video Assisted
Thoracic Surgery (VATS), is a minimally invasive (keyhole) surgical
procedure. It allows the surgeon to directly examine the chest cavity
without a big incision. Three or four small incisions will be made
to allow the surgeon to use the special instruments (video camera
and endoscope) needed for this operation. A very small video camera
is used to project pictures of the chest cavity onto a screen during
the procedure.
VATS avoids the extensive damage to the chest wall. Specific tools
and implant systems permit the spine surgeon to remove thoracic
discs, biopsy vertebral masses/tumors, release scoliotic curves,
bone graft disc spaces and even to instrument the spine working
through these small (1-2 inch) puncture incisions.
Discectomy
A discectomy is a surgical procedure in which part or all of an
intervertebral disc is removed from the spine. This is commonly
done when a disc is herniated (slipped disc) and is causing symptoms
of pain and nerve irritation or injury. In the thoracic area, discectomies
are usually done through an incision on the side of the ribcage.
A small window is created in the bone overlying the disc herniation.
The nerve root is gently retracted to expose the disc herniation.
The disc material is then removed using special instruments which
snip it away.
Fusion
Fusion is a surgically created solid bone bridge between two or
more adjacent (usually freely mobile) bones. In the spine, this
procedure is used to create a stability between vertebrae. In order
to achieve a fusion, bone must grow across the desired area in a
gradual and solid fashion. A number of techniques can increase the
chance of this to occur. The basis principle is to place bone tissue
(bone graft) into the area of desired fusion, ensure sufficient
immobility across that area (brace, cast, spinal instrumentation)
and then wait for the fusion to take place (6-9 months or more).
Spinal Instrumentation
For spine operations to be successful, solid healing of bone across
the spine must be achieved. The use of metal devices, also called
instrumentation (screws, rods, plates, cables, wires) can help correct
a deformed spine and will also increase the probability of obtaining
a solid spinal fusion.
Spinal instrumentation can be placed in the front or in the back
portion of the spine. The devices are usually made of metal, commonly
stainless steel or titanium. In order to place this instrumentation
into the spine, the spine is at first exposed by making a skin incision,
and then gently clearing the muscles, ligaments and other soft tissues
from the levels of the vertebrae to be fused. Specific tools are
used to carefully prepare the bone in such a way to obtain good
seating of the implants (screw, rod, wire, cable or other). When
these devices are in the proper position, a rod or plate is positioned
to link the implants together. Screws are inserted into the pedicles,
which are part of the arch of the vertebra. This essentially forms
a rigid scaffolding to hold the spine in the desired position. The
bone graft which has been placed into the area of fusion gradually
solidifies over several months. The spinal instrumentation is gradually
covered by scar tissue and sometimes bone which the body lays down.
uters, software and tracking technology.
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John
J. Regan, M.D.