Spinal Stenosis
Introduction
The spine is composed of 33 vertebrae, uniquely aligned to support
the body and provide a passageway for the spinal cord and nerves.
The vertebrae and connecting intervertebral (between the vertebrae)
discs are stacked upon each other in such a way as to provide a
clear, open channel for the spinal cord. As part of the central
nervous system, the spinal cord connects the nerves of the body
to the brain.
What is spinal stenosis?
Stenosis refers to a narrowing of an opening that is normally larger.
In spinal stenosis, the normally clear, open channel in the spine
has become narrow, resulting in too small of a pathway for the spinal
cord.
What causes spinal stenosis?
Genetic or congenital problems can influence the development of
spinal stenosis. More frequently, self-destructive activities contribute
to stenosis, such as poor posture and body mechanics, obesity, physical
abuse, smoking and inadequate diet. In addition, other spinal diseases
such as osteo- and rheumatoid arthritis, scoliosis, osteoporosis
and lordosis (sway back) can result in spinal stenosis.
Can spinal stenosis be prevented?
Addressing the causes is the key to prevention. Although genetics
and congenital problems usually are not controllable, preventing
spinal disease is, even for those with a genetic tendency towards
stenosis. Lifelong practices of good spinal and joint health can
help reduce the chance for spinal stenosis.
What treatment options exist for spinal stensois?
Foraminotomy
The foramen is the natural passage or tunnel between the vertebrae
of the spine through which a nerve root exits from the spinal canal
on its path to a specific tissue or organ. When this foramen becomes
narrowed, the nerve can become irritated or dysfunctional.
Removing bone and soft tissues to enlarge the passage for the nerve
is called a foraminotomy. A foraminotomy is commonly performed as
part of a decompression of the spinal canal itself. In some cases
a foraminotomy may be performed from outside the canal and not involve
any direct decompression of the central canal if the pressure is
strictly on the nerve root. To perform this operation, specialized
instruments are used to remove portions of bone from the laminae,
facets and facet capsules.
Surgical decompression
This refers to any surgical technique which aims to free the space
for the nerves in the spinal canal or foramena. A spinal decompression
for stenosis can be performed in the cervical spine (neck), the
thoracic spine, and in the lumbar spine. A decompression involves
removing tissue which is constricting or compressing nerve structures.
In some cases the spine becomes unstable and a spinal fusion is
performed at the time of surgery.
A number of different surgical methods are commonly used to achieve
a decompression, including: laminectomy, laminotomy, laminoplasty,
foramenotomy, anterior discectomy. The ideal technique to use will
depend largely upon the level of the spine that must be decompressed,
the elements which are causing the compression (bone, disc, ligaments
or other), the stability of the spine, and the surgeon's experience.
Laminectomy
In the laminectomy procedure, the spine is approached through a
two-inch to five-inch incision in the midline of the back, and the
left and right back muscles are detached from the lamina on both
sides. The lamina is removed (laminectomy), which allows the doctor
to see the nerve roots. The facet joints, which are directly over
the nerve roots, may then be trimmed to give the nerve roots more
room.
Laminoplasty
When the spinal canal becomes narrowed and the spinal cord and
nerves are compressed, surgery may become necessary. One type of
surgical procedure is called a laminoplasty, which refers to opening
up the space of the spinal canal by splitting the laminae. The laminae,
which, in simple terms are like a set of double doors over the spinal
canal, are "swung open". First the spinous process (the
"bump" you feel at the back of the spine) is removed.
Then the central portion of the laminae is split and each lamina
(right and left) is hinged open. The hinged laminae are kept open
through bone struts, sutures, or other techniques. A laminoplasty
can lead to marked enlargement of the space available for nerves
and the spinal cord.
Laminotomy
When the spinal canal becomes narrowed or the nerves compressed,
a laminotomy can be performed to free up the space of the spinal
canal by removing a portion of the lamina. The procedure involves
making an incision into the layer of muscles and ligaments that
sits on either side of the spine, and freeing up the attachments
to the spinous process and lamina to expose the laminae to full
view. Using a special instrument that removes little bites of bone,
the lamina is gradually trimmed until sufficient bone is removed
to free the compressed nerve This "unroofs" a portion
of the spinal canal and resulting in enlargement of the space available
for the nerves.
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John
J. Regan, M.D.