TERMINOLOGY (SYNONYMS)
- Central
spinal stenosis
- Lateral
spinal stenosis
- Narrowing
of the spinal canal
- Congenital
spinal stenosis
- Acquired
spinal stenosis
INTRODUCTION
Spinal
stenosis is a narrowing of spaces in the spine (backbone) that results in
pressure on the spinal cord and/or nerve roots. The term stenosis refers to
narrowing of an opening. The term
spinal stenosis refers to narrowing of the central spinal canal or of the
lateral openings along the side of the spine where the nerve roots exits. This
disorder usually involves the narrowing of one or more of three areas of the
spine: (1) the canal in the center of the column of bones (vertebral or spinal
column) through which the spinal cord and nerve roots run, (2) the canals at
the base or roots of nerves branching out from the spinal cord, or (3) the
openings between vertebrae (bones of the spine) through which, nerves leave the
spine and go to other parts of the body. The narrowing may involve a small or
large area of the spine. Pressure on the lower part of the spinal cord or on
nerve roots branching out from that area may give rise to pain or numbness in
the legs. Pressure on the upper part of the spinal cord (that is, the neck
area) may produce similar symptoms in the shoulders, or even the legs.
The primary three types of stenosis
are 1) neuroforaminal stenosis, 2) central stenosis
and 3) far lateral stenosis. The central spinal canal can become too
narrow, reducing the blood flow to the nerves supplying both legs or on one
side only. Some people are more prone to develop spinal stenosis and are at
greater risk for nerve compression and developing chronic back problems because
they are born with a spinal canal which is smaller than normal. An individual
is at greater risk if they have a developmentally small spinal canal and they
acquire degenerative changes and/or disc pathology. Spinal stenosis may be
acquired or developmental (congenital).
Spinal
stenosis can occur in any part of the spine, but tends to be more prevalent in
the low back or lumbar region due to the presence of more advanced degenerative
changes. The pain associated with
lumbar (low back) stenosis is often experienced in the low back but may extend
to the buttock, thigh and calf regions.
X-ray studies may reveal changes suggesting the possibility of
underlying stenosis, although advanced imaging in the form of CT or MRI must be
performed to confirm the presence and degree of spinal stenosis involving the
central spinal canal. MRI is
better at representing the effects of stenosis on the spinal core and spinal
nerves than convention CT scanning. The most common causes of spinal stenosis
are disc herniation, bone spurs (osteophytes), bony enlargement (bone
hypertrophy) and a developmentally narrow canal.
Spinal stenosis is not always
associated with symptoms. It can exist in the absence of pain or neurological
compromise. Narrowing of the central spinal canal (stenosis) in the neck or
midback regions can lead to compromise of the spinal cord. Narrowing of the central spinal canal
in the low back can lead to progressive compromise of the spinal nerves. The
symptoms of lumbar central spinal stenosis often involve radiating pain
extending into one or both legs. In more severe cases of nerve compromise the
pain will be accompanied by varying degrees of numbness and muscle weakness.
Severe lumbar stenosis can be associated with difficulty voiding the bladder.
The symptoms associated with lumbar stenosis are often worse with prolonged
standing or walking. Sitting and leaning forward at the low back increase the
dimensions of the central spinal canal and subsequently often provide some
relief of low back and lower extremity complaints.
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