CHAPTER 5
LUMBAR SPIAL STEOSIS
What is it?
This condition is characterised by a narrowing of the spinal canal that carries
the nerve roots. This leads to compression and ultimately dysfunction of these
nerve roots. The process usually starts off in the disc with a decrease in the
height of the disc as well as the weight-carrying ability of the disc. The col-
lapse of the disc leads to compression of the nerve roots. The compressive
elements are a combination of a thickening of the normal ligament of the
spine, the ligamentum flavum, and the enlargement of the facet joints (see the
chapter Anatomy of the Spine). The facet joints enlarge in response to their
greater weight-carrying responsibility as the disc becomes damaged. There is
usually a degree of slippage of the vertebrae on top of one another and the
spine can be bent from side to side (scoliosis) or have an abnormal angle of
bending forwards (kyphosis) or backwards (lordosis). This is part of the nor-
mal ageing process and is called acquired spinal stenosis. Another term is
spondylosis or spinal osteoarthritis.
Another type is that of an inborn abnormality, which predisposes people to
this condition. People who are born with congenital spinal stenosis have a
very small spinal canal. This is because the pedicles (see the chapter Anatomy
of the Spine) are shorter than normal and do not allow for sufficient space in
the spinal canal. Spinal stenosis leads to a syndrome of nerve compression
that is usually a slow and progressive disease.
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