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In-Depth Information
2.3 Spinal Stenosis
2.3.1 De
nition and Occurrence
Spinal stenosis is a condition of narrowing of the central spinal canal, causing
compression on the structures within the canal, mainly the spinal cord and spinal
nerve roots, with associated nerve dysfunction. The spinal cord extends from the
base of the brain and ends at the level of the first and second lumbar vertebrae
(L1
L2). Spinal nerves branch off the spinal cord and course alongside it before
exiting the spinal canal. Below the L1
-
L2 level, the spinal nerves form a bundle
called the cauda equina. Anatomically, when compression happens above the
L1
-
L2 level, both the spinal cord and the nerve roots can be affected, while below
the L1
-
L2 level, compression of the nerve roots alone is seen. Both direct
mechanical compression and secondary changes due to lack of blood supply con-
tribute to damage of the spinal cord and nerve roots. When the spinal cord is
affected, it is called myelopathy, and when the spinal nerve roots are involved, it is
termed radiculopathy.
Spondylosis is the most common cause of spinal stenosis in people older than 60
[
23
]. Osteophytes of the facet joints, disk bulging, and calci
-
cation and overgrowth
of the posterior longitudinal ligament and ligamentum
flavum can slowly encroach
the spinal canal, and eventually lead to compression of the spinal cord or nerve
roots. Spondylolisthesis, a condition in which the one vertebra slips relative its
neighboring vertebra, can be a cause of lumbar spinal stenosis, especially at the
L4
fl
L5 level.
Conditions other than degenerative changes can cause spinal stenosis, including
tumors and post-operative scar tissue. In
-
ammatory conditions, such as rheumatoid
arthritis, may lead to overgrowth of the synovium at the facet joints, with com-
pression of the spinal cord in severe cases. Some people are born with a narrow
spinal canal and are susceptible to spinal stenosis with even minor changes in spine
anatomy or mild degrees of degenerative disease. Spina bifida is another congenital
cause of spinal stenosis.
Spinal stenosis usually has an insidious onset. It can be an incidental
fl
finding on
radiologic study in asymptomatic individuals. It occurs in 20
30 % of people older
than 60 years of age [
24
]. In a study of 187 individuals, the prevalence of lumbar
spinal stenosis increased with age, affecting 2.1 % of people aged 40
-
49, 6.1 % of
-
people aged 50
59, and 16.3 % of people older than 60 years [
25
].
-
2.3.2 Clinical Manifestations
In patients with cervical spinal stenosis, neck pain or pain in the area below the
shoulder blades is frequently reported. When the narrowing and compression
damage the cord, neurological symptoms develop. Clumsiness and weakness are
common, and both the arms and legs may be affected. Many patients experience
