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).
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.