HOW DOES SPINAL STENOSIS CAUSE PROBLEMS?
When the cord or nerves are compressed they are
unable to work; this causes weakness of the muscles, and loss
of feeling and “pins and needles” in the parts of
the arms or legs that they supply. This is often felt as a lame
or dead feeling.
Pain may be caused by the nerves being squeezed, but also by the
degeneration of the spine, and it may be necessary to treat both
problems to relieve all the symptoms.
Often the patient is only affected when standing or walking, and
he feels relief if he bends forward, sits or lies down.
Rarely, the nerves supplying the bladder and bowels can be affected
and lead to poor control, with incontinence of urine or faeces.
IS SPINAL STENOSIS DANGEROUS?
It is rare for spinal stenosis to cause paralysis.
If this does happen, it usually follows a neck injury (such as
a fall), where the spinal cord in the narrowed part of the spinal
canal is squashed and damaged, perhaps permanently.
HOW DO I KNOW IF I HAVE SPINAL
STENOSIS?
Often the diagnosis is made from the patient’s
symptoms when he describes them to the doctor. In some cases there
are signs of abnormal nerve function when the patient is examined.
Normal X-rays do not show nerves or discs, only the bony part
of the spine, so they are not enough for a definite diagnosis.
The diagnosis is confirmed by an MRI scan, or a CT scan after
a myelogram (injection of dye into the spinal canal by a lumbar
puncture), which shows the narrowing of the canal, and the compression
of the nerves.
IF I HAVE SPINAL STENOSIS
DOES THAT MEAN AN OPERATION?
Not at all. Most patients stay the same, or get
slowly worse, with only about 10% worsening rapidly. Many patients
can live with their symptoms, once they know what causes them,
with help from physiotherapy, weight loss, anti-inflammatory drugs
and pain medicines. Often a corset helps for low back problems,
or a neck brace for the neck. Pain blocks with cortisone may also
help.
Surgery may be needed if the pain is severe and
does not improve with treatment, or if there is severe nerve compression,
shown by difficulty with bladder control, walking even short distances
or doing other basic tasks.
Surgery is often performed earlier if -the stenosis
is in the neck, as the cord is more easily damaged than in the
lower back, -if the vertebrae have slipped out of position, as
this may get worse and increase the nerve compression, or -if
the patient is diabetic, as the nerves once damaged do not recover
as well as in normal patients.
WHAT DOES THE OPERATION INVOLVE?
During the operation, bone and ligaments are removed
to open up the spinal canal and foramen to make space for the
nerves. This operation is called a decompression. This is usually
done from behind in the lower back, and is called a laminectomy.
A laminectomy may also be done in the neck if more than two levels
need to be decompressed, but if only one or two levels are narrowed,
decompression is usually done through the front of the neck. A
decompression may need an additional operation to fix the decompressed
vertebrae together in some patients; this operation is called
a fusion. Bone is packed between the vertebrae, so that they grow
together permanently to form a single piece of bone. Often metal
plates or rods are fixed to the spine with screws to hold everything
in place until the bone has healed. It is not usually necessary
to remove this fixation. A fusion is usually needed if the vertebrae
have already slipped, or are expected to slip after the operation,
or if the spine is deformed or so badly worn or arthritic that
it is expected to continue to cause pain even though the nerves
have been decompressed. A neck decompression almost always needs
a fusion.
