Spinal Stenosis

This is a critical narrowing of the space available in the channel for the spinal cord and nerve roots which run down the spine. This channel is called the spinal canal, and the narrowing which occurs is usually due to a combination of bulging of the intervertebral disc, encroaching on the canal from the front, and overgrowth of the facet joints narrowing the canal from the sides and the back of the canal. With these changes, ligaments within the canal thicken and bulge, particularly when standing upright, adding to the problem.

Sometimes an individual may constitutionally have a rather narrow canal to start off with, leaving them prone to stenosis even with fairly modest degenerative changes. But in most people the changes tend to be quite advanced. Since these degenerative changes tend to progress with age, spinal stenosis is more common in older age groups.

The commonest form of narrowing, central canal stenosis, affects the whole of the spinal canal, constricting all nerves at that level of the spine. This often causes a rather diffuse back ache which spreads into the buttocks. Standing or walking typically causes an aching heaviness and tiredness in the legs which, together with the back ache, steadily builds up to the point that the person may be unable to carry on walking and has to sit down. The distance they can walk is a useful indicator of the severity of the stenosis. Sitting down often brings on very rapid relief because this position bends the spine forwards, stretching out the ligaments which were buckling into the canal. After a few minutes of sitting, a person with spinal stenosis will generally be able to continue walking until their symptoms stop them again after a little while. Walking in a somewhat stooped posture, for example while pushing a shopping trolley, is often easier since this again stretches out the ligaments in the spinal canal. The patient with spinal stenosis often becomes stooped for this very reason. Aching and cramping in the legs at night is another common feature, often experienced by those who usually sleep flat on their back. A pillow under the knees may help but those affected commonly report that they have had to resort to sleeping curled up on their side.

Sometimes the narrowing will be confined to the outer edges of the spinal canal, called the lateral recess, or the opening between the vertebrae for the nerves called the neural foramina. If so, specific nerve roots tend to be affected, causing leg pain where the nerve goes to in the leg (sciatica) and sometimes other features such as altered sensation and pins and needles.

About Spinal Stenosis

back to top