Spinal Stenosis (Lumbar Spine)

Spinal stenosis occurs when there is a narrowing of the canal around the spinal cord (central stenosis) or a narrowing in the course traveled by the nerve to its outlet (lateral recess stenosis). Sometimes the narrowing is enough to put pressure on the nerve tissue and produce symptoms (symptomatic lumbar stenosis). Symptomatic lumbar stenosis is most common in the middle aged and elderly population, and men are affected slightly more than women.

Cause

There are many factors that can contribute to the narrowing of the spinal canal. Some of these factors can be congenital and some are acquired.

Congenital factors relate to the inherited make up of an individual’s spine. For instance the size and shape of the spinal canal vary, or significant spinal curvatures (eg scoliosis) can impact on canal size. Some of these inherited features can leave an individual with a greater chance of suffering stenosis during their lifetime. It is uncommon for these changes to be the sole cause of stenosis.

Acquired conditions relate to the changes that occur in the spine during life and are the most common cause of stenosis. The changes are many and varied and in respect of stenosis relate specifically to those changes that result in narrowing the spinal canal. Some examples are narrowing and bulging of the intervertebral disc, the formation of bony spurs in the canal, or thickening of the joints that surround the spinal canal etc.

Effect of Narrowing

Simply put the narrowing can cause a build up of pressure within the canal. The build up of pressure gradually compresses the nerves, starts affecting nerve function, and results in symptoms.

The Symptoms

The symptoms can be varied. The pain will start in the low back and will normally cause symptoms to radiate into the leg, or legs, as the problem worsens. The symptoms will radiate to one leg when the stenosis is affecting only one side of the spinal canal (lateral recess stenosis), and both legs when the stenosis affects the central portion of the spinal canal (central canal stenosis).

The symptoms in the legs can be in the form of pain, tightness, altered sensation, or a combination of these. It is only in severe cases that nerve function will be compromised sufficiently to produce true weakness in the muscles supplied by the affected nerves. Also in severe cases of central canal stenosis the function of the bladder and bowel can be disrupted.

Activities and Positions That Influence Symptoms

When stenosis is present activities or positions causing further narrowing of the spinal canal become a problem. People with stenosis will find these activities or positions difficult to sustain for any length of time, as the symptoms will steadily intensify till intolerable. For example standing and walking are commonly limited and painful when stenosis is present. These increase extension in the lumbar spine, that is where the spine arches backwards, and results in narrowing of the spinal canal.

To relieve the symptoms the opposite is true. That is activities or positions that increase the space in the spinal canal will reduce the symptoms. Flexion of the spine, that is where the spine is bent forwards, has this affect. Commonly people will sit, stand leaning forward and supporting themselves on something, squat down, or stand with one foot on a step to achieve this and relieve symptoms.

Treatment

Where the symptoms are very debilitating surgical options have the greatest chance of success. It is necessary to increase the space in the spinal canal to decompress the nerves. For more specific information your GP, or the author of this handout can recommend a spinal surgeon to consult.

Non surgical treatment is limited and needs to focus on education about the problem and ways to best manage it. The principles of self-treatment are quite simple, and the aim is to control symptoms while keeping as active as possible. For more information see your GP or contact the author.