Spinal Stenosis

What is Spinal stenosis

The term “stenosis” comes from Greek and means a “choking”. The spinal canal, through which the nerve roots pass, can be thought of as a cylinder with roots “sneaking out” every few centimeters to supply the arms and legs with power and sensation. When that canal becomes narrowed, notably by degeneration in the discs or facet joints, then the nerve roots become squashed. When those nerves that supply the legs with power and sensation are squashed, they can produce symptoms of pain, tingling, weakness or numbness that radiates into the buttocks and legs. This commonly happens in the low back (approximately 75%) but can happen elsewhere in the spine. It must be noted that, when this occurs in the low back, it doesn’t involve the spinal cord. The spinal cord is classically thought to pass the whole length of the spinal canal. In fact it stops just beyond the junction of the thoracic spine (just beyond the lowest rib at the back, at the L1/2 disc level).

Most cases will produce pain into the legs with walking, and the pain will be relieved with sitting. It can start to occur in the late 40’s but most people will be over 60 years old. Patients need only seek treatment for lumbar spinal stenosis if they no longer wish to live with significant activity limitations.

There are different types of stenosis (central, foraminal, far lateral) but these differences are not particularly important from a clinical symptom point of view, which is why all forms of stenosis are typically referred to as simply spinal stenosis. However, if surgery is to be performed, the differences are very important in guiding the surgery. Thus the position of the tight areas must be exactly identified in advance to guide the approach for their removal, hence the need for an MRI scan.

What are the symptoms of Spinal Stenosis

The symptoms of spinal stenosis generally develop slowly over time and may come and go, as opposed to being a continuous pain. They are often worsened by certain activities and/or positions and are relieved by rest and/or any flexed forward position. Spinal stenosis is therefore (at least initially) a dynamic condition. This means the nerve compression may be there when the patient is standing but not lying; it may be there when walking but not when bending forwards (this opens up the canal and allows more space for the nerve roots to “breathe”). This is why the symptoms of spinal stenosis vary from time to time and the physical examination generally will not show any neurological deficits or motor weakness.

How is Spinal Stenosis diagnosed

Diagnostic imaging studies for spinal stenosis patients include either a MRI scan or a CT scan +/- myelogram. The MRI scan is by far the more common investigation but some people find it too claustrophobic while others have metal in their bodies which preclude them going in such a powerful magnetic environment. Therefore the enhanced CT scan is occasionally used. X-rays are a very blunt instrument in the diagnosis of stenosis. They can show degeneration but not nerve compression and are therefore quite non-specific.

How is Spinal Stenosis treated?

Non-surgical treatment for Spinal Stenosis

Depending on the severity of symptoms, spinal stenosis can often be managed through non-surgical means. The most common treatments for spinal stenosis include:

• Activity modification to treat spinal stenosis. Examples of activity modification might include: walking while bent over and leaning on a zimmer or shopping trolley instead of walking upright; stationary biking instead of walking for exercise.
• Epidural injections to treat spinal stenosis. An injection of cortisone into the space outside the dura (the epidural space) can temporarily relieve symptoms of spinal stenosis. While these injections cannot be considered curative, they can alleviate the pain in about 50-65% of cases. Up to three injections over a course of several months can be tried. If the pain caused by spinal stenosis is relieved by an injection it is reasonable to expect the patient to have a good result if they later choose surgery.
• Anti-inflammatory medication (such as ibuprofen, aspirin) may be helpful in treating spinal stenosis. Exercise is important to maintain strength, but usually has little lasting value in alleviating the symptoms.

Surgical treatment for Spinal Stenosis

Some people may successfully manage the symptoms of spinal stenosis with the non-surgical therapies either for a period of time or indefinitely. When the patient can no longer do those activities of daily living that they reasonably want to, then surgery should be entertained. In most cases of advanced stenosis, decompressive surgery is required.

Microdecompression

In a microdecompression, a small portion of the bone over the nerve root and/or disc material from under the nerve root is removed to relieve neural impingement and provide more room for the nerve to recover. A microdecompression is typically performed for a very localized 1 level stenosis.

Open Lumbar Decompression

Similar to a microdecompression, a lumbar open decompression is a procedure involving a larger midline incision in the back, a more extensive stripping of the muscles of the back, and a limited removal of the bone compressing the nerve root, thus relieving the root(s).

Post-operatively, patients are in the hospital for one to three days, and the individual patient's mobilization (return to normal activity) is largely dependent on his/her pre-operative condition and age. Directly following the procedure, patients are encouraged to walk. However, it is recommended that patients avoid excessive bending, lifting or twisting for six weeks in order to avoid pulling on the suture line before it heals.