Lumbar Spine Stenosis
is a term many people don’t understand at first. One can pretty much figure out what the spinal part means but what does this stenosis word mean? Well, simply put stenosis is when something become narrow or becomes smaller. One can get the idea that something has narrowed in the spine, but what? Why is this a problem? What in the spine is narrowed?
By far the most common cause of spinal stenosis is the process of the wear and tear on the spine over time. While there are many changes that take place in the lumbar spine, there are a few parts of it that commonly cause the problem, arthritis of the spine, usually in middle-aged or elderly people can also be the cause. Congenital defects of the spine, like short pedicles can also lead to this condition. Other causes of stenosis include, disc herniation, Paget disease of the bone, trauma to the spine and spinal tumors. The most common location affected by spinal stenosis is L3-L4 and L5-S1.
For illustrative purposes we can liken the discs to a jelly doughnut. A tough outer layer and a softer inner layer, changing in shape as you move around and use your back throughout the day. The main problem that occurs with the disc is that they lose their volume over time and thin out .This will be all good and fine , except that when the disc becomes thinner, the two vertebrae they sit in between come close together which causes the holes on the side where the nerve exits to become narrow .
Unfortunately the story does not end there, when the two vertebrae start getting close to each other as a result of the disc thinning not only do the holes on the sides become smaller , but it also puts extra stress on the facet joints, the joints the connect each vertebrae together. And when there is too much stress on the facet joint, well, they react by getting bigger over the time. The last common structural change that takes place with the stenosis has to do with one of the ligaments (ligamentum flavum ). It becomes thicker. And this of course means s that it now takes more space in the central canal
All these changes with the disc getting thinner, the facet joints getting larger, and ligaments getting thicker, all narrow the holes and the canal causing the condition known as spinal stenosis. This whole process goes through three stages, a dysfunctional stage, an instability stage, and a stage of stabilization. It is easier to distinguish between a painful stenosis and a non painful stenosis by looking at the functional changes.
Clinical presentation of patients with lumbar spine stenosis can be in the form of hypoesthesia, pain and ache in the lower limb. Paresis or paralysis of upper or lower limb can be present in a small number of patients.
A condition known as neurogenic claudication can also be associated with spinal stenosis. This occurs when there is narrowing of the sagittal diameter of the spinal canal, whether it be developmental or from degenerative causes. This results in the compression of the dural sac or the cauda equina fibers with in it at one or more disc levels.
Epidural pressure in patients with stenosis is increased as compared to the normal spine and pressure is further increased on walking and is reduced on walking with the flexed lumbar spine .
So activities like walking downhill increases the lumbar stenosis while walking with uphill reduces lordosis and relieves the symptoms. Cycling with flexed lumbar spine is well tolerated. Imaging tests such as X-ray, CT, MRI of spine and EMG can be helpful in diagnosis.
Most patients with spinal stenosis complicated with back pain can be treated with non surgical treatments such as physiotherapy or various other treatments such as chiropractic. Explaining to patients that it is a non progressive disease which is very common will help them to cope with the symptoms. Medications such as NSAIDS and analgesics can be very helpful as well. Adjustment to the work situation and day to day life including an increase in exercise and weight loss are often much more effective than other modalities. A small number of patients will develop more severe symptoms which will require more intensive physical therapy in the form of rehabilitation.
Surgery is indicated as a last resort in selected patients who are non-responsive to medication and conservative care. Surgery to fuse or stabilize the spine can be used .Combined anterior and posterior surgery probably has the best result in these patients. Lumbar Laminectomy or multiple laminotomy to decompress the roots in lateral recess can also result in a good outcome. Foraminotomy can also be done to relieve pressure on the existing nerves and help lumbar spine stenosis.