Lumbar spinal stenosis is a condition in which the spinal canal is narrowed, causing the spinal cord or spinal nerve roots to be compressed. Spinal stenosis is related to degeneration of the spine, as the facet joints get larger and place pressure on the nerve roots. The condition usually affects patients over the age of 60.
Approximately 75% of spinal stenosis cases affect the lumbar area of the spine, and most will affect the sciatic nerve which runs along the back of the leg. Standing upright further decreases the space available for the nerve roots, and can block the outflow of blood from around the nerve. Congested blood then irritates the nerve and the pain travels into the legs.
The compression of lumbar spinal stenosis can produce the following symptoms, which radiate into the buttocks and legs:
- Weakness (rare)
These symptoms typically develop slowly over several years (although they do occasionally come on suddenly), they are intermittent as opposed to continuous, they occur during certain activities and in certain positions, and they are relieved by rest or any flexed forward position. The most common symptom of lumbar spinal stenosis is pain in the legs while walking, which is relieved only by sitting and resting (not simply by stopping walking).
The longer a patient with spinal stenosis stands or walks the worse the leg pain will get. Flexing forward or sitting will open up the spinal canal and relieve the leg pain and other symptoms, but they will recur when the patient gets back into an upright posture. Numbness and tingling can accompany the pain. Weakness is a rare symptom of spinal stenosis.
The nerve compression of spinal stenosis will vary, depending on the activity or position of the patient (standing, sitting, walking). Physical examination alone will not be enough to correctly diagnose stenosis.
Either a Magnetic Resonance Imaging (MRI) scan or a Computed Tomography (CT) scan with myelogram can be useful in diagnosing lumbar spinal stenosis. Sometimes both are used. A non-enhanced CT scan (without myelogram) is not useful in diagnosing this condition.
A spinal stenosis at two or even three levels can affect a single emerging nerve. If surgery is considered, a combination of anatomical and clinical examination is needed in order to make sure one surgical procedure will address all contributing components of spinal stenosis.
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Lumbar spinal stenosis can be treated by non-surgical or surgical means. The key to deciding which one to choose is the degree of disability and pain resulting from the stenosis. If a patient can no longer walk well enough to be independent, then surgery may be recommended. Otherwise a non-surgical approach may be tried for a period of time, or indefinitely if the results are satisfactory.
Conservative (non-surgical) treatments
There are two common non-surgical treatments for lumbar spinal stenosis. These are:
- Activity modification. Since patients are more comfortable when they are flexed forward, they can concentrate their activity in that position. Modifications can include changing exercise from walking to stationary biking, using a cane or walker for walking while flexed forward, and sitting in a recliner rather than a straight-back chair.
- Epidural injection. This is an injection of cortisone into the space outside the dura (the epidural space). Approximately 50% of patients will experience good pain relief after an epidural injection, although the results tend to be temporary. If the injection is helpful it can be done up to three times within a year. The action of the injection is not clearly known, but is probably a combination of the anti-inflammatory effect of the steroid and a flushing effect due to injecting a volume of fluid. Although the injection can not be considered diagnostic, typically if the pain from spinal stenosis is relieved by an injection the patient can be expected to have a good result if they later choose to undergo a surgical procedure.
Anti-inflammatory medication (such as ibuprofen, aspirin or Cox-2 inhibitors) may also be helpful in treating spinal stenosis. Exercise is important to maintain strength, but usually does not relieve the symptoms.
If conservative treatments do not adequately increase the level of activity a patient is able to tolerate, a surgical procedure might be considered.
An open decompression or laminectomy is the only way to change the anatomy of the spine and give the nerves more room. Decompressing the nerves by removing a portion of the enlarged facet joint prevents the nerve from being pinched when the patient stands up. There are several methods, but there are key components common to all such approaches:
- A correct and very detailed anatomical diagnosis is required. The surgeon must consider the possibility of a double or triple location of choking of a nerve, on one or both sides.
- The surgery should not create a new problem, such as a nerve injury or a structural instability that might require additional surgeries.
- The approach to correcting spinal stenosis should be minimally destructive of normal structures. The surgeon should strive to leave as much as possible of the normal or slightly abnormal tissues alone. This again points to the importance of exactly identifying the stenosis.
- The metabolic and physical status of the patient is important. Even in experienced hands a decompressive procedure may require a few hours of anesthesia, and this is not well tolerated by some patients. Some surgeons will perform the spinal stenosis surgery using an epidural anesthetic instead of a general.
Decompression surgery for spinal stenosis is effective in approximately 80% of cases, but the results tend to deteriorate over a 5-year period. Patients generally do well and are able to increase their activity level and have a better walking tolerance. The results are just as effective whether the surgery is done right away, or delayed for years.
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