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Spinal Stenosis

Spinal Stenosis
Charles Dean Ray, MD

The term �stenosis� comes from Greek and means a �choking�. In lumbar spinal stenosis, the spinal cord or spinal nerve roots are compressed, or choked, and this can produce symptoms of pain, tingling, weakness or numbness that radiates into the buttocks and legs.

When nerves are compressed they can produce symptoms of pain, numbness and tingling into the legs with activity. In rare cases, it can produce severe pain and even weakness. Most cases will produce pain into the legs with walking, and the pain will be relieved with sitting.

Spinal stenosis is related to degeneration in the spine and usually will become significant in the 5th decade of life and extend throughout every subsequent age group. Most patients first visit their doctor with symptoms of spinal stenosis at about age 60 or so. Patients need only seek treatment for lumbar spinal stenosis if they no longer wish to live with significant activity limitations.

Spinal stenosis can occur in a variety of ways in the spine. Approximately 75% of cases of spinal stenosis occur in the low back (lumbar spine), and most will affect the sciatic nerve which runs along the back of the leg.

What is Spinal Stenosis?

The skull, vertebral column in the spine and sacrum (at the bottom of the spine) serve to support the structures of the body and to protect the delicate brain, spinal cord and nerves beneath. Each of these bony structures has holes through which nerves pass outward to the major parts of the body.

The entire length of the spinal column has a large central canal or passage through which the spinal cord descends, and then secondary holes to each side of the canal to allow emergence of spinal nerves at each level. The spinal cord stops at the upper part of the low back, and below that the tiny contained nerve rootlets descend loosely splayed out – like a horse�s tail � and protectively enclosed in a long sack. All central nerve structures are protected further by membranes, with a tough outer membrane called the dura (tough) mater (mother).

Major Types of Stenosis include:

Foraminal Stenosis. As the nerve root is about to leave the canal through a side hole (lateral foramen), a bone spur (osteophyte) can press on the nerve root. This type of stenosis may also be called lateral spinal stenosis. This is by far the most common form of spinal stenosis. 72% of cases of foraminal stenosis occur at the lowest lumbar level, trapping the emerging nerve root (a major part of the sciatic nerve).

Central Stenosis. A choking of the central canal, called central spinal stenosis in the lumbar (low back) area can compress the sack of the horse�s tail (cauda equina, or cauda equine). Central spinal stenosis is more common at the second lowest lumbar spinal level and above and is largely caused by redundancy of a ligament (ligamentum flavum) which is associated with protecting the dura and arises from the inside part of the facet joint.

Far Lateral Stenosis. After the nerve has left the spinal canal it can also be compressed on the outside of the spine from either a bony protrusion or disc bulge.

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. That is, the bad spot(s) must be exactly known in advance to guide the approach for its removal.

Symptoms of Spinal Stenosis

Generally speaking the various types of stenosis produce similar symptoms. Pain with limitations on walking is the most common symptom of lumbar spinal stenosis.

Pain in the legs with walking (claudication) can be caused by either vascular insufficiency (vascular claudication) or from spinal stenosis (neurogenic or pseudoclaudication). Pain with either condition will go away with rest, but with spinal stenosis the patient usually has to sit down to ease the leg pain. Vascular claudication will go away if the patient simply stops walking.

Although occasionally the symptoms and leg pain from spinal stenosis will come on acutely, they generally develop over several years. 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 recur if the patient gets back into an upright posture. Numbness and tingling can accompany the pain, but weakness is a rare symptom of spinal stenosis.

Overall, the symptoms of spinal stenosis are often characterized as follows:

    • Develop slowly over time
    • May come and go, as opposed to continuous pain
    • Occurs during certain activities and/or positions
    • Relieved by rest and/or any flexed forward position

Diagnosis of Spinal Stenosis

Diagnostic imaging studies for spinal stenosis patients include either a MRI scan or a CT scan with myelogram, and sometimes both. Unenhanced CT scans are of limited value.

It can be shown that each form of spinal stenosis has a dynamic (changing) effect on nerve compression, such as when bearing weight. Due to this changing compression, the symptoms of spinal stenosis vary from time to time and the physical examination generally will not show any neurological deficits or motor weakness.

Foraminal Stenosis can be pinpointed not only by the CT and MRI scans, but also by injecting the suspicious nerve with a local anesthetic (selective nerve root block). After the injection a remission of spinal stenosis symptoms on walking, along with true temporary weakness of the limb, is clinically diagnostic and helps the patient to decide about surgery.

Since a spinal stenosis at two or even three levels (sub-laminar, foraminal and far lateral) can affect a single emerging nerve, a combination of anatomical and clinical clarification is needed in order to make sure that one surgical procedure will address all contributing components of spinal stenosis.

Spinal Stenosis Treatment Options

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

Activity modification to treat spinal stenosis. Patients are usually counseled to avoid activities that cause the adverse symptoms of spinal stenosis. Patients are typically more comfortable while flexed forward. Examples of activity modification might include: walking while bent over and leaning on a walker or shopping cart instead of walking upright; stationary biking instead of walking for exercise; sitting in a recliner instead of on a straight-back chair.

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 can seldom be considered curative, they can alleviate the pain in about 50% of cases. Up to three injections over a course of several months can be tried. Although they are not considered diagnostic in and of themselves, generally, if the pain caused by spinal stenosis is relieved by an injection the patient can also be expected to have a good result if they later choose surgery.

Anti-inflammatory medication (such as ibuprofen, aspirin) may be helpful intreating spinal stenosis. Exercise is important to maintain strength, but usually has little lasting value in alleviating the symptoms. Some physicians recommend a multiple B-complex vitamin with 1200 mg of folic acid daily, but this has not been substantiated in the literature.

Some people may successfully manage the symptoms of spinal stenosis with the non-surgical therapies either for a period of time or indefinitely. The key in choosing whether or not to have surgery is the degree of disability and disabling pain pain from spinal stenosis. As a guideline, when the (usually elderly) patient can no longer walk sufficiently to care for himself or herself, or to go shopping for essentials, then surgery for spinal stenosis is usually recommended.

Surgery for spinal stenosis is mainly designed to increase a patient�s activity tolerance, so they can do more activity with less pain.

Surgery Treatment for Spinal Stenosis In most cases of advanced stenosis (spinal or vascular), decompressive surgery is required. There are several opinions and techniques used in spinal stenosis surgery, but there are key components common to all such approaches.

First and foremost, a correct and very detailed anatomical diagnosis is required – knowing exactly where to go while considering the possibility of a double or triple location of choking of a nerve, on one or both sides.

Secondly, the surgery should not create a new problem, such as nerve injury or a structural instability that might require additional surgeries.

Thirdly, 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 offending stenosis.

Fourthly, the metabolic and physical status of the patient is important. Even in experienced hands a decompressive procedure, especially if more than one level and if bilateral procedures are needed, may require a few hours of anesthesia, and this is not well tolerated by some patients. Some surgeons will perform the spinal stenosis surgery under an epidural anesthetic instead of a general.

Fortunately, a decompression surgery for spinal stenosis is among the most rewarding surgical methods used on the spine (second only to herniated disc), because generally patients do well and are able to increase their activity and have a better walking tolerance postoperatively.

For more information on decompression surgery, please see Lumbar decompression surgery.

“Read the full article at Spine-health.com:” Spinal Stenosis Symptoms, Diagnosis and Treatment