Background

The term lumbar stenosis refers to any narrowing of the spinal canal. The causes are many. The most common is degenerative, occurring in essentially the entire population with age, to varying degrees and with varying clinical significance. This degenerative narrowing is referred to as spondylosis. Another cause of stenosis is the slippage of one vertebra on another, with malalignment and consequent narrowing of the canal; this slippage is called spondylolisthesis. Again, spondylolisthesis can have many causes, most commonly degenerative and traumatic. One of the causes of spondylolisthesis is a defect in a supporting structure of the vertebra called the pars; this defect is known as spondylolysis. As the reader may guess, spondylolysis can have several causes. These include degeneration, trauma, and congenital defects.

Several factors contribute to the narrowing of the spinal canal with degenerative changes. First, wear and tear causes the joints, called facets ("fa-SETS"), to hypertrophy. This may be analogous to degeneration and swelling of other joints in the body. Second, the major ligament of the spinal canal, the ligamentum flavum, undergoes hypertrophy and buckling. Third, the intervertebral discs may bulge posteriorly into the canal or herniate. Fourth, as mentioned above, the vertebrae may slip forward. Finally, these changes may be superimposed on a congenitally narrow canal.

Clinical Evaluation

The hallmark of lumbar stenosis is pain in the back and legs which is aggravated by standing and walking and relieved by sitting or forward bending. The syndrome of pain induced by walking is known as neurogenic claudication (from the Latin claudico, to limp). The major condition which this must be distinguished from is vascular claudication, or leg pain on walking caused by insufficient blood flow to the legs. The features which help to distinguish neurogenic from vascular claudication are the folowing:

1. Pain occurs after varying amounts of exercise, with standing, or with coughing. Vascular claudication is reliably produced with a fixed amount of exercise, such as walking a certain number of blocks, and is rare at rest.
2. Relief of pain with rest is variable and slow, usually requiring sitting or stooping. Resting in a standing position is usually not sufficient, or may even aggravate the pain. In contrast, the pain of vascular insufficiency is usually immediately relieved by resting in a standing position. This is a key distinguishing feature.
3. Pain is in a dermatomal distribution (that of a nerve root[s]) rather than the muscles exercised.
4. Sensory loss is also dermatomal, whereas with vascular insufficiency it is in a stocking-glove distribution.
5. Signs of vascular insufficiency should be absent: diminished pulses, foot pallor on elevation, and decreased temperature of the feet.

Lumbosacral spine X-rays are taken to assess alignment and the diameter of the canal. Oblique films help to evaluate the foramina and the presence of pars defects. CT scan is excellent in showing the shape and dimensions of the canal, ligamentum flavum hypertrophy, facet arthropathy, and disc bulges and herniation. CT may be plain or following myelography. MRI has significant limitations in defining bone detail, but is good in defining root impingement and foraminal narrowing.

Treatment

Symptoms may be ameliorated by nonsteriodal anti-inflammatory drugs (NSAIDs, such as ibuprofen) and physical therapy.

Surgery for decompression is indicated when conservative measures fail to provide a level of relief which is appropriate or desired by the patient. This must be individualized for each patient. The goals of surgery are primarily the relief of pain and stopping the progression of symptoms. Neurologic deficits, that is, weakness, sensory loss, or loss of sphincter or sexual function, may be reversed to some extent. This depends on, among other factors, their severity and duration prior to surgery.

At surgery, the laminae and ligamentum flavum of the affected levels are removed, effectively unroofing the spinal canal. The neural foraminae are also opened. Alternatively, hemilaminotomies may be performed in cases where the anteroposterior canal diameter is relatively normal. This is a more limited bone removal than laminectomy. The advantages of this procedure over laminectomy have not been conclusively demonstrated.

The issue of stabilization and fusion with laminectomy is controversial. Lumbar instability following decompressive laminectomy for stenosis is rare, occurring at a frequency of about 1%. The majority of patients who develop postoperative instability have some predisposing factor prior to surgery, such as a pre-existing spondylolisthesis. Moreover, lumbar fusions have a high failure rate, and may even promote spondylosis at adjacent levels. Most surgeons presently perform fusions with laminectomy if preoperative X-rays demonstrate instability, and otherwise follow their patients with postoperative X-rays. Stability is maintained if the majority of the facet is left intact and if the disc is not violated. Younger and more active patients may be at more risk to develop instability later.

Postoperatively, patients may feel immediate pain relief and are usually walking by the morning following surgery. Most patients are discharged home in 3 to 5 days.

Outcome

Good or excellent results have been reported in 80-85% of cases. Relief of leg pain is more consistent than back pain.

Back Pain

Cervical Spondylosis

Cervicle Disc Disease

Lumbar Disc Disease

Salmonella

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