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Keywords
Sciatica
Neurogenic Claudication
Lumbar Fusion and Instrumentation
Lumbar Laminectomy

Definition
Lumbar Spinal Stenosis is the result of narrowing of the spinal canal producing pressure on the lumbar spinal nerves.

Indications
The operations for lumbar spinal stenosis are indicated for the relief of leg pain, leg numbness, and/or leg weakness from pressure on a single lumbar nerve root or multiple lumbar nerve roots. Occasionally, lumbar spinal stenosis places pressure on the nerves to the bowel and bladder requiring urgent surgery.

The table below illustrates the findings associated with a single nerve root in the lumbar spine.

Technical Considerations
The goal of spinal stenosis surgery is the removal of the mechanical pressure on the lumbar spinal nerves. Different surgical options are available to the patient.

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Natural History
The natural history of the lumbar spinal stenosis is listed in the table below. (reference #4) The natural history is the percentage patients of resolving symptoms from spinal stenosis measured against the time from the onset of those symptoms. The numbers were the result of following 32 patients for 4 years: (reference #4)

Timing of Surgery
The best results in lumbar spinal stenosis cannot be clearly related to the duration of symptoms. (reference #1, 2, 3) The exception would be patients with cauda equina syndrome (loss of control of bowel and bladder) and those patients with progressive weakness in the leg or legs.

Natural History and Surgical Treatment at 4 Years
Comparison between conservative and surgical treatment has been completed in this 4 year study. (reference #2)

Important facts in this study: (reference #2)
1. 6.2% reoperation rate for surgically treated patients.
2. 22.1% of the initial conservatively treated group underwent surgery during this 4 year period due to unacceptable symptoms.
3. Surgical results for the 22.1% subsequently undergoing surgery were inferior to the group initially undergoing surgery in the first year of the study.

Surgery versus Degree of Symptoms
The initial study related the degree of symptoms (severe, moderate, mild) to the choice of surgery for lumbar spinal stenosis. (reference #3) Severe symptoms were almost always operated on and mild symptoms rarely operated on. 50% of patients with moderate symptoms chose surgery and 50% chose not to have surgery. At the conclusion of the study at 1 year, 71% of patients with surgery were definitely improved, compared to 43% in the non-operative group. (reference #3)

Ten Year Study
The ten year prospective study on lumbar spinal stenosis compared coservative treatment to surgery. (reference #1)

Important facts in this study: (reference #1)
1. After the 4 year period, the conservatively and surgically treated groups maintained their clinical result (didn't deteriorate over time). 2. In addition, in this study, single level spinal stenosis did not fare better than those with multiple spinal level involvement for either the conservatively treated or surgically treated group.
3. Optimum timing of surgery not related to duration of symptoms.
4. Results of those patient undergoing later surgery were the same as those with initial surgery.
5. No single clinical characteristic of patients or imaging measurement predicted the results.

Complications
The risks of lumbar stenosis surgery are death, paralysis, infection, wound problems, nerve root injury, spinal fluid leak, failure to improve, future instability.

Author’s Comment
The best indications for surgery for the lumbar spinal stenosis are loss of control of the bowel and bladder (rare), weakness in an important muscle in the leg, and leg pain due to nerve pressure. In the final analysis, the choice for surgery is related to the degree of patient disability from the symptoms from lumbar spinal stenosis matched to the anatomy causing mechanical pressure on the spinal nerves. Once this principle is established, the choice of operative technique is made.

References
1. Amundsen T.W.,Weber H., et al.: Lumbar Spinal Stenosis Conservative or Surgical Managment? A Prospective 10-Year Study. Spine, 2000. 25: p. 1424-1436.
2. Atlas, S.J., et al., The Maine Lumbar Spine Study, Part III. 1-year outcomes of surgical and nonsurgical management of lumbar spinal stenosis. Spine, 1996. 21(15): p. 1787-94; discussion 1794-5.
3. Atlas, S.J., et al., Surgical and nonsurgical management of lumbar spinal stenosis: four-year outcomes from the maine lumbar spine study. Spine, 2000. 25(5): p. 556-62.
4. Johnsson K-E, Rosen I, Uden A.: The natural course of lumbar spinal stenosis. Clin Orhop, 1992(279): p. 82-86.