Spinal stenosis

Spinal stenosis is a narrowing of the vertebral canal. Approximately 1.2 million people in the United States have back and leg pain that is related to spinal. (1) The narrowing of the vertebral canal may lead to compression of the spinal nerves or nerve roots, especially in the area of the lumbar vertebrae. (2,3)

Degenerative lumbar stenosis is common in elderly adults; bony overgrowth and ligament enlargement into the spinal canal, intervertebral disc herniation, or vertebral slippage (spondylolisthesis) may be responsible for nerve compression. This compression results in low back pain, leg fatigue and pain, and reduced capacity for physical activity.

Neurogenic claudication describes a combination of low back pain, leg pain, numbness, and motor weakness that starts or intensifies on standing or walking and is eased by sit-ting or lying down. Although symptomatic stenosis involves some degree of neurogenic claudication, not all patients with lumbar spinal stenosis are symptomatic or exhibit neurogenic claudication.

Symptoms of lumbar spinal stenosis may be categorized as mild, moderate, or severe, based on the extent of leg pain and pain-related disability. (4,5) Patients with severe symptoms have exercise intolerance and greatly restricted walking capacity, and may have bladder dysfunction (i.e., urinary incontinence). (3,6) Conservative treatment with pain-relieving agents seems to be the natural choice when symptoms are mild. (3,5) Decompressive surgery to remove the bone and ligaments around the stenosis usually is recommended for patients with severe symptoms when conservative therapy has not provided adequate pain relief. (3,5) Patients with moderate symptoms fall into a gray zone in which the most appropriate treatment is not obvious. (7)

This article reviews the evidence for conservative and surgical treatments for degenerative lumbar spinal stenosis. A detailed discussion of the anatomy, pathophysiology, clinical history, physical examination, and differential diagnosis of lumbar spinal stenosis has appeared in American Family Physician. (3)

Our systematic review of the evidence revealed problems with study design and quality. These problems complicated the literature assessment for conservative and surgical interventions. However, some important findings from the better studies were identified and are summarized in Table 1. (4-12) Our findings should be viewed as showing potential relationships between treatments, patient characteristics, and treatment outcomes. Definitive evidence-based conclusions about the efficacy of conservative or surgical treatments for lumbar spinal stenosis await the results of well-designed clinical trials.

Data Sources

Candidate studies for inclusion in this review were identified by searching 25 bibliographic databases (including MEDLINE, Embase, the Cochrane Database of Systematic Reviews, CRISP, and CINAHL) as part of a systematic review requested by the Agency for Healthcare Research and Quality. Search dates spanned from database inception through May 2000 and were updated through March 2003 for this article. Search terms included spinal stenosis, lumbar stenosis, sciatica, backache, spinal disease, neurogenic claudication, nerve root entrapment, nerve root compression, and spondylosis. Controlled trials of conservative treatments were included, as were any clinical studies of surgical treatment, regard-less of study design. All reviewed studies enrolled 10 or more patients.

Treatment for Mild Symptoms

One randomized placebo-controlled trial (8) examined the effects of epidural steroid injections and a local anesthetic on neurogenic claudication. The results of this study suggest that the local anesthetic mepivacaine reduces symptoms and increases walking distance in the short-term, but effects last for no more than one month. Epidural steroids offer no additional benefit to the effects of the anesthetic block. (8) [Evidence level B, good-quality randomized controlled trial (RCT)]

Treatment for Moderate Symptoms

In patients with moderate symptoms, surgery may be more beneficial than conservative therapy. The Maine Lumbar Spine Study) (4) (a prospective, observational cohort study) contained a subgroup of patients with moderate symptoms (31 patients underwent surgery, and 23 were treated with bed rest, physical therapy, exercise, braces, traction, transcutaneous electrical nerve stimulation [TENS], spinal manipulation, narcotic analgesics, or epidural steroids). The patients who had surgery showed significantly better improvement, suggesting that surgery may be more beneficial than conservative treatment in patients with moderate pain. (4) [Evidence level B, clinical cohort study] After four years of follow-up, the outcomes continued to be better in patients who had moderate pain initially and underwent surgery. (9) [Evidence level B, clinical cohort study]

Randomization of patients to surgical or conservative treatment was considered ethical in two trials (5,7) where treatment was deemed appropriate for patients with moderate symptoms. In the first trial, (7) 44 patients with mild to moderate leg pain were randomized to receive conservative treatment (i.e., back braces, physical therapy, and exercise programs) or surgery. Although both treatment groups showed clinically and statistically significant improvement one year after treatment, only the surgery group continued to show improvement after two years. [Evidence level B, good-quality RCT]

In the second trial, (5) patients with moderate pain were randomized to undergo surgery or receive conservative therapy (i.e., bracing and physical therapy), patients with severe pain underwent surgery, and patients with mild symptoms received conservative therapy. Within three to 27 months of entering the study, 10 of the 18 (56 percent) conservatively treated patients with moderate symptoms crossed over to undergo surgery. Among patients with moderate symptoms, a higher percentage of surgery patients were rated excellent or fair.

These data suggest that surgery may be more beneficial than conservative therapy in patients with moderate symptoms. How-ever, physicians may have underestimated pain and severity of symptoms in some patients, resulting in their inclusion in the moderate group rather than the severe group. As a result, many patients who belonged in the severe group may have been assigned to the moderate group and, therefore, were randomized to receive conservative treatment. These patients would be more likely to have unsuccessful results and to need surgery, thereby artificially reducing the reported effectiveness rate of conservative treatment in moderate patients. [Evidence level B, lesser quality RCT]

Treatment for Severe Symptoms

Although the study (5) discussed above suggests that patients with severe symptoms benefit more from surgery than conservative therapy, this theory is based on the assumption that some patients with severe symptoms were misclassified and thus received conservative therapy initially and improved after they underwent surgery. In general, data are lacking on the effect of conservative treatment in patients with severe stenosis because these patients seem to receive surgery shortly after diagnosis. (5) [Evidence level B, lesser quality RCT]

Treatment for Neurogenic Claudication

Evidence from four prospective uncontrolled trials that measured pre- and post-surgery walking ability suggests that these patients significantly improved after surgery. Patients in these studies had severe lumbar spinal stenosis that resulted in greatly limited walking capacity and had received conservative therapy that failed to relieve their symptoms. One study (10) per-formed an exercise treadmill test before and after surgery in 50 patients. These patients showed statistically significant increases in time to symptoms of first leg pain (mean increased from two minutes to 12 minutes) and total ambulation time (mean increased from seven minutes to 13 minutes). [Evidence level B: uncontrolled study]

In the other three studies, average walking distance among 30 patients increased from 100 yards to 1,320 yards (three fourths of a mile), (11) walking tolerance increased from less than 15 minutes in 50 of 51 patients to more than 30 minutes in 39 of 48 patients (19 with unlimited tolerance), (6) and 50 patients with significant walking limitations (an average of 200 yards) increased to 1,000 yards. (12) [References 6, 11, and 12-Evidence level B, uncontrolled studies]

The value of walking ability as an outcome to evaluate the efficacy of surgery is limited by the extent of comorbidities in elderly patients. Leg pain could have provided an additional outcome to evaluate the efficacy of surgery, but too few studies reported this feature before and after surgery or used a similar pain measurement scale.

The full evidence report prepared by ECRI is available from the Agency for Healthcare Research and Quality. Printed copies may be obtained free of charge from the AHRQ Publications Clearinghouse by calling 1-800-358-9295 and asking for Evidence Report/Technology Assessment No. 32, Treatment of Degenerative Lumbar

Spinal Stenosis (AHRQ Publication No. 01-E048). Internet users can access the report online through AHRQ's Web site at http://www.ahrq.gov. ECRI is a nonprofit health services research agency and a Collaborating Center for Healthcare Technology Assessment of the World Health Organization.

No statement in this article should be construed as an official position of the Agency for Healthcare Research and Quality or the U.S. Department of Health and Human Services.

The authors indicate that they do not have any conflicts of interest. Sources of funding: none reported.

This article exemplifies the AAFP 2004 Annual Clinical Focus on caring for America's aging population.

See page 422 for levels-of-evidence definitions.

REFERENCES

(1.) Hart LG, Deyo RA, Cherkin DC. Physician office visits for low back pain. Frequency, clinical evaluation, and treatment patterns from a U.S. national survey. Spine 1995;20:11-9.

(2.) Amundsen T, Weber H, Lilleas F, Nordal HJ, Abdelnoor M, Magnaes B. Lumbar spinal stenosis. Clinical and radiologic features. Spine 1995;20:1178-86.

(3.) Alvarez JA, Hardy RH Jr. Lumbar spine stenosis: a common cause of back and leg pain. Am Fam Physician 1998;57:1825-34,1839-40.

(4.) Atlas SJ, Deyo RA, Keller RB, Chapin AM, Patrick DL, Long JM, et al. The Maine Lumbar Spine Study, part III. 1-year outcomes of surgical and nonsurgical management of lumbar spinal stenosis. Spine 1996;21:1787-94.

(5.) Amundsen T, Weber H, Nordal HJ, Magnaes B, Abdelnoor M, Lilleas F. Lumbar spinal stenosis: conservative or surgical management? A prospective 10-year study. Spine 2000;25:1424-35.

(6.) Kleeman TJ, Hiscoe AC, Berg EE. Patient outcomes after minimally destabilizing lumbar stenosis decompression: the "Port-Hole" technique. Spine 2000;25:865-70.

(7.) Mariconda M, Fava R, Gatto A, Longo C, Milano C. Unilateral laminectomy for bilateral decompression of lumbar spinal stenosis: a prospective comparative study with conservatively treated patients. J Spinal Disord Tech 2002;15:39-46.

(8.) Fukusaki M, Kobayashi I, Hara T, Sumikawa K. Symptoms of spinal stenosis do not improve after epidural steroid injection. Clin J Pain 1998;14:148-51.

(9.) Atlas SJ, Keller RB, Robson D, Deyo RA, Singer DE. Surgical and nonsurgical management of lumbar spinal stenosis: four-year outcomes from the Maine Lumbar Spine Study. Spine 2000;25:556-62.

(10.) Deen HG, Zimmerman RS, Lyons MK, McPhee MC, Verheijde JL, Lemens SM. Use of the exercise treadmill to measure baseline functional status and surgical outcome in patients with severe lumbar spinal stenosis. Spine 1998;23:244-8.

(11.) Weiner BK, Walker M, Brower RS, McCulloch JA. Micro-decompression for lumbar spinal canal stenosis. Spine 1999;24:2268-72.

(12.) Khoo LT, Fessler RG. Microendoscopic decompressive laminotomy for the treatment of lumbar stenosis. Neu-rosurgery 2002;51(5 Suppl):146-54.

The Authors

DAVID L. SNYDER, PH.D., is a senior research analyst in the Health Technology Assessment Group at ECRI (formerly the Emergency Care Research Institute), Plymouth Meeting, Pa. He received his doctoral degree in nutrition and physiology from Pennsylvania State University, University Park, Pa.

DAVID DOGGETT, PH.D., is a senior research analyst in the Health Technology Assessment Group at ECRI. He received his doctoral degree in cell and molecular biology from the University of Southern California, Los Angeles.

CHARLES TURKELSON, PH.D., is chief research analyst in the Health Technology Assessment Group at ECRI. He received his doctoral degree in physiologic psychology from Tulane University, New Orleans.

Address correspondence to David L. Snyder, Ph.D., ECRI, 5200 Butler Pike, Plymouth Meeting, PA 19462-1298 (e-mail: dsnyder@ecri.org). Reprints are not available from the authors.

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