The purpose of this report is to assess, in an evidence-based fashion, the efficacy of methods for the diagnosis and treatment of degenerative lumbar spinal stenosis. Lumbar spinal stenosis is defined as a focal narrowing of the spinal canal, although the precise amount of narrowing that must occur before the canal is considered stenotic differs among individuals (Alvarez and Hardy Jr, 1998; Bueff and Van der Reis, 1996; Fast and Greenbaum, 1995; Herkowitz, Abrahan, and Fischgrund, 1998; Herno, Saari, Suomalainen et al., 1999; Postacchini, 1996; Spivak, 1998). The general term spinal stenosis can be applied to three root compression mechanisms alone or in combination: (1) disk protrusion or herniation, (2) osteotic overgrowth into the spinal canal or the foramina through which the roots pass laterally, and (3) vertebral slippage or spondylolisthesis. Although symptoms overlap for these three mechanisms, the second category, osteotic stenosis, is specifically termed spinal stenosis; this category is the focus of this evidence report, with spondylolisthesis also being addressed.
In extreme cases, lumbar stenosis can cause cauda equina syndrome, which is characterized by severe neuromuscular, bladder, and rectal dysfunction, and is considered to require immediate surgery to prevent permanent nerve damage (Gunzburg and Szpalski, 1999). However, because many studies excluded patients with cauda equina syndrome, virtually no evidence related to this syndrome could be evaluated, and, therefore, consideration of cauda equina syndrome is beyond the scope of this evidence report.
This evidence report, therefore, focuses on less extreme manifestations of lumbar spinal stenosis and considers the evidence surrounding all aspects of this condition. This includes evidence concerning the natural history of lumbar stenosis. This is important because it is not firmly established that this condition is progressive, nor has it been firmly established that stenosis per se is responsible for the symptoms experienced by many patients. Among these symptoms are low back pain, radiculopathy, and neurogenic claudication (Alvarez and Hardy Jr, 1998; Bueff and Van der Reis, 1996; Fast and Greenbaum, 1995; Herkowitz, Abrahan, and Fischgrund, 1998; Herno, Saari, Suomalainen et al., 1999; Postacchini, 1996; Spivak, 1998).
This report also considers the methods used to diagnose lumbar spinal stenosis. Among these methods are myelography, computed tomography (CT), and magnetic resonance imaging (MRI). In evaluating these methods, the typical quantities used to gauge test performance (sensitivity, specificity, and positive and negative predictive values) are considered. Also considered is whether these methods can be used to predict which patients may respond to treatment. Evaluating the efficacy of diagnostic methods for spinal stenosis has many difficulties because imaging is often performed after medical management has proved unsuccessful. Therefore, a common use of imaging is for planning surgery.
Finally, treatments for lumbar spinal stenosis are considered. Included are both medical and surgical treatments. Our searches for information about both classes of treatments were comprehensive. In this analysis, particular attention is paid to patient-oriented outcomes (i.e., relief of symptoms). This is because reducing or eliminating the stenosis may not provide a concomitant reduction in the intensity of symptoms.