Lumbar spinal stenosis is a clinical-anatomic syndrome. Radiographic evidence of cauda equina compression is necessary but not sufficient to establish the diagnosis. Patients must have a clinical syndrome consisting of back and lower extremity discomfort exacerbated by lumbar extension or relieved by flexion, or evidence of lower extremity neurologic deficits. Symptomatic lumbar spinal stenosis may arise from a variety of specific etiologies and frequently coexists with other pain syndromes.