Instructional Course Lectures, The American Academy of Orthopaedic Surgeons - Spinal Stenosis*†

Abstract

Spinal stenosis is a narrowing or stricture of the spinal canal. Cauda equina and nerve-root compression are noted in many asymptomatic individuals8. Therefore, narrowing alone does not explain all of the symptoms and signs seen in patients who have the clinical syndrome of spinal stenosis, or neurogenic claudication. The spinal degenerative process associated with aging leads to pathoanatomical and pathophysiological changes with occasional clinical consequences. Not only does narrowing occur, but abnormal spinal motion can further increase the degree of compression. With progressive degenerative changes and compression, spinal stenosis may become symptomatic, although the severity of the symptoms is not necessarily associated with the magnitude of the compression seen on imaging studies. Spinal stenosis can be classified as either congenital or acquired3 (Table I). Congenital stenosis is commonly seen in individuals who have achondroplasia or another short-stature syndrome. The congenital classification also includes stenosis in individuals of normal stature who have congenitally short pedicles accompanied by bulging discs at multiple levels. The latter group frequently has symptoms when they are between the ages of thirty and forty years old. View this table: TABLE I CLASSIFICATION OF STENOSIS OF THE SPINAL CANAL Acquired degenerative stenosis tends to lead to symptoms in women at a mean age of seventy-three years and in men at a somewhat younger age86. Degenerative spondylolisthesis, seen more often in women than in men, also may contribute to the symptoms of spinal stenosis67,69,70,147. Although there are many causes of spinal stenosis, this discussion will focus on the degenerative process. Degenerative changes and narrowing can occur (1) centrally; (2) in the lateral recess, leading to nerve-root impingement from an overhanging, hypertrophic facet joint; (3) within the nerve-root canal (foraminal stenosis); or (4) extraforaminally, frequently because of entrapment by osteophytes, …