What Is Spinal Stenosis?
Spinal stenosis is a narrowing of the spinal canal that results in pressure on the spinal cord and/or nerve roots.
This disorder usually involves the narrowing of one or more of three areas of the spine: the canal in the center of the column of bones (vertebral or spinal column) through which the spinal cord and nerve roots run, the canals at the base or roots of nerves branching out from the spinal cord, or the openings between vertebrae (bones of the spine) through which nerves leave the spine and go to other parts of the body.
The narrowing may involve a small or large area of the spine. Pressure on the lower part of the spinal cord or on nerve roots branching out from that area may give rise to pain or numbness in the legs. Pressure on the upper part of the spinal cord (that is, the neck area) may produce similar symptoms in the shoulders.
What Causes Spinal Stenosis?
The normal vertebral canal provides adequate room for the spinal cord and cauda equina. Narrowing of the canal, which occurs in spinal stenosis, may be inherited or acquired. Some people inherit a small spinal canal or have a curvature of the spine (scoliosis) that produces pressure on nerves and soft tissue and compresses or stretches ligaments. In an inherited condition called achondroplasia, defective bone formation results in abnormally short and thickened pedicles that reduce the diameter of the spinal canal.
How Do I Know If I Have Spinal Stenosis?
The space within the spinal canal may narrow without producing any symptoms; however, if the narrowing places pressure on the spinal cord, cauda equina, or nerve roots, there may be a slow onset and progression of symptoms. The neck or back may or may not hurt. More often, people experience numbness, weakness, cramping, or general pain in the arms or legs. If the narrowed space within the spine is pushing on a nerve root, people may feel pain radiating down the leg (sciatica).