SIGNS AND SYMPTOMS

The space within the spinal canal may narrow without producing any symptoms. However, if 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). Sitting or flexing the lower back should relieve symptoms. (The flexed position "opens up" the spinal column, enlarging the spaces between vertebrae at the back of the spine.) Flexing exercises are often advised, along with stretching and strengthening exercises.

People with more severe stenosis may have problems with bowel and bladder function and weakness in the legs. For example, cauda equina syndrome is a severe, and very rare, form of spinal stenosis. It occurs due to compression of the cauda equina, and symptoms may include loss of control of the bowel, bladder, or sexual function and/or pain, weakness, or loss of feeling in one or both legs. Cauda equina syndrome is a serious condition requiring urgent medical attention.

The symptoms of spinal stenosis typically result in limitation of physical activity. This contributes to deconditioning with resultant reduced endurance, flexibility and strength. It can be helpful for the individual with spinal stenosis to modify their home environment to make the performance of activities of daily living more efficiently.

CAUSES

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 (distance across) of the spinal canal. Acquired conditions that can cause spinal stenosis are explained in more detail in the sections that follow.

Degenerative Conditions

Spinal stenosis most often results from a gradual, degenerative aging process. Either structural changes or inflammation can begin the process. As people age, the ligaments of the spine may thicken and calcify (harden from deposits of calcium salts). Bones and joints may also enlarge: when surfaces of the bone begin to project out from the body, these projections are called osteophytes (bone spurs).