Spinal stenosis is the narrowing of spaces in the spine (backbone) which causes pressure on the spinal cord and nerves. About 75% of cases of spinal stenosis occur in the low back (lumbar spine). In most cases, the narrowing of the spine associated with stenosis compresses the nerve root, which can cause pain along the back of the leg.
There are many potential causes for spinal stenosis, including:
Aging: With age, the body's ligaments (tough connective tissues between the bones in the spine) can thicken. Spurs (small growths) may develop on the bones and into the spinal canal. The cushioning disks between the vertebrae may begin to deteriorate. The facet joints (flat surfaces on each vertebra that form the spinal column) also may begin to break down. All of these factors can cause the spaces in the spine to narrow.
Heredity: If the spinal canal is too small at birth, symptoms of spinal stenosis may show up in a relatively young person. Structural deformities of the involved vertebrae can cause narrowing of the spinal canal.
Instability of the spine, or spondylolisthesis: When one vertebra slips forward on another, that can narrow the spinal canal.
Tumors of the spine: Abnormal growths of soft tissue may affect the spinal canal directly by causing inflammation or by growth of tissue into the canal. Tissue growth may lead to bone resorption (bone loss due to overactivity of certain bone cells) or displacement of bone and the eventual collapse of the supporting framework of the spinal column.
Trauma: Accidents and injuries may either dislocate the spine and the spinal canal or cause burst fractures that produce fragments of bone that penetrate the canal.
What Are the Symptoms of Spinal Stenosis?
Spinal stenosis may result in low back pain as well as pain in the legs. Stenosis may pinch the nerves that control muscle power and sensation in the legs. Additional symptoms may include:
Frequent falling, clumsiness
Pain and difficulty when walking
Numbness, tingling, hot or cold feelings in the legs
How Is Spinal Stenosis Diagnosed?
Spinal stenosis can be difficult to diagnose because its symptoms can be caused by other conditions. Usually, people who develop stenosis have no history of back problems or any recent injury. Often, unusual leg symptoms are a clue to the presence of spinal stenosis.
If simple treatments, such as postural changes or nonsteroidal anti-inflammatory drugs, do not relieve the problem, special imaging studies may be needed to determine the cause of the problem. An MRI (magnetic resonance image) or CT (computed tomography) scan may be requested. A myelogram (an X-ray taken after a dye is injected into the spine) may be performed. These and other imaging studies can offer details about the bones and tissues and help with diagnosis.