Spinal stenosis is a narrowing of spaces in the spine that results in pressure on the spinal cord or nerve roots. Pressure on the lower part of the spinal cord or on nerve roots may cause pain or numbness in the legs. This disorder is most common in men and women older than 50. However, it may occur in younger people who are born with a narrowing of the spinal canal or who suffer a spinal injury.
Some common signs and symptoms of spinal stenosis are:
- Pain that radiates down the leg (sciatica)
- Weakness in the legs
- Problems with bowel or bladder function
The space within the spinal canal may narrow without producing any symptoms. However, if narrowing places pressure on the spinal cord or nerve roots, there may be a slow onset 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, called sciatica.
People with more severe stenosis may have problems with bowel and bladder function and foot disorders. 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 pain, weakness or loss of feeling in one or both legs. Cauda equina syndrome is a serious condition requiring urgent medical attention.
- 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, called scoliosis, which produces pressure on nerves and soft tissue and compresses or stretches ligaments.
- Achondroplasia is a defective bone formation that can also be an inherited condition. It results in abnormally short and thickened pedicles that reduce the diameter of the spinal canal.
- The aging process may also lead to spinal stenosis as a result of gradual, degenerative aging. As people age, the ligaments of the spine may thicken and calcify, or harden from deposits of calcium salts. Bones and joints may also enlarge sometimes causing bone spurs, areas of the bone that protrude causing pain. A herniated or bulging disk can also place pressure on the spinal cord or nerve root.
- Two forms of arthritis that may affect the spine are osteoarthritis and rheumatoid arthritis.
- Spinal stenosis may be acquired from tumors of the spine. These tumors may affect the spinal canal directly by inflammation or by growth of tissue into the canal.
Other causes include trauma that either dislocate the spine and the spinal canal or cause fractures that produce bone fragments that penetrate the canal.
The patient’s medical history, such as information about any prior injuries or general health problems, can help with the diagnosis. A physical examination can determine the extent of limitation of movement, as well as identify areas of pain, and check for normal neurological functions, such as sensation, muscle strength and reflexes in the arms and legs.
X-ray: Prior to other testing, an X-ray may be conducted to look for signs of an injury, tumor or inherited problem. This test can show the structure of the vertebrae and the outlines of joints and can detect calcification.
MRI: An MRI, or magnetic resonance imaging, produces signals that are detected by a scanner and analyzed by computer. An MRI is particularly sensitive for detecting damage or disease of soft tissues, such as the disks between vertebrae or ligaments. It shows the spinal cord, nerve roots and surrounding spaces, as well as enlargement, degeneration or tumors.
Computerized axial tomography (CAT): X-rays are passed through the back at different angles, detected by a scanner and analyzed by a computer. This produces a series of cross-sectional images and three-dimensional views of the parts of the back. The scan shows the shape and size of the spinal canal, its contents and the structures surrounding the spinal canal.
Myelogram: A liquid dye is injected into the spinal column. The dye circulates around the spinal cord and spinal nerves, which appear as white objects against bone on an X-ray film. A myelogram can show pressure on the spinal cord or nerves from herniated disks, bone spurs or tumors.
Bone scan: Radioactive material is injected into the bone. This material attaches itself to bone, especially in areas where bone is actively breaking down or being formed. The test can detect fractures, tumors, infections and arthritis, but may not distinguish between disorders. Therefore, a bone scan is usually performed along with other tests.
Sitting or flexing the lower back should relieve symptoms. The flexed position opens the spinal column, enlarging the spaces between vertebrae at the back of the spine. Flexing, stretching and strengthening exercises are often advised.