Updated July 26, 2015.
Spinal stenosis is a condition that is caused by a narrowing of the space surrounding the spinal cord or the spinal nerves. The spinal cord extends from the brain to the bottom of the spine. Along the spinal cord, spinal nerves exit the spine and extend to the rest of the body. Together, the spinal cord and spinal nerves perform two important functions:

• Sensory Information
  Nerves pass messages from the body to the brain. The sensations we feel, including pain, pressure, vibration, and other sensations, are detected and passed through these spinal nerves, up the spinal cord, and to our brain.

• Motor Instructions
  Nerves also send messages the other direction, from the brain to the body. These messages direct muscle functions, both voluntary and involuntary. The signals help us perform all functions from walking to breathing.

In patients with spinal stenosis, these nerves can become compressed, either within the spinal cord, or as the spinal nerves exit the spinal cord. Compression of these nerves leads to the common symptoms experienced by patients who have spinal stenosis. When the nerves are compressed, abnormal signals are sent to and from the brain, or sometimes the signals don't get past the area of compression. Therefore, patients with spinal stenosis may experience pain, numbness or weakness.

Spinal stenosis affects men and women equally, and most often is seen in people over the age of 50. People who have careers that are labor intensive are more prone to developing symptoms of spinal stenosis. The most common cause of spinal stenosis is arthritis of the spine, and it is uncommon to find this condition in individuals younger than 30 years old.

When spinal stenosis does occur in younger patients, it is often related to traumatic injury to the spinal column.

Causes of Stenosis

Spinal stenosis may be caused by a wide variety of conditions, all of which lead to a narrowing of the spinal canal. These conditions may be either acquired or inherited. Spinal stenosis is most often caused from spine arthritis, a process that causes arthritic changes in the spine leading to nerve compression. Common changes of spinal arthritis include the formation of bone spurs, calcification of spinal ligaments, thickening of joint tissue due to chronic inflammation, and degeneration of the spinal disc. All of these changes narrow the space around the nerves, eventually leading to nerve compression.

Other acquired conditions that may lead to spinal stenosis include rheumatoid arthritis, spinal tumors, Paget's disease, and traumatic damage to the vertebral column. Inherited conditions that lead to spinal stenosis include congenital spinal stenosis, scoliosis, and achondroplasia.

Symptoms of Stenosis

Spinal stenosis can cause a wide variety of symptoms throughout the body. The most common symptoms are:

• pain,
• numbness,
• tingling, and
• weakness.

If the area of narrowing of the spine is in the cervical (neck) region, the symptoms are felt in the arms, and if the area of narrowing is in the lumbar (low back) the symptoms are felt in the legs.
Other symptoms may occur as a result of spinal stenosis. One particularly worrisome symptom is bowel or bladder dysfunction (inability to control urination or bowel movements). This can be a symptom of cauda equina syndrome, and should be treated as a medical emergency. Cauda equina syndromemay require immediate surgery to decompress (create more space) the area of the spine that is seriously affected by nerve compression.