Spinal stenosis (sten-oh-sis) is when the spinal canal – the area where the spinal cord travels through the spine – narrows. It may occur because of aging or degeneration of the bones in the spine, and can cause back and leg pain that comes and goes with activities such as walking. Stenosis can occur in all areas of the spine, but it is most common in the lumbar spine. Spinal stenosis usually affects people over 60 years of age. However, it can also occur in younger people who have abnormally small spinal canals from birth.
Anything that narrows the spinal canal places the spinal cord and spinal nerves at risk. The lack of space puts pressure on them, causing irritation and inflammation. Conditions that can narrow the spinal canal include:
Spinal stenosis usually occurs in older people due to years of wear and tear (degeneration) of the spine. The changes that happen from this process include thickened ligaments, bone spurs, facet joint enlargement (hypertrophy), and bulging discs.
In some cases, simply bending over can relieve the symptoms. Bending makes the spinal canal larger and provides more space so that the blood flow to the spinal nerves increases. Activities that increase the demand for blood flow cause the blood vessels to swell and enlarge. If there is no room for this to occur, the blood flow cannot increase. This causes pain and weakness because the nerves cannot get enough oxygen to meet the demand.
Some people have a narrow spinal canal from birth. This does not mean they automatically feel symptoms of stenosis. But if the spinal canal is too narrow, it can lead to pressure on the spinal nerves. People who have a very narrow canal are at risk for stenosis because even minor crowding inside the spinal canal can lead to symptoms.
The main symptoms of spinal stenosis are felt in the legs and include:
The symptoms of spinal stenosis are caused by the nerve roots getting squeezed, which upsets the normal signals traveling from the brain to the body. Irritation of the nerves becomes worse when you are standing or walking due to pressure and stretching of the nerves. Symptoms often disappear with rest. Sitting down seems to take pressure of the nerve roots.