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Spinal stenosis describes narrowing inside the spinal canal and mainly occurs from a combination of aging and degenerative changes in the spine. Wear and tear on the parts of the spine can cause discs to bulge, spine ligaments to thicken, and joints near the spinal canal to become enlarged. These can take up space inside the spinal canal and put pressure on the spinal nerves. Changes like these mostly affect people over 60 years of age. However, spinal stenosis also occurs in younger people who have abnormally small spinal canals from birth. Spinal stenosis usually causes back pain 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. The spinal canal is a tube within the bones of the spinal column. The spinal cord and spinal nerves are normally protected inside this bony tube. Bordered by bone and tough ligaments, the spinal canal cannot expand when something crowds the space within the canal. Normally there is space between the spinal cord and the edges of the surrounding spinal canal.
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 infection, tumors, trauma, herniated discs, arthritis, thickening of ligaments, and bone spurs.
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 relieves the symptoms. This 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-heaviness, weakness, and pain with walking or prolonged standing. The symptoms are caused by the nerve roots getting squeezed, which upsets the normal signals traveling from the brain to the body. Irritation of the nerves is worse when 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.
You may be asked to take a variety of diagnostic tests. The tests are chosen based upon what the physician suspects is causing your pain. The most common diagnostic tests to determine whether you have spinal stenosis are X-rays of your lower back and an MRI scan. In some cases, a CT scan may be ordered, either in addition to an MRI or instead of one.
Conservative treatment options can include epidural steroid injection (ESI), also called a nerve block, medications, and physical therapy.
Spinal stenosis may continue to get worse over time and surgery may be considered as a treatment option. Surgical treatments can include a decompressive laminectomy to free up or “decompress” the nerves, the surgeon must remove a section of bone from the back of the spine (lamina). Your procedure might also include fusion. Patients with spinal instability who need surgery for spinal stenosis will likely also need lumbar fusion.