Spinal stenosis describes narrowing inside your spinal canal and mainly occurs from a combination of aging and degenerative changes in your spine. Wear and tear on the parts of your spine can cause discs to bulge, spine ligaments to thicken, and joints near your spinal canal to become enlarged. These can take up space inside your spinal canal and put pressure on your 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.
Anything that narrows your spinal canal places your spinal cord and spinal nerves at risk. The lack of space puts pressure on them, causing irritation and inflammation. Conditions that can narrow your 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 ) on the spine. The changes that happen from this process include thickened ligaments, bone spurs, facet joint enlargement (hypertrophy), and bulging discs.
As we age, the discs in our spine lose some of their water content and, as a result, some of their shock absorbing ability. The first changes that occur in the disc are tears in the outer ring of the disc, called the annulus. Tears in the annulus may occur without symptoms. You may not notice when they occur or what caused them. These tears heal by forming scar tissue.
Scar tissue is weaker than normal tissue. Repeated injuries and tears cause more wear and tear to the disc. As the disc wears, it gets less and less “spongy”, eventually becoming unable to act as a shock absorber.
As the disc continues to wear, it begins to collapse . The space between each vertebra becomes smaller. This collapse affects how the facet joints in the back of your spine “line up.” Like any other joint in your body, the change in the way your spine bones fit together causes abnormal pressure on the articular cartilage covering your facet joints. Articular cartilage is a smooth, shiny material that covers the end of the bones in most joints in your body. Over time, this abnormal pressure causes wear and tear arthritis(osteoarthritis) of the facet joints.
Bone spurs may form around your vertebrae and facet joints. Eventually, bone spurs may begin to form. These spurs may begin to press against your spinal cord, leading to symptoms of myelopathy. Or the spurs can put pressure on your nerves where they leave your spinal canal. This can lead to symptoms ofradiculopathy .
The combined effects of the bone spurs, bulging discs, and thickened ligaments place the spinal cord at risk of being squeezed inside the spinalcanal.
In some cases, simply bending over relieves the symptoms. This makes your spinal canal larger and provides more space so that the blood flow to your spinal nerves increases. Activities that increase the demand for blood flow cause your 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 your 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 your spinal canal is too narrow, it can lead to pressure on your spinal nerves. People who have a very narrow spinal canal are at risk for stenosis because even minor crowding inside the spinal canal can lead to symptoms.
The symptoms of spinal stenosis depend on whether pressure is affecting your spinal nerve roots or your spinal cord. A pinched nerve (radiculopathy) in your neck usually only causes symptoms in your neck and arms. Pressure on your spinal cord (myelopathy) can affect your arms and legs.
Radiculopathy is a condition that can happen from pressure on a spinal nerve root. Commonly thought of as a “pinched nerve,” this type of pressure feels different than pressure on your spinal cord. Pressure on an irritated or inflamed nerve root may produce feelings of pins and needles in the area supplied by the nerve root. The pain may feel deep, dull, and achy. Or you may have sharp, shooting pain along the path of the nerve. Muscles controlled by the affected nerve root may also weaken.
Myelopathy is a greater concern because it can lead to permanent spinal cord damage. Symptoms from myelopathy vary. Feelings of numbness or weakness can affect both your arms and legs. A loss of muscle control in your legs, called spasticity, may cause difficulty walking. “Position sense” may be lost in your arms or legs. This affects your ability to know where your arms or legs are when your eyes are closed. When this occurs it becomes difficult to use your arms and hands and to know where you are placing your feet as you walk. Myelopathy may also disturb the normal function of your bowels and bladder.
Finding the cause of your spinal stenosis begins with a complete history and physical exam. Afterward, your doctor will have a good idea of the cause of your pain and symptoms. To make sure of the exact cause of your pain, several diagnostic tests can be used. Standard X-rays, taken in your doctor’s office, are usually a first step in looking into any spinal problem and will give your doctor an idea of whether spinal stenosis exists. These include an oblique (angled) view, along with X-rays taken as you bend forward (flexion) and backward (extension).
Your doctor will also determine whether other tests, such as an MRI or a CT scan, are needed. An MRI can be used to verify loss of water in a disc, facet joint hypertrophy (enlargement), stenosis (narrowing of spinal canal), or a herniated disc (protrusion or rupture of the intervertebral disc). A CT scan forms a set of cross-sectional images that can show disc problems and degeneration of bones, such as bone spur formation or facet hypertrophy (enlargement). CT scan images are not as clear as either X-rays or an MRI. To make the soft tissues easier to see, the CT scan is often combined with a myelogram. Other tests are sometimes used to make sure there are not additional problems causing your back or neck pain.
X-rays of cervical disc degeneration.
MRI scan showing cervical stenosis.
On your first visit to a back specialist, the initial determination that must be made is the seriousness of the problem. Some problems need immediate attention–possibly even surgery. The vast majority of back problems do not require surgery. Spinal stenosis is a slowly progressive back problem that may respond to conservative care.
A variety of treatment options exists for spinal stenosis. In most cases, simple therapies such as mild pain medications and rest are effective in relieving the immediate pain. Physical therapy may be beneficial if symptoms are not relieved with simple measures. The overall goal of treatment is to make you as comfortable as soon as possible, and to get you back to normal activity in a timely manner.
Epidural Steroid Injection (ESI)
An epidural steroid injection (ESI) can be used to relieve the pain of stenosis and irritated nerve roots, as well as to decrease inflammation. Injections can help reduce swelling from inflamed tissues in your spinal canal, which may result in less irritation on your nerves. The steroid injections are a combination of cortisone (a powerful anti-inflammatory steroid) and a local anesthetic that are given through your back into the epidural space. Epidural steroid injections are not always successful in relieving symptoms of inflammation. They are only used when conservative treatments have failed.
Spinal stenosis may continue to get worse over time. Surgery may be considered as a treatment option if:
You experience an increase in the weakness in your arms or legs
You can no longer walk or use your arms without pain
You begin to have trouble controlling your bowels or bladder
Your pain becomes unbearable
Because spinal stenosis is more common in elderly people, one of the considerations for suggesting surgery is your overall physical condition. Back surgery is a major undertaking. If you have serious medical problems, the risks may be too great to have spine surgery.
The main goal of any surgical procedure used to treat spinal stenosis is to remove the pressure on the nerve roots in your spinal canal. This means that the tube of the spinal canal must be made larger, and any bone spurs that are pushing into your nerve roots must be removed. This type of surgical procedure is usually called a decompression or a decompressive laminectomy.
In order to free up or “decompress” the affected nerves in your spine, the doctor must remove a section of bone from the back of the spine (lamina). The doctor may also have to remove a portion of the facet joints. The lamina and facet joints normally provide stability in the spine. Removal of either or both can cause the spine to become loose and unstable. When this occurs, doctors will include fusion as part of the procedure. Likewise, patients with spinal instability who need surgery for spinal stenosis will likely also need spinal fusion.
Discectomy, the removal of one or more discs, may be suggested if your stenosis is coming from problems of disc herniation. This surgery may be done from the front or back of the spine.
Or your surgeon may suggest an operation that is done from the front of the neck, called a corpectomy and strut graft .This operation involves removing the discs and vertebral bodies in the area where your problems are occurring. Bone spurs that are pushing into your spinal cord are also removed . The affected vertebrae are then replaced with a solid piece of bone graft (called a strut graft). The strut graft heals over time to create a solid fusion of your spine where the vertebral bodies have been removed.