Spinal stenosis is a narrowing of the spinal canal, which places pressure on the spinal cord. If the stenosis is located on the lower part of the spinal cord it is called lumbar spinal stenosis. Stenosis in the upper part of the spinal cord is called cervical spinal stenosis. While spinal stenosis can be found in any part of the spine, the lumbar and cervical areas are the most commonly affected.
What Causes Spinal Stenosis?Some patients are born with this narrowing, but most often spinal stenosis is seen in patients over the age of 50. In these patients, stenosis is the gradual result of aging and "wear and tear" on the spine during everyday activities. There most likely is a genetic predisposition to this since only a minority of individuals develops advanced symptomatic changes. As people age, the ligaments of the spine can thicken and harden (called calcification). Bones and joints may also enlarge, and bone spurs (called osteophytes) may form. Bulging or herniated discs are also common. Spondylolisthesis (the slipping of one vertebra onto another) also occurs and leads to compression. When these conditions occur in the spinal area, they can cause the spinal canal to narrow, creating pressure on the spinal nerve.
Symptoms of StenosisThe narrowing of the spinal canal itself does not usually cause any symptoms. It is when inflammation of the nerves occurs at the level of increased pressure that patients begin to experience problems. Patients with lumbar spinal stenosis may feel pain, weakness, or numbness in the legs, calves or buttocks. In the lumbar spine, symptoms often increase when walking short distances and decrease when the patient sits, bends forward or lies down. Cervical spinal stenosis may cause similar symptoms in the shoulders, arms, and legs; hand clumsiness and gait and balance disturbances can also occur. In some patients the pain starts in the legs and moves upward to the buttocks; in other patients the pain begins higher in the body and moves downward. This is referred to as a "sensory march". The pain may radiate like sciatica or may be a cramping pain. In severe cases, the pain can be constant. Severe cases of stenosis can also cause bladder and bowel problems, but this rarely occurs. Also paraplegia or significant loss of function also rarely, if ever, occurs.
How Stenosis is DiagnosedBefore making a diagnosis of stenosis, it is important for the doctor to rule out other conditions that may have similar symptoms. In order to do this, most doctors use a combination of tools, including :
- History
The doctor will begin by asking the patient to describe any symptoms he or she is having and how the symptoms have changed over time. The doctor will also need to know how the patient has been treating these symptoms including what medications the patient has tried.
- Physical Examination
The doctor will then examine the patient by checking for any limitations of movement in the spine, problems with balance and signs of pain. The doctor will also look for any loss of extremity reflexes, muscle weakness, sensory loss, or abnormal reflexes which may suggest spinal cord involvement.
- Tests
After examining the patient, the doctor can use a variety of tests to look at the inside of the body. Examples of these tests include :
- X-rays - these tests can show the structure of the vertebrae and the outlines of joints and can detect calcification.
- MRI (magnetic resonance imaging) - this test gives a three-dimensional view of parts of the back and can show the spinal cord, nerve roots, and surrounding spaces, as well as enlargement, degeneration, tumors or infection.
- Computerized axial tomography (CAT scan) - this test shows the shape and size of the spinal canal, its contents and structures surrounding it. It shows bone better than nerve tissue.
- Myelogram - a liquid dye is injected into the spinal column and appears white against bone on an x-ray film. A myelogram can show pressure on the spinal cord or nerves from herniated discs, bone spurs or tumors.
- Bone Scan - This test uses injected radioactive material that attaches itself to bone. A bone scan can detect fractures, tumors, infections, and arthritis, but may not tell one disorder from another. Therefore, a bone scan is usually performed along with other tests.
Non-surgical Treatment of Spinal StenosisThere are a number of ways a doctor can treat stenosis without surgery. These include :
- Medications, including non-steroidal anti-inflammatory drugs (NSAIDs) to reduce swelling and pain, and analgesics to relieve pain.
- Corticosteroid injections (epidural steroids) can help reduce swelling and treat acute pain that radiates to the hips or down the leg. This pain relief may only be temporary and patients are usually not advised to get more than 3 injections per 6-month period.
- Rest or restricted activity (this may vary depending on extent of nerve involvement).
- Physical therapy and/or prescribed exercises to help stabilize the spine, build endurance and increase flexibility.
Surgical Treatment of Spinal StenosisIn many cases, non-surgical treatments do not treat the conditions that cause spinal stenosis, however they might temporarily relieve pain. Severe cases of stenosis often require surgery. The goal of the surgery is to relieve pressure on the spinal cord or spinal nerve by widening the spinal canal. This is done by removing, trimming, or realigning involved parts that are contributing to the pressure.
The most common surgery in the lumbar spine is called decompressive laminectomy in which the laminae (roof) of the vertebrae are removed to create more space for the nerves. A surgeon may perform a laminectomy with or without fusing vertebrae or removing part of a disc. Various devices (like screws or rods) may be used to enhance fusion and support unstable areas of the spine.
Other types of surgery to treat stenosis include the following :
- Laminotomy - when only a small portion of the lamina is removed to relieve pressure on the nerve roots;
- Foraminotomy - when the foramin (the area where the nerve roots exit the spinal canal) is removed to increase space over a nerve canal. This surgery can be done alone or along with a laminotomy;
- Medial Facetectomy - when part of the facet (a bony structure in the spinal canal) is removed to increase the space;
- Anterior Cervical Discectomy and Fusion - the cervical spine is reached through a small incision in the front of the neck. The intervertebral disc is removed and replaced with a small plug of bone, which in time will fuse the vertebrae.
- Cervical Corpectomy - when a portion of the vertebra and adjacent intervertebral discs are removed for decompression of the cervical spinal cord and spinal nerves. A bone graft, and in some cases a metal plate and screws, is used to stabilize the spine.
- Laminoplasty - a posterior approach in which the cervical spine is reached from the back of the neck and involves the surgical reconstruction of the posterior elements of the cervical spine to make more room for the spinal canal.
Overhead View of a Cervical Vertebra
- Spinous Process
- Lamina
- Zygapophysial Joint (Facet)
- Posterior Tubercle
- Foramin
- Pedicle
- Body
If nerves were badly damaged before the surgery, the patient may still have some pain or numbness after the surgery. Or there may be no improvement at all. Also, the degenerative process will likely continue, and pain or limitation of activity may reappear 5 or more years after surgery.
Most doctors will not consider surgical treatment of spinal stenosis unless several months of non-surgical treatment methods have been tried. Since all surgical procedures carry a certain amount of risk, patients are advised to discuss all treatment options with their doctor before deciding which procedure is best.