Lumbar Spinal Stenosis
When the spinal canal in the lower or lumbar portion of the spine becomes narrowed the condition is known as lumbar stenosis. The spinal cord and various nerves pass through the spinal canal. Many factors can cause lumbar stenosis or narrowing of the spinal canal. It typically occurs due to changes that accompany the process of growing older, such as the vertebrae moving out of alignment.
When the spinal canal or the side canals the provide protection for the nerves become narrow, nerves can become compressed. As the canal grows smaller, the compression worsens and the nerves become more irritated.
It is estimated that 8% to 11% of the general population of the United States has lumbar spinal stenosis (LSS).
Lumbar stenosis affects both men and women. The risk of developing the condition increases with age. It is especially prevalent in people who are in their seventh decade of life. Other medical conditions such as urological disorders, spinal fractures and osteoarthritis, diabetes mellitus and depressive symptoms are associated with LSS.
It is estimated that by the year 2012, approximately 2.4 million Americans will be affected by lumbar stenosis.
You are at increased risk of developing lumbar stenosis if you:
- Are female
- You were born with a spinal canal that is unusually narrow
- You are older than 50 years
You are also at increased risk for lumbar stenosis if you have a history of spinal surgery or a spinal injury
Some people are born with a spinal canal that is smaller than usual, but in most cases, lumbar stenosis is caused by another factor that decreases the amount of available room inside the canal. Some of the causes of lumbar stenosis include:
- Overgrowth of bone tissue: Bones spurs form and grow into the spinal canal due to wear and tear damage. A bone disease called Paget's disease can also cause an overgrowth of bone tissue causing lumbar stenosis.
- Herniated discs: The intervertebral discs that help to cushion your vertebrae dehydrate as they age. If the edges of a disc cracks, some of the gel-like material may leak out of the center and press on the spinal nerves or on the spinal cord.
- Thickened ligaments: Ligaments are the tough cords that bind your spine together. With age, they can become thickened and stiff and bulge into the canal, causing compression and lumbar stenosis.
- Tumors: Tumors that grow within the membranes covering the spinal cord, inside the spinal cord or in the spaces between the vertebrae and the spinal cord, causing compression and lumbar stenosis.
- Spinal injuries: Any trauma such as motor vehicle accidents can cause fractures or dislocations that move the vertebrae out of place. The displaced bone may injure the tissue inside the spinal canal. Swelling and inflammation following spinal surgery can also create pressure on the nerves or the spinal cord and cause lumbar stenosis.
Narrowing of the spinal canal is very common, especially in people over the age of 50, but many times it doesn't cause any symptoms. Symptoms begin when the nerve roots are pinched. The most common symptom of lumbar stenosis is a pain in the leg.
The most common symptom of lumbar stenosis is a pain in the leg that occurs with walking or standing and is relieved by sitting down or bending forward. The pain is felt in the legs because the nerves that travel through the lower portion of spine extend down into the legs. When the legs are out straight, as they are when you are standing or walking, the pain can be felt. In lumbar stenosis, when the spine is flexed, as it is when you are sitting, leaning over or walking up an incline, the pain feels better. That explains why people who have severe lumbar stenosis will often walk with a stooped, bending forward gait.
Other symptoms of lumbar stenosis may include:
- Cramping, weakness or numbness in the buttocks, legs or feet
- Stiffness in the thighs and legs can occur with lumbar stenosis
- Lower back pain
- Loss of bowel and bladder control in severe cases of lumbar stenosis
Your doctor will ask you how your pain of lumbar stenosis first began and how it has progressed. He or she will ask questions about your past medical history and complete a physical exam that is focused on your lower back and the nerve functioning of your lower extremities. Your gait and balance will also be checked if your doctor suspects lumbar stenosis.
Your doctor may want you to have x-rays taken to see if there are signs of degeneration of the facet joints or disc spaces associated with lumbar stenosis.
Your doctor may also recommend magnetic resolution imaging. An MRI allows your doctor to see structures that may be compressing the spinal cord or the nerve roots. Sometimes a dye is injected into the spinal canal, followed by a computerized tomography (CT) scan.
Nerve conduction studies are also sometimes ordered to help diagnose lumbar stenosis.
Treatment for lumbar stenosis usually includes one of the following treatments or a combination of treatments:
- Activity modification: People who have lumbar stenosis are usually the most comfortable when their back is flexed. For instance, patients may be helped by using a walker, a cane or a rolling walker. People with the condition may find activity tiring, so frequent rest breaks are recommended.
- Exercise: Most people with lumbar stenosis will be given some type of an exercise program. This will help to prevent further decline in their condition and help to relieve discomfort associated with the condition. Physical therapy is often recommended.
- Non-steroidal anti-inflammatory drugs (NSAIDs): Inflammation is a major component of lumbar stenosis, so anti-inflammatory drugs such as ibuprofen, naproxen, or Cox-2 inhibitors may be used as effective treatments.
- Epidural injections: These are usually given in an out-patient setting. The doctor administers a steroid medication into the epidural space, which is located between the vertebrae and the covering around the nerve root. Steroids help to reduce the pain and inflammation caused by lumbar stenosis.
If a patient's lumbar stenosis progresses to a point that the person can no longer walk or care for themselves, surgery may be recommended. The goal of lumbar stenosis surgery is usually to relieve pain and increase the patient's tolerance for activity so they can be more self-sufficient.
Surgery for lumbar stenosis
Usually, there are two techniques used in surgery for lumbar stenosis:
- Decompression: In decompression surgery for lumbar stenosis, a tissue that is pressing against a nerve or the spinal cord is removed, creating more room in the spinal canal
- Stabilization: In stabilization, movement between the vertebrae is restricted
Decompression Surgery for Lumbar Stenosis
In order to remove tissue that may be compressing a nerve or the spinal cord in lumbar stenosis, one of the following types of procedures may be performed:
- Foraminotomy: The nerves exist in the vertebrae through openings called foramen. If a bone spur or a portion of a disc is compressing a nerve in one of these openings, the opening may need to be enlarged. This procedure is called a foraminotomy and it may be recommended for lumbar stenosis.
- Laminotomy: The lamina is the bony plates of the vertebrae that protect the spinal cord and canal. These may be compressing nerves and may need to be made smaller. The procedure called a laminotomy makes the lamina smaller.
- Laminectomy: In a laminectomy, all or a large portion of the lamina is removed to make more room in the spinal canal. Sometimes this is performed with laminoplasty for lumbar stenosis, which preserves the anatomy of the bone.
Indirect decompression is a procedure in which the bones are spread apart, rather than removed in some cases of lumbar stenosis. Instrumentation (surgical hardware) can be used or sometimes artificial discs can be inserted to restore height between vertebrae that lie next to each other.
Stabilization Surgery for Spinal Stenosis
Stabilization is also called spinal fusion. It is not required in all cases of surgery for lumbar stenosis. It is helpful though if one or more vertebrae have come out of alignment. When the vertebrae are not in alignment, the spine is unstable and painful. Bones slipping in cases like this can cause nerve compression with lumbar stenosis. Whether or not stabilization is needed also is dependent on how many vertebrae need to be operated on. For instance, if the surgeon needs to perform a laminectomy on several vertebrae, this will create spinal instability and fusion will most likely be needed. Stabilization surgery can be completed at the same time as decompression for lumbar stenosis or it can be done as a separate procedure. A bone graft is taken from a donor site, usually a bone from your own body for the procedure. As an alternative, a biological material can be used which will stimulate bone to grow. The surgeon will also possibly use instrumentation such as wires, screws, metal plates or rods to help the spine be more stable while the graft and your vertebrae fuse into one solid piece of bone. The fusion stops unstable movement between the vertebrae. The instrumentation is permanent and does not need to be removed.