The Bonati Institute Glossary: Spinal Stenosis

The mission of The Bonati Institute is to provide hope to people suffering with chronic pain from a back or neck condition. We believe that a well-informed patient is vital to restoring hope and finding answers to pain. We developed this web site primarily to help educate pain sufferers and their families. We’ve found that the more individuals in pain learn about their anatomy, their condition and the options available to them the more likely they will be to choose the advanced arthroscopic procedures offered by The Bonati Institute.

Definition of Spinal Stenosis

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.

Description

Spinal stenosis is a progressive narrowing of the opening in the spinal canal. The spine is a long series of bones called vertebrae. Between each pair of vertebra is a fibrous intervertebral disc. Collectively, the vertebrae and discs are called the backbone. Each vertebra has a hole through it. These holes line up to form the spinal canal. A large bundle of nerves called the spinal cord runs through the spinal canal. This bundle of 31 nerves carries messages between the brain and the various parts of the body. At each vertebra, some smaller nerves branch out from these nerve roots to serve the muscles and tissue in the immediate area. When the spinal canal narrows, nerve roots in the spinal cord are squeezed. Pressure on the nerve roots causes chronic pain and loss of control over some functions because communication with the brain is interrupted. The lower back and legs are most affected by spinal stenosis. The nerve roots that supply the legs are near the bottom of the spinal cord. The pain gets worse after standing for a long time and after some forms of exercise. The posture required by these physical activities increases the stress on the nerve roots. Spinal stenosis usually affects people over 50 years of age. Women have the condition more frequently than men do.

Cervical spinal stenosis is a narrowing of the vertebrae of the neck (cervical vertebrae). The disease and its effects are similar to stenosis in the lower spine. A narrower opening in the cervical vertebrae can also put pressure on arteries entering the spinal column, cutting off the blood supply to the remainder of the spinal cord.

Causes

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.

Spinal stenosis causes pain in the buttocks, thigh, and calf and increasing weakness in the legs. The patient may also have difficulty controlling bladder and bowel functions. The pain of spinal stenosis seems more severe when the patient walks downhill. Spinal stenosis can be congenital, acquired, or a combination. Congenital spinal stenosis is a birth defect. Acquired spinal stenosis develops after birth. It is usually a consequence of tissue destruction (degeneration) caused by an infectious disease or a disease in which the immune system attacks the body's own cells (autoimmune disease). The two most common causes of spinal stenosis are birth defect and progressive degeneration of the tissue of the joints (osteoarthritis). Other causes include improper alignment of the vertebrae as in spondylolisthesis, destruction of bone tissue as in Paget's disease, or an overgrowth of bone tissue as in diffuse idiopathic skeletal hyperostosis. The spinal canal is usually more than 0.5 in (12 mm) in diameter. A smaller diameter indicates stenosis. The diameter of the cervical spine ranges is 0.6-1 in (15-12 mm). Any opening under 0.5 in (13 mm)in diameter is considered evidence of stenosis. Acquired spinal stenosis usually begins with degeneration of the intervertebral discs or the surfaces of the vertebrae or both. In trying to heal this degeneration, the body builds up the spinal column. In the process, the spinal canal can become narrower.

Symptoms

The 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.

Diagnosis

The physician must determine that the symptoms are caused by spinal stenosis. Conditions that can cause similar symptoms include a slipped (herniated) intervertebral disc, spinal tumors, and disorders of the blood flow (circulatory disorders). Spinal stenosis causes back and leg pain. The leg pain is usually worse when the patient is standing or walking. Some forms of spinal stenosis are less painful when the patient is riding an exercise bike because the forward tilt of the body changes the pressure in the spinal column. Doppler scanning can trace the flow of blood to determine whether the pain is caused by circulatory problems. X-ray images, computed tomography scans (CT scans), and magnetic resonance imaging (MRI) scans can reveal any narrowing of the spinal canal. Electromyography, nerve conduction velocity, or evoked potential studies can locate problems in the muscles indicating areas of spinal cord compression.

How Stenosis is Diagnosed

Before 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.

Treatment

Mild cases of spinal stenosis may be treated with rest, nonsteroidal anti-inflammatory drugs (such as aspirin), and muscle relaxants. Spinal stenosis can be a progressive disease, however, and the source of pressure may have to be surgically removed..

Surgical Treatment

In 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 - the cervical spine is reached through a small incision in the front of the neck.