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Homeostatic Imbalances Of The Spinal Cord: Spinal Stenosis

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Autor:  webster  14 December 2009
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Stenosis means “closing in” or “choking”. Spinal stenosis describes a condition in which the nerves in the spinal canal are closed in, or compressed. The spinal canal is the hollow vertical hole formed by the bones of the spinal column. Anything that causes this bony hole to shrink can squeeze the nerves inside. This narrowing can irritate the nerve roots that branch out from the spinal cord, or it can squeeze and irritate the spinal cord itself. This may cause pain, numbness, or weakness, most often in the legs, feet and buttocks. As a result of many years of wear and tear on the parts of the spine, the tissues nearest the spinal cord sometimes press against the nerves. The actual narrowing of the spinal canal does not cause symptoms. Symptoms develop when the spinal cord or nerve roots are compressed. Spinal stenosis may affect the cervical, thoracic or lumbar spine. The most common area affected is the lumbar spine followed by the cervical spine. Although many people older than age 50 have some narrowing of the spinal canal, not all experience symptoms. This helps explain why lumbar spinal stenosis is a common cause of back problems in adults over 50 years old.

In the lumbar spine, the spinal canal usually has more than enough room for the spinal nerves. The canal is normally 17 to 18 millimeters around, slightly smaller than a penny. Spinal stenosis develops when the canal shrink to 12 millimeters or less. When the size drops below 10 millimeters, severe symptoms of lumbar spinal stenosis occur. There are many reasons why symptoms of spinal stenosis develop. Some of the more common reasons include congenital stenosis (being born with a small spinal canal), spinal degeneration, spinal instability and disc herniation.

• Congenital stenosis happens when someone is born with a spinal canal that is narrower than normal. They may not feel problems early in life. However, having a narrow spinal canal puts them at risk for stenosis. Even a minor back injury can cause pressure against the spinal cord. People born with a narrow spinal canal often have problems later in life, because the canal tends to become narrower due to the effect of aging.
• Degeneration is the most common cause of spinal stenosis. Wear and tear on the spine from again and from repeated stresses and strains can cause many problems in the lumbar spine. The intervertebral disc can begin to collapse and the space between each vertebrae shrinks. Because discs are 80% water, as you age, they dry out and the space shrinks. Bone spurs may form that stick into the spinal canal and reduce the space available to the spinal nerves. The ligaments that hold the vertebrae together may thicken and also push into the spinal canal. All of these conditions cause the spinal canal to narrow.
• Spinal instability can cause spinal stenosis. Spinal instability means that the bones of the spine move more than they should. Instability in the lumbar spine can develop is the supporting ligaments have been stretched or torn from a severe back injury. People with diseases that loosen their connective tissues may also have spinal instability. What ever the cause, extra movement in the bones of the spine can lead to spinal stenosis.
• When an interverebral disc in the low back herniates or ruptures, spinal stenosis can occur. Normally, the shock-absorbing disc is able to handle the downward pressure of gravity and the strain from daily activities. However, if the pressure on the disc is too strong, such as landing from a fall in a sitting position, the nucleus inside the disc may rupture through the outer annulus and squeeze out of the disc. This is called a disc herniation. If an intervertebral disc herniates straight backward, it can press against the nerves in the spinal canal, causing symptoms of spinal stenosis.

Other causes of lumbar spinal stenosis include facet joint hypertrophy, spondylolisthesis, Paget’s disease and fluorosis. These ailments are not as common.

Spinal stenosis usually develops slowly over a long period of time. This is because the main cause of spinal stenosis is spinal degeneration in later life. Symptoms rarely develop quickly when degeneration is the source of the problem. A severe injury or a herniated disc may cause symptoms to develop immediately. People with stenosis don’t always feel back pain. Primarily, they have pain and weakness in their legs, usually in both legs at the some time. Some people say they feel that their legs are going to give out on them. Symptoms mainly affect sensation in the lower limbs. Nerve pressure from stenosis can cause a feeling of pins and needles in the skin where the spinal nerves travel. Reflexes become slowed. Some people report “charley horses” in their leg muscles. Others report strange sensation like water trickling down their legs. Symptoms change with the position of the low back. Flexion, or bending forward, widens the spinal canal and usually eases symptoms. That’s why people with stenosis tend to get relief when they sit down or curl up to sleep. Activities such as reaching up, standing and walking require the spine to straighten or even extend (bend back slightly). This position of the low back makes the spinal canal smaller and often worsens symptoms. In cases of severe spinal stenosis, some people even lose bladder and bowel control.

Diagnosis begins with a complete history and physical examination. The doctor usually asks questions about symptoms and how the problem is affecting the daily the activities of the patient. This will also include question about pain and feelings of numbness or weakness in the legs. The doctor will want to know whether the symptoms are worse when standing up or walking and if they go away when sitting down. During the physical examination, the doctor will test to see which back movements cause pain or other symptoms. Skin sensation, muscle strength and reflexes are also tested. X-rays can show if the problems are from changes in the bones of the spine. The images can show if degeneration has caused the space between the vertebrae to collapse. X-rays may also show any bone spurs sticking into the spinal canal.

When more information is needed, the doctor may order a magnetic resonance imaging (MRI) scan. The MRI machine uses magnetic waves rather than x-rays to show the soft tissues of the body. This test gives a clear picture of the spinal canal and whether the nerves inside are being compressed. This machine creates pictures that look like slices of the area the doctor is interested in. The test does not require dye or a needle. Also, the computed tomography (CT) scan may be ordered. The CT scan is a detailed x-ray that lets the doctor see slices of bone tissue. The image can show any bone spurs that may be sticking into the spinal column and taking up space around the spinal nerves.

When the diagnosis is still not clear, doctors may recommend electrical tests of the nerves that go to the legs and feet. An electromyogram (EMG) checks whether the motor pathway of a nerve is working correctly. Motor impulses travel down the nerve and work to energize muscles. To locate more precisely where the spinal nerves are being compressed, a somatosensory evoked potential (SSEP) test can be used to measure nerve sensations. These sensory impulses travel up the nerve, informing the body about sensations such as pain, temperature and touch. The function of a nerve is recorded by an electrode placed over the skin in the area where the nerve travels. Studies have documented that myelography with water soluble contract media and CT scans are the most accurate tests for confirming the diagnosis of spinal stenosis.

Not all causes of spinal stenosis are from degenerative conditions. Doctors use blood tests to determine whether symptoms are coming from other conditions, such as arthritis or infection. Various other medical causes can create back pain and mimic spinal stenosis. These include, but are not limited to duodenal ulcers, abdominal aneurysms, kidney stones, pancreatitis and renal tumors.

Unless the condition is causing significant problems or is rapidly getting worse, most doctors will begin with nonsurgical treatments. At first, the doctor may prescribe ways to immobilize the spine. Keeping the back still for a short time can calm inflammation and pain. This might include one to two days of bed rest. A lumbar support belt or corset may be prescribed, though the benefits are controversial. The support can limit pressure in the discs and prevent extra movement in the spine, but it can also cause the back and abdominal muscles to weaken. Some doctors have their patients wear a rigid brace that holds the spine in a slightly flexed position, widening the spinal canal. Corsets are normally worn for one or two weeks.

Other nonsurgical treatments include medications such as nonsteroidal anti-inflammatory drugs (NSAID’s) or aspirin. These medications can cause side effects in the kidneys and gastrointestinal tract. Also, because most stenosis patients are elderly, doctors closely monitor patients who are using these medications to avoid complications. Narcotic drugs, such as codeine or morphine, are generally not prescribed for stenosis patients. They are addictive when used too much or improperly. Muscle relaxants are occasionally used to calm muscle spasms. Symptoms of stenosis can lead to mood changes and as a result, doctors sometimes prescribe anti-depressants called tricyclics. These medications also seem to calm back pain by affecting the membranes around pain nerves.

Some patients are given epidural steroid injections (ESI). It is thought that injecting steroid medication into the epidural space fights inflammation around the nerves, the disc and the fact joints. This can reduce swelling and five the nerves more room inside the spinal canal. Other injections given include facet joint injections and nerve blocks. Some patients respond well to physical therapy. The therapist may suggest traction which gently stretches the low back taking pressure off the spinal nerves. Strengthening and aerobic exercises are also recommended.

Severe symptoms that are getting worse or restrict normal daily activities usually will not improve with nonsurgical therapy and may require surgery. In these cases surgery to remove bone and tissue that are compressing the spinal cord can help relieve leg pain and allow one to resume normal daily activities. This surgery is called a decompressive laminectomy. Pressure on the spinal nerves can cause a loss of control in the bowels or bladder. This is an emergency. If the pressure is not relieved, it can lead to permanent paralysis of the bowels and bladder. Some patients also require fusion surgery immediately after the laminectomy procedure if spinal instability in present. The fusion surgery joins two or more bones into one solid bone. In this procedure, the surgeon lays small grafts of bone over the back of the spine. Most surgeons also apply metal plates and screws to prevent two vertebrae from moving. This protects the graft so it can heal better and faster.

Some alternative treatments for spinal stenosis include chiropractic treatment and acupuncture. More research is needed on the value of these treatments. Some doctors may suggest alternative treatments in addition to standard treatments.

In the absence of severe or progressively abnormal neurologic signs, the prognosis is based on the patient’s symptoms. With operative treatments, the duration of care is six to twelve months. In either case, complete or partial relief of back and leg pain is expected along with improved quality of life.

Research in this field in ongoing and include new procedures such as the X-Stop and laminoplasty. Also, scientists are trying to answer question on whether surgery or other treatments are more effective in treating spinal stenosis and can MRIs identify who should have surgery.

In conclusion, since I am not a nursing student, I can only give the same advice that I have received from my doctor. I was diagnosed with lumbar spinal stenosis in 2004 and have routinely been receiving epidural steroid injections, facet joint injections and most recently an L-5 nerve block. At this time, pain relief is minimal and short lived. So for the patient new to this treatment, my advice would be to continue to search for new options, but don’t be disappointed at road blocks. New treatments are always being discovered. I look for any treatment that will delay having a laminectomy. The X-Stop procedure sounds promising but one of the criteria for this treatment is being at least 50 years of age. That just means I’ll have to wait another three years before I’m eligible. In the mean time, I remain optimistic.


• American Association of Neurological Surgeons, “Your Aging Back: Understanding Lumbar Spinal Stenosis”, 2007

• Chiu, John C. “Treatment of Lumbar Spinal Stenosis with Interspinous Process Decompression System (IPD) (X-Stop)
The Internet Journal of Minimally Invasive Spinal Technology. 2007. Volume 1 Number 1.

• Eidelson, Stewart G. “Spinal Stenosis: Cervical and Lumbar Nerve Compression”

• Filler, Aaron. “Do You Really Need Back Surgery”. Oxford University Press Online

• National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS). “What is Spinal Stenosis? Fast Facts: An Easy-to-Read Series of Publications for the Public”. September 2005.

• Sama, Andrew A.; Girardi, Federico P.; Cammisa, Frank P. Jr. “Lumbar Stenosis- An Overview”. May 1,2003.

• Spivak, Jeffrey. “Current Concepts Review-Degenerative Lumbar Spinal Stenosis”. The Journal of Bone and Joint Surgery 80:1053-66 (1998)

• U.S. National Library of Medicine and the National Institutes of Health. “Medical Encyclopedia: Spinal Stenosis”. September 26,2006.

• WebMD Medical reference from Healthwise. “Back Pain Health Center”. March 7, 2006.


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