The spine is made up of 33 bones (vertebrae) held together by fibrous bands (ligaments). There are seven cervical vertebrae in the neck and 12 thoracic vertebrae in the middle of the back. The five large lumbar vertebrae in the lower back carry most of the body’s weight. Below the lumbar vertebrae are the sacrum, made from five fused vertebrae, and the coccyx (tailbone). Together, these bones are referred to as the spine, spinal column or vertebral column.
The spine supports the upper body’s weight. It also houses and protects the spinal cord, which along with the brain forms the central nervous system. The spinal cord is made up of nerves and nerve cells that extend the length of the spine. Thirty-one pairs of nerves branch off from the spinal cord and transmit electrical signals between the brain and the nerves in the legs, arms and other areas of the body. The spinal cord extends from the base of the brain to just below the rib cage. A bundle of nerves known as the cauda equina continues from the lumbar region, where the spinal cord ends, and downward. This provides neurologic function to the lower part of the body.
Spinal stenosis is a result of a narrowing of the spine that puts pressure on the spinal cord or nerve roots. It is categorized as one of the following two varieties:
Spinal stenosis may affect a large or small portion of the spine. It tends to affect one or more of three areas:
- Primary stenosis. Relatively uncommon, it is the result of congenital disorders (those present at birth), such as being born with a narrow spinal canal.
- Acquired stenosis. Develops later in life, usually as a result of degenerative changes in the spine that occur with aging. This is the more common source of stenosis.
- The canal in the center of the spinal column through which the spinal cord and nerve roots run
- The canals at the base or root of nerves that branch out from the spinal cord
- The openings between the vertebrae through which the nerves leave the spine on their way to other parts of the body
Signs and symptoms of spinal stenosisIn some cases, spinal stenosis does not cause any symptoms. However, it is more likely that patients will experience gradual symptoms that will worsen over time. These may include:
Patients may also experience symptoms as a result of other conditions associated with spinal stenosis. For example, loss of sensation in the feet and legs may allow cuts and wounds to fester and become infected because the patients are not aware of their presence. Spinal stenosis also may cause muscle atrophy (wasting) that is sometimes permanent, even after the condition has been successfully treated.
- Leg pain or cramping in the legs. Compression of nerves or spinal cord in the lower spine may lead to a condition known as neurologic intermittent claudication, more commonly known as pseudoclaudication. Pseudoclaudication triggers pain or cramping in the legs of those who walk or stand for extended periods of time.
- Patients with pseudoclaudication usually find that bending forward relieves symptoms, as this takes pressure off the nerves. Unlike true (vascular) claudication, a common pain symptom caused by constriction of blood vessels in the leg (typically due to peripheral arterial disease), at least 20 minutes of rest rather than a few minutes may be required to ease leg pain caused by spinal stenosis.
- Sciatic nerve pain (sciatica). Discomfort that radiates down the back, hip and into the leg. This is usually the result of a herniated disc pressuring the sciatic nerve, which extends down the back of each leg. For most patients, pain usually affects just one leg and worsens during sitting. In addition to pain, patients may experience numbness, weakness and tingling in the leg or foot.
- Neck pain and shoulder pain. Occurs when the nerves or spinal cord of the neck are compressed and may occur either occasionally or chronically. In some patients, pain extends into the arm or hand and can cause headaches, loss of sensation or muscle weakness.
- Loss of balance. Pressure on the cervical spinal cord can affect the nerves that control balance, causing clumsiness or a tendency to fall.
- Loss of bowel and bladder function. Patients with these symptoms may have cauda equina syndrome, a very dangerous condition that affects the nerves at the lower end of the spinal cord. Immediate medical attention is necessary to prevent serious and permanent damage.
How is it diagnosed?
Patients who experience unexplained pain, stiffness, numbness or weakness in the back, legs, neck or shoulders should seek medical care. Spinal stenosis is especially likely when a patient has leg pain that worsens during walking but improves when sitting or bending forward.
Sudden inability to control bladder or bowel movements (incontinence) is a sign of cauda equina syndrome, a serious but rare form of spinal stenosis in which there is compression of the sack of nerve roots below the spinal cord. This condition demands immediate medical attention to prevent neurological damage.
In diagnosing spinal stenosis, a physician will review a medical history and perform a physical examination. Spinal stenosis is sometimes difficult to diagnose, as symptoms may come and go. In addition, symptoms associated with spinal stenosis can sometimes be mistaken for those of routine aging. The patient may be asked to complete a pain assessment.
Spinal stenosis is sometimes difficult to diagnose, as symptoms may come and go. In addition, symptoms associated with spinal stenosis can sometimes be mistaken for those of routine aging. A physician may therefore use various imaging tests to identify the source of symptoms. These tests include:
In some cases, a physician may inject a patient with a spinal nerve block or epidural corticosteroids. The patient is monitored for improvement in symptoms.
- X-ray. Though this test is unlikely to reveal spinal stenosis, it can help rule out other conditions that cause similar symptoms, including fractures, bone tumors or inherited defects.
- MRI (magnetic resonance imaging). The cross-sectional images revealed by this test can highlight damage to intervertebral discs and ligaments, and uncover the presence of tumors.
- CAT scan (computed axial tomography). Producing cross-sectional x-ray images, CAT scans may be used to reveal the shape and size of the spinal canal. However, this test exposes patients to more radiation than an x-ray and is not recommended for women who are pregnant.
- Myelography. Perhaps the most sensitive test for detecting spinal stenosis, it involves injecting a contrast dye into the spinal column that circulates around the spinal cord and spinal nerves. Myelograms can reveal herniated discs, bone spurs and tumors. However, because the test requires an injection into the spinal column, it poses slightly higher risks than some other procedures.
- Bone scan. A small amount of radioactive material is injected into a vein in the arm. The material attaches to bone and emits waves of radiation that are detected by a gamma camera. This type of radionuclide imaging can detect many bone disorders but usually cannot specify the type of disorder. For this reason, other tests are usually performed with bone scans to help diagnose bone conditions.
How is Spinal stenosis treated?
The degenerative process that leads to spinal stenosis generally cannot be treated. However, nonsurgical and surgical treatments can relieve the nerve compression that leads to pain suffered by those with spinal stenosis.
Nonsurgical treatments include:
In some cases, spine surgery will be necessary to address spinal stenosis. The goal of surgery is to relieve pressure on the spinal cord or nerves while maintaining the integrity and strength of the spine. Examples of surgery include:
- Over-the-counter medications. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin, ibuprofen or naproxen can reduce inflammation and pain. Analgesics such as acetaminophen relieve pain but do not reduce inflammation. Supplements such as glucosamine and chondroitin have been shown to have a positive effect for pain relief in some cases of moderate to severe knee osteoarthritis. However, it is not known whether this benefit extends to osteoarthritis of the spine. As with all medications, patients should consult with a physician before using these supplements.
- Moderate exercise or rest. Moderate rest may improve symptoms but should not be overdone. Research shows that moderate exercise is even more beneficial to symptom relief. Walking can especially benefit patients with neurogenic claudication (pseudoclaudication). Biking may also be beneficial, as it keeps the back in a flexed rather than extended position. Patients may be referred to physical therapy for supervised exercise and for pain-relieving modalities such as thermotherapy (heat), hydrotherapy or electrical therapy.
- Back brace or corset. This can provide support to the spine, and may particularly benefit patients who have weak abdominal muscles or degeneration in more than one area of the spine.
- Nonsurgical spinal decompression. The U.S. Food and Drug Administration has approved systems in which the patient lies on a special mechanical table designed to relieve pressure on the discs. A patient may have sessions of up to an hour most days of the week for several weeks to relieve conditions such as spinal stenosis, herniated discs or sciatica. But more research is needed on this modality at this point.
- Injection therapy. Anesthetic injections, also known as nerve blocks, can be used near affected nerves to temporarily relieve pain. With epidural corticosteroid injections, the medication is injected into the spinal fluid around the spinal cord and nerve roots. Corticosteroids suppress inflammation and may be especially beneficial in treating pain that radiates down the back of the leg. However, they must be taken in limited doses to avoid potentially serious side effects, such as osteoporosis. In patients who are not candidates for surgery or do not want surgery, sometimes having epidural steroid injections at reasonable intervals may be the best option. \
Risks associated with laminectomy and laminotomy include infection, a tear in the membrane that covers the spinal cord (the dura), bleeding, a blood clot in a leg vein, decreased intestinal function (paralytic ileus) and neurologic deterioration.
- Decompressive laminectomy. Removal of the back part of the bony arch over the spinal canal (lamina) to open more space for the spinal nerves. This procedure also allows the surgeon to access bone spurs or herniated discs that may be removed. In some cases, the procedure is performed through a single incision. In other instances, it may be performed though a series of small incisions in a technique known as laparoscopy (similar to arthroscopy).
- Laminotomy. Partial removal of the lamina to remove or relieve pressure to allow access to a disc or bone spur that is pressing on a nerve.
Fusion is another form of surgery used to treat spinal stenosis. In this procedure, two or more vertebrae are permanently connected. It is often used when stenosis causes one vertebra to slip over another. The extra bone may come from a bone bank or from the patient’s own body. A section of pelvic bone is often used when the patient is a self-donor.
Surgery can help relieve pressure in the spine, but patients frequently continue to feel pain for weeks or months after the procedure. In addition, surgery does not halt the degenerative process, and patients may find that their symptoms return within a few years.
In many cases, successful treatment of spinal stenosis will be followed or accompanied by physical therapy. Such treatments can increase strength and endurance, and help maintain the flexibility and stability of the spine. Occupational therapy can benefit patients who have difficulty performing daily tasks.
Prevention methods for spinal stenosisThe age-related changes to the back that are the primary cause of spinal stenosis cannot be fully prevented. However, people can take various steps to keep their spine and joints healthy for as long as possible. These include:
- Regular exercise. A combination of aerobic activities, weight training and stretching can help maintain strength and flexibility in the spine, joints and ligaments. Stronger abdominal muscles and limbs take stress off of the back. People are generally advised to aim for at least 30 minutes of moderate exercise on most days. However, a person should consult a physician before starting an exercise program.
- Proper body mechanics. Good posture and ergonomics can relieve the pressure on the back. When standing, maintain the pelvis in a neutral position. When lifting heavy objects, bend at the knees and hips and keep the back straight. Hold objects close to the body while carrying them. When sitting, choose a seat with good lower back support, arm rests and a swivel base. A rolled-up towel or pillow in the small of the back can help maintain the spine’s normal curve. Keep knees and hips level. Also, sleep on a medium-firm mattress. Recent studies indicate that sleeping on such a mattress is better for the back than sleeping on a firm mattress. Pillows can also offer good support, but only if they do not force the neck up at a severe angle.
- Maintain a healthy weight. Excessive weight puts additional stress on the joints and bones.
What might complicate it?
Since secondary spinal stenosis is a result of degeneration of the spine, other degenerative changes of the spine may cause complications.
Spinal stenosis often runs a gradual course or symptoms may not worsen for several years.
Surgery is successful in eliminating leg pain and allowing individuals to walk in about 80% to 85% of cases.
A spinal cord tumor and diabetes mellitus can produce some of the same signs and symptoms of spinal stenosis.
Vascular insufficiency (atherosclerosis of the aorta and/or leg arteries) may produce similar symptoms.
Lumbar region: Physical therapy, three times a week, for a period of two to four weeks.
Neurosurgeon, orthopedic surgeon, and physiatrist.
Last updated 27 June 2015