Introduction

Spinal stenosis is a narrowing of one or more areas in your spine — most often in your upper or lower back. This narrowing can put pressure on the spinal cord or on the nerves that branch out from the compressed areas. This can lead to a number of problems, depending on which nerves are affected. In general, spinal stenosis can cause cramping, pain or numbness in your legs, back, neck, shoulders or arms; a loss of sensation in your extremities; and sometimes problems with bladder or bowel function.

Mild symptoms of spinal stenosis are often helped by pain relievers, physical therapy or a supportive brace. In more serious cases of spinal stenosis, doctors may recommend surgery to create additional space for the spinal cord or nerves. Although this usually provides some relief, it can't repair damaged nerves or stop the degenerative processes that often lead to spinal stenosis. Unfortunately, even after surgery, symptoms of spinal stenosis may recur or worsen over time.

Signs and symptoms

Spinal narrowing doesn't always cause problems. But if the narrowed areas compress the spinal cord or spinal nerves, you're likely to develop signs and symptoms. These often start gradually and grow worse over time. The most common include:

• Pain or cramping in the legs. Compressed nerves in your lower spine can lead to a condition called pseudoclaudication, false claudication or neurogenic intermittent claudication, which causes pain or cramping in your legs when you stand for long periods of time or when you walk. The discomfort usually eases when you bend forward or sit down, but it continues if you stand upright.

  Another type of intermittent claudication (vascular claudication) occurs when there's a narrowing or blockage in the arteries in the legs.

  Although both types of claudication cause similar symptoms, they differ in two important ways: Vascular claudication becomes worse when you walk uphill and improves when you stand still. Pseudoclaudication is usually worse when going downhill and gets better when you lean forward or sit down.

• Radiating back and hip pain. A herniated disk can compress nerves in your lumbar spine, leading to pain that starts in your hip or buttocks and extends down the back of your leg. The pain is worse when you're sitting and generally affects only one side.

  You also may experience numbness, weakness or tingling in your leg or foot. For some people, the radiating pain is a minor annoyance, but for others, it can be debilitating.

• Pain in the neck and shoulders. This is likely to occur when the nerves in your neck are compressed. The pain may occur only occasionally or it may be chronic, and it sometimes can extend into your arm or hand. You also may experience headaches, a loss of sensation or muscle weakness.
• Loss of balance. Pressure on the cervical spinal cord can affect the nerves that control your balance, resulting in clumsiness or a tendency to fall.
• Loss of bowel or bladder function (cauda equina syndrome). In severe cases, nerves to the bladder or bowel may be affected, leading to partial or complete urinary or fecal incontinence. If you experience either of these problems, seek medical care right away.

Causes

Knowing more about the anatomy of your spine makes it easier to understand how spinal stenosis develops and how it can lead to various problems. The main parts of the spine include:

• Vertebrae. Your spine is made up of 24 bones stacked on top of one another, plus the sacrum and tailbone (coccyx). Most adults have seven vertebrae in the neck (cervical vertebrae), 12 at the back wall of the chest (thoracic vertebrae) and five vertebrae at the inward curve of the lower back (lumbar vertebrae). The sacrum consists of five fused vertebrae between the hip bones. The tailbone is composed of three to five fused bones at the very end of the spine.
• Ligaments. These tough, elastic bands of tissue help keep the vertebrae in place when you move.
• Intervertebral disks. These elastic pads of cartilage separate the vertebrae. They keep your spine flexible and act as shock absorbers to cushion the vertebrae when you move. Each disk consists of a ring of tough fibrous tissue (annulus fibrosis) surrounding a jelly-like center (nucleus pulposus).
• Facet joints. Located on the sides, top and bottom of each vertebra, these joints connect the vertebrae to one another and stabilize the spine while still allowing flexibility. The joints are coated with a lubricant so that they slide smoothly.
• Spinal cord. This long bundle of nerves extends from the brain stem at the base of your skull to the second lumbar vertebra in your lower back. When the spinal cord ends, another group of nerves (cauda equina) continues down the spinal canal.

  The nerves within the spinal cord (upper motor neurons) carry messages between your brain and the nerves that go to all the parts of your body below your head. Two spinal nerves — one leading to the right side of your body and one to the left side — extend out from the spinal cord between each vertebra. The nerves exit through openings on either side of the vertebrae (intervertebral foramina).

  In all, there are 31 pairs of spinal nerves in your neck and back. Some transmit information from your body to your brain, and others send messages from your brain to your muscles, skin and other organs.

• Spinal canal. The spinal cord passed through this channel in your spine. Normally, the spinal canal is spacious enough to accommodate the spinal cord, but degenerative changes in the spine can narrow the channel.

How spinal stenosis develops
Doctors categorize stenosis as either primary or acquired. Primary stenosis, which is relatively uncommon, is present at birth. But most people have acquired spinal stenosis, which develops later in life, usually as a result of degenerative changes in the spine that occur with aging.

The main cause of spinal degeneration is osteoarthritis, an arthritic condition that affects the cartilage that cushions the ends of bones in your joints. With time, the cartilage begins to deteriorate and its smooth surface becomes rough. If it wears down completely, bone may rub painfully on bone. In an attempt to repair the damage, your body may produce bony growths called bone spurs. When these form on the facet joints in the spine, they narrow the spinal canal.

Other factors that can cause a narrowing of the spinal canal include:

• Herniated disk. By the time you're 30, your disks may start to show signs of deterioration. They begin to lose their water content, becoming flatter and more brittle. Eventually, the tough, fibrous outer covering of the disk may develop tiny tears, causing the jelly-like substance in the disk's center to seep out (herniation or rupture). The herniated disk presses on the surrounding nerves, causing pain in your back, leg or both. Sometimes you may also have numbness, tingling or weakness in the buttock, leg or foot on the affected side.
• Ligament changes. Ligaments in your back can undergo degenerative changes, becoming stiff and thick over time. This loss of elasticity may shorten the spine, narrowing the spinal canal and compressing the nerve roots.

  Sometimes wear and tear on the disks and ligaments cause one lumbar vertebra to slip over another — a condition called spondylolisthesis. This often compresses the spinal nerves, leading to numbness, tingling and weakness in your legs, especially when you stand for long periods or when you walk.

• Spinal tumors. In the spine, abnormal growths can form inside the spinal cord, within the membranes (meninges) that cover the spinal cord, or in the space between the spinal cord and the vertebrae — the most common site.

  Tumors may also spread (metastasize) to the spine or the spinal cord from other parts of the body. Primary or metastastic tumors can occur anywhere along the spine, including the sacrum and thoracic spine, where osteoarthritis is rare.

  Growing tumors may compress the spinal cord and nerve roots. This can cause severe back pain that may extend to your hips, legs or feet; muscle weakness and a loss of sensation — especially in your legs; difficulty walking or even paralysis; and sometimes loss of bladder or bowel function.

• Injury. Car accidents and other trauma can profoundly affect the spine and spinal cord. Sometimes the spine or spinal canal may be dislocated, putting pressure on the cord and lower motor neurons. In other cases, fragments of bone from a spinal fracture may penetrate the spinal canal. Swelling of tissue after back surgery can also put pressure on the spinal cord or nerves.
• Paget's disease of bone. Bone is living tissue engaged in a continuous process of renewal. During this remodeling process, old bone is removed and replaced by new bone. In Paget's disease, your body generates new bone at a faster-than-normal rate. This produces soft, weak bones that are prone to fractures. It can also create bones that are deformed or abnormally large.

  When unusually large bones develop in the spine, they compress the spinal cord or the nerves exiting your brain and spinal cord. The resulting pain is often severe and may radiate from your lower back into your legs. You also may experience numbness, tingling or weakness in the legs or, in some cases, double vision.

• Achondroplasia. This genetic disorder slows the rate at which bone forms during fetal development and in early childhood. As a result, people with achondroplasia are of short stature — often no more than four feet tall when fully grown. They often have small hands and fingers and unusually short upper arms and thighs. They also have a narrow spinal canal, which puts pressure on the spinal cord.

  This can cause severe back and leg pain and may even lead to paralysis of the legs. In some cases, babies or children with achondroplasia die suddenly — often in their sleep — when compression of the upper end of the spinal cord interferes with their breathing.

Between each vertebra is an elastic pad of cartilage called an intervertebral disk. The disks consist of a tough, fibrous outer covering (annulus fibrosus) and a jelly-like center (nucleus pulposus).

Your back is composed of 24 vertebrae plus your sacrum and tailbone (coccyx), 31 pairs of nerves, 40 muscles, and a number of connecting tendons and ligaments. Between your vertebrae are fibrous, elastic pads of cartilage called intervertebral disks. These shock absorbers keep your spine flexible and cushion the hard vertebrae when you move.

Osteoarthritis that affects the spine can cause the disks to narrow, putting pressure on the spinal cord. Bone spurs that form on the facet joints may compress the nerve roots.

Risk factors

Age is the main known risk factor for spinal stenosis.

Also at risk are people with skeletal fluorosis, a sometimes crippling bone disease caused by high levels of fluoride in the body. Although the disease is rare in the United States, several million people worldwide have severe skeletal fluorosis.
When to seek medical advice

Many people ignore the symptoms of spinal stenosis, believing that the pain and stiffness they experience are a normal part of aging. But discomfort, especially if it interferes with your mobility, is never normal. Seek medical advice if you have pain, stiffness, numbness or weakness in your back, legs, neck or shoulders that's not related to exercise or overexertion.

Spinal stenosis is especially likely if you have leg pain that gets worse when you walk and improves when you sit or bend forward. Get immediate care if you suddenly have trouble controlling your bowels or bladder.

Screening and diagnosis

Spinal stenosis can be difficult to diagnose because its signs and symptoms are often intermittent and because they resemble those of many age-related conditions. To help diagnose spinal stenosis and rule out other disorders, your doctor will ask about your medical history and perform a physical exam that may include checking your peripheral pulses, range of motion, and leg reflexes.

You are also likely to have one or more of the following tests:

• Spinal X-ray. Although an X-ray isn't likely to confirm that you have spinal stenosis, it can help rule out problems that cause similar symptoms, including a fracture, bone tumor or inherited defect.
• Magnetic resonance imaging (MRI). In many cases, this is the imaging test of choice for diagnosing spinal stenosis. Instead of X-rays, an MRI uses a powerful magnet and radio waves to produce cross-sectional images of your back. The test can detect damage to your disks and ligaments, as well as the presence of tumors.
• Computerized tomography (CT) scan. This test uses a narrow beam of radiation to produce detailed, cross-sectional images of your body, including the shape and size of your spinal canal. Because you receive more radiation from a CT scan than from a regular X-ray, you should avoid this test if you're pregnant.
• CT myelogram. This may be the most sensitive test for detecting spinal stenosis, but because it poses more risks than either MRI or CT, it may not be your doctor's first choice. If you're contemplating surgery, however, your doctor may recommend a CT myelogram to assess the severity of the stenosis. In a myelogram, a contrast dye is injected in your spinal column. The dye then circulates around your spinal cord and spinal nerves. A myelogram can show herniated disks, bone spurs and tumors.
• Bone scan. In this test, a small amount of a radioactive material that attaches to bone is injected into vein in your arm. The material emits waves of radiation that are detected by a gamma camera. The camera then produces images of your bones. In a sense, a bone scan is the opposite of a standard X-ray, in which radiation passes through your body to create an image on film. A bone scan can detect a number of bone disorders, but often can't distinguish among them. For that reason, it's usually performed with other tests.
• Other diagnostic procedures. Sometimes your doctor may inject you with a spinal nerve block or epidural steroids. If your symptoms improve after the injection, spinal stenosis is likely the cause of your discomfort. The problem with this approach is that a negative finding doesn't mean you don't have spinal stenosis.

Complications

Depending on which nerves are compressed, spinal stenosis may cause a loss of feeling in your arms, hands, feet or legs. As a result, cuts or wounds may become seriously infected because you're not aware of them. In addition, spinal stenosis sometimes interferes with bowel or bladder function — a problem that can affect your quality of life.

Although treatment can relieve symptoms of spinal stenosis, it doesn't stop degenerative changes. Some of these changes, such as muscle atrophy, may be permanent, even after the pressure is relieved.

Treatment

Many people with spinal stenosis can be effectively treated with conservative measures. But if you have disabling pain or your ability to walk is severely impaired, your doctor may recommend spinal surgery. Acute loss of bowel or bladder function is usually considered a medical emergency and requires immediate surgical intervention.

Nonsurgical treatments
Before considering surgery, your doctor is likely to recommend trying one or more of the following for at least three months:

• Nonsteroidal anti-inflammatory drugs (NSAIDs). These include over-the-counter and prescription medications such as aspirin, ibuprofen (Advil, Motrin, others) or indomethacin (Indocin) to reduce inflammation and pain. Although they can provide real relief, NSAIDs have a "ceiling effect" — that is, there's a limit to how much pain they can control.

  If you have moderate to severe pain, exceeding the recommended dosage won't provide additional benefits. What's more, NSAIDS can cause serious side effects, including stomach ulcers that may bleed. If you take these medications, talk to your doctor so that you can be monitored for problems.

• Analgesics. This group of pain relievers includes acetaminophen (Tylenol, others). Analgesics don't reduce inflammation, but they can effectively treat pain. Yet chronic overuse of acetaminophen can cause kidney and liver damage. Drinking alcohol increases your risk of serious side effects.
• Nonproprietary drugs. Nonprescription supplements such as chondroitin sulfate and glucosamine, either alone or in combination, have shown positive effects on osteoarthritis. But it's not yet known whether they're effective at treating or preventing osteoarthritis of the spine. Talk to your doctor if you're interested in these supplements — they may interfere with other medications you're taking, especially warfarin (Coumadin).
• Rest or restricted activity. Moderate rest followed by a gradual return to activity may improve symptoms. Walking is usually the best exercise, especially for people with neurogenic claudication, but biking is also recommended because it keeps your back in a flexed position rather than in an extended one.
• Physical therapy. Working with a physical therapist can build up your strength and endurance and help maintain the flexibility and stability of your spine.
• A back brace or corset. This helps provide support and may especially benefit people who have weak abdominal muscles or degeneration in more than one area of the spine.
• Epidural steroid injections. In some cases, your doctor may inject a corticosteroid medication into the spinal fluid around your spinal cord and nerve roots.

  Corticosteroids suppress inflammation and can be especially helpful in treating pain that radiates down the back of your leg — in fact, a single dose may provide significant relief. But because corticosteroids can cause a number of serious side effects, the number of injections you can receive is limited, usually to no more than three in one year.

Surgery
The goal of surgery is two-fold: to relieve pressure on the spinal cord or nerves, and to maintain the integrity and strength of your spine. This can be accomplished in several ways, depending on the cause of the problem. The most common surgical procedures include:

• Decompressive laminectomy. In this procedure, your surgeon removes all of the lamina — the back part of the bone over the spinal canal — to create more space for the nerves and to allow access to bone spurs or ruptured disks that may also be removed. A laminectomy is often performed through a single incision in your back (open surgery), although in some cases, your surgeon may use a laparoscopic technique. In that case, a tiny camera and surgical instruments are inserted through several small incisions, and your surgeon views the operation on a video monitor.

  Laparoscopic back surgery is complex and requires great skill and is not appropriate for many people with spinal stenosis. When done properly, however, you're likely to have less pain and to recover from surgery more quickly with this technique. Risks of laminectomy include infection, a tear in the membrane that covers the spinal cord at the site of the surgery, bleeding, a blood clot in a leg vein, decreased intestinal function (paralytic ileus) and neurological deterioration.

• Laminotomy. In this procedure, just a portion of the lamina is removed to relieve pressure or to allow access to a disk or bone spur that's pressing on a nerve. The risks are the same as for laminectomy.
• Fusion. This procedure may be performed on its own or at the same time as laminectomy. It's used to permanently connect (fuse) two or more vertebral bones in your spine and may be especially indicated when one vertebra slips over another. To fuse the spine, small pieces of extra bone are needed to fill the space between two vertebrae. This may come from a bone bank or from your own body, usually your pelvic bone. Wires, rods, screws, metal cages or plates also may be used, especially if your spine is unstable or the operation takes place to correct a deformity.

Back surgery can relieve pressure in your spine, but it's not a cure-all. You may have considerable pain immediately after the operation, and you might continue to have pain for a period of time. For some people, recovery can take weeks or months and may require long-term physical therapy. What's more, surgery won't stop the degenerative process, and symptoms may return — sometimes within just a few years.

Prevention

You can't always prevent age-related changes in your back, but the following steps can help keep your spine and joints as healthy as possible:

• Exercise regularly. This helps maintain strength and flexibility in your spine, joints and ligaments. For the best results, combine aerobic activities such as walking and biking with weight training and stretching. Toning and stretching before exercise can help reduce wear and tear on your back. It also reduces your risk of injury by warming up your muscles and increasing your flexibility. Strength training can make your arms, legs and abdominal muscles stronger, which takes stress off your back.

  If you're not used to exercise, start out gradually and increase the duration and intensity of your workout as you become stronger. Aim for at least 30 minutes of moderate exercise on most days.

• Use good body mechanics. Being conscious of how you sit, stand, lift heavy objects and even how you sleep can go a long way toward keeping your back healthy.

  To minimize stress when you sit, choose a seat that supports your lower back. If necessary, place a pillow or a rolled towel in the small of your back to maintain its normal curve.

  When you drive, adjust your seat to keep your knees and hips level, and move the seat forward to avoid overreaching for the pedals.

  Before you lift something heavy, decide where you'll place it and how you'll get there. Pushing is safer than pulling. Always bend your knees so that your arms are level with the object. Avoid lifting overhead.

  For the best sleep posture, choose a firm mattress. Use pillows for support, but don't use one that forces your neck up at a severe angle.

• Maintain a healthy weight. Extra weight puts additional stress on your joints and bones.