Neck and Back

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Lumbar Spinal Stenosis

Anatomy

The spinal column is made up of small bones (vertebrae) stacked on top of one another, creating the natural curves of the back. Between the vertebrae are flat, round, rubbery pads (intervertebral disks) that act as shock absorbers and allow the back to flex or bend. Muscles and ligaments connecting the vertebrae allow motion while providing support and stability for the spine and upper body. Each vertebra has an opening (foramen) in the center and these line up to form the spinal canal. Protected by the vertebrae, the spinal cord and other nerve roots travel through the spinal canal. Nerves branch out from the spinal column through vertebral openings, carrying messages between the brain and muscles. Facet joints align at the back of the spinal column, linking the vertebrae together and allowing for rotation and movement. Like all joints, cartilage covers the surface where facet joints meet.

The spine contains three segments: lumbar, thoracic and cervical. The lumbar spine consists of five vertebrae located in the lower back; lumbar vertebrae are larger because they carry more of the body's weight. The thoracic spine consists of 12 vertebrae and begins at the upper chest, extending to the middle back and connecting to the rib cage. The cervical spine includes the neck and consists of seven small vertebrae, beginning at the base of the skull and ending at the upper chest. Disks in the lumbar spine are composed of a thick outer ring of cartilage (annulus) and an inner gel-like substance (nucleus). In the cervical spine, disks are similar but smaller in size.

Description

Lumbar spinal stenosis is a common cause of pain in the lower back and legs. As we grow older, our spines change and over time, normal wear-and-tear and the effects of aging can lead to a narrowing of the spinal canal (spinal stenosis). This puts pressure on the spinal cord and spinal nerve roots, and may cause pain, numbness or weakness in the legs. Spinal stenosis most often occurs in adults over 60 years of age, however, degenerative changes of the spine can be observed in up to 95% of people by age 50. While pressure on nerve roots due to age-related spinal stenosis is equally common in men and women, a small number of patients are born with back problems that develop into lumbar spinal stenosis—this is known as congenital spinal stenosis and occurs most frequently in men. Symptoms of congenital spinal stenosis are usually first noticed between 30 and 50 years of age.

Cause

In children and young adults, intervertebral disks have high water content. As we age, they dry out, causing them to stiffen and weaken. The disks settle, or collapse, and lose height and begin to bulge. The space between disks grows smaller and the vertebrae move closer together. The facet joints experience increased pressure and also begin to degenerate and develop arthritis, similar to what occurs in a hip or knee joint. The cartilage that covers and protects these joints wears away. If it erodes completely, the result is bone rubbing against bone. The body may respond to this degeneration and lost cartilage by growing new bone to strengthen and support the vertebrae. Over time, this bone overgrowth (bone spurs) may narrow the foramen where the nerves pass through (stenosis), resulting in radiculopathy (pinched nerve) or spondylosis (arthritis). Arthritis is the most common cause of spinal stenosis. The body responds to arthritis in the lower back by increasing the size of ligaments around the joints, which further reduces the space available for the nerves to travel through. Once the space becomes small enough to irritate spinal nerves, painful symptoms result.

Symptoms

Patients with spinal stenosis may or may not experience back pain, depending on the degree of arthritis that has developed.

  • Burning pain in buttocks or legs (sciatica)—Pressure on spinal nerves can result in pain (described as an ache or burning feeling) in areas those nerves supply. The pain typically starts near the buttocks, radiates down the leg, and may progress into the foot.
  • Numbness or tingling in buttocks or legs—As pressure on the nerve increases, numbness and tingling often (but not always) accompany the burning pain.
  • Weakness in the legs or "foot drop"—Once pressure reaches a critical level, weakness can occur in one or both legs and some patients may have the sensation of their foot slapping on the ground while walking (foot drop).
  • Less pain with leaning forward or sitting—Studies of the lumbar spine show that leaning forward can actually increase the space available for the nerves. Many patients may experience relief when leaning forward, especially while sitting, while pain is usually made worse by standing up straight and walking. Some patients are able to ride a stationary bike or walk as they lean on a shopping cart, however walking more than 1 or 2 blocks may bring on severe sciatica or weakness.

Diagnosis

After reviewing your medical history and discussing your symptoms, your physician will perform a physical examination on your back, pressing on various areas to test for pain. You may also be asked to bend forward, backward and side-to-side to reveal any limitations or discomfort. Additional imaging studies, such as X-rays, magnetic resonance images (MRI), computed tomography (CT) or myelogram may be required to fully assess your condition and confirm your diagnosis.

Nonsurgical Treatment

Nonsurgical treatment options focus on restoring function and relieving pain. Although nonsurgical methods do not improve the narrowing of the spinal canal, many patients report that these treatments help relieve symptoms.

  • Physical therapy—Stretching exercises, massage, and lumbar and abdominal strengthening are often helpful in managing symptoms.
  • Lumbar traction—Although helpful for some patients, traction has very limited results and there is no scientific evidence of its effectiveness.
  • Anti-inflammatory medications—Because stenosis pain is caused by pressure on a spinal nerve, reducing inflammation and swelling around the nerve may relieve pain. Nonsteroidal anti-inflammatory drugs (NSAIDs) initially provide pain relief and when used over the course of 5-10 days, they can also have an anti-inflammatory effect. Most people are familiar with nonprescription NSAIDs such as aspirin and ibuprofen, however, whether using over-the-counter or prescription strength, they must be used carefully. These medications can lead to gastritis or stomach ulcers. If you develop acid reflux or stomach pains while taking an anti-inflammatory, be sure to talk with your doctor.
  • Steroid injections—Cortisone (a powerful anti-inflammatory) injections around the nerves or into the space next to the covering of the spinal cord (epidural space) can reduce swelling and pain, as well as numbness (but not weakness) in the legs. Patients should receive no more than 3 injections a year.
  • Acupuncture—Acupuncture can be helpful in treating some of the pain in less severe cases of lumbar stenosis. Although the treatment can be very safe, long-term success has not been proven scientifically.
  • Chiropractic manipulation—Chiropractic manipulation is generally safe and can help with some of the pain from lumbar stenosis. Care should be taken if a patient has osteoporosis or disk herniation as manipulation of the spine in these cases can worsen symptoms or cause other injuries.

Surgery

Surgery for lumbar spinal stenosis is generally reserved for patients who have poor quality of life due to pain and weakness. Difficulty walking for extended periods of time is a common reason that patients consider surgery. Laminectomy and spinal fusion are the two primary surgical options for the treatment of lumbar spinal stenosis. Both can result in excellent pain relief, however it is important to discuss the advantages and disadvantages of both with your surgeon. Recent developments in surgical options, such as interspinous process devices and minimally invasive decompression, may be appropriate for certain patients. Discuss these procedures with your physician to determine if you may be a candidate.

Rehabilitation

The length of your stay in the hospital will depend on your health and the procedure performed. Following a decompression procedure only, healthy patients may go home the same or next day and return to normal activities after only a few weeks. Fusion typically adds 2 to 3 days to the length of the hospital stay.

Following surgery, your surgeon will likely encourage you to begin walking as soon as possible, and you may be given a brace or corset to wear for comfort. For most patients, physical therapy alone is all that is required to strengthen the back. Your physical therapist will create an individualized program for you that takes your health and history into consideration. A spine conditioning program or low back exercises may be recommended. You will be given exercises to help build and maintain strength, endurance and flexibility for spinal stability, including exercises to strengthen abdominal muscles, which help support the back. Most patients are able to return to a desk job within a few days to a few weeks after surgery, and may return to normal activities after 2 to 3 months. Older patients who need more care and assistance may be transferred from the hospital to a rehabilitation facility prior to going home.

Complications

As with any surgery, there are some risks, and these vary from person to person. These are typically minor, treatable and unlikely to affect your final outcome. For most people, surgery can provide relief of symptoms and return to function with relatively low risk of complications. Overall, elderly patients have higher rates of complications from surgery, as do patients who are overweight, diabetics, smokers, or suffering from multiple medical problems. General, potential risks for surgery include infection, bleeding and blood clots, and reactions to anesthesia. Discuss the potential risks and benefits specific to each technique with your surgeon prior to surgery.

Specific complications from surgery for spinal stenosis include: tearing of the sac covering the nerves (dural tear), failure of the bone fusion to heal, failure of screws or rods, nerve injury, need for further surgery, failure to relieve symptoms or return of symptoms.

Outcomes

Overall, results of laminectomy, with or without spinal fusion, for lumbar stenosis are good to excellent in the majority of patients. Patients tend to see more improvement of leg pain than back pain, and most are able to resume a normal lifestyle after a period of recovery from surgery.

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