Lumbar canal stenosis: A common cause of back pain

Your spine takes a lot of abuse over the years; standing, lifting, bending, and twisting take a toll on the 24 vertebrae that align to hold you upright and protect the delicate network of nerves that makes up your spinal cord. It’s not surprising that over time, disks degenerate, vertebrae and ligaments thicken, and osteoarthritis develops. These age-related changes might cause nothing more than an occasional backache. But sometimes, as these changes narrow the spinal canal (refer to illustration), pressure placed on the nerves sends pain shooting down into the groin, buttocks, and legs. These symptoms of spinal stenosis can severely curtail normal activities, including walking and standing.

The condition usually develops after age 50 but occurs earlier in people who have had spinal injury or were born with a narrow spinal canal. As many as 35 percent of those seeking help for chronic low back pain may have the disorder. In the US, for example, it is the main reason for spinal surgery in people over the age of 65.

The usual recommendation for treating lower back pain is to take a conservative approach, trying other options — medications, physical therapy, lifestyle modification, and possibly injections into the spine — before resorting to surgery. These strategies don’t always work for people with symptomatic spinal stenosis, who are usually older, and have other conditions that exacerbate their back problems. But even when conservative treatments fail, clinicians may hesitate to recommend surgery except in cases of extreme pain or disability. That’s partly because the findings on surgical treatment have been limited and inconsistent.

Diagnosing lumbar spinal stenosis

Your physician can usually diagnosis spinal stenosis on the basis of your symptoms, your medical history, and a physical exam. Imaging studies — usually MRI or CT scans — may be needed to confirm the diagnosis before deciding on surgery.

The hallmark of spinal stenosis is neurogenic claudication — low back, buttock, and leg pain that worsens with walking or standing and improves with sitting, crouching, or leaning forward. A person with lumbar spinal stenosis may be uncomfortable walking upright but finds it easier to ride a bike or walk while leaning on a shopping cart or other support — activities that flex the lower back and reduce pressure on nerves in the lumbar spine. Symptoms are usually felt on both sides of the lower body, though sciatica may affect only one leg.

Your clinician will check your reflexes, assess any movement limitations, examine your spine for pain and numbness, and conduct tests to rule out other possible causes. He/she may ask you to stand with your feet together and your eyes closed to find out if your balance has been affected, a technique called the Romberg maneuver. Harvard researchers have found that patients with spinal stenosis are unsteady on their feet and have a wide-based gait.

Treatment

The goal is relieving pain and discomfort while improving mobility and function. Unless symptoms are severe, your physician will usually try other strategies before suggesting surgery. Even if your symptoms don’t improve much while you’re taking the conservative route, they’re not likely to worsen, and you are not likely to suffer progressive nerve damage. But chronic disability symptoms can put you at risk for other health problems. If pain and discomfort are interfering with your normal activities and quality of life, you may prefer surgery sooner rather than later.

Here are the options:

• Conservative treatment. Physical therapy is the foundation of non-surgical treatment. The aim is to strengthen abdominal and back muscles, preserve motion in the spine, and improve overall fitness. Stretching, strengthening, and aerobic activity (bicycling, for example) are usually recommended. Abdominal corsets or braces can help ease pain, but they may also weaken postural muscles, so you shouldn’t wear a corset or brace for a long time unless you are also actively exercising. Pain-relieving medications include acetaminophen, aspirin, and other non-steroidal anti-inflammatory drugs and opiates. No studies have shown one class of drugs to be superior to another, so the choice is guided by individual tolerance and risk profile.

Injections of corticosteroids into the space surrounding the nerve roots or into the facet joints can reduce inflammation and relieve pain for weeks to months. Anesthestic injections may also be given.

There’s some clinical evidence that chiropractic manipulation helps relieve pain, but it hasn’t been found more effective than traditional non-surgical care. Controlled clinical trials show that acupuncture consistently reduces low back pain, but — again — there’s no reliable evidence that it’s better than other treatments.

• Surgery. The aim of surgery is to relieve pressure on the spjnal cord and nerve roots, and restore the alignment of the spine. This is done by removing the bony or diseased parts that are causing the pressure or malalignment. In the most common procedure, laminectomy, the surgeon makes an incision in the back and removes the lamina (roof) of one or more of the vertebrae to create more space for the nerves. Parts of the paired facet joints may also be removed, along with any bone spurs or disk herniation. People with both stenosis and spondylolisthesis, a condition wherein a lumbar vertebra slips forward on the one below it, may also undergo spinal fusion, a procedure that joins the vertebrae and permanently fixes their position, often with plates and screws.

Until recently, the data comparing surgery with non-surgical care have been limited. A new study reports that for up to at least two years, laminectomy is more effective than non-surgical treatment for people with severe pain for spinal stenosis not related to spondylolisthesis. The study is part of the Spine Patients’ Outcomes Research (SPORT), a five-year multicenter investigation funded by the US National Institutes of Health. Results were published in the Feb. 21, 2008 issue of the New England Journal of Medicine. In this study, surgical patients got greater pain relief and more improved function, and they were more satisfied with the results. The findings have to be qualified, however, because there was some “crossing over” during the trial — non-surgical patients opting for surgery and vice versa.

Results for other SPORT studies suggest that surgery is more effective over two years for spinal stenosis related to spondylolisthesis (New England Journal of Medicine, May 31, 2007), and that surgery and non-surgical care are equally helpful for sciatica and disk herniation (Journal of the American Medical Association, November 22/29, 2006). However, crossover rates in these studies were so high that the findings are inconclusive. In none of the studies was conservative treatment associated with increased pain or lower physical functioning. This may be reassuring to patients who fear that they will get worse if they postpone or avoid surgery. Longer-term data from other studies suggest that 60 to 90 percent of spinal stenosis patients improve in the first year after surgery, but the benefit diminishes over time. Some 10 to 25 percent need another operation.

What does this mean for you?

Lumbar spinal stenosis is becoming more common as the population ages, and more evidence on its treatment is needed. Meanwhile, several rules of thumb may help you sort out the options. If you experience sudden or severe pain, numbness, or weakness, see your clinician immediately. If you notice weakness in the legs, disturbances in bowel or bladder function, or numbness in the anal or genital regions, seek help right away. These symptoms could result from compression of the cauda equina, the nerve roots at the lower end of the spinal cord. Pressure in this region can lead to permanent nerve damage, so it demands prompt medical assessment and possible emergency surgery. If you can manage your symptoms with conservative care and engage in most of your usual activities, stay the course. If your symptoms don’t improve, get worse, or interfere with your quality of life, discuss the surgical options with your clinician. And if surgery is a possibility, find an orthopedic surgeon or neurosurgeon who has extensive experience with low back problems.

Sources: “Lumbar Spinal Stenosis,” The Center for Women’s Health Care Publication, Weill Medical College of Cornell University, November 2002

“Treating Lumbar Spinal Stenosis,” Howard Health Publication, May 2008

Selected Resources: National Institute of Arthritis and Musculoskeletal and Skin Diseases, www.niams.nih.gov

American Academy of Orthopedic Surgeons, www.aaos.org

North American Spine Society, www.spine.org