Ankylosing Spondylitis
by Harvard Medical School
Ankylosing spondylitis is a chronic, systemic inflammatory disease that may strike in the prime of life, often between the ages of 20 and 40. It's more common in men than in women. The disease develops as tendons attaching muscles to the spine become inflamed, causing pain and limiting movement. As ankylosing spondylitis progresses, vertebrae in the spinal column may fuse (see Figure 10). In its most advanced stages, the disease may affect joints in the lower back and upper buttocks and also cause inflammation in the eyes, heart, and lungs.
Figure 10: X-ray of thpdiv style="width: 236px;"> ankylosing spondylitis" align="" border="" height="" hspace="" width="" />
X-ray of the spine
This x-ray shows a fused bamboo-like spine characteristic of ankylosing spondylitis. |
Ankylosing spondylitis runs in some families. An unusually high percentage of people with ankylosing spondylitis — 96% in one study — carry the HLA-B27 gene, which occurs more commonly in white people than in other racial groups. A person who carries the HLA-B27 gene has only about a 1%–2% chance of developing ankylosing spondylitis. If a parent or sibling has the condition, however, experts estimate that the risk for a person with the gene rises to 10%–20%. Conversely, not having the gene is no guarantee of protection.
- back pain and stiffness that develop gradually over weeks
- back pain and stiffness that persist for months
- discomfort that is most noticeable in the morning, but improves with exercise
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Ankylosing spondylitis is one of the more difficult rheumatic diseases to diagnose early because the symptoms are similar to other causes of low back pain. It may take up to five years after the onset of symptoms for ankylosing spondylitis to show up on an x-ray. At first, x-rays will show that the margins of the sacroiliac joints appear indistinct. Later, the bones ankylose (or fuse).
Most people with ankylosing spondylitis can lead normal lives by using a combination of anti-inflammatory drugs and physical therapy. Your doctor may start by prescribing an NSAID such as indomethacin, but if this doesn't reduce the inflammation, a second choice is often a DMARD such as sulfasalazine or methotrexate. Several studies have demonstrated that anti-TNF agents are beneficial for ankylosing spondylitis. (See Appendix for more information about these drugs.)
If you develop ankylosing spondylitis, you can take steps to prevent spine deformity; in fact, such measures are an essential part of treatment. At least twice a day, try to practice stretching exercises that extend the spine, preferably after a hot shower has reduced stiffness. Rheumatologists recommend swimming as the best overall exercise because it does not stress the back as much as running or other weight-bearing exercises.