Ankylosing spondylitis is a type of arthritis of the spine.
It causes inflammation between your vertebrae, which are the bones that make up your spine, and in the joints between your spine and pelvis. In some people, it can affect other joints.
AS is more common and more severe in men. It often runs in families. The cause is unknown, but it is likely that both genes and factors in the environment play a role.
Early symptoms of AS include back pain and stiffness. These problems often start in late adolescence or early adulthood. Over time, AS can fuse your vertebrae together, limiting movement. Some people have symptoms that come and go. Others have severe, ongoing pain.
A diagnosis of AS is based on your medical history and a physical examination. You may also have imaging or blood tests.
AS has no cure, but medicines can relieve symptoms and may keep the disease from getting worse. Eating a healthy diet, not smoking, and exercising can also help. In rare cases, you may need surgery to straighten the spine.
Ankylosing spondylitis typically begins in adolescents and young adults, but it affects people for the rest of their lives. Men are more likely to develop ankylosing spondylitis than are women.
AS is the main member of a family of similar forms of arthritis called spondyloarthritis. Other members include psoriatic arthritis, arthritis of inflammatory bowel disease and reactive arthritis. The family of arthritis appears to be quite common and affects up to 1 in 100 people.
The cause of AS is unknown. Genes seem to play a role.
The disease often begins between ages 20 and 40, but it may begin before age 10. It affects more males than females.
AS starts with low back pain that comes and goes. Low back pain becomes present most of the time as the condition progresses.
- Pain and stiffness are worse at night, in the morning, or when you are less active. The discomfort may wake you from sleep.
- The pain often gets better with activity or exercise.
- Back pain may begin in the between the pelvis and spine (sacroiliac joints). Over time, it may involve all or part of the spine.
- Your lower spine may become less flexible. Over time, you may stand in a hunched forward position.
Other parts of your body that may be stiff and painful include:
- Swelling and pain in the joints of the shoulders, knees and ankles
- The joints between your ribs and breastbone, so that you cannot expand your chest fully
- Swelling and redness of the eye
Fatigue is also a common symptom.
Less common symptoms include:
- Slight fever
Ankylosing spondylitis may occur with other conditions, such as:
- Ulcerative colitis or Crohn disease
- Recurring or chronic eye inflammation (iritis)
A diagnosis of ankylosing spondylitis is based largely on the findings of a medical history and physical exam. Radiologic tests and lab tests may be used to help confirm a diagnosis, but both have some limitations.
The medical history involves answering questions, such as the following:
- How long have you had pain?
- Where specifically is the pain in your back or neck? Are other joints affected?
- Is back pain better with exercise and worse after inactivity, such as when you first get up in the morning?
- Do you have other problems, such as eye problems or fatigue?
- Does anyone in your family have back problems or arthritis?
- Have you recently suffered from a gastrointestinal illness?
- Do you have any skin rashes such as psoriasis?
From your answers to these questions, your doctor can begin to get an idea of the diagnosis.
During the physical exam, the doctor will look for signs and symptoms that are consistent with ankylosing spondylitis. Your doctor may ask you to move and bend in different directions to check the flexibility of your spine and to breathe deeply to check for any problems with chest expansion, which could be caused by inflammation in the joints where the ribs attach to the spine.
X rays and magnetic resonance imaging (MRI) may be used in making or confirming a diagnosis of ankylosing spondylitis, but these tests have limitations. X rays may show changes in the spine and sacroiliac joints that indicate ankylosing spondylitis; however, it may take years of inflammation to cause damage that is visible on x rays. MRI may allow for earlier diagnosis, because it can show damage to soft tissues and bone before it can be seen on an x ray.
The main blood test for ankylosing spondylitis is one to check for the HLA-B27 gene, which is present in the majority of Caucasians with ankylosing spondylitis. The gene is found in much lower percentages of African Americans with ankylosing spondylitis, and in ankylosing spondylitis patients from some Mediterranean countries. Also, the gene is found in many people who do not have ankylosing spondylitis, and will never get it. Still, when the gene is found in people who have symptoms of ankylosing spondylitis and/or x-ray evidence of ankylosing spondylitis, this finding helps support the ankylosing spondylitis diagnosis.
Your health care provider may prescribe drugs such as NSAIDs to reduce swelling and pain.
- Some NSAIDs can be bought over-the-counter (OTC). These include aspirin, ibuprofen (Advil, Motrin), and naproxen (Aleve, Naprosyn).
- Other NSAIDs are prescribed by your provider.
- Talk to your provider or pharmacist before using any over-the-counter NSAID.
You may also need stronger medicines to control pain and swelling, such as:
- Corticosteroid therapy used for short periods of time
- A TNF-inhibitor (such as etanercept, adalimumab, infliximab, certolizumab or golimumab)
Surgery may be done if pain or joint damage is severe.
Exercises can help improve posture and breathing. Lying flat on your back at night can help you keep a normal posture.
The course of the disease is hard to predict. Over time, signs and symptoms of AS flareup and quiet down. Most people are able to function well unless they have a lot of damage to the hips. Joining a support group of others with the same problem may often help.
Treatment with NSAIDS often reduces the pain and swelling. Treatment with TNF inhibitors appears to slow progression of the spine arthritis.
Rarely, people with ankylosing spondylitis may have problems with:
- Psoriasis, a chronic skin disorder
- Inflammation in the eye (iritis)
- Inflammation in the intestine (colitis)
- Abnormal heart rhythm
- Scarring or thickening of the lung tissue
- Scarring or thickening of the aortic heart valve