Ankylosing Spondylitis

National Organization for Rare Disorders, Inc.

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It is possible that the main title of the report Ankylosing Spondylitis is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.


  • Marie Strumpell Disease
  • Spondyloarthritis
  • Von Bechterew-Strumpell Syndrome
  • Marie-Strumpell Spondylitis
  • Bechterew Syndrome
  • AS
  • Spondyloarthropathy
  • Chronic inflammatory conditions
  • Bechterew disease
  • Marie-Strumpell arthritis

Disorder Subdivisions

  • None

General Discussion

Ankylosing spondylitis is a progressive inflammatory disease that typically becomes evident during early to mid adulthood. The disease is characterized by inflammation (arthritis), stiffness, and pain of various joints of the spine and potential loss of spinal mobility. It may involve joints between the spine and the pelvis, known as the sacroiliac joints; joints within the spinal column of the lower back (lumbar spine), the upper back (thoracic spine), and the neck (cervical spine) to varying degrees; as well as joints of the limbs, particularly the legs. Progression may spontaneously subside at any stage of involvement; however, in some individuals, all regions of the spinal column may eventually become involved.

Many affected individuals develop lower back and hip pain that may be more severe at night and after rest. In addition, there is often associated stiffness of affected regions in the morning. In some cases, those with involvement of joints joining the ribs with the spine (costovertebral joints) may have a limited ability to expand the chest to take a deep breath. In addition, in some affected individuals, other associated findings may include recurrent inflammation of the colored region of the eyes (acute iritis), leakage of the aortic valve resulting in a backflow of blood into the lower left chamber (ventricle) of the heart (aortic insufficiency or regurgitation), and/or other abnormalities.

The exact cause of ankylosing spondylitis is not known. However, researchers suggest that genetic, immunologic, and/or environmental factors may play some role.


The most common symptoms of ankylosing spondylitis include back pain and abnormal postures in response to the inflamed (arthritic) vertebrae in the spine. Pain is frequently worse after periods of rest and at night, and may be associated with morning stiffness. Pain typically improves with exercise and the application of heat.

Early in the course of ankylosing spondylitis, symptoms may include muscle spasms in the back that inhibit normal motion of the spine during bending (flexion). Eventually, immobility of the vertebrae may also limit the motion of the spine. In advanced disease ankylosing spondylitis may result in immobility or fusion (ankylosis) of the entire spine, resulting in a straight or "poker" spine.

Symptoms of ankylosing spondylitis may involve joints outside the spinal area (peripheral), especially the hips and shoulders, which are the first affected joints in 20 percent of cases. Neck movement may also be limited in some people with this disorder.

About 30 percent of people with ankylosing spondylitis develop inflammation of the iris of the eyes (iritis) which is characterized by pain, excessive tearing (lacrimation), extreme sensitivity to light (photophobia), and/or visual impairment. Breathing capacity may be diminished and the chest may become fixed due to immobility of the rib cage (costovertebral joints). Neurological complications of ankylosing spondylitis may include the inability to control urination and defecation (incontinence) and the absence of normal reflexes in the ankles (ankle jerks) due to pressure on the lower portion of the spinal cord (cauda equina).

In fewer than 10 percent of people with ankylosing spondylitis, the function of the heart may also be impaired including interference with the normal electrical impulses of the heart (heartblock), irregular heartbeat (arrhythmia), and/or aortic insufficiency after longstanding disease.


The specific underlying cause of ankylosing spondylitis is unknown. However, investigators indicate that over 90 percent of individuals with the disorder have a particular, genetically determined HLA, or "human leukocyte antigen," known as HLA-B27. HLAs are proteins that play an important role in the body's immune system. The possible role that HLA-B27 may play in genetically predisposing individuals to ankylosing spondylitis remains unknown.

The genes that determine and regulate production of such proteins (major histocompatibility complex [MHC]) have been mapped to a region on the short arm (p) of chromosome 6 (6p21.3). Researchers suggest that certain genes on other chromosomes may also possibly be a factor in genetically predisposing to ankylosing spondylitis in some cases.

Chromosomes are found in the nucleus of all body cells. They carry the genetic characteristics of each individual. Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males and two X chromosomes for females. Each chromosome has a short arm designated as "p" and a long arm identified by the letter "q." Chromosomes are further subdivided into bands that are numbered. Therefore, for example, 6p21.3 refers to band 21.3 on the short arm of chromosome 6.

Some investigators suggest that ankylosing spondylitis may follow exposure to certain intestinal (enteric) bacteria, leading to an abnormal immune reaction directed against the body's own tissues (autoimmune response) in genetically predisposed individuals. Tests have indicated that many affected individuals have increased levels of antibodies in the blood directed against particular enteric bacteria, such as the bacterium Klebsiella pneumoniae. Further research is needed to learn more about the underlying genetic, immunologic, and/or other mechanisms that may result in ankylosing spondylitis.

Affected Populations

Ankylosing spondylitis is a rare disorder that affects at least 3 times more males than females. The symptoms usually begin between the ages of 20 and 40 years. Ankylosing spondylitis occurs more frequently among Americans of European descent than Americans of African descent who typically experience milder symptoms. In the US about 1.4% of the population is affected by this condition.

Standard Therapies


Treatment of ankylosing spondylitis is aimed at reducing inflammation in the joints and maintaining flexibility. Most people with ankylosing spondylitis respond well to medications that help reduce pain and inflammation, along with exercises that improve posture and strengthen muscle groups.

The U.S. Food and Drug Administration (FDA) has approved infliximab (Remicade) for the treatment of symptoms, such as spinal pain, of ankylosing spondylitis. This drug is produced by Centocor, Inc., of Malvern, Pa. For information, go to

Amgen/Wyeth received approval from the U.S. Food and Drug Administration (June 2003) to include ankylosing spondylitis among the indications for the use of the biotech drug etanercept (Enbrel). To date (2004), it is the first and only biologic approved as a treatment for ankylosing spondylitis.

Exercises may be prescribed under a doctor's supervision stressing back movements, deep breathing, straightening of the chest portion of the spine, deep-bending exercises, and a full range of motion of the spine in all directions. Bending (flexion) postures should not be maintained for long periods of time. To avoid flexion of the neck and upper back, affected individuals should sleep on their backs with a firm mattress and use no pillow or a very flat pillow. The chest muscles can be stretched and the upper back straightened by locking the fingers behind the head and pushing the elbows as far back as possible. Swimming is also excellent exercise for people with this disorder. Prior to exercise, hot baths or warm showers may be helpful to relax muscles and to attain better range of motion. People with ankylosing spondylitis should have ample rest each day and avoid exhaustion.

These exercises and physical therapy can be administered immediately upon diagnosis to retain as normal an upright posture as possible and reduce the potential for physical deformity. This is particularly important for people who are diagnosed early in life.

Nonsteroidal anti-inflammatory drugs (NSAIDs) or other painkillers such as naproxen, sulindac, diclofenac or phenylbutazone may help to relieve pain, permitting better sleep and increasing the ability to exercise. Narcotics and systemic corticosteroids are usually avoided.

Some people with ankylosing spondylitis may benefit from the use of a back brace, but it is frequently unnecessary. Therapeutic measures often eliminate the need for surgery to straighten the spine. However, in rare cases, if the above treatments are not successful, surgery may be performed to straighten the spine.

Investigational Therapies

Information on current clinical trials is posted on the Internet at All studies receiving U.S. government funding, and some supported by private industry, are posted on this government website.

For information about clinical trials being conducted at the National Institutes of Health (NIH) in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222

TTY: (866) 411-1010


For information about clinical trials sponsored by private sources, contact:

There are five trials listed on the NIH site that involve ankylosing spondylitis. One of them is an investigation of the drug, adalimumab (HUMIRA), manufactured by Abbott Laboratories. A phase III trial was launched in April 2004 to determine its effectiveness in treating ankylosing spondylitis. Patients are being recruited for several testing locations across 16 states. For information, use the NIH sources listed above or contact:

Gretchen Behrens

Phone: (973) 394-5517


There are three trials evaluating various aspects of genetics and one trial assessing the best testing methods for spinal fusion and other symptoms of ankylosing spondylitis. All of them are presently (2004) recruiting volunteers. For information, use the NIH tollfree phone number or the Clinical Trials web site listed above.

Sulfasalazine has been tested for the treatment of seronegative spondyloarthropathies. The drug is found to be helpful in arthritis symptoms of ankylosing spondylitis but has little effect on spinal pain and general treatment of the disease. More studies are needed to determine the long-term safety and effectiveness of this treatment.

The protein molecule HLA-B27, known to be a genetic marker for ankylosing spondylitis and some forms of arthritis, has aided researchers in developing an animal model for the disease. This will be a great help in understanding the cause and progression of this disorder, and testing new treatments for arthritis and ankylosing spondylitis. In 1999, The National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) awarded $4.5 million to establish the North American Spondylitis Consortium to identify genes that determine susceptibility to ankylosing spondylitis. John D. Reveille, M.D. at the University of Texas-Houston Health Science Center, coordinates this work. Affected individuals and physicians interested in participating in the study should contact:

Spondylitis Association of America

Family Genetic Research Project

P.O. Box 5872

Sherman Oaks, CA 91413

Toll free: (800) 777-8189



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eMedicine-Ankylosing Apondylitis: Article by Alan Schaffert, MD


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