The term ankylosing is a combination of the Greek word ankylos—stiffening of a joint—and spondylos—vertebra. Ankylosing spondylitis is basically a seronegative arthritis usually found in the axial skeleton, particularly sacroiliac and spinal facet joints and the paravertebral soft tissues. Other manifestations of ankylosing spondylitis are peripheral arthritis, iritis, and pulmonary involvement.
Clinical presentation of ankylosing spondylitis
The common lesion seen in ankylosing spondylitis is inflammation of sites of attachment to bone of ligaments, tendons, and joint capsules. The inflammation results in erosion and eburnation of the subligamentous bone. Within the outer layers of the annulus fibrosis of intervertebral disks, there is formation of new bone. During this process, the disk margins are invaded by granulation tissue from the subchondral bone that replaces disk fibers with new bone.
In synovial joints, the synovitis is basically the same that occurs in rheumatoid arthritis. The difference is that subchondral bone and cartilage are invaded by reactive tissue originating from bone. The resultant bony bridges between adjacent vertebrae and ossification of extraspinal joint capsules and ligaments are characteristic of ankylosing spondylitis.
There is a strong genetic influence in ankylosing spondylitis. 90% to 95% of patients with ankylosing spondylitis have the tissue antigen human leukocyte antigen B27 (HLA-B27), In the normal population, only 1% carry the antigen. (http://www.emedicine.com/radio/topic41.htm)
Ankylosing spondylitis affects males almost exclusively. Symptoms typically begin between the ages of 15 and 45. The stiffening of the spinal joints and ligaments can become so painful that if it involves ribs, even breathing is difficult.
The array of ankylosing spondylitis symptoms include intermittent low back pain that is most severe in the morning or following inactivity; limited motion of the lumbar spine; pain and decreased tidal volume in the chest if there is involvement of the costovertebral joints; peripheral arthritis that affects shoulders, hips and knees; iritis; decrease in the range of motion of hips; tenderness over the sites of inflammation; aortic regurgitation and cardiomegaly; and upper lobe fibrosis that may look like tuberculosis. (http://www.healthscout.com/ency/68/415/main.html)
Diagnosis of ankylosing spondylitis
On physical examination, the earliest objective sign of spinal involvement is a loss of lateral flexion of the lumbar spine. Percussion over the sacroiliac joints may produce pain. Examination of the peripheral joints may reveal decreased joint motion. Sites where muscle attaches to bone, e.g. the heel, may be tender.
Extra-axial manifestations of ankylosing spondylitis are the murmurs of aortic incompetence because of aortitis, decreased chest expansion, and anterior uveitis.
If the disease has impinged upon nerve roots, it may be manifested by neurological signs similar to those seen in degenerative disc disease.
Sed rates are elevated during ankylosing spondylitis acute phases. There may also me a mild leucocytosis and a normochromic normocytic anemia. As noted above, the HLA-B27 may be positive, but may this test cannot be used diagnostically since only a small percentage of individuals with positive test results for HLA-B27 develop the disease develop. Gamma-globulin levels may be raised. Rheumatoid factors are negative.
Since there is no specific test that identifies ankylosing spondylitis, criteria were established in 1963. As might be expected, the criteria have some difficulties—there is considerable overlap amongst the seronegative spondyloarthropathies.
Sacroiliitis is the hallmark of criteria. The Rome criteria also included low back pain and stiffness for more than 3 months, pain and stiffness in the thoracic region, limited motion in the lumbar region, and limited chest expansion. (http://www.emedicine.com/radio/topic41.htm)
Treatment of ankylosing spondylitis
Nonsteroidal medications are the mainstay of treatment for ankylosing spondylitis. Narcotics and corticosteroids are to be avoided. Antirheumatic drugs such as methotrexate, leflunomide, and sulfasalazine, are not recommended for the treatment of axial disease. Recent international guidelines have stated that these medications, "may be considered in patients with peripheral arthritis rather than for patients with axial disease, but a recent study of patients with early-stage ankylosing spondylitis reported that sulfasalazine was beneficial only to those patients who did not have peripheral arthritis. Oral or parenteral use of corticosteroids use is not supported by the evidence.”
The 3 anti-tumor necrosis factor (TNF) agents, Enbrel, Humira, and Remicade have proven to be remarkably effective against ankylosing spondylitis, particularly when the disease is persistent and aggressive. There are those who feel that TNF-blockers should be given on a long-term basis. (http://www.medscape.com/viewarticle/544971_5)