Ankylosing spondylitis is a form of chronic inflammatory arthritis that significantly affects the joints of the spine. This autoimmune condition causes swelling between the vertebrae, and often affects one or both sacroiliac joints, the joints that attach the spine to the pelvis. In severe cases, the extreme swelling may cause the bones of the spine to fuse. Pain, swelling, and stiffness in the lower back are the typical symptoms of ankylosing spondylitis, but inflammation may occur in other parts of the body, including the eyes. Men are more likely than women to develop ankylosing spondylitis and it most commonly occurs in late adolescence or early adulthood.
Causes of Ankylosing Spondylitis
The exact cause of ankylosing spondylitis is unknown, though the disorder is believed to have a genetic link. Research indicates that individuals who carry a gene known as HLA-B27 are at a greater risk of developing the condition, although most people who carry the gene never develop it. Having a family history of ankylosing spondylitis is also a risk factor for the disorder.
Symptoms of Ankylosing Spondylitis
Early symptoms of ankylosing spondylitis are most commonly evident in young adult males and often include pain in the lower back and hips. Pain may also be experienced in parts of the body where tendons and ligaments attach to the bones. Over time, these symptoms may worsen or may only occur intermittently. Symptoms of ankylosing spondylitis may include:
- Pain in the sacroiliac joints
- Pain in the shoulders, knees, feet, breastbone or ribs
- History of gastrointestinal infections, Crohn's disease or ulcerative colitis
- Fatigue because of chronic inflammation
- Eye inflammation or sensitivity (iritis or uveitis)
Complications of ankylosing spondylitis may, in severe but rare cases, affect circulation and respiration. Over time, the disorder may cause the bones of the vertebrae to fuse and parts of the spine and ribcage to become inflexible. As a result, lung capacity may become restricted, causing breathing difficulty. It is also possible for ankylosing spondylitis to affect the heart, impairing heart function by distorting the shape of the aortic valve.
Diagnosis of Ankylosing Spondylitis
To diagnose ankylosing spondylitis, the doctor must take a complete medical history and perform a full physical examination. During the exam, the patient's spinal mobility and chest expansion capability are evaluated. Blood tests may be performed to detect for inflammation or infection, including a genetic test to discover the telltale HLA-B27 gene. Diagnostic imaging tests may also be administered for more accurate, detailed visualization of bone and soft tissue. These may include X-rays and MRI scans.
Treatment of Ankylosing Spondylitis
There is no cure currently available for ankylosing spondylitis. A range of medications, including over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs) and prescribed corticosteroids, may be administered. In more problematic cases, anti-rheumatic drugs (DMARDS) may be prescribed. These can be very effective in reducing swelling and pain. Physical therapy and exercise are also very beneficial for many patients. In the most severe cases, treatment may include surgery to replace joints in the hip or knee, or to straighten the spine.