Back pain is one of the most common ailments in the United States today. In fact, according to the National Institute of Neurological Disorders and Stroke, it’s the second most common neurological ailment reported. Many of these cases are caused by injury or damage. However, some cases may be the result of another condition.

One such condition is ankylosing spondylitis (AS). As much as one percent of Americans, or about 2.7 million adults, may be affected by AS. Men are affected more often than women. For the millions of Americans suffering day in and day out with chronic back pain, understanding this disease may hold the key to managing the pain.

What Is Ankylosing Spondylitis?

Ankylosing spondylitis is a progressive inflammatory disease and form of arthritis. The disease causes swelling in the spine and nearby joints. Over time, the chronic inflammation can cause the vertebrae in the spine to fuse together. As a result, the spine will be less flexible. Many people with the disease hunch forward to compensate for their rigid spine. In advanced cases of the disease, the inflammation may be so bad that a person cannot lift their head in order to see in front of them.

What Makes Ankylosing Spondylitis Different from Other Forms of Arthritis?

Ankylosing spondylitis primarily affects the spine and the vertebrae. Most people with the disease experience chronic back pain and loss of flexibility in the spine. However, ankylosing spondylitis can also affect joints outside the spine, including the shoulders, feet, knees, and hips. In rare cases, it can also affect organs and tissue.

Ankylosing spondylitis does have one unique characteristic when compared to other forms of arthritis: sacroiliitis. This is the inflammation of the sacroiliac joint, or the joint where the spin and the pelvis join. It is very common in people with ankylosing spondylitis, but is not common in people with other forms of arthritis.

What Tests Are Used to Diagnose Ankylosing Spondylitis?

Doctors do not have a single test with which to diagnose this disease. In order to diagnose this disease, your doctor must exclude other possible explanations for your symptoms. Several tests can rule out other possible causes. These tests include:

Your Medical History

To help understand your symptoms, your doctor will want to get your full health history. Your doctor will want to know:

  • how long you’ve been experiencing symptoms
  • when your symptoms are worse
  • what treatments you’ve tried, what has worked, and what hasn’t
  • what other symptoms you are experiencing
  • your history of medical procedures or problems
  • any family history of problems similar to what you’re experiencing 

A Full Physical Exam

Your doctor may want to conduct a physical exam. The exam allows them to find telltale signs and symptoms of ankylosing spondylitis. Your doctor may also have you do a few exercises so they can observe the range of motion in your joints.

Imaging Tests

Imaging tests give your doctor an idea of what’s happening inside your body. The imaging tests you may need include:

  • X-ray: An X-ray allows your doctor to see your joints and bones. He or she will look for signs of fusing or damage.
  • magnetic resonance imaging (MRI): An MRI sends radio waves and a magnetic field through your body to produce an image of your body’s soft tissues. This helps your doctor see inflammation around joints.
  • computed tomography (CT): A CT scan is another form of X-ray medical imaging. It allows doctors to see inside the body layer by layer.

Laboratory Tests

Lab tests your doctor may order include:

  • the HLA-B27 gene test: Decades of research into this disease has revealed one detectable risk factor: your genes. People with the HLA-B27 gene are more susceptible to developing ankylosing spondylitis. However, not everyone with the gene will develop the disease. In fact, only two percent of people with the gene will eventually get spondylitis. Still, a test can help your doctor understand if this is a possibility for you.
  • complete blood count (CBC): This test measures the number of red and white blood cells in your body. A CBC test can help identify and rule out other possible conditions.
  • erythrocyte sedimentation rate (ESR): An ESR test uses a blood sample to measure inflammation in the body.

Before Your Appointment

Before your appointment, make a list of all the questions you have for your doctor. Bring with you a timeline of your symptoms, any test results you may have, and any medicine you may be taking. Take notes while you’re talking with your doctor. Being an informed patient makes you a better patient.