Ankylosing spondylitis (AS) is a type of arthritis that affects your spine. It’s considered both an autoimmune and an autoinflammatory disorder. Non-radiographic ankylosing spondylitis is a form of AS that causes symptoms but doesn’t show damage to your joints or ligaments on X-rays or MRI.
Ankylosing spondylitis can be present for years before X-rays show any damage. Magnetic resonance imaging (MRI) can sometimes identify signs of AS earlier than X-rays. It’s still possible to have AS with “clear” X-ray and MRI results.
A physical examination, symptom history, and certain blood tests all help doctors make a diagnosis of AS. However, some doctors won’t classify your condition as AS without positive findings on X-rays or an MRI. You may also receive a broader diagnosis such as non-radiographic axial spondyloarthritis.
Keep reading to learn more about how imaging tests for AS work, other diagnostic approaches, and what treatments are available.
X-rays of the sacroiliac (SI) joint are considered the best place to start when evaluating AS. The SI joint refers to where your spine meets your pelvis. Pain and inflammation in the SI joint is considered a
Other findings may include bony bridging (the connection formed between two bone fragments) and disc calcifications, among indications. However, the Spondylitis Association of America notes that it can take 7 to 10 years before AS damage can be significant enough to be revealed on standard X-rays.
If you have certain symptoms of AS, but your doctor can’t make a definitive diagnosis, you may be diagnosed with unclassified or undifferentiated spondyloarthritis. This diagnosis will be adjusted if later imaging shows clear changes in your joints.
Ankylosing spondylitis belongs to a “family” of diseases called the spondyloarthropathies. This includes undifferentiated types of spondyloarthritis including axial (affecting your spine) and peripheral (affecting your arms, legs, and other distal joints).
Per the American College of Rheumatology, other members of this family are:
- reactive arthritis or Reiter’s syndrome (arthritis that occurs in response to an infection)
- psoriatic arthritis (sometimes accompanies psoriasis)
- enteropathic arthritis (found in people with inflammatory bowel diseases [IBD] such as ulcerative colitis and Crohn’s disease)
When doctors are looking at the possibility of your symptoms being due to AS, they’ll ask about other chronic conditions in your family, keeping a special eye out for other spondyloarthropathies.
When evaluating you for AS or another inflammatory joint condition, doctors will collect the following information:
- your medical history, including any other chronic conditions you have, previous surgeries, and medications you take
- your family’s medical history
- what symptoms you have, including when they started, where the pain is located, and if anything relieves the pain or makes it worse
You’ll also have a physical examination that focuses on the joints of your spine and pelvis, as well as other joints that may be causing you problems. During the exam, you may be asked to gently bend, stretch, and move in different directions. Your doctor may also ask you to inhale deeply to see if there’s any rib cage stiffness.
Doctors often employ something called the Schober test when evaluating AS. This test involves having you bend forward while the doctor measures the flexion of your lumbar spine, which can show if there’s a decrease in your range of motion (common in AS).
You’ll likely have a screening via blood test for a mutation of the HLA-B27 gene, which is associated with AS. Upwards of 95 percent of white people with AS have this marker. This rate is lower in Black Americans and people from Mediterranean countries.
However, most people with the marker don’t have AS, and it’s still possible to have AS with a negative test result.
Doctors will also look for other possible signs of AS that can appear in bloodwork, including general markers of systemic inflammation — your ESR rate and C-reactive protein levels.
Because X-rays may not show any signs of AS at first, you may be advised to have an MRI, which can better display tissue, not just bone. MRIs can show signs of inflammation due to AS before changes appear on X-rays.
Another type of imaging, computed tomography (CT), is becoming more widely used. According to a
It’s possible to have AS with negative (clear) results on both X-ray and MRI, since it can take years for changes to occur. Effective and timely management of your disease may also slow or prevent the appearance of more dramatic changes.
Unlike other causes of back pain, AS pain often worsens with rest. Walking, stretching, and taking regular breaks from sitting or lying down can help alleviate discomfort.
Ankylosing spondylitis doesn’t just manifest as musculoskeletal pain. While everyone will experience AS differently, the following symptoms can also be signs of the condition:
- abdominal pain and changes in your bowel movements
- trouble breathing deeply due to inflammation around your ribs
- fatigue and trouble sleeping
- loss of appetite
- skin rashes
- eye inflammation (uveitis)
Your posture may also be adversely affected, which can then lead to other complications, such as neck pain and headaches. Learn more about improving your posture with AS
The two main goals of AS treatment are to slow progression of the disease and to ease symptoms.
- Medications: A doctor may recommend a few different types of medications to help lower the inflammation and pain that AS can cause.
- over-the-counter pain relievers such as Aleve or Advil (nonsteroidal anti-inflammatory drugs, or NSAIDS)
- prescription medications, in particular injectable biologics such as Humira or Cimzia, which change your immune system
- localized corticosteroid injections to joints, which lower inflammation
- Physical therapy: Working with a physical therapist may help you achieve improved flexibility, better posture, pain relief, and overall strengthening. A physical therapist will work with you to create an individualized treatment regimen consisting of exercises to complete both during sessions and at home. Occupational therapy can also be beneficial.
- Lifestyle changes: In order to limit inflammation, you may have to make certain adjustments to your habits and schedule. Pain with AS usually improves with movement and worsens with rest. Necessary lifestyle changes could mean limiting sitting time and scheduling regular breaks to walk or stretch.
- Surgery: If the injury to your spine is severe, surgery may be necessary in rare cases to repair the joints and correct posture. Surgery to repair damaged joints comes with risks and benefits, so be sure you understand what’s involved with the procedure and what you can realistically expect afterward.
Ankylosing spondylitis can be a painful chronic condition, leading to reduced mobility and negatively impacting your overall quality of life. There’s no one diagnostic test for AS, and a diagnosis is usually made with a combination of symptom history, physical exam, imaging, and bloodwork.
While X-rays can show changes to your joints due to AS, this can take years. MRIs and CT scans may show inflammation sooner, but it’s possible to have AS with clear imaging results. This is what we call non-radiographic ankylosing spondylitis, or undifferentiated spondyloarthritis.
If you’re being evaluated for AS but have a clear X-ray, consider asking your doctor about further imaging tests if they haven’t already ordered them. Timely treatment for AS, via medications, physical therapy, and lifestyle changes, can both effectively manage symptoms and slow disease progression.