Axial spondyloarthritis is a chronic rheumatic disease that causes intense pain and damage, mainly in the spine and sacroiliac (SI) joint, where the hip and spine connect.
The most common early symptom of axial spondylitis is chronic lower back pain that starts before age 45. Back pain in axial spondyloarthritis is inflammatory in nature. Unlike mechanical back pain caused by strained muscles or injury, inflammatory back pain improves with physical activity and worsens with rest. About 70 percent to 80 percent of people with axial spondyloarthritis experience chronic inflammatory back pain. This pain often involves the SI joint, a symptom which is considered a hallmark of the disease.
Read more about Early Signs and Symptoms of Spondyloarthritis.
Diagnosing axial spondyloarthritis can be a challenge. That’s because the early form of the disease is “invisible,” meaning it doesn’t show up on X-rays. This can lead to a delay in diagnosis and treatment, as well as poorer outcomes.
There are two types of axial spondyloarthritis:
Radiographic axial spondyloarthritis, also known as ankylosing spondylitis, is the most severe form of the condition. It’s caused by new bone growth on the spine and sacroiliac joints that can lead to fused vertebrae, pain, and immobility. Because this disease type is significantly advanced, joint damage can be seen on X-rays or computed tomography (CT) scans.
Nonradiographic axial spondyloarthritis, on the other hand, refers to early disease, which starts as inflammation in the sacroiliac joints. X-rays and CT scans are not sensitive enough to detect joint inflammation and swelling, making nonradiographic axial spondyloarthritis more challenging for rheumatologists to diagnose. However, joint inflammation may be visible with magnetic resonance imaging (MRI).
It can take six to 10 years for inflammation to create enough damage to become visible on X-rays. By that time, nonradiographic axial spondyloarthritis can progress to ankylosing spondylitis, with significant bone destruction and fusion.
Read more about How Axial Spondyloarthritis Is Diagnosed.
Diagnostic criteria developed in 1984 relied on X-rays to detect structural changes in the spine and sacroiliac joints. X-rays can depict bone erosion and any new bone growth caused by chronic inflammation, the key feature in axial spondyloarthritis. X-rays are typically used to evaluate people who’ve had back pain for more than three months.
However, X-rays have shortcomings. In the early stages of axial spondyloarthritis, X-rays can’t detect inflammation in the joints, nor distinguish between nonspecific chronic low back pain and inflammatory back pain.
Even when X-rays don’t show bone changes or fusions, it’s still possible to experience severe pain. In fact, nonradiographic axial spondyloarthritis can be just as painful and debilitating as radiographic axial spondyloarthritis. For that reason, many people with “invisible” axial spondyloarthritis suffer unnecessarily for many years before getting a proper diagnosis.
One member of MySpondylitisTeam described being “given painkillers and left to rot” after her X-rays showed no damage. “I’ve been made to feel like a fraud every time I’ve tried to explain what’s going on with me,” she wrote. Another member said, “My main problem now is with my neck, but doctors don't seem to be concerned with it because they can’t see evidence on X-ray.”
For these reasons, magnetic resonance imaging (MRI) is now considered the imaging method of choice for diagnosing axial spondyloarthritis.
Magnetic resonance imaging increases diagnostic accuracy. It detects both active inflammation and structural changes in people with symptoms of axial spondyloarthritis, even when joints look normal on X-rays. MRI also provides less radiation exposure than X-rays.
“My rheumatologist ordered more MRIs to look at different joints, and lots of things are showing up. Just needed to find the right doctor — after 35 years of pain,” said one member of MySpondyliitisTeam.
Considered the key imaging biomarker of axial spondyloarthritis, sacroiliitis is visible on MRI before radiographic structural damage appears. This provides a "window of opportunity" for early treatment that could improve long-term outcome.
But MRI scans also have drawbacks. While MRI can detect joint inflammation, the scans are not very specific. Swelling and other inflammatory changes could be caused by wear and tear or aging, for example, not nonradiographic axial spondyloarthritis.
Research also shows that it could take more than a year for swelling to be visible on an MRI. And scans can appear negative even in people who have axial spondyloarthritis, requiring expensive future MRI follow-ups.
MRI scans can monitor the progression of axial spondyloarthritis over time, from nonradiographic to radiographic. But sometimes, the disease never progresses. One 12-year study found that up to 25 percent of people with pain from axial spondyloarthritis showed no progression on imaging studies.
For this reason, rheumatologists now look at the entire clinical picture when diagnosing axial spondyloarthritis — including symptoms, family medical history, physical examination, blood tests to detect presence of the HLA-B27 gene, and imaging scans.
“I went for all these X-rays and MRIs! They found nothing in my neck or left-side shoulder and hand. Frustrated!” shared one member of MySpondylitisTeam. Another said,“If my doctors had listened to the symptoms and not relied on X-rays, they might have figured it out.”
By joining MySpondylitisTeam, the social network and online support group for those living with spondylitis, you gain a support group more than 51,000 members strong who understand what it’s like.
As a long-time member wrote to someone newly joined, “We all understand this invisible disability can affect you from your head to your toes. Kick your shoes off, you are among friends now. By morning you will have new friends to share good and bad with. Welcome!”
Are you experiencing severe pain even though your X-rays don’t show axial spondyloarthritis? Has your rheumatologist ordered an MRI scan to confirm a diagnosis? Share your tips and experiences in a comment below or on MySpondylitisTeam. You'll be surprised how many other members have similar stories.