An Overview of Non-Radiographic Axial Spondyloarthritis

Symptoms, Causes, Diagnosis, and Treatment

Man with back pain sitting on the edge of the bed

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Non-radiographic axial spondyloarthritis (nr-AxSpA) is a type of inflammatory arthritis that falls under a category of diseases called spondyloarthritis (SpA). Spondyloarthritis conditions have a common and very specific symptom affecting that affects all people with spondyloarthritis conditions—inflammation of the spine. Axial spondyloarthritis (AxSpA) affects the axial joints. Non-radiographic means that while there are symptoms, x-rays do not show visible damage. Axial relates to the spine, chest, and hip bones. Spondyloarthritis means it affects the joints and the entheses, tissues between bone and ligament or tendons.

Symptoms

Back pain is a hallmark symptom of nr-AxSpA. Back pain is distinguishable based on when it occurs, how long it lasts, the age of when the back pain starts and what it takes to treat it.

  • Timing: Back pain associated with nr-AxSpA wakes you up at the night and you hurt in the morning. You may also feel stiffness in the morning or after sitting for long periods. This type of stiffness makes moving difficult.
  • Movement: Back pain associated with a strain or slipped disc improves with rest. However, with nr-AxSpA, the pain is better with movement, including exercising and stretching.
  • Age of onset: People who are diagnosed with nr-AxSpA usually start experiencing symptoms in late adolescence and early adulthood, usually getting a diagnosis before age 40.

Inflammation from nr-AxSpA also causes inflammation throughout the body, including:

  • Enthesitis: Inflammation of the entheses, the area where a bone attaches to a tendon or ligament, is another factor that sets spondyloarthritis apart fro other forms of arthritis. Disease progression eventually causes the spinal bones to fuse together. These changes will affect mobility. 
  • Psoriatic arthritis and enteropathic (inflammatory bowel disease-related) arthritis: Both these types of arthritis fall under the SpA umbrella and tend to overlap with nr-AxSpA. Therefore, it is possible to have related symptoms, including psoriasis plaques and gastrointestinal troubles.
  • Eye inflammation: While the research on eye inflammation in people with nr-AxSpA is limited, at least a quarter of people with nr-AxSpA experience some form of eye inflammation—usually anterior uveitis—eye inflammation that causes redness, pain, and blurred vision of the iris (colored part of the eye).
  • Sausage digits: Some people might experience “sausage digits,” also known as dactylitis, where the fingers and/or toes take on the appearance of sausages due to swelling and inflammation.
  • Fatigue: Chronic and long-term fatigue in AxSpA is common, affecting up to 68% of people with nr-AxSpA. People who have this condition describe their fatigue as a type of tiredness never before experienced. It is unrelenting and overwhelming, and sleep is not refreshing no matter how much sleep a person gets.

Ankylosing Spondylitis

Many people with nr-AxSpA eventually develop ankylosing spondylitis (AS), an inflammatory type of arthritis that mostly affects the spine and large joints. One 2015 population-based study shows that in as early as five years 6% of people with nr-AxSpA develop AS, 17% after 10 years, and 26% after 15 years.

Researchers now recognize that people with earlier stages of AS do not have radiological changes, but have similar symptoms, risk factors, and family history.

People with nr-AxSpA who eventually become disabled are later confirmed as having AS, but those early stages of AS are considered nr-AxSpA. Of course, some people with nr-AxSpA and AxSpA never go on to develop AS. Others live with AxSpA for many years—even decades—before developing AS.

Causes

A specific cause of nr-AxSpA is difficult to pinpoint as most people with this condition may go undiagnosed for many years. 

What researchers know about nr-AxSpA is that it is an autoimmune disease. This means that the immune system thinks the body is being attacked. As a result, it produces inflammation to protect itself, damaging healthy tissue in the process.  

While researchers don't know exactly why the immune system overreacts in nr-AxSpA, or spondyloarthritis in general, they believe there is a genetic component. For example, people with all types of spondyloarthritis carry the immune gene variant called HLA-B27 more frequently than other people.

Diagnosis

No single test can make a definitive diagnosis of non-radiographic axial spondyloarthritis, so doctors look at clinical symptoms, blood work, and imaging to make a diagnosis.

Your doctor will order blood work that measures inflammation in the body. This may include c-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) testing. While these tests cannot show exactly where inflammation is occurring, doctors take blood test results into consideration towards a diagnosis. 

Your doctor will also do blood work to see if you have the HLA-B27 gene, which is present in 83% of people with axial spondyloarthritis. But HLA-B27 is not enough to confirm a diagnosis because the majority of people with this gene do not go on to develop the condition. And this gene is not present in certain groups of people who also develop Ax-SpA.

Doctors can also use magnetic resonance imaging (MRI) to confirm a diagnosis of nr-AxSpA. MRIs can show inflammation in the SI joints long before the disease progresses enough to see bone fusions on an X-ray.  

Even if inflammation isn’t evident on MRIs and blood work is inconclusive, a doctor can make a diagnosis and prescribe treatments if symptoms and other clinical characteristics and/or testing results meet the clinical criteria of the Assessment of Spondyloarthritis International Society, and there no other explanations for symptoms. 

Treatment

At this point, your doctor's focus on nr-AxSpA treatment is addressing symptoms such as pain and stiffness. Non-steroidal anti-inflammatory drugs (NSAIDs) and physical therapy are effective in this regard. 

When these treatments fail, tumor necrosis factor (TNF) inhibitors and biologic drugs are a next line treatment. These drugs target specific inflammation-promoting molecules. While the U.S. Food and Drug Administration (FDA) has approved several any TNF inhibitors and biologics for the treatment of spondyloarthritis, but not specifically for treating nr-AxSpA. However, evidence suggests these drugs can be successful in slowing down disease progression.

Intra-articular corticosteroid injections can treat local inflammation. However, oral corticosteroids have not been helpful in treating nr-AxSpA. 

Disease-modifying anti-rheumatic drugs (DMARDs) usually are not recommended for people with AxSpA or AS due to their lack of effectiveness for treating these conditions.

A Word From Verywell

Uncontrolled pain can be a serious complication of non-radiographic axial spondyloarthritis. Fortunately, most people respond well to treatment. If for some reason your nr-AxSpA pain isn’t tolerable or manageable, talk to your doctor about finding solutions and a plan to treat the pain. 

If symptoms and pain make it hard to do everyday activities—such as cooking, cleaning or doing your job—your doctor can refer you to an occupational therapist who will assess your needs and help find ways to control symptoms. That person should help you figure out what you to need, give advice about assistive equipment that may help, and check in with you to see if therapy is meeting your needs.

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