Non-radiographic ankylosing spondylitis (nr-AsSpA) is a type of inflammatory arthritis that primarily affects the spine. “Non-radiographic” means that an X-ray does not show any damage from arthritis, even though symptoms appear.
While the term “nr-AsSpA” may refer to a period before damage is visible on the spine’s joints, a person who uses this term is likely referring to non-radiographic axial spondyloarthritis (nr-AxSpA), which falls into the same category of inflammatory arthritis as ankylosing spondylitis (AS).
The main difference between nr-AxSpA and AS is that a person with AS has spinal damage that is visible on an X-ray.
This article reviews nr-AxSpA, AS, their symptoms, information about diagnosis, and more.
“Nr-AsSpA” is not an official diagnosis. If a doctor uses this term to describe a person’s condition, the person likely has nr-AxSpA, which is an official diagnosis. A defining feature of AS is visible damage to the joints in the spine.
Both nr-AxSpA and AS are types of spondyloarthritis — a group of arthritis types that cause inflammation in the spine.
Experts often consider nr-AxSpA an earlier form of AS because damage from the disease does not yet appear on X-rays.
According to the Spondylitis Association of America, 5–30% of people living with nr-AxSpA develop AS over 2–30 years, meaning that their condition progresses to the point that damage shows on X-rays.
To receive a diagnosis of AS, a person must have an X-ray showing changes or damage to their spine. However, the two conditions can cause similar symptoms, and both can lead to disability.
Nr-AxSpA and AS have similar symptoms.
According to the Arthritis Foundation, common symptoms include:
- stiffness and pain on either side of the body, where the spine meets the pelvis
- pain in the lower back, buttocks, and hips that develops slowly over weeks or months
- stiffness when first waking up after periods of rest
- back pain during the night or early morning
- appetite loss
In addition, a person may experience symptoms related to inflammation in the body, such as:
- pain, swelling, redness, and warmth (inflammation) in the knees, heels, ankles, fingers, toes, ribcage, upper spine, shoulders, or neck
- chronic diarrhea or gastrointestinal upset and pain (such as Crohn’s disease or ulcerative colitis)
- pain and redness in the eyes (uveitis)
- red, flaky skin patches (psoriasis)
Nr-AxSpA, like other forms of spondylitis, occurs as a result of chronic inflammation. A person’s immune system mistakenly attacks healthy tissue, which causes inflammation. Over time, the inflammation can damage healthy cells.
Some experts suspect that the cause may be genetic. A gene variant known as HLA-B27 is present in many people living with nr-AxSpA.
“Axial spondyloarthritis” is the main term to describe inflammatory arthritis that primarily affects the spine. Both Nr-AxSpA and AS are types of axial spondyloarthritis.
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AS is another type of axial spondyloarthritis. Some experts believe that nr-AxSpA is an early stage of AS. This is because, in nr-AxSpA, the condition has not yet damaged the spine to the point that a doctor can see it on an X-ray. In some cases, it can take up to 10 years before the damage appears on an X-ray.
The symptoms of AS and nr-AxSpA can be similar.
One reason for the delay may be that nr-AxSpA does not have a single set of diagnostic criteria. Among other diagnostic methods for the condition, doctors may use a blood test to check for the HLA-B27 gene and inflammation. They may also review a person’s clinical symptoms, such as lower back pain near the pelvis.
To diagnose nr-AxSpA, a doctor may use the following methods:
- blood tests
- MRI scans to check for inflammation
- review of a person’s symptoms
- physical examination
- review of family history
Treatment often focuses on pain management instead of attempting to prevent disease progression, as is common with AS. Often, the first line of treatment is pain medications such as nonsteroidal anti-inflammatory drugs (NSAIDs). A doctor may also recommend physical therapy.
In some cases, a doctor may recommend using tumor necrosis factor (TNF) inhibitors, a type of biologic drugs that can suspend disease progression and reduce inflammation.
A doctor may be able to prescribe the medication using comorbidities as a leveraging point for nr-AxSpA.
If a person’s nr-AxSpA transitions to AS, a doctor may make additional treatment recommendations to help prevent disease progression.
A person living with nr-AxSpA can experience the same symptoms as someone with AS. A person may develop debilitating pain that interferes with their daily life.
There is no cure for nr-AxSpA or AS.
In some cases, nr-AxSpA may develop into AS. However, progression is not guaranteed. About 10–40% of people living with nr-AxSpA go on to develop AS, though no predictor exists.
Some potential risk factors for progression include:
- high inflammatory markers in blood tests
- family history
- being male
AS and nr-AxSpA are two types of spondyloarthritis. The main difference is that AS causes visible damage to the joints, while nr-AxSpA does not. Doctors who use the term “Nr-AsSpA” are likely referring to nr-AxSpA. The symptoms and treatment for the two conditions are similar.
Experts do not fully agree on whether nr-AxSpA is an earlier form of AS. However, only a small percentage of people living with nr-AxSpA develop AS.