What Is Non-Radiographic Axial Spondyloarthritis?

Axial spondyloarthritis is a chronic inflammatory disease affecting the axial skeleton of the human body. A form of this illness known as non-radiographic axial spondyloarthritis is identified by plain X-rays showing no discernible alterations to the sacroiliac joint.

The word "arthritis" is used to describe a wide range of illnesses affecting the body's connective tissues, joints, and bones that cause pain, inflammation, and decreased function.

Axial spondyloarthritis (axSpA) is the term used to describe arthritis that mostly affects your spine and the joints that connect it to your pelvis, known as the sacroiliac (SI) joints.

As with many other arthritic disorders, diagnostic imaging is used to evaluate axSpA. AxSpA is diagnosed as non-radiographic axSpA or nr-axSpA if symptoms are present but plain radiographs (X-rays) do not clearly show alterations to the SI joints.

What is non-radiographic axial spondyloarthritis (nr-axSpA)?

The spine and pelvis are the main areas affected by non-radiographic axial spondyloarthritis (nr-axSpA), a chronic inflammatory disease. Although the illness is thought to be immune-mediated, the precise underlying causes are unknown.

The AxSpA subtype known as Nr-axSpA represents one extreme of the potential illness spectrum associated with axSpA.

Nr-axSpA characterises axSpA with little to no X-ray evidence of SI joint injury. The ilium bones of the pelvis and the sacrum at the base of the spine are joined by your SI joints. They are in charge of stabilising and absorbing shocks while bearing the weight of your erect body.

What sets out nr-axSpA from the other extreme of the axSpA spectrum, ankylosing spondylitis (AS), is an injury to the SI joint.

AS also known as radiographic axial spondyloarthritis (r-axSpA), is characterised by obvious X-ray damage in one or both SI joints.

What are the causes of non-radiographic axial spondyloarthritis?

Uncertainty surrounds the precise aetiology of axSpA and its subtypes, including nr-axSpA. It is believed that overreactive immune responses, genetics, and environmental factors all play a role.

There is a genetic susceptibility to axSpA in certain individuals. HLA-B27 is the most often implicated gene; nevertheless, carrying this gene does not ensure that you will get axSpA.

Some individuals who have axSpA get it as a result of coming into contact with a virus or bacteria. Following physical trauma from an injury, repeated stress, or improper body mechanics, some people acquire axSpA.

Research from 2022 indicates that the axSpA's formation and progression involve both innate and adaptive immunity.

Your body's natural defence against potentially harmful invaders, like germs and viruses, is known as innate immunity. A focused immune response is known as adaptive immunity. It involves unique antibodies that have been developed to combat a particular infection.

Traditional autoimmune disorders are caused by overactive adaptive immunity, in which the body targets its cells directly.

However, the fact that innate immunity plays a role in axSpA implies that inflammation may potentially be indirectly caused by other immunological processes. Because of this, axSpA may be classified as an immune-mediated illness with autoimmune characteristics.

What are the symptoms?

The symptoms of non-radiographic axial spondyloarthritis usually appear gradually over weeks to months, beginning with lower back and buttock discomfort and stiffness. In addition, it may hurt in other parts of the body, such as the following:
  • jaw
  • neck
  • shoulders
  • knees
  • heels
  • toes
  • fingers
  • wrists
  • hips
  • ribs
  • eyes
In contrast to mechanical back pain, inflammatory back pain (IBP) is typically the cause of discomfort from nr-axSpA. IBP is caused by chronic inflammation, whereas mechanical back pain is caused by problems with the structure of the bones and connective tissues.

Among the IBP characteristics of nr-axSpA are:
  • beginning of symptoms before the age of forty
  • discomfort that is worse in the morning or at night
  • Exercise improves symptoms, but rest does not
  • symptom relief using nonsteroidal anti-inflammatory medicines (NSAIDs)
  • frequently no prior trauma in the area
  • alternating buttock pain
Before lower back discomfort, some individuals with nr-axSpA have pain in other parts of their bodies. Women are more likely than men to report experiencing discomfort initially in the neck or peripheral joints.

Additionally, Nr-axSpA is observed in common co-occurring diseases like:
  • inflammatory bowel disease
  • psoriasis
  • acute anterior uveitis

How is it diagnosed?

There are no conclusive tests available to determine nr-axSpA.

Based on your symptoms and the findings of diagnostic imaging, a rheumatologist will make a diagnosis.

A key component of diagnosis is an X-ray. They enable your rheumatologist to check for damage to your SI joints.

The "modified New York criteria" need to be satisfied to be diagnosed with nr-axSpA. The updated axSpA diagnostic recommendations that resulted from a consensus gathering of specialists in New York are known as the modified New York criteria.

They claim that the presence of nr-axSpA occurs when any one of the following conditions is satisfied:
  • More than three months of inflammatory lower back discomfort were experienced.
  • There is restricted lumbar mobility in the frontal (side-to-side) and sagittal (forward and backwards) planes.
  • limitation of chest expansion
  • Inflammation of SI (sacroiliitis) corresponds to grade 2 in both joints or to grade 3 or 4 in at least one joint.

A score of 2 or above shows that the SI joint has undergone noticeable alterations.

MRIs and other diagnostic imaging techniques may be used in certain situations to diagnose nr-axSpA. Similar to X-rays, particular proof of SI joint participation needs to be observed.

Apart from diagnostic imaging, nr-axSpA diagnosis can also be supported by blood work and genetic screening, which confirm the presence of certain inflammatory markers and genes such as HLA-B27.

What is the treatment for nr-axSpA?

Although nr-axSpA has no known cure, medication can increase your comfort and functional abilities.

It is advised to make lifestyle adjustments including exercising and eating a balanced diet. Although there isn't currently a single diet that supports the treatment of nr-axSpA, avoiding inflammatory foods, especially those that are anti-inflammatory, may be helpful.

Given that nr-axSpA is primarily caused by IBP, exercise frequently helps reduce pain. Your mobility and flexibility can be preserved and even improved with a range of motion exercises, cardiovascular activity, balance training, and strengthening exercises.

NSAID medication is also effective in treating IBP problems. The treatment of moderate to severe nr-axSpA involves these drugs. If your rheumatologist finds that your symptoms are seriously interfering with your everyday activities, they may recommend more focused medications such as biologics or JAK inhibitors, which block particular inflammatory pathways in the body.

What to expect with this condition

Chronic Nr-axSpA can be well controlled, but it cannot be cured. Your general quality of life and physical function can both be enhanced by treatment.

There may be flare-ups, or times when the symptoms get worse.

AxSpA disorders can worsen with time, particularly if untreated, although each person's experience with the illness is unique. Not all cases of Nr-axSpA advance to AS. Indeed, only 5–30% of individuals with nr-axSpA are expected to acquire SI joint involvement.

Nevertheless, Nr-axSpA can progress in various ways. For example, you might never have SI involvement yet later acquire psoriasis or other nr-axSpA-related illnesses.

The takeaway

One subtype of axSpA, a chronic inflammatory disease mostly affecting the spine and pelvis, is non-radiographic axial spondyloarthritis. When axSpA is present but your SI joints have little to no visible damage, you are diagnosed with Nr-axSpA.

Although nr-axSpA has no known cure, medication can help you restore and maintain your physical function as well as enhance your quality of life.

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