Axial spondyloarthritis: inflammation, or a sensitized spine, or both.

Some back pain labelled axial spondyloarthritis is inflammatory. Some is neuroplastic. Many people have a mix, and the mix decides what will help.

This page is about understanding the condition and the role the brain and nervous system can play in it. It is not a diagnosis. Your own clinicians know your case.

What axial spondyloarthritis is

Axial spondyloarthritis is an inflammatory condition that targets the axial skeleton: the sacroiliac joints between the base of the spine and the pelvis, and the joints of the spine itself. The hallmark is inflammatory back pain, which starts before age 45, comes on gradually, is worse at night and in the early morning, and improves with exercise rather than rest. Fatigue, hip and heel pain, eye inflammation, psoriasis and inflammatory bowel disease can go along with it.

The term covers two groups. In radiographic axSpA, better known as ankylosing spondylitis, X-rays show damage to the sacroiliac joints. In non-radiographic axSpA, which this index entry describes, the person has the symptoms, often with inflammation on MRI or a positive HLA-B27 gene test, but no X-ray changes yet. Some will develop them; many will not.

Treatment starts with regular exercise and non-steroidal anti-inflammatory drugs. People who do not respond may move on to biologic medicines that block specific inflammatory signals. These treatments can be very effective for inflammatory pain.

The neuroplastic contribution

The ATNS Index of Neuroplastic Symptoms says that axial spondyloarthritis itself is not caused by neuroplastic symptoms. It then makes a point that matters for anyone with this label: some people whose pain and stiffness are attributed to axSpA have neuroplastic symptoms instead, or as a significant contributing factor. The index recommends assessing for neuroplastic symptoms as part of a complete evaluation, particularly when the response to NSAIDs and physical therapy is less than anticipated.

Neuroplastic symptoms are real symptoms produced by learned pathways in the brain and nervous system, a sensitized alarm system, rather than by ongoing inflammation or damage. They are not imaginary. Because the brain can change, they are reversible.

Why is this so relevant to axSpA?

• The non-radiographic diagnosis rests heavily on symptoms. Chronic back pain and stiffness in a young person with a positive gene test can be inflammatory, neuroplastic, or both.
• Years of pain, fear of a progressive disease and the stigma of an invisible illness are exactly the conditions that sensitize a nervous system.
• Fibromyalgia-type widespread pain, poor sleep and fatigue are very common in people with axSpA, and they do not respond to anti-inflammatory treatment.

Sorting out which part is which is not about doubting your diagnosis. It is about matching treatment to mechanism. Our guides to central sensitization and chronic back pain and ACT go further, and the index's rows on ankylosing spondylitis and spondyloarthritis are closely related.

What the research shows

Research in this area has grown quickly. A study of 100 people with axial spondyloarthritis found that central sensitization, pain catastrophizing, sleep disturbance and fibromyalgia-like features were common and were linked to worse outcomes, and it recommended that nociplastic and psychosocial dimensions be assessed routinely in care. A systematic review of fibromyalgia and central sensitization in rheumatoid arthritis, psoriatic arthritis and spondyloarthritis reported that comorbid fibromyalgia affects a meaningful minority of people with axSpA, that higher central sensitization symptom burden tracks with higher disease activity scores and poorer patient-reported outcomes, and that this can make disease look more active than the inflammation justifies.

A review of inflammation and pain as interconnected targets in axSpA argues that residual pain after treatment often reflects non-inflammatory processes, and that co-existing fibromyalgia is associated with a reduced response to anti-inflammatory therapy. A study assessing fibromyalgia in people with axSpA and rheumatoid arthritis adds to the evidence of overlap. Together these studies support the index's position closely: inflammation is real, a sensitized nervous system is also common, and when treatment underdelivers, the second deserves attention.

Signs the brain may be part of the picture

• Your inflammatory markers and MRI are quiet, but pain and stiffness continue.
• NSAIDs or biologics helped less than your rheumatologist expected, or the benefit faded without a change in inflammation.
• Pain has spread beyond the spine and pelvis to many areas, with tenderness to light pressure.
• Fatigue, poor sleep, brain fog and low mood are as disabling as the back pain.
• Flares follow stress, conflict or poor sleep more than physical strain.
• You feel frightened of the disease progressing and guard your back or avoid exercise, even though movement is meant to help.

A solution that addresses it

Treating inflammation remains essential in axSpA. For the neuroplastic part of the pain, there is an approach that addresses it. Pain and symptom reprocessing combines education about how a sensitized nervous system produces real pain, somatic tracking (observing back sensations with curiosity rather than alarm), reducing fear and threat, a graded return to exercise and daily activity, emotional awareness and expression, and acceptance and commitment skills. It is delivered by trained clinicians and increasingly through digital programs, and it sits alongside your rheumatology care.

Cindra is a daily AI companion built around these approaches, with daily check-ins, short practices and plain-language lessons for people whose symptoms have a neuroplastic component. If your inflammation is controlled and your pain is not, you can join the waitlist.

What to do next

Stay with your rheumatologist. Confirm the diagnosis, make sure inflammation is being measured and treated, and keep up the exercise that is central to axSpA care.

If your response to treatment is less than expected, ask directly: how much of my pain is inflammatory right now, and how much could be a sensitized nervous system? Ask whether a screen for central sensitization or fibromyalgia makes sense.

If a neuroplastic component is likely, start learning and practicing alongside your medical treatment. Seek prompt care for a painful red eye, sudden severe back pain after a fall, numbness in the legs or saddle area, or loss of bladder or bowel control.

This article is for general education and is not medical advice, and it does not diagnose or treat any condition. Persistent symptoms deserve a proper medical assessment to rule out disease or injury before a neuroplastic explanation is considered. If your symptoms are new, changing, or come with red-flag signs such as fever, unexplained weight loss, numbness or weakness, chest pain, or loss of bladder or bowel control, see a clinician promptly.