Ankylosing Spondylitis (AS) is a chronic inflammatory condition that mainly affects the spine and sacroiliac joints. It can cause persistent back pain, morning stiffness, fatigue, and reduced mobility. Modern treatments, including biologic medicines, can help control inflammation and improve symptoms.
However, some people with Ankylosing Spondylitis continue to experience pain even after their inflammation appears to be under control.
This can be confusing. If inflammation is reduced, why does the pain remain?
The answer is that pain in Ankylosing Spondylitis is not always caused by active inflammation alone. Other factors, such as changes in pain processing, muscle problems, structural damage, and sleep disturbances, may contribute to ongoing symptoms.
Understanding these different causes is important because persistent pain does not always mean that the disease is getting worse or that stronger medication is automatically needed.
Can Ankylosing Spondylitis Cause Pain Without Active Inflammation?
Yes. People with Ankylosing Spondylitis may experience persistent pain even when inflammatory activity is low.
AS-related pain can involve several mechanisms:
- Inflammatory pain caused by active disease
- Mechanical pain caused by posture, muscle strain, or structural changes
- Nociplastic pain caused by altered pain processing
- Less commonly, neuropathic pain involving the nervous system
These mechanisms may occur individually or together.
A patient may have controlled inflammation but still experience stiffness, tenderness, fatigue, or widespread discomfort.
Recent research highlights that persistent pain in axial spondyloarthritis can involve multiple pain mechanisms beyond inflammation.
1. Central Sensitization: When the Nervous System Becomes More Sensitive
One important reason for persistent pain is central sensitization.
The nervous system normally processes pain signals to help protect the body. However, in some people with chronic pain, the nervous system becomes more sensitive and may amplify pain signals.
This means that a stimulus that would normally cause mild discomfort may feel much more painful.
Central sensitization may develop after prolonged pain or inflammation and can sometimes continue even when the original inflammatory activity has reduced.
Symptoms of Central Sensitization
Some people may experience:
- Pain that feels stronger than expected
- Tenderness in multiple body areas
- Pain from gentle pressure or touch
- Widespread body discomfort
- Increased sensitivity to movement
- Persistent fatigue
- Difficulty sleeping
Central sensitization does not mean that the pain is imaginary. The pain is real, but the nervous system may be processing signals differently.
Research suggests that central sensitization contributes to persistent pain in a substantial proportion of people with axial spondyloarthritis.
2. Fibromyalgia and Ankylosing Spondylitis
Fibromyalgia is a chronic condition associated with widespread pain, fatigue, sleep disturbances, and increased sensitivity to pain.
Some people with Ankylosing Spondylitis may also have fibromyalgia.
When both conditions occur together, pain may continue even when AS inflammation is well controlled.
How Can Fibromyalgia Affect AS Symptoms?
Fibromyalgia may contribute to:
- Widespread muscle pain
- Tenderness throughout the body
- Persistent fatigue
- Poor sleep
- Difficulty concentrating
- Pain in areas beyond the spine
For example, a patient may have reduced inflammatory activity on treatment but continue to experience pain in the shoulders, neck, hips, and muscles.
This does not necessarily indicate that Ankylosing Spondylitis is becoming more active.
A rheumatologist may evaluate whether fibromyalgia or another pain condition is contributing to symptoms before changing AS treatment.
3. Mechanical Pain and Muscle Problems
Not every back pain episode in a person with AS is caused by inflammation.
Mechanical pain may develop due to muscle strain, posture, reduced flexibility, or changes in the way the body moves.
When spinal mobility becomes limited, certain muscles may work harder to compensate. This can contribute to muscle tightness and discomfort.
Common Causes of Mechanical Pain
- Sitting for prolonged periods
- Poor posture
- Sudden increase in physical activity
- Muscle weakness
- Reduced flexibility
- Improper lifting techniques
- Repetitive movements
Mechanical pain may worsen with particular activities or positions.
Unlike inflammatory pain, it may not consistently improve with movement and can sometimes become worse after physical exertion.
Identifying mechanical contributors can help prevent unnecessary changes in anti-inflammatory medication.
4. Structural Changes in the Spine
Ankylosing Spondylitis can cause structural changes in the spine over time.
These may include:
- Reduced spinal flexibility
- Formation of new bone around vertebrae
- Changes in posture
- Reduced movement of spinal joints
- Increased muscle strain
Even when active inflammation is controlled, existing structural changes may continue to affect movement and comfort.
For example, a person with reduced spinal flexibility may experience discomfort while turning, bending, or sitting for extended periods.
However, persistent pain does not automatically indicate that spinal fusion or structural progression is occurring.
A clinical assessment is necessary to determine whether symptoms are related to existing damage, active inflammation, or another cause.
5. Sleep Problems and Fatigue
Sleep disturbances are common in people living with chronic inflammatory conditions.
Pain may interrupt sleep, while poor sleep can increase pain sensitivity the following day.
This can create a cycle:
Pain → Poor sleep → Increased sensitivity → More pain
People with Ankylosing Spondylitis may experience difficulty falling asleep, waking during the night, or feeling tired even after sleeping for several hours.
Fatigue may also be associated with inflammation, medication effects, mood changes, or other health conditions.
Improving sleep quality may help reduce the overall burden of pain, although it does not replace treatment for active inflammation.
6. Stress and Emotional Health
Living with a chronic condition can be physically and emotionally challenging.
Stress, anxiety, and low mood may influence how the nervous system processes pain. They can also affect sleep, physical activity, and coping strategies.
This does not mean that AS pain is caused by emotions.
Instead, emotional health and physical pain can influence each other.
Patients experiencing persistent pain may benefit from discussing stress, anxiety, or sleep difficulties with their healthcare team.
Supportive counselling, relaxation techniques, and appropriate psychological care may be useful components of comprehensive pain management.
7. Could the Inflammation Still Be Active?
Yes. Persistent pain can sometimes indicate ongoing inflammation.
Symptoms alone cannot reliably determine whether inflammation is controlled.
A patient may continue to experience active inflammation despite improvement in some symptoms. In other cases, pain may persist even when objective signs of inflammation are limited.
A rheumatologist may evaluate:
- Morning stiffness
- Pain intensity and pattern
- Joint tenderness
- Functional limitations
- C-reactive protein levels
- Erythrocyte sedimentation rate
- MRI findings, when clinically appropriate
Blood tests can be normal even when inflammation is present. Similarly, elevated inflammatory markers may have causes other than AS.
Therefore, treatment decisions should be based on the overall clinical picture rather than pain alone.
How Do Doctors Evaluate Persistent Pain in Ankylosing Spondylitis?
When pain continues despite treatment, the first step is to understand its underlying cause.
Medical History and Examination
The rheumatologist may ask:
- Where is the pain located?
- Is it worse in the morning or after rest?
- Does movement improve or worsen it?
- Is the pain widespread or limited to the back?
- Are there sleep problems or fatigue?
- Have medications been taken regularly?
- Have new symptoms developed?
A physical examination can help identify muscle tenderness, joint inflammation, reduced mobility, and other possible causes.
Blood Tests and Imaging
Blood tests may help assess inflammation.
MRI may be considered when there is uncertainty about ongoing inflammatory activity or when imaging could clarify the cause of symptoms.
However, imaging is not required at every appointment. The need for additional testing depends on the patient’s symptoms and examination findings.
Review of the Original Diagnosis
If treatment repeatedly fails to improve symptoms, the doctor may reconsider whether the original diagnosis is correct.
Some conditions can resemble Ankylosing Spondylitis, including mechanical back pain and degenerative changes.
This is particularly important before increasing or switching advanced medications. Current clinical recommendations emphasize reassessing the diagnosis, inflammatory activity, and other contributing conditions when treatment response is inadequate.
How Can Persistent Pain Be Managed?
Treatment depends on whether the pain is caused by active inflammation, mechanical problems, central sensitization, or a combination.
1. Continue Appropriate AS Treatment
If active inflammation is present, the rheumatologist may adjust treatment.
Depending on the patient’s condition, options may include non-steroidal anti-inflammatory drugs, biologic medicines, or targeted therapies.
Do not stop or change prescribed medication without medical advice.
2. Physiotherapy and Exercise
Appropriate exercise can help improve:
- Spinal flexibility
- Muscle strength
- Posture
- Balance
- Physical function
A physiotherapist can design a program that considers spinal stiffness, pain levels, and existing structural changes.
Exercise should be adjusted if it repeatedly aggravates symptoms.
3. Improve Sleep Quality
Helpful strategies may include:
- Maintaining a regular sleep schedule
- Choosing a comfortable sleeping position
- Reducing screen use before bedtime
- Avoiding excessive caffeine late in the day
- Discussing persistent sleep problems with a doctor
4. Address Fibromyalgia or Other Pain Conditions
If fibromyalgia or another chronic pain condition is present, treatment may involve a combination of exercise, sleep management, education, and selected medications.
Anti-inflammatory medicines alone may not adequately treat pain caused by central sensitization.
5. Manage Stress and Overall Health
Relaxation techniques, supportive counselling, and maintaining social connections may help people cope with chronic pain.
A comprehensive treatment plan should consider physical, emotional, and lifestyle factors.
When Should You Consult a Rheumatologist?
Seek medical advice if:
- Pain continues despite prescribed treatment
- Morning stiffness becomes significantly worse
- New joint swelling develops
- Pain begins affecting sleep or daily activities
- Symptoms become widespread
- You experience new neurological symptoms
- You notice a significant change in your usual pain pattern
Sudden severe spinal pain, especially after a fall or injury, requires urgent medical evaluation. People with advanced spinal changes may be at increased risk of spinal fractures.
Frequently Asked Questions
Can Ankylosing Spondylitis pain continue after inflammation is controlled?
Yes. Pain may persist due to central sensitization, fibromyalgia, mechanical problems, structural changes, or sleep disturbances.
Does persistent pain mean my Ankylosing Spondylitis is getting worse?
Not necessarily. Persistent pain does not always indicate active inflammation or disease progression. A rheumatologist can assess the cause.
Can biologic medicines completely eliminate AS pain?
Biologic medicines can reduce inflammation and improve symptoms, but they may not eliminate every source of pain.
What is central sensitization in Ankylosing Spondylitis?
Central sensitization occurs when the nervous system becomes more sensitive and amplifies pain signals. It may contribute to ongoing pain even when inflammation is controlled.
Can fibromyalgia occur with Ankylosing Spondylitis?
Yes. Fibromyalgia can coexist with AS and may contribute to widespread pain, fatigue, and sleep disturbances.
Should I change my AS medication if pain continues?
Do not change medication on your own. Persistent pain should first be evaluated to determine whether inflammation is active or another condition is contributing.
Conclusion
Ankylosing Spondylitis pain can continue even when inflammation is controlled because pain involves more than one mechanism.
Central sensitization, fibromyalgia, mechanical problems, structural changes, poor sleep, and emotional stress may all contribute to persistent symptoms.
The most important step is to identify the actual cause of the pain rather than automatically assuming that the disease is worsening.
A personalized treatment plan combining appropriate medication, physical activity, sleep management, and assessment of other pain conditions can help improve comfort and daily function.
If you continue experiencing pain despite treatment, discuss your symptoms with a rheumatologist. Understanding the cause can help guide more effective and appropriate management.
