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Ankylosing Spondylitis: Symptoms, Causes and Treatment

Ankylosing Spondylitis or AS is a medically advanced variety of arthritis that generates undesired inflammation of the spine joints. In turn, it causes the vertebrae to amalgamate, resulting in spinal new bone formation. Severe cases could permanently immobilize the spine, affecting general body postures. It can evolve from feelings of discomfort into severe, chronic pain.

“The term spondyloarthritis refers to a group of immune-mediated diseases characterized by inflammation of the axial skeleton, peripheral joints, and entheses. Ankylosing spondylitis (AS) is the most common and characteristic of these entities and even though it was first described over two centuries ago, the understanding of the underlying disease mechanism remains incomplete. It is known that around 40% of patients with AS have subclinical bowel inflammation, suggesting that the origin of the disease could be in the gut. Also, more genes and new molecules have demonstrated a role in the pathogenesis of AS.”1 

The concept of Ankylosing Spondylitis

“The dramatic phenotype caused by the fusion of the sacroiliac, vertebral, and apophyseal joints was recognized in postmortem specimens in the 17th and 18th centuries. The classic clinical description of ankylosing spondylitis was made in the late 1800s and was refined by the addition of radiographic descriptions during the 1930s. After World War II, the hereditary nature of ankylosing spondylitis was established, and descriptions of large patient cohorts led to the formulation of diagnostic criteria in the 1960s. These criteria emphasized the detection of advanced sacroiliitis on radiography, together with pain, stiffness, and limited motion of the lumbar and thoracic spine. The concept of spondyloarthritis was proposed in 1974 to emphasize the interrelatedness of ankylosing spondylitis and several other conditions that had previously been described separately. Spondyloarthritis is currently classified as predominantly axial, affecting the spine, pelvis, and thoracic cage, or predominantly peripheral, affecting the extremities.”2

Certain discoveries have arisen about AS over the years, including incidence between genders, age, and misdiagnosis. “The primary sites of inflammation in AS are the sacroiliac joints. Males tend to be more commonly affected than females, although studies over the years have shown this sex difference to be a lot more marginal than was initially thought. It primarily affects young adults, with a higher incidence in patients younger than 45 years old. As the disease progresses it can result in total fusion of the axial skeleton, and can cause loss of physical function and spinal mobility. Patients in which the disease has been inadequately treated or undiagnosed can develop a characteristic ‘bamboo spine’ where there is total spinal fusion. As well as chronic pain, this can also result in restrictive lung function, leading to respiratory failure.”3  

On-time diagnosis may prevent the development of body deformations, although the main characteristics of the disease vary among patients. Back pain is a general symptom. At the early stages, the diagnosis of AS through X-rays detection is rare.

How can a person develop Ankylosing Spondylitis?

As today, scientists cannot determine the cause of AS. However, both genetics and environmental elements may cause the disease. If your family has had AS, you might have it too. 

“Thanks to advances in imaging techniques, clinicians have a better understanding of how AS results in structural damage to the axial skeleton. While the underlying mechanism triggering the inflammatory process is unknown, study of the pathology of AS has revealed cells that are involved in the process. HLA-B27, a Class 1 surface antigen, is found in ≤89% of AS patients, and is strongly associated with the spondyloarthropathy group of diseases. HLA-B27 binds antigenic peptides for presentation to cytotoxic T cells, thus enabling normal function of the immune response in targeting pathogens such as the influenza virus. The exact mechanism by which HLA-B27 plays a role in AS is so far unexplained. Nevertheless, it is thought to involve abnormalities in antigen presenting cells, subsequently triggering the inflammatory cascade.”4   

The incidence of AS affects more men than women and they do so usually during young adulthood. They could also become sick when they are less than fifty years old. In fewer numbers, both children and older people can experience the disease.

What are the typical symptoms?

AS mostly occurs in adolescence or young adulthood. Usually, the person will experience low back pain for a long time. The pain can stay for more than three months, becoming chronic. Hurting frequently becomes stronger after resting and reduced after exercising.

AS symptoms appear progressively. It affects the spine and can cause rigidness and changes in normal standing posture. Eventually, AS causes mobility impairment due to a lack of body flexibility. Symptoms such as fever, fatigue, and loss of appetite also appear.

“Back pain is a common symptom that most people experience at one time or another during their lives. There are many different causes of back pain and, therefore, clinicians need to be aware of how to distinguish symptoms characteristic of inflammation from other causes. Inflammatory back pain characteristically improves upon activity and worsens with rest. It should be present for at least 3 months to warrant further investigation. The pain is described as dull and insidious in onset and may be nocturnal, interfering with the patient’s sleep pattern. Early morning stiffness lasting longer than 30 minutes is an important feature. Patients commonly complain of lower back or buttock pain.3 This could be unilateral initially but become bilateral as the disease progresses. The cervical and thoracic spine can also be affected but less commonly.”5 

Characteristic features of inflammatory back pain


Characteristic features of inflammatory back pain
Characteristic features of inflammatory back pain (6)

AS can affect the neck, shoulders, hips, hands, arms, knees, ankles and heel joints. Even eyes can swell and show irritation, becoming reddish, watery and painful.

Not all patients experience the most severe forms of AS, some only experiment pain sporadically and general discomfort. However, AS tends to escalate and lead to body limitations.

How is AS diagnosed and treated?

AS has no cure so far, although medications can delay its deteriorating progress. During the diagnosis, the doctor will ask about the symptoms and perform a physical exam and lab testing such as back X-ray, magnetic resonance imaging and blood tests. You will need to visit a rheumatologist for a firm diagnosis and treatment.  

Consulting physical and occupational therapists is advisable. They will check for various signs, such as inflammatory back pain and/or previous joint inflammation, as well as genetic factors. Inflammatory back pain and/or joint inflammations occurring previously and having a parent who showed the disease are all alarms to be checked.

Modified New York Criteria for Ankylosing Spondylitis


Modified New York Criteria for Ankylosing Spondylitis
Modified New York Criteria for Ankylosing Spondylitis (7)

Inflammatory back pain occurs if four of the following five features are present: “(a) age at onset <40 years; (b) back pain >3 months; (c) insidious onset; (d) morning stiffness; and (e) improvement with exercise. On the basis of the 1984 modified New York criteria, the diagnosis of AS can be made if radiological sacroiliitis (either grade II bilaterally, or grade III unilaterally) is present in conjunction with clinical signs (inflammatory back pain or restriction of spinal mobility). However, in the absence of definite radiographic findings, one can calculate individual disease probabilities depending on the presence of typical SpA manifestations (such as inflammatory back pain, enthesitis, uveitis, asymmetric arthritis, positive family history, response to NSAIDs, HLA-B27, raised CRP). For example, the disease probability of axial SpA (early AS) in a patient with inflammatory back pain increases from 14% to around 50–60% if there are one or two more clinical SpA features present. It further increases from 50% to 90% if HLA-B27 is positive or if the MRI is positive. Thus, in patients reaching disease probabilities of 80–90%, the diagnosis of axial SpA should be made, as indicated in the diagnostic algorithm shown in fig 6. The important conclusion from the probability calculations is that an early diagnosis of axial SpA can be made with sufficient probability, even in the absence of typical radiological changes.”8 

Complications of Ankylosing Spondylitis

“The most serious complication encountered in AS is spinal fracture. Even minor trauma to the rigid, fragile spinal column can cause severe damage. The cervical spine is the most susceptible site; fractures at this site can result in quadriplegia. Prostatitis is highly prevalent among men with AS. Aortic insufficiency and cardiac conduction disturbances can occur in patients with long term disease. Amyloidosis, cauda equina syndrome, and pulmonary fibrosis are rare complications.”9  

Palliative Treatment of Ankylosing Spondylitis

Medications include drugs to reduce inflammation, pain, and rigidness, such as ibuprofen, aspirin and other pain relievers; prescribed anti-rheumatic and anti-depressants aimed at slowing AS progression; and steroid formulations directly placed in severely affected sites.

“Following approval of the first tumor necrosis factor-alpha inhibitor (TNFi) for use in ankylosing spondylitis (AS) 15 years ago, TNFi treatment has become the mainstay treatment for active AS. The main reason for this is the high response rate, where randomized controlled trials (RCTs) have suggested that up to 30% of patients with axial spondyloarthritis (SpA) or AS may even achieve inactive disease, defined as ASDAS (ankylosing disease activity score) below 1.3, at 24 weeks after treatment start.”10  

Surgery can also help affected areas through the replacement of joints. Other treatments such as physical therapy and yoga might be useful.

Specialist recommend daily exercise (except jumping), avoid smoking, maintain a straight-up posture to avoid deformities. Selecting natural and healthy food will provide some means to fight the disease.

Several social organizations around the world have a mission of solidarity with people having AS. Joining a group that fits your needs and sharing your experience with others might be helpful. 

AS is a long-term disease. Going to a rheumatologist as soon as you detect symptoms might help delay the degenerative process. Please, consult your doctor for additional advice on how to confront Ankylosing Spondylitis.



(1) Recent advances in ankylosing spondylitis: understanding the disease and management. Garcia-Montoya, L. F1000 Research. 2018. 

(2) Ankylosing Spondylitis and Axial Spondyloarthritis. Taurog, J.D., Chhabra, A. & Colbert, R.A. The New England Journal Of Medicine. 2016. 

(3, 4, 5, 6) Ankylosing Spondylitis: A review. Mahmood, F. & Helliwell, P. 2017. European Medical Journal. 

(7, 8, 9) Ankylosing spondylitis: an overview. Sieper, J., Braun, J., Rudwaleit, M., Boonen, A. & Zink, A. 2002.

(10) Biological treatment of ankylosing spondylitis: a nationwide study of treatment trajectories on a patient level in clinical practice. Lindström, U., Olofsson, T., Wedrén, S., Qirjazo, I. & Askling, J. Arthritis Research & Therapy. 2019. 


María Laura Márquez
13 October, 2018

Written by

María Laura Márquez, general doctor graduated from The University of Oriente in 2018, Venezuela. My interests in the world of medicine and science, are focused on surgery and its breakthroughs. Nowadays I practice my more:

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