Ankylosing spondylitis: eye, cardiovascular, respiratory and gastro-intestinal complications, everything there is to know!

What is ankylosing spondylitis and what causes it? 

Ankylosing spondylitis is the arthritis of the spine. The term "ankylosing" means that there is stiffness. In fact, ankylosing spondylitis is a type of arthritis that makes the spine stiff and painful.

In addition to pain in the spine, ankylosing spondylitis also causes swelling, stiffness and pain in the large joints, toes and fingers.

Ankylosing spondylitis is 3 times more common in men than in women and usually appears between the ages of 20 and 40.

The causes of ankylosing spondylitis are currently unknown. Nevertheless, the disease tends to develop in people with a family history of AS. Genetics is, partly, a contributing factor.

In fact, this condition is 10 to 20 times more frequent in people whose parents or siblings are also affected. 

>> To learn more about ankylosing spondylitis, its diagnosis and treatments,
click here to access the AS fact sheet << 

What are the complications of ankylosing spondylitis?

Ankylosing spondylitis can have extra-articular manifestations such as uveitis (inflammation of the inside of the eye), aortic insufficiency, intestinal disorders or other systemic disorders the frequency and severity of which vary from one patient to another.

Eye problems 

Uveitis is the most common extra-articular complication of ankylosing spondylitis. It occurs in 20 to 30% of AS cases. In 90% of these cases, uveitis is anterior, acute and unilateral.

The clinical signs are a watery eye, redness, pain and hypersensitivity to light; all these symptoms lead to a decrease in visual acuity.

If treated, the condition can be cured in 2 to 3 months and leaves no sequelae.

Nevertheless, episodes of uveitis may recur. If treatment has been inadequate, serious complications may occur, such as synechiae (inflammatory adhesions between posterior iris and the anterior lens capsule), cataract, glaucoma and, in rarer cases, blindness.

Uveitis is a therapeutic emergency in which local corticosteroid therapy must be combined with pupil-dilating eye drops to avoid the formation of synechiae.

When uveitis is complete (called panuveitis) and does not respond to local treatment, subconjunctival injections and sometimes short courses of general corticosteroids can be considered.

Cardiovascular disease 

Heart disease usually occurs late in the course of AS. The most common forms are: conduction disorders (abnormal changes in the heart's rate and rhythm), valvular heart disease (malfunctioning of the heart valve), especially aortic insufficiency and different types of cardiomyopathy.

Numerous studies have reported that patients with ankylosing spondylitis have an estimated 20-40% higher mortality rate from cardiovascular causes than the general population. In addition, the risk of heart attack is multiplied by 3.

Chronic inflammation, elevated CRP, decreased HDL-cholesterol and TNFα, as well as the use of NSAIDs, are major factors that increase cardiovascular risk in patients with ankylosing spondylitis.

Certain recommendations have been put forward in order to limit the risk of cardiovascular disease.

The management of these complications requires adequate control of ankylosing spondylitis. Prescription of non-steroidal anti-inflammatory drugs (NSAIDs) should be done with caution, and corticosteroids should be used at the lowest possible dose. Risk assessment for heart disease should be performed annually.

Respiratory disorders

Another complication of ankylosing spondylitis is respiratory disorders. In the existing literature, the incidence of respiratory problems varies from 0 to over 30%.

In fact, chest wall rigidity, secondary to costovertebral joint dysfunction, disturbs the respiratory mechanics, and a restrictive lung disease is detected during pulmonary function tests.

Pleuropulmonary lesions have also been described. The most frequent are upper lobe pulmonary fibrosis, interstitial lung disease and pleural thickening.

However, as these manifestations are often asymptomatic and chest X-rays cannot detect early lung damage, pleuropulmonary involvement has long been considered a rare and late manifestation of ankylosing spondylitis.

That is why clinicians must strictly adhere to the recommendations for screening and prevention of pleuropulmonary involvement, especially in cases of pre-existing lung damage.

Gastro-intestinal disorders 

Links between ankylosing spondylitis and inflammation of the gastrointestinal tract have been highlighted in various studies. In fact, in patients affected by ankylosing spondylitis, a chronic inflammatory bowel disease (Crohn's disease or ulcerative colitis) appears in 2 to 18% of cases, with a delay of up to 20 years.

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