Symptoms of Ankylosing Spondylitis

More Than Just Arthritis of the Spine

Ankylosing spondylitis(AS) is a chronic inflammatory disease of the spine joints and the sacroiliac joint. People with AS may also have inflammation in other joints like the shoulders or knees. Sometimes people have symptoms in other organ systems as well, like the eyes.

Symptoms of ankylosing spondylitis
Illustration by Cindy Chung, Verywell.

Symptom Variations

The symptoms of AS most commonly begin in early adulthood. These symptoms do not affect everyone the same way. In other words, some people with AS have much milder disease with minimal impact on their daily lives. Others have much more debilitating symptoms.

While symptoms vary in type and severity, they also may vary by gender. In a 2011 study in Clinical Rheumatology, back pain was reported as the main AS problem in both men and women. But women with AS were more likely to have pain in their neck, knee, or hip, whereas men were more likely to have feet pain.

Women may be more likely to experience fatigue and depression in relation to AS.

Research into sex differences is still relatively recent, however, and people of both sexes can have any of the symptoms of AS.

Frequent Symptoms

Low Back Pain

The most common symptom of AS is low back pain and stiffness, which is caused by inflammation of the spinal joints (called vertebrae). For this reason, it is sometimes called "inflammatory back pain."

The inflammatory back pain of AS has distinct features. These features help doctors differentiate it from mechanical back pain, which is much more common. Inflammatory back pain is often characterized by the following:

  • Chronic, lasting three months or longer
  • Onset when a person is less than 40 years of age
  • Coming on slowly over weeks to months
  • Improving with exercise and not improving with rest or lying down
  • Being worse at night (even waking a person up)
  • Improving with a non-steroidal anti-inflammatory (NSAID)

The quality of the pain in AS can also be helpful in distinguishing it from mechanical back pain. For instance, a person with AS will usually describe his or her back pain as dull and "all over," though sometimes the pain radiates into the buttock region.

The duration of back stiffness can be a clue in identifying inflammatory back pain. Back stiffness in AS usually lasts more than 30 minutes upon waking in the morning, and improves with exercise. Back stiffness from osteoarthritis (a non-inflammatory form of arthritis) lasts less than 30 minutes.

Back pain in AS can become quite disabling, and it tends to expand with time. 

So while the pain of AS may begin on one side of the back, it eventually moves to both sides. The pain may eventually move up the spine and even into the neck.

Joint Pain

Sometimes AS causes pain in joints outside of the spine. For example, some people with AS also experience joint pain in places like the shoulders, hips, knees, elbows, and ankles. However, not everyone with AS will have problems with these other joints.

Enthesitis

Another symptom of AS is inflammation of the entheses (called enthesitis), which are the areas of the body where a tendon or ligament connects to a bone. The heel is the most common site of enthesitis. This might lead to symptoms of heel pain. Depending on which entheses are affected, you might have pain at other body sites as well.

Anterior Uveitis

Anterior uveitis, which refers to inflammation of the colored part of the eye, occurs in approximately 26 percent of people with AS, according to a 2015 study in Annals of Rheumatic Disease. Uveitis usually causes pain in one eye, sensitivity to light, and blurry vision. It is more likely to occur in those who have had AS for a longer time and who test positive for the genetic variation human leukocyte antigen (HLA)-B27. 

Systemic Symptoms

In addition to joint and tissue inflammation, a person may also experience symptoms of whole-body inflammation like malaise, tiredness, mild fever, and a diminished appetite. Some people also experience difficulties sleeping, due to pain.

"Hunchback" Appearance and Limited Mobility

As ankylosing spondylitis becomes more advanced, the inflammation can cause spinal deformities on the spine. This new bone formation may lead to spinal fusion, causing a person's back to curve forward (called hyperkyphosis). In severe cases, this can create a permanent "hunchback" appearance. In some cases, other changes to the spine may occur as well.
However, it's important to note that this only happens in a subset of people. This process may limit spinal mobility, making it more difficult to pick something up from the floor. Getting treatment early on may help you prevent these long-term problems.

Rare Symptoms

Less commonly, AS can affect other systems of the body as well. For example, some complications may affect the heart, lung, or kidney. Both inflammation of the aorta and aortic valve regurgitation can cause heart failure, which can be fatal. Heart conduction defects are also possible.

Lung problems in AS may arise from limited chest wall and spine movement, or from lung fibrosis. Kidney problems such as IgA nephropathy can also occur. Though some of these problems may be life-threatening, they are much less common than the spinal symptoms of AS.

Research also shows an increased prevalence of inflammatory bowel disease and psoriasis in people with AS, so people with AS are more likely to have these other diseases as well. However, these are not thought to be direct complications of the disease. Instead, they probably reflect a shared genetic factors which may increase the risk of all three diseases.

Complications

Complications from vertebral compression or fracture

People with AS have an increased risk of vertebral fracture. In some cases, such a fracture might damage the spinal cord. A spinal cord injury can lead to a variety of neurological symptoms like weakness, numbness, or even paralysis. Severe misalignment of the spine from AS can also cause spinal cord compression, which is a neurological emergency. However, it is important to note that most people with AS will not experience these complications.

When to See a Doctor

If your symptoms are worsening or not responding to treatment, make an appointment to see your physician. You may need to explore other treatment options.

Also make sure you know the symptoms that may signal a serious complication of AS, like sudden weakness or paralysis.

If you do experience sudden symptoms like weakness, paralysis, intense back pain, eye pain, or chest pain, see a doctor right away. That will give you the best chance of a good medical outcome.

A Word From Verywell

Ankylosing spondylitis is a lifelong form of arthritis that affects the spine, sacroiliac joints, peripheral joints, and potentially other organs in the body like the eye, heart, and lung. It is a serious condition and affects everyone a little differently. But with close communication with your health team, you can optimize your health and minimize potential complications.

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