What Are the Symptoms of Ankylosing Spondylitis?
Ankylosing spondylitis (AS) is a chronic inflammatory disease of the spine joints and the sacroiliac joints. People with AS may also have inflammation in other joints like the shoulders or knees.
The symptoms of AS usually begin in early adulthood between the ages of 20 and 30, and they do not affect everyone the same way. In other words, some people with AS have a much milder disease with minimal impact on their daily lives whereas others have much more debilitating symptoms.
While symptoms vary in type and severity, they also 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.
Low Back Pain in Ankylosing Spondylitis
Inflammatory 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).
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:
- Chronic, lasting 3 months or longer
- Begins when a person is less than 40 years of age
- Comes on slowly over a period of weeks to months
- Improves with exercise and does not improve with rest or lying down
- Worse at night (even waking a person up)
- Improves 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,” as opposed to being localized to one area.
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, whereas back stiffness from osteoarthritis (a non-inflammatory form of arthritis) lasts less than 30 minutes.
Expansion of Pain
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, followed by movement up the spine (even into the neck in some people). This can significantly limit mobility, making daily tasks like picking something up off the floor a daunting activity
As ankylosing spondylitis becomes more advanced (and this only happens in a subset of people), the inflammation can cause new bone to form 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.
Other severe complications related to the back include an increased risk of vertebral fracture (with or without spinal cord injury) in people with AS. 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, a neurologic emergency.
Other Symptoms of Ankylosing Spondylitis
Besides lower back pain and stiffness, upper buttock pain is also common in AS. This indicates an involvement of the sacroiliac joints (where the spine connects to the pelvis). Pain may also occur in joints outside of the spine like the shoulders, hips, knees, elbows, and ankles.
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.
It is where the plantar fascia (the ligament that connects your heel bone to your toe bones) inserts. The heel is also where the Achilles tendon (connects your calf muscles to your heel bone) inserts.
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.
Organ Complications of Ankylosing Spondylitis
Non-joint complications may occur in AS like heart, lung, or rarely kidney disease. Regarding heart-related complications in AS, inflammation of the aorta (the artery that carries oxygenated blood away from the heart) and aortic valve regurgitation can cause heart failure, which can be fatal. Lung problems in AS may arise from limited chest wall and spine movement.
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 human leukocyte antigen (HLA)-B27.
Research also shows an increased prevalence of inflammatory bowel disease and psoriasis in people with AS.
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. But with proper knowledge and close follow-up and communication with you or your loved one’s health team (even if your symptoms are mild), you can optimize your AS health and minimize potential complications.