What is ankylosing spondylitis?
Ankylosing spondylitis (AS), also known as axial spondyloarthritis, is a chronic inflammatory condition that primarily affects the spine. Over time, inflammation can lead to the fusion of some vertebrae, which are the bones that make up your spine. This fusion can cause stiffness and reduce flexibility, leading to discomfort.
AS typically starts at the sacroiliac joints, where the base of your spine (the sacrum) connects with your pelvis (the ilium). These joints are some of the largest in the body and are essential for movement, especially when shifting or rotating your hips. The inflammation in these joints is often one of the earliest signs of the condition.
While the sacroiliac joints are most affected, ankylosing spondylitis can also impact other areas of the body. Less frequently, AS affects other joints, including:
- Shoulders
- Hips
- Knees
While there is no cure for ankylosing spondylitis, early diagnosis and treatment can help manage the symptoms, slow the progression of the condition and improve the quality of your life.
Ankylosing spondylitis symptoms
Everyone with ankylosing spondylitis experiences different symptoms. The most common symptom is lower back pain caused by sacroiliitis, which is painful inflammation in the sacroiliac joints.
The pain can spread to other areas, including:
- Hip pain
- Pain in your buttocks
- Neck pain
- Abdominal pain
Other symptoms of AS may include:
- Stiffness or difficulty moving your hips and lower back, especially in the morning or after resting for a long time
- Fatigue
- Shortness of breath
- Loss of appetite or unexplained weight loss
- Diarrhea
- Skin rashes
- Vision problems
When to see a doctor
See a doctor if you have persistent lower back pain, stiffness or discomfort that spreads to your hips, buttocks or neck. Also, get medical advice if you're feeling constantly fatigued, losing weight without explanation or having digestive issues like diarrhea. Early diagnosis and treatment can help manage symptoms and prevent complications.
Ankylosing spondylitis causes
Ankylosing spondylitis is an autoimmune condition. This means your immune system mistakenly attacks your body instead of protecting it.
The exact cause of ankylosing spondylitis isn’t fully understood. However, studies show that certain genetic mutations are strongly linked to the condition. Genetic mutations are changes in your DNA that occur when your cells make copies of themselves.
More than 60 genes may be linked to AS. One example is the human leukocyte antigen-B (HLA-B27) gene. Having a gene known as HLA-B27 increases your risk, but not everyone with this gene develops the condition, which means environmental factors could also play a part.
Ankylosing spondylitis risk factors
While researchers aren’t exactly sure what causes ankylosing spondylitis, certain risk factors can make it more likely to develop. These include:
- Age: Symptoms usually start between the ages of 18 and 40.
- Family history: If you have family members with ankylosing spondylitis, you may be at a higher risk.
- Sex: Ankylosing spondylitis is more common in men than women.
- Certain conditions: If you have conditions like Crohn’s disease, ulcerative colitis or psoriasis, you may be more likely to develop ankylosing spondylitis.
Complications of ankylosing spondylitis
In severe cases of ankylosing spondylitis, the body forms new bone as it tries to heal itself. Over time, this new bone can connect the vertebrae in the spine, causing sections of the spine to fuse. This makes the spine stiff and less flexible. The fusion can also affect the rib cage, limiting how much your lungs can expand.
Other possible complications include:
- Eye inflammation (uveitis): This is a common issue with ankylosing spondylitis and can cause sudden eye pain, sensitivity to light and blurry vision.
- Fractures: Early in the disease, bones can weaken, especially in the spine. This can cause vertebrae to collapse, which can lead to a stooped posture. These fractures may also put pressure on the spinal cord or nerves, which can cause further damage.
- Neurological impairment: In the later stages of the condition, when the bones in the spine have fused together, a break in the spine can be very serious. It can snap straight across and damage the nerves, leading to neurological problems like weakness or paralysis.
- Heart problems: Ankylosing spondylitis can affect the aorta, the large artery in your body. Inflammation can make the aorta enlarge, which can affect how the aortic valve works. This can increase the risk of heart disease as well.
How is ankylosing spondylitis diagnosed?
Diagnosing ankylosing spondylitis can be difficult. Many of its symptoms are similar to those of other conditions and no definitive test exists for it. Your doctor will do a physical exam and talk to you about your personal and family health history. Imaging tests and blood work can also help your doctor determine the cause of your symptoms and make an accurate diagnosis.
Ankylosing spondylitis treatment
Ankylosing spondylitis treatment focuses on managing discomfort, reducing inflammation and helping you keep your mobility and posture. While there’s no cure, effective treatments can make a big difference in your quality of life by controlling symptoms and slowing the condition's progression. Treatment usually includes medications, physical therapy, exercise, and in some cases, surgery.