Anything from lugging a backpack or heavy purse, toting a child, or playing a weekend warrior can make your back scream “Stop!” It’s no wonder, then, that it can take years to diagnose ankylosing spondylitis (AS), a chronic inflammatory condition of the spine. Still, there are some red flags that AS isn’t your garden-variety backache. Learning the unique symptoms of AS is key to getting the treatment you need—and to keep living the life you want.
What Is AS, Again?
Ankylosing spondylitis (AS) is a chronic, lifelong form of arthritis that strikes early, usually between the ages of 17 and 45. Pronounced ank-eye-low-sing spon-dill-eye-tiss, it’s considered a type of autoimmune condition, meaning the immune system mistakes part of the body as a foreign invader and attacks it.
AS primarily affects the spine but can also cause inflammation, pain, and stiffness in other areas of the body including the shoulders, hips, ribs, heels, and small joints of the hands and feet. The hallmark characteristic is inflammation in the sacroiliac (SI) joints located at the base of the spine, where it joins the pelvis. The condition is largely believed to be hereditary.
The symptoms come on slowly but gradually worsen—usually over many years—as the small interlocking bones of the spine (the vertebrae) fuse together, further limiting back movement. Ankylosis is the term used to describe this progressive bony fusion, while spondylitis refers to inflammation in the vertebrae.
The Spondylitis Association of America estimates that 1 out of every 200 adults in the U.S., or 1.1 million people, has ankylosing spondylitis.
The Anatomy of AS
To truly understand what’s going on in AS, it helps to have a little anatomy lesson. Ever heard of the term enthesis? Don’t panic—most "Jeopardy!" winners wouldn’t have either. Enthesis is the connective tissue between bone and tendons, ligaments, and joint capsules (the sacs that encase each joint and provide stability).
When this tissue becomes inflamed in AS, it leads to swelling and tenderness along the spine, pelvic bones, SI joints, and sometimes the chest and the heels. This condition is known as enthesitis, and these sites of inflammation are sometimes called hot spots—your doc will literally be able to feel the heat of inflammation when touching them.
The recurring process of healing and repair that takes place after inflammation both scars the entheses (the plural form of enthesis) and leads to extra bone formation.
When this occurs repeatedly over many years, the additional bone begins to fuse with the surrounding ligaments and joints, restricting movement. In extreme cases, the spine may even fuse in a forward-curving position. Fortunately, new treatment advances have made this complication much less common.
Do I Have AS Symptoms?
Back pain is so ridiculously common that it’s easy to just pop an OTC pain reliever and solider on, but when it comes to AS, that’s a big mistake. If it really is AS, it’s important to begin treatment ASAP to help minimize any potential long-term damage.
How to tell the difference? Remember that the symptoms usually appear at younger ages than mechanical back problems—the kind that are due to injury, or wear-and-tear damage such as slipped or herniated discs—although it is possible to be diagnosed with AS at any point in life. And while a common backache usually occurs in short, painful spells, the pain from AS is likely to be long lasting, we're talking three months or more. Here are some more early-stage clues:
- You wake up with stiffness and pain in your lower back in the early morning that lasts at least 30 minutes and then improves throughout the day or with physical activity. We can’t emphasize this enough: Such improvement with movement is a big, big hint that you may have this condition. It’s the primary difference between AS—an inflammatory form of arthritis—and the much more common osteoarthritis, which is caused by wear and tear and improves with rest while worsening with activity.
- The back pain is usually dull and diffuse, rather than localized and sharp.
- You may also have pain in one or both buttocks and sometimes the backs of the thighs that may feel either like a dull ache or sharp and stabbing. (We know, opposite sensations and similar to other forms of back pain. That's why you need to look at all the symptoms.)
- The buttock pain may start on one side, then alternate sides, but eventually is felt on both sides.
- The pain may wake you during the night.
- You may also have neck, shoulder, hip, or thigh pain that’s worse when you’re not active—like when you’ve been sitting at a desk for a long time.
- You may have pain, stiffness, and swelling in your knees or ankles.
- You will likely be fatigued. The body is expending energy to battle inflammation, and you may have a mild fever and experience loss of appetite. Anemia, a deficiency of healthy red blood cells, can result from inflammation, as well.
Other symptoms you may experience include:
- Soreness at the heel or in the arch of your foot due to inflammation. About 30% of AS patients experience heel pain, which can really do a number on your mobility, making it difficult to walk at times and often requiring custom-made orthotics. The two areas that can be affected are the Achilles tendon at the back of the heel and the plantar fascia at the base of the heel.
- Inflammation of the eye, known as iritis or uveitis, which affects about 40% of AS patients. The first signs are usually eye pain, redness, and sensitivity to bright lights. If you experience these symptoms in one or both of your eyes, or if you have changes to your vision such as partial loss of sight, blurred vision, or floaters, get to an eye doctor as soon as possible.
- Tenderness at the base of your pelvis due to inflammation in the sacroiliac joints, which can make sitting uncomfortable
- Chest pain or tightness that comes on gradually and may cause tender ribs and shortness of breath after moderate activity. Coughing or sneezing may also hurt, and it can be difficult to take deep breaths. This is common in later stages of AS because long-term inflammation in the joints between the ribs and spine, and where the ribs meet the breastbone, results in decreased chest expansion.
- GI issues including diarrhea, cramping, and abdominal pain may occur. Up to 10% of people with AS also have a form of inflammatory bowel disease (IBD), which may be Crohn’s disease (more likely) or ulcerative colitis (less likely).
- Pain and swelling in the joints of the fingers or toes, which occurs in about 5% of AS patients
When to See a Doctor
If you develop any of the above symptoms and they persist for three months, it’s time to get to a rheumatologist, a medical doctor who treats musculoskeletal disease that affects the joints, muscles, tendons, ligaments, connective tissue, and bones—and systemic autoimmune conditions. Ask your primary care physician for a referral or check out the Spondylitis Association of America’s patient-recommended directory of rheumatologists.
AS Patterns: Everyone is Different
The course of AS can vary greatly from person to person, even among family members who share the illness.
You may have only some or many of the symptoms, depending on the severity of your disease, and the chronic pain caused by inflammation can range from mild to very severe.
As with other autoimmune conditions, AS patients may experience flares—periods when their symptoms get worse—and remission, when there is little to no disease activity and symptoms are mild or non-existent.
The upside: Although it’s a lifelong condition, many people with AS do not progress to the more debilitating stage.
Studies have found rates of progression to the ankylosing stage (when damage is visible on an X-ray or MRI) ranging from as low as 5% to as much as 30%, over a period of two to 30 years. This is especially true of women, who may have a milder form and are often diagnosed at later ages, possibly because doctors don’t look for it in women.
Some recent research indicates that women may be more likely to be initially affected in different areas, such as the neck as well as the peripheral joints, which are the joints in the arms and legs, while men more commonly experience lower back and spine pain at the onset. Other early symptoms that may be more common in women include uveitis, psoriasis, and IBD.
Does AS Have Serious Complications?
The most serious complication of AS is ankylosis itself, because a fused spine can severely limit mobility and result in breathing difficulties if the rib cage is also involved.
People with AS are also at increased risk for fractures and osteoporosis because the inflammation causes a loss of bone mineral. They are also at increased risk for heart attack and stroke.
Cardiovascular issues occur because the chronic inflammation at the base of the heart and around the aorta—the heart’s largest artery—limits its ability to carry enough blood to the rest of the body, which causes hypertension (high blood pressure). Rarely, the aorta may become enlarged, changing the shape of the aortic valve and allowing blood to leak back into the heart. This can cause chest pain and leave you tired and short of breath.
But remember, as long as your AS symptoms are treated properly, your level of inflammation will go down body-wide, and the risk of these complications will be much, much lower.