Your spine does more than just hold you upright. It interacts with your immune, skeletal, muscular, and nervous systems. So when something goes wrong with your spine, it may have far-reaching effects throughout your body. Keeping your spine happy is an important part of your overall health.

Ankylosing spondylitis (AS) is a case in point. It’s a form of arthritis associated with long-term inflammation of the joints in your spine. The first symptoms of AS are usually pain in your low back and hips, which you might pass off as just a “bad back.” But AS tends to worsen with time, especially if not treated. As the disease progresses, it may affect many parts of your body, including other joints and your eyes, bowels, feet, and heart.

AS typically starts with pain in the low back and hips caused by inflammation of spinal joints there. As time passes, inflammation — and the symptoms caused by it — may gradually move up the spine and give rise to complications. It may also skip areas in the spine.

These are three important features of AS:

  • Sacroiliitis:
    An early hallmark of AS is inflammation of the sacroiliac joints, located where
    your spine meets your pelvis. This inflammation causes pain in your hips.
    Sometimes the pain radiates down your thighs, but never below your knees.
  • Enthesitis:
    Another characteristic of AS is inflammation of entheses — places where
    ligaments and tendons attach to bones. This type of inflammation causes much of
    the pain and loss of function that’s seen in the disease.
  • Fusion:
    Your body’s repeated attempts to heal inflamed entheses can lead to the
    scarring of tissue, followed by the formation of extra bone. Ultimately, two or
    more bones of your spine may become fused, limiting flexibility in your back.
    In severe cases, your spine may develop a forward curvature, causing a
    permanently stooped posture. It’s far less common to reach this stage today,
    thanks to treatment advances.

As time goes by, the inflammation caused by AS may affect other parts of your body as well:

  • Other
    Inflammation may cause pain and stiffness in joints of your neck,
    shoulders, hips, knees, ankles, or, rarely, fingers and toes.
  • Your
    About 70 percent of people with AS develop inflammation at the
    junction of the ribs and spine. The point where your ribs meet your breastbone
    in front may also be affected, leading to chest pain. Eventually, stiffening of
    your ribcage may limit how much your chest can expand, reducing how much air your
    lungs can hold.
  • Your eyes:
    Up to 40 percent of people with AS develop inflammation of the eye, called
    uveitis or iritis. This inflammation may cause eye pain and redness,
    sensitivity to light, and blurred vision. If not treated promptly, it can lead
    to vision loss.
  • Your feet:
    Inflamed entheses may occur at the back or base of your heel. The pain and
    tenderness can seriously hamper your ability to walk.
  • Your
    Inflammation may cause symptoms of inflammatory bowel disease,
    including abdominal cramps and diarrhea, sometimes with blood or mucus in the
  • Your jaw:
    Inflammation of your jaw is uncommon, affecting no more than 15 percent of AS
    patients. But it can be especially troublesome, making it difficult to eat.
  • Your
    . In rare cases, your body’s largest artery, called the aorta, becomes
    inflamed. It may enlarge so much that it distorts the shape of the valve
    connecting it to your heart.

People with very advanced AS may develop cauda equina syndrome, a disorder affecting a bundle of nerve roots at the bottom of your spinal cord. These nerve roots transmit messages between your brain and lower body. When damage caused by AS compresses the nerve roots, it can impair functioning of your pelvic organs or sensation and movement in your lower limbs.

Be alert for warning signs of cauda equina syndrome:

  • Problems
    with bladder or bowel function:
    You might either retain waste or be unable
    to hold it.
  • Severe or
    progressively worsening problems in your lower limbs:
    You may experience
    loss of or changes in sensation in key areas: between your legs, over your
    buttocks, on the backs of your legs, or in your feet and heels.
  • Pain,
    numbness, or weakness spreading to one or both legs:
    The symptoms may make
    you stumble when you walk.

If you develop these symptoms, it’s crucial to seek prompt medical attention. Left untreated, cauda equine syndrome can lead to impaired bladder and bowel control, sexual dysfunction, or paralysis.

This long list of potential complications can be intimidating. However, treatment for AS may be able to prevent or delay many problems. In particular, a group of medications called tumor necrosis factor (TNF) inhibitors are able to change the course of the disease.