What Are the Symptoms of Ankylosing Spondylitis? 10 Signs of This Rare Inflammatory Condition

Bothersome back pain and joint stiffness are good reasons to see a doctor, regardless of the ultimate diagnosis.

Ankylosing spondylitis (AS) is an inflammatory condition that can lead to the fusion of bones along the spine. Many people, no doubt, are unfamiliar with the disease, let alone the signs and symptoms that may lead to an AS diagnosis.

While the condition, a form of arthritis, is rare—fewer than 1% of people in the US will experience it, per Johns Hopkins Medicine—it's an important one to identify early in order to prevent its worst outcomes.

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What are the symptoms of ankylosing spondylitis?

Not everyone with AS experiences the condition the same way, the Cleveland Clinic points out. Symptoms typically surface between the ages of 17 and 45 but may also affect younger children and older adults. Likewise, the severity of the disease ranges from mild to severe, and people may have periods during which their symptoms flare up and then improve.

These are the symptoms that people with AS may exhibit:

Reduced spinal mobility or joint stiffness

The main identifying feature of ankylosing spondylitis is when joints that were once able to move freely in the spine become immobile. In most people, this change starts off feeling like stiffness in major joints, like the sacroiliac joint (connecting your pelvis and lower spine), the hips, the shoulder area, or the neck, explains Anand Veeravagu, MD, assistant professor of neurosurgery and director of minimally invasive neurospine surgery at Stanford Medicine.

As you might imagine, as the joints begin to lose their mobility, other areas of the body are affected. "That stiffness results in a reduced range of motion that may cause other joints that are functioning to compensate," Dr. Veeravagu explains. This can lead to more pain and arthritis in the functioning joints.

People with AS may have rib pain and tenderness, for example, where the ribs attach to the spine, says the UK-based National Axial Spondyloarthritis Society (NASS).

Back pain

Back pain is very common among people with ankylosing spondylitis, per Johns Hopkins.

More specifically, a 2021 review posted by the US National Library of Medicine (NLM) says the type of back pain that people with AS experience generally includes four of the five following characteristics:

  • generally strikes people before the the age of 40
  • comes on slowly
  • improves with exercise
  • does not improve with rest
  • causes pain at night, which improves upon waking

Some people may have mild episodes that come and go, while others will develop chronic pain, per the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS).

Stooped neck and shoulders

As ankylosing spondylitis progresses, more bones can be fused together, including those in the cervical spine.

We look down a lot—looking at our phones, computers, or even our dinner plates. But ankylosing spondylitis patients also lean forward because it helps to relieve other back pain, explains Johns Hopkins Medicine. This puts the spine in a flexed position, explains Nick Shamie, MD, chief of orthopedic spine surgery and professor of orthopedic surgery and neurosurgery at UCLA School of Medicine, and ankylosing spondylitis patients can end up with their bones fused in this position.

"If you look down at your feet right now and imagine your neck was locked in that position it would make life very difficult, not only for mobility but even eating, because...you can't open your mouth as well," Dr. Shamie tells Health.

Stooped posture that has frozen that way is one of the biggest reasons surgery might become necessary for ankylosing spondylitis patients, says Dr. Shamie.

Inability to take a deep breath

In particularly severe cases, the vertebrae and ribs can fuse to the spine, making it difficult for patients to fully inhale, says Dr. Shamie. Smoking is a risk factor for disease progression in people with AS, says NIAMS.

Pain or stiffness in the joints of the arms and legs

While ankylosing spondylitis usually starts in the low back or neck, sometimes it appears first in the peripheral joints, says the Spondylitis Association of America. Vulnerable areas include the ankles, elbows, knees, and heels. These symptoms are the result of inflammation at the site where a ligament or tendon meets bone.

Eye inflammation

Ankylosing spondylitis can lead to uveitis, or inflammation of the eye, says NIAMS. And according to the Spondylitis Association of America, roughly one in three people with AS will develop this complication at least once. It can cause eye pain and vision changes such as blurriness and light sensitivity, according to the Mayo Clinic.

Inflammatory bowel disease

Given the role that inflammation plays, it may not be surprising to learn that ankylosing spondylitis can affect the GI tract too. Up to half of people with AS develop inflammatory bowel disease, per the review posted by the NLM. That includes conditions such as Crohn's disease and ulcerative colitis, says the NASS.

Heart disease

The same NLM review article notes that ankylosing spondylitis is associated with an increased risk of cardiovascular disease. But heart involvement is less common than back, joint, or eye symptoms, per Johns Hopkins.

Skin rash

About one in 10 people with ankylosing spondylitis also develop psoriasis, says the NASS. These itchy, scaly patches may be limited to small areas of the skin or more extensive. The rashes that people with AS develop should not be confused with psoriatic arthritis, which is a different condition, explains CreakyJoints.

Fatigue and other flu-like symptoms

NIAMS cites fatigue and loss of appetite or weight loss among the symptoms of ankylosing spondylitis. Johns Hopkins includes fever on the list.

These areas of discomfort might not show up on an X-ray the way that bone fusions do, but they're very real.

Diagnosing ankylosing spondylitis

If a patient shows up with back pain and stiffness, a doctor will often do a physical exam and order blood tests and X-ray images.

On the X-ray, one of the early indicators of ankylosis spondylitis is the fusion of the sacroiliac joints—where the spine and the pelvis meet, says Dr. Shamie. Doctors look for a genetic marker in the blood called HLA-B27, which many ankylosing spondylitis patients will be positive for, although not always.

Symptoms are an important piece of the puzzle. Back pain that persists three or more months, improves with exercise, and worsens when at rest are among the signs that it could be AS, per Johns Hopkins.

Ultimately, if a patient is diagnosed with ankylosing spondylitis, the goal is to reduce both pain and the inflammatory process, while preserving as much movement as possible. Early diagnosis can help ward off some of the worse effects of AS, says Dr. Shamie says, who encourages anyone who has concerns to get evaluated. "Information is power," he says.

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