Axial spondyloarthritis (axSpA) is a form of chronic inflammatory arthritis that primarily impacts the spine and the sacroiliac (SI) joints, which connect the pelvis and lower spine. This condition is driven by the body’s immune system mistakenly attacking its own tissues, leading to persistent inflammation. Unlike mechanical back pain that results from injury or strain, axSpA is a systemic disease. Symptoms typically begin in early adulthood, often before the age of 45, and can gradually develop over months or years.
Common Symptoms of Axial Spondyloarthritis
The characteristic symptom of axSpA is inflammatory back pain. This pain is distinct because it improves with physical activity and worsens with rest. Individuals experience significant pain and stiffness in the lower back and buttocks, especially upon waking or after long periods of inactivity. The onset is gradual, persisting for more than three months, and the discomfort can be a dull, diffuse ache that may alternate between sides.
Beyond the spine, inflammation can occur where tendons and ligaments attach to bone, a condition known as enthesitis. A common site for enthesitis is the back of the heel, affecting the Achilles tendon, or the sole of the foot. Other joints, including the hips, shoulders, and knees, can also become painful and stiff.
Systemic symptoms are also a frequent part of the experience with axSpA. Overwhelming fatigue is a common complaint, caused by widespread inflammation. Another potential manifestation is uveitis, or eye inflammation, which causes redness, pain, and light sensitivity. In some cases, individuals may experience gastrointestinal issues associated with inflammatory bowel disease.
How Axial Spondyloarthritis Is Diagnosed
Diagnosing axial spondyloarthritis is complex, as no single test can confirm the condition. A rheumatologist reviews a patient’s medical history and symptoms, focusing on the nature of the back pain. A physical examination helps assess spinal mobility, identify tender points, and check for inflammation in other joints.
Blood tests look for evidence of inflammation and a specific genetic marker. Tests for C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) can indicate an inflammatory process, though they are not specific to axSpA. A blood test can also identify the HLA-B27 gene, present in a high percentage of people with axSpA. However, carrying the gene does not mean a person will definitely develop the condition.
Imaging studies are part of the diagnostic process. X-rays are often performed first to look for changes in the sacroiliac joints, a sign called sacroiliitis. These structural changes may not be visible in the early stages of the disease. For this reason, an MRI is frequently used. An MRI is more sensitive and can detect inflammation in the joints and spine before permanent damage appears on an X-ray, allowing for an earlier diagnosis.
Treatment and Management Strategies
The management of axSpA is centered on reducing inflammation, managing pain, and maintaining spinal flexibility and good posture. Physical therapy and regular exercise are core components of treatment. A targeted exercise program with stretching and range-of-motion exercises helps preserve joint mobility and reduce stiffness. Activities like swimming are recommended because they provide a full-body workout with low impact on the joints.
Medications are important in controlling symptoms and slowing disease progression. Nonsteroidal anti-inflammatory drugs (NSAIDs) are the first line of treatment to alleviate pain and stiffness. For those who do not respond adequately to NSAIDs or have more severe disease, biologic medications are prescribed. These drugs target specific parts of the immune system, such as TNF or IL-17 inhibitors, which are effective at reducing inflammation.
Lifestyle adjustments also help manage the condition. Quitting smoking is recommended, as smoking can worsen axSpA symptoms and accelerate spinal fusion. Maintaining a healthy weight is also important, as excess weight puts additional stress on the spine and other joints.
Distinguishing Between Types of AxSpA
Axial spondyloarthritis is categorized into two types based on whether structural damage is visible on an X-ray. This classification helps doctors understand the disease stage and guide treatment, though both types are considered part of the same disease spectrum.
The first type is non-radiographic axial spondyloarthritis (nr-axSpA). In this form, individuals experience symptoms of inflammatory back pain and may show inflammation on an MRI, but there is no damage to the sacroiliac joints visible on an X-ray. Many people with nr-axSpA have clear evidence of inflammation on MRI, but some may not, making diagnosis more reliant on clinical symptoms and other tests.
The second type is radiographic axial spondyloarthritis (r-axSpA), also known as ankylosing spondylitis. This diagnosis is made when an X-ray shows structural damage, such as bone erosion or fusion, in the sacroiliac joints. This form represents a more advanced stage where chronic inflammation has led to lasting changes in bone structure.
Associated Health Complications
The chronic inflammation of axSpA can lead to long-term health complications. One significant complication is spinal fusion, also known as ankylosis. Over time, the body may form new bone that can bridge the gaps between vertebrae, causing them to fuse. This process results in a loss of spinal flexibility and can lead to a rigid, hunched posture.
Individuals with axSpA have an increased risk of developing osteoporosis. The persistent inflammation can interfere with the body’s normal bone remodeling process, leading to weaker, more brittle bones that are susceptible to fractures, particularly in the spine.
Systemic inflammation also elevates the risk of cardiovascular disease. Chronic inflammation can affect blood vessels and contribute to conditions like heart attacks and strokes. Recurrent eye inflammation (uveitis) is another serious complication. If not treated promptly, severe or repeated uveitis can lead to permanent eye damage and vision loss.