Seronegative spondyloarthritis is a group of chronic inflammatory rheumatic diseases primarily affecting the spine and other joints. These conditions also impact entheses, the areas where ligaments and tendons attach to bones.
What is Seronegative Spondyloarthritis?
Spondyloarthritis refers to a family of inflammatory conditions causing pain and swelling, mainly affecting the spine and joints. Unlike osteoarthritis, it is an inflammatory type of arthritis, often linked to autoimmune processes where the immune system mistakenly attacks the body’s own tissues.
The “seronegative” part of the term indicates that standard blood tests for certain autoantibodies, such as rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPA), typically come back negative. These antibodies are commonly present in other rheumatic conditions like rheumatoid arthritis. The absence of these specific markers helps differentiate seronegative spondyloarthritis from other forms of inflammatory arthritis.
Key features of seronegative spondyloarthritis include inflammation of the spine, known as axial involvement, and inflammation in joints located away from the spine, referred to as peripheral involvement. Another hallmark is enthesitis, which is inflammation at the points where tendons or ligaments connect to bone, often seen in areas like the heels or knees. Dactylitis, often called “sausage digits,” involves the swelling of an entire finger or toe.
The main conditions categorized under seronegative spondyloarthritis include ankylosing spondylitis (AS), psoriatic arthritis (PsA), reactive arthritis, and enteropathic arthritis (associated with inflammatory bowel disease). Undifferentiated spondyloarthritis is for individuals who show features of the condition but do not fit a specific subtype.
Identifying the Symptoms
Symptoms of seronegative spondyloarthritis can vary among individuals and fluctuate in intensity. A common manifestation is inflammatory back pain, which often worsens with rest and improves with activity. This pain can be particularly bothersome at night and is frequently accompanied by morning stiffness lasting more than 30 minutes.
Axial symptoms involve the spine, including pain in the lower back that might spread to the buttocks. Persistent back pain, especially if it begins before age 45, can signal an autoimmune disorder. Over time, spinal mobility may become impaired, and a gradual curvature of the spine can develop.
Peripheral symptoms involve joints outside of the spine, such as the knees, ankles, hips, and shoulders. Arthritis in these joints often presents asymmetrically, affecting one side of the body more than the other. Dactylitis (swelling of an entire finger or toe) and enthesitis (pain at tendon or ligament insertion points) are also common peripheral symptoms.
Beyond joint-related issues, seronegative spondyloarthritis can present with extra-articular manifestations, affecting other body systems. These can include uveitis, an inflammation of the eye that can cause redness and pain. Skin conditions like psoriasis may also be present, particularly in psoriatic arthritis. Some individuals may experience inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis. General fatigue is also a common complaint.
Diagnosis and Confirmation
Diagnosing seronegative spondyloarthritis can be complex because there isn’t one single definitive blood test, and symptoms can overlap with other conditions. The diagnostic process involves a comprehensive approach combining clinical evaluation, imaging studies, and specific blood tests.
A detailed clinical evaluation begins with a thorough patient history, focusing on symptom patterns, their duration, and any family history of similar conditions. A physical examination assesses joint tenderness, swelling, and range of motion in affected areas.
Imaging studies play a significant role in confirming the diagnosis and assessing the extent of disease progression. X-rays, particularly of the sacroiliac joints (where the spine meets the pelvis), are used to look for inflammation and structural damage, though early changes may not be visible. Magnetic resonance imaging (MRI) is more sensitive and can detect early inflammation in joints and soft tissues, such as the sacroiliac joints, even before changes appear on X-rays.
Blood tests are part of the diagnostic workup. Markers of inflammation, such as erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), may be elevated, indicating systemic inflammation. While not diagnostic on its own, the HLA-B27 genetic marker is often checked, as it is present in a significant percentage of individuals with seronegative spondyloarthritis, particularly in ankylosing spondylitis. The absence of rheumatoid factor and anti-citrullinated protein antibodies helps distinguish this condition from other forms of inflammatory arthritis.
Treatment Approaches and Management
The primary goals of treating seronegative spondyloarthritis are to manage pain, reduce inflammation, prevent further joint damage, and improve quality of life. Treatment approaches are tailored to the specific type and severity of the condition.
Nonsteroidal anti-inflammatory drugs (NSAIDs) are typically the first-line therapy for alleviating pain and stiffness. If NSAIDs are insufficient, disease-modifying antirheumatic drugs (DMARDs) like sulfasalazine may be used, particularly for peripheral joint involvement. However, these traditional DMARDs are generally not effective for spinal inflammation.
For more severe or persistent cases, especially those with significant spinal involvement or extra-articular manifestations, biologic medications are often prescribed. These include TNF inhibitors (e.g., adalimumab, etanercept, infliximab, golimumab, certolizumab pegol) and IL-17 inhibitors (e.g., ixekizumab, secukinumab), which target specific inflammatory pathways. Corticosteroids may be used for short-term management of acute flares, often administered as localized injections into affected joints rather than orally for long-term use.
Physical therapy and regular exercise are highly recommended to maintain flexibility, strength, and good posture. Occupational therapy can assist individuals in adapting daily activities to reduce joint strain. Lifestyle modifications, such as smoking cessation and maintaining a healthy weight, also contribute to better outcomes. A multidisciplinary approach involving rheumatologists, physical therapists, and other specialists is important for comprehensive, long-term management.