Ankylosing Spondylitis

Ankylosing spondylitis (AS) is a type of arthritis primarily affecting the spine, leading to inflammation, pain, and potentially severe joint stiffness. It is a chronic condition with no cure, affecting approximately 0.1% to 0.8% of the population, typically manifesting in young adults.

The exact cause remains unknown, but genetic factors, particularly the presence of the HLA-B27 antigen, play a significant role.

Signs and Symptoms

The initial symptoms of AS often include chronic pain and stiffness in the lower back and gluteal region, particularly in the early morning. As the disease progresses, spinal mobility decreases, and patients may experience severe pain and stiffness that improves with physical activity.

Other systemic features can include weight loss, fever, and fatigue. AS may also cause arthritis in the hips and shoulders, and in younger patients, it can affect large lower limb joints.

Around 30% of individuals with AS experience anterior uveitis, leading to eye pain, redness, and blurred vision. Cardiovascular complications such as aortitis and aortic valve insufficiency, as well as lung issues characterised by upper lobe fibrosis, are also associated with AS.

Pathophysiology

AS is a systemic rheumatic disease primarily involving inflammation of the spine and sacroiliac joints. The disease mechanism involves autoimmune or autoinflammatory processes, with a significant association with the HLA-B27 antigen.

The exact pathogenic role of HLA-B27 is not fully understood, but it is believed to involve CD8+ T cells. Other implicated factors include TNF-alpha and IL-1.

Diagnosis

Diagnosis of AS is based on clinical symptoms, imaging, and blood tests. Key diagnostic criteria include chronic inflammatory back pain, a history of joint or tendon inflammation, family history, HLA-B27 positivity, and elevated inflammatory markers like CRP and ESR.

Imaging, particularly MRI, can detect early sacroiliitis and other spinal changes.

Imaging

Radiographic changes include erosions and sclerosis in the sacroiliac joints, vertebral squaring, and the formation of syndesmophytes, leading to the characteristic "bamboo spine" appearance. MRI can reveal early inflammatory changes before they are visible on X-rays.

Treatment

Medication

Medications for AS include NSAIDs, TNF inhibitors, IL-17 antagonists, and DMARDs. NSAIDs are the first line of treatment to reduce pain and inflammation.

TNF inhibitors (e.g., etanercept, infliximab) and IL-17 antagonists (e.g., secukinumab) are used for patients with inadequate response to NSAIDs. Glucocorticoid injections are used for acute flare-ups.

Surgery

In severe cases, surgery such as joint replacement or corrective surgery for spinal deformities may be necessary. However, these procedures are considered high-risk due to potential complications.

Physical Therapy

Physical therapy is very important for managing AS, focusing on maintaining spinal mobility and overall function. Recommended exercises include low-impact aerobic activities, swimming, and stretching routines.

Aquatic therapy and heat/cold treatments can also provide symptomatic relief.

Prognosis

AS can range from mild to severely debilitating, with potential complications including osteoporosis, spinal fractures, and cardiovascular issues. Long-term management and regular monitoring are essential to mitigate these risks and improve the quality of life for individuals with AS.

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Self-assessment MCQs (single best answer)

Which antigen is most commonly associated with ankylosing spondylitis?

What is the primary characteristic of ankylosing spondylitis?

Which symptom is commonly associated with ankylosing spondylitis in its early stages?

What type of imaging is most effective in early detection of sacroiliitis in ankylosing spondylitis?

Which non-pharmacological treatment is considered essential for managing ankylosing spondylitis?

Which complication is NOT typically associated with ankylosing spondylitis?

What is the primary goal of using NSAIDs in the treatment of ankylosing spondylitis?

Which of the following is a disease-modifying treatment for ankylosing spondylitis?

What is a typical radiographic feature of advanced ankylosing spondylitis?

Which of the following symptoms would most likely indicate a severe progression of ankylosing spondylitis?