For Patients & General Readers
Ankylosing Spondylitis is a chronic inflammatory disease that primarily affects the spine, causing pain and stiffness. It often begins in young adults, particularly men, and can lead to a gradual fusion of the vertebrae, limiting mobility. Early diagnosis and management are crucial to control inflammation, alleviate pain, and prevent long-term disability.
Clinical Overview
Ankylosing Spondylitis (AS) is a chronic, systemic inflammatory arthropathy belonging to the spondyloarthritis (SpA) group, characterized by inflammation of the axial skeleton, particularly the sacroiliac joints and spine. It is strongly associated with the HLA-B27 gene and typically presents with inflammatory back pain in individuals under 45 years of age.
Clinical Presentation
- Insidious onset of inflammatory back pain, typically worse with rest and improved with activity.
- Morning stiffness in the lumbar spine, lasting for at least 30 minutes.
- Pain and stiffness in the buttocks and hips, often alternating sides.
- Peripheral arthritis, enthesitis (inflammation at tendon-bone insertions), and dactylitis.
- Extra-articular manifestations including uveitis, inflammatory bowel disease (IBD), psoriasis, and cardiac conduction abnormalities.
Signs & Symptoms
Symptoms (Patient-Reported)
- Chronic low back pain and stiffness, especially in the morning.
- Pain that improves with exercise and worsens with rest.
- Pain in the neck and hips.
- Fatigue and general malaise.
- Pain in other joints, such as the shoulders, knees, or ankles.
- Eye inflammation (uveitis) causing redness, pain, and blurred vision.
- Shortness of breath due to chest wall stiffness.
Signs (Clinician-Observed)
- Limited range of motion in the lumbar spine (e.g., reduced flexion, extension, and lateral bending).
- Positive Schober's test (measuring lumbar flexion).
- Tenderness over the sacroiliac joints.
- Enthesitis, particularly at the Achilles tendon insertion or plantar fascia.
- Reduced chest expansion.
Differential Diagnoses
| Condition | Distinguishing Feature |
|---|
| Mechanical Low Back Pain | Typically improves with rest, is activity-related, and lacks systemic inflammatory features or morning stiffness. |
| Degenerative Disc Disease/Osteoarthritis | Pain is usually activity-related, stiffness is less pronounced and shorter-lived, and imaging shows degenerative changes rather than inflammatory erosions. |
| Fibromyalgia | Widespread musculoskeletal pain, fatigue, and sleep disturbances without objective inflammatory signs or characteristic spinal involvement. |
| Reactive Arthritis | Can present with similar axial symptoms but is typically triggered by an infection elsewhere in the body and often involves peripheral arthritis, conjunctivitis, and urethritis. |
| Psoriatic Arthritis | Axial involvement can mimic AS, but is distinguished by the presence of psoriasis, nail changes, and often dactylitis or peripheral arthritis. |
| Infectious Spondylitis | Usually has a more acute onset, fever, elevated inflammatory markers, and may show vertebral osteomyelitis on imaging. |
Red Flags — Seek Immediate Care
- Sudden onset of severe back pain, especially with neurological deficits (e.g., weakness, numbness, bowel/bladder dysfunction) suggesting cauda equina syndrome or spinal fracture.
- Fever, chills, or unexplained weight loss, raising suspicion for infection or malignancy.
- Progressive neurological impairment.
- Significant chest pain or shortness of breath not attributable to musculoskeletal causes.
Key Investigations
- Human Leukocyte Antigen B27 (HLA-B27) testing (while not diagnostic, it increases suspicion).
- Radiographs of the sacroiliac joints and spine (AP pelvis, lateral lumbar spine) to assess for sacroiliitis, syndesmophytes, and vertebral body squaring.
- Magnetic Resonance Imaging (MRI) of the sacroiliac joints and spine to detect early inflammatory changes (bone marrow edema) before radiographic changes are apparent.
- Erythrocyte Sedimentation Rate (ESR) and C-reactive protein (CRP) to assess for systemic inflammation.
Management Overview
Management focuses on reducing inflammation, controlling pain, maintaining spinal mobility, and preventing functional disability. Non-steroidal anti-inflammatory drugs (NSAIDs) are the first-line pharmacotherapy for symptomatic relief, while disease-modifying antirheumatic drugs (DMARDs) like sulfasalazine or methotrexate may be used for peripheral manifestations. Biologic agents, particularly TNF inhibitors and IL-17 inhibitors, are highly effective for axial disease refractory to NSAIDs and are crucial for achieving remission and preventing structural damage.
Disclaimer: This article is for educational purposes only and does not constitute medical advice.
Always consult a qualified healthcare professional for diagnosis and treatment.
TruelyserMD does not replace clinical judgement.