Ankylosing Spondylitis (Spondyloarthropathy)
The syndrome that includes both uveitis and ankylosing spondylitis is the spondyloarthropathy spectrum, with ankylosing spondylitis itself being the primary condition that encompasses both manifestations. 1
Key Clinical Features
Ankylosing spondylitis is the most common variant of the spondyloarthropathies, which are linked by strong association with HLA-B27 and absence of rheumatoid factor 1. Acute anterior uveitis is reported in up to 40% of patients with ankylosing spondylitis 1, making it the most common extra-articular manifestation of this condition.
Diagnostic Characteristics
The spondyloarthropathies share several common features 1:
- Sacroiliitis (inflammation of sacroiliac joints)
- Inflammatory arthritis or enthesitis (inflammation of tendon insertions)
- Associations with inflammatory bowel disease or psoriasis
- Aortitis and heart block
- Acute anterior uveitis
Clinical Presentation Pattern
Ankylosing spondylitis typically:
- Begins with back pain and stiffness in the second or third decade of life 1
- Affects men 2 to 3 times as often as women 1
- Worsens with inactivity and improves with exercise
- Takes years for diagnosis to be made
Uveitis Characteristics in This Context
The uveitis associated with ankylosing spondylitis has a distinctive phenotype 2, 3:
- Sudden onset
- Anterior location
- Unilateral presentation
- Recurrent episodes (high tendency to recur, sometimes in the contralateral eye)
- More often affects males
This contrasts with uveitis in psoriatic arthritis or inflammatory bowel disease, which tends to be more insidious, bilateral, and chronic 2, 4.
Important Clinical Pitfall
Approximately 40% of patients presenting with idiopathic acute anterior uveitis have undiagnosed spondyloarthritis 3. The occurrence of acute anterior uveitis presents a unique opportunity for identifying undiagnosed spondyloarthritis patients, as it may be their first interaction with medical care 3. HLA-B27 positive patients with acute anterior uveitis should be specifically questioned about inflammatory low back pain and evaluated for other clinical features of spondyloarthritis 3.
Relationship Between Manifestations
Uveitis and ankylosing spondylitis run independent courses - the uveitis activity does not mirror the activity of the underlying joint disease 5, 6. This is an important distinction from other extra-intestinal manifestations that parallel disease activity.