Ankylosing spondylitis

Question 1

What gene is this spondyloarthropathy associated with?

Answer 1

HLA-B27

Question 2

Who does this usually present in?

Answer 2

Males (sex ratio 3:1) aged 20-30 years old

Question 3

Symptoms?

Answer 3

• lower back pain
• stiffness of insidious onset
• stiffness is usually worse in the morning and improves with exercise
• patient may experience pain at night which improves on getting up

Question 4

What may be seen on clinical examination?

Answer 4

• reduced lateral flexion
• reduced forward flexion - Schober’s test - a line is drawn 10 cm above and 5 cm below the back dimples (dimples of Venus). The distance between the two lines should increase by more than 5 cm when the patient bends as far forward as possible
• reduced chest expansion

Question 5

Other features - the ‘A’s?

Answer 5

• Apical fibrosis
• Anterior uveitis
• Aortic regurgitation
• Achilles tendonitis
• AV node block
• Amyloidosis
• and cauda equina syndrome
• peripheral arthritis (25%, more common if female)

Question 6

What inflammatory markers are typically raised?

Answer 6

ESR and CRP although normal levels do not exclude ankylosing spondylitis

Question 7

Is HLA-B27 of use in making a diagnosis?

Answer 7

No as it is positive in:
• 90% of patients with ankylosing spondylitis
• 10% of normal patients

Question 8

What is the most useful investigation in establishing the diagnosis?

Answer 8

Plain x-ray of the sacroiliac joints

Question 9

What changes may be seen on radiographs?

Answer 9

Radiographs may be normal early in disease, later changes include:
• sacroiliitis: subchondral erosions, sclerosis
• squaring of lumbar vertebrae
• ‘bamboo spine’ (late & uncommon)
• syndesmophytes: due to ossification of outer fibers of annulus fibrosus
• chest x-ray: apical fibrosis

Question 10

What if x-ray is negative for sacroiliac joint involvement in ankylosing spondylitis but suspicion remains high?

Answer 10

Obtain an MRI of the sacroiliac joints.

Signs of early inflammation involving sacroiliac joints confirm the diagnosis of AS.

Question 11

What may be seen on spirometry?

Answer 11

Spirometry may show a restrictive defect due to a combination of pulmonary fibrosis, kyphosis and ankylosis of the costovertebral joints.

Question 12

Management?

Answer 12

• encourage regular exercise such as swimming
• NSAIDs are the first-line treatment
• physiotherapy

Question 13

When are DMARDs used?

Answer 13

They are only really useful if there is peripheral joint involvement.

Question 14

When should anti-TNF therapy be used?

Answer 14

Anti-TNF therapy should be given to patients with persistently high disease activity despite conventional treatments

Question 15

Examples of anti-TNF therapies?

Answer 15

Etanercept and adalimumab

Question 16

What is dagger sign?

Answer 16

A sign seen on radiograph where there is a single central radiodense line in the spine related to ossification of supraspinous and interspinous ligaments