Ankylosing spondylitis

Question 1

what is the definition of AS?

Answer 1

Axial spondyloarthritis (axSpA) is a chronic progressive inflammatory arthropathy. Patients present with severe pain and spinal stiffness, which ultimately may lead to radiographic changes in the spine and sacroiliac joints. This radiographic stage is known as ankylosing spondylitis (AS). Progression of disease may lead to spinal fusion. Patients with complete spinal fusion suffer extreme disability.

Question 2

what is the epidemiology of AS?

Answer 2

More common further north of the equator (scandinavia)
HIV induced in africa
Presentation in late teens and early 20s
More common and more severe in males

Question 3

what is the aetiology of AS?

Answer 3

HLA B27 tissue type - antigen presenting cell - dominant inheritance genetic (preset in around 90% of patients)
Unknown exact aetiology: 
Molecular mimicry 
Mis-folding theory 
HLA B27 heavy chain homodimer hypothesis
Klebsiella, salmonella, shingella

Question 4

what are the risk factors of AS?

Answer 4

HLA B27
Endoplasmic reticulum aminopeptidase 1 and IL23 receptor genes
Male
Klebsiella pneumonia

Question 5

what is the pathophysiology of AS?

Answer 5

AS involves inflammation, cartilage erosion, and an additional process, which is subsequent repair (ossification). Inflammation in the axial skeleton in patients with AS is initially dominated by mononuclear cell infiltrates and by increased number of osteoclasts
Syndesmophyte:
• New bone formation and vertical growth from anterior vertebral corners

Question 6

what are the key presentations of AS?

Answer 6

Inflammatory back pain, Stiffness in bed, wake up the patient
iritis/uveitis - red swollen eyes
Enthesitis - swelling between tendon or ligaments and bone (e.g. tennis elbow, heel)
Presentation in late teens
Male
Family history
Risk factors

Question 7

what are the signs of AS?

Answer 7

Loss of lumbar lordosis
Kyphosis 
Risk factors and family history 
Psoriasis 
IBD

Question 8

what are the symptoms of AS?

Answer 8

Fatigue 
Sleep disturbance
Tenderness in sacroiliac joint 
Dyspnoea
Back pain

Question 9

what are the first line and gold standard investigations for AS?

Answer 9

Pelvic x-ray - sacroiliitis, can be normal
MRI - bone marrow oedema on T2 weighted sagittal short-tau inversion recovery image
HLA B27
Blood - ESR and CRP - rasied, normocytic anaemia, HLA-B27 positive

Question 10

what are the differential diagnoses for AS?

Answer 10

Osteoarthritis 
DISH 
Psoriatic arthritis 
Reactive arthritis 
Enteropathic arthritis

Question 11

how is AS managed?

Answer 11

Adults:
NSAIDs (naproxen), physio, analgesic, intra-articular corticoid injection, sulfasalazine or methotrexate, anti TNF drugs
Children:
NSAIDs, physio, intra-articular corticosteroids injection, sulfasalazine, TNF-alpha inhibitor

Question 12

how is AS monitored?

Answer 12

Clinical outcomes should be measured annually to monitor disease progression and identify those with rapidly progressive disease. All patients with AS should be routinely assessed for cardiovascular risk, and modifiable risk factors should be aggressively treated

Question 13

what are the complications of AS?

Answer 13

Osteoporosis, cardiac involvement, hip involvement, iritis, pulmonary involvement, neurological involvement

Question 14

what is the prognosis of AS?

Answer 14

Patients who do well are those who lead active lifestyles and maintain a disciplined exercise programme. However, these patients may also have less severe disease, enabling them to be more vigilant in their exercise regimens