Ankylosing spondylitis Flashcards
definition of ankylosing spondylitis
Seronegative inflammatory arthropathy affecting preferentially the axialskeleton and large proximal joints.
chronic inflammatory disease of the spine and sacroiliac joints
aetiology of ankylosing spondylitis
unknown
Strong linkage with HLA-B27 gene (>90% HLA-B27 positive, general population frequency 8%).
potential infection triggers and ag cross-reactivity with self-peptides have been suggested
Inflammation starts at the entheses (sites of attachment of ligaments to vertebral bodies)
persistant inflamm -> reactive new bone formation
changes start in lumbar and progress to thoracic and cervical
bone changes in ankolysing spondylitis
changes start in lumbar and progress to thoracic and cervical
- squaring of vertical bodies
- formation of syndesmophytes (vertical ossifications bridging the margins of the adjacent vertebrae).
- fusion of syndesmophytes and facet joints (ankylosis and spinal immobility)
- calcification of anterior and lateral spinal ligaments
epidemiology of ankylosing spondylitis
common
Affects 0.25–1% of UK population - prevalence
earlier presentation in men than women
90% are HLA B27 +ve
young, <40 and often <25
sx of ankylosing spondylitis
Low back and sacroiliac (SI) pain disturbing sleep (worse in morning, improves on activity, returning with rest).
pain radiates from the sacroiliac joints to hips/buttucks - improves towards the end of the day
progressive loss of spinal movement = reduced thoracic expansion
symptoms of asymmetrical peripheral arthritis
Pleuritic chest pain (caused by costovertebral joint involvement).
heel pain - plantar fasciitis
achilles tendonitis
enthesitis at the tibial and ischial tuberosities, and iliac crests
non-specific symptoms - malaise, fatigue
signs of ankolysing spondylitis
reduced range of spinal movements - particularly hip rotation
reduced lateral spinal flexion and occiput-wall distance (with pt standing next to wall)
Schober’s test: A mark is made on the skin of the back in the middle of a line drawn between the posterior iliac spines. A mark 10 cm above this is made. The patient is asked to bend forward and the distance between the two marks should increase by>5 cm on forward flexion. This is reduced in ankylosing spondylitis.
tenderness over the SI joints
In later stages, thoracic kyphosis, neck hyperextension and spinal fusion, question-mark posture.
extra-articular disease
reduced thoracic expansion - because of progessive loss of spinal movement
extra-articular signs of ankylosing spondylitis
anterior uveitis (red eye) - can lead to blindness
apical lung fibrosis
reduced chest expansion - fusion of costovertebral joints
aortic regurg - cardiac diastolic murmur
osteoporosis
Ix for ankylosing spondylitis
dx is clinical
blood
anteroposterior and lateral radiographs of spine
Anteroposterior radiographs of the SI joints:
CXR - look for association with apical fibrosis
lung function test - assesses mechanical ventilatory impairment from kyphosis
MRI - detection of active inflammation of SI joint nad entheses (bone marrow oedema), destructive changes: erosions, sclerosis and ankylosis
what is seen on anteroposterior and lateral radiographs of the spine in ankylosing spondylitis
vertebral syndesmophytes are characteristic (T11-L1 initially) - bony proliferations due to enthesitis between ligaments and vertebrae
they fuse with the vertebrae above = ankylosis
later - calcification of ligaments with ankylosis = bamboo spine
what is see on Anteroposterior radiographs of the SI joints in ankolysing spondylitis
Symmetrical blurring of joint margins.
Later - erosions, sclerosis, ankylosis and SI joint fusion (joint space narrowing)
(Sacroiliitis also occurs in other seronegative arthropathies: Reiter’s syndrome (reactive arthritis), enteropathic arthropathy (inflammatory bowel disease), psoriatic arthropathy.)
typical history
man
<30yrs
gradual onset lower back pain
worse during the night
morning stiffness relieved by exercise
bloods for ankylosing spondylitis
FBC - normocytic anaemia of chronic disease
rheumatoid factor - -ve
high ESR/CRP
HLA B27 +ve in 90% cases
HLA B27 association with ankyosing spondylitis
HLA system has role in immunity and self recognition
role of HLA B27 in triggering inflammatory response is not well understood
5% population are HLA B27 +ve and most have no disease
chance of a HLA B27 +ve person developing spondyloarthritis or eye disease is 1 in 4
90% people with ankylosing spondylitis are HLA B27+ve
late stage radiology for ankylosing spondylitis
complete loss of joint space in SI joints
calcification of the anterior and posterior ligaments
syndesmophytes - bridging bone between the vertebrae = rigid spine
progression of axial spondyloarthritis
men are more likely to progress
HLA-B27 +ve more likely to progress
do MRI early otherwise delay treatment by 7yrs until XR changes
