Spondyloarthritis Flashcards
What conditions come under the group SpA?
juvenile idiopathic arthritis undifferentiaed SpA reactive arthritis enteropathic arthritis psoriatic arthritis acute anterior uveitis/iritis
What protein molecule are all the spondoarthropathies assoiciated with?
HLA B27 - human leucocyte antigen class I part of the antigen presenting unit
Do all people who are HLA B27 + develop SpA?
no
What are the three theories that suggest how HLA B27 affects development of SpA
- molecular mimicry
- mis-folding theory
- HLA B27 heavy chain homodimer hypothesis
What is the theory of molecular mimicry?
an infection generates an immune response that produces Abs. Thew infectious agent has a similar shape to the HLA B27 protein and so autoantibodies are produced
What is the HLA B27 misfolding theory?
HLA B27 becomes unfolded and accumulates in the ER of the cell
this triggers an inflammatory cascade and this leads to the release of IL-23 by macrophages
Il-23 is a pro-inflammatory molecules that sets of inflammatory events such as triggering Th17 cells to release IL-17, which triggers IL-17 responsive cells to produce IL-6, IL-1 and TNF-alpha which lead to inflammation
Explain the heavy chain homodimer hypothesis
B27 heavy chains can form dimers and accumulate in the ER
this initiates the pro-inflammatory ER unfolded protein response
the heavy chains and dimers can bind to natural killer receptors which causes expression and survival of more proinflammatory leukocytes and as a result production of proinflammatory mediators
there is inhibitors of immune regulatory cells to form a pro-inflammatory response
what are the clinical features of SpA?
fusion of vertebrae - axial spondyloarthritis
enthesitis incl. tennis elbow or golfers elbow
acute anterior uveitis (iritis)
peripheral arthritis - often large joint oligoarthritis, but can be small joints as in RA
skin psoriasis
subclinical inflammatory bowel disease
What is the pneumonic to remember the features of SpA?
SPINE ACHE Sausage digit - dactylitis Psoriasis Inflammatory back pain NSAIDs good reponse Enthesitis
Arthritis
Crohn’s/colitis/elevated CRP
HLA B27 +
Eye - itritis/anterior uveitis
What is ankalosing spondylitis. axial spondyloarthritis?
inflammatory arthritis of the spine and rib cage - eventually leading to new bone formation and fusion of the joints
What is the radiological features of the spine called in ankylosing spondylitis?
bamboo spine
What makes for a poor prognosis in ankylosing spondylitis?
male smokers B27+ syndesmophytes at presentation high CRP
What two features are seen on an X-ray of ankylosing spondylitis?
syndesmophytes
scaroiliitis
What does are the features of the sacroiliac joint on X-ray in ankylosing spondylitis?
sclerosis
erosions
loss of joint space
bone fusion
Where does the pt get the pain with sacroilitis?
the middle of their buttock
What radiological scan is used to make the diagnosis of sacroilititis and why?
MRI - it may take many years for the changes to be detected on X-ray, so MRI is more sensitive, can make the diagnosis earlier
what are the features of sacroiliitis on MRI?
inflammation
white patches - show subchondral, periarticular bone marrow oedema
what is the name given to the shape of the spine in advanced ankylosing spondylitis?
kyphosis
what is the sequence of structural damage in ankylosing spondylitis?
- inflammation of the anterior corners of the vertebrae
- get an exagerated immune response, so get erosion
- the syndesmophytes grow in the area of inflammation
What is the delayed damage theory?
once inflammation of the spine has occurred in ankylosing spondylitis, the new bone formation is inevitable and so once treatment has started, new bone continues to form for some time after
What questions would you ask a pt to diagnose inflammatory back pain in ankylosing spondylitis?
a) do they have back stiffness in the morning?
b) does the pain wake them up at night, clasically in the second half of the night due to stiffening up?
c) do they get alternating buttock pain?
d) improvement of pain with exercise?
e) <40 at the age of onset?
if they have 4/5 of these then it is IBP
Describe the spectrum of disease within ankylosing spondylitis
1) non-radiographic stage -back pain, MRI changes are seen ie sacroiliitis, but XR normal
2) radiographic stage: back pain,XR shows sacroiliitis
3) radiographic stage: back pain, XR shows syndesmophytes
Describe a diagnostic tool that is used for ankylosing sponylitis
pts have had >3months back pain age of onset <45 yrs old sacroiliits on imaging (either MRI or XR) and >=1 SpA feature ie from SPINE ACHE --------------------------------------- or pts have had >3months back pain age of onset <45 yrs old HLA-B27 +ve >=2 SpA features from SPINE ACHE
what treatments are available for ankylosing spondylitis?
anti-nflammatories
physio
biological therapies - these are disease modifying where the other two are just for symptom control
Give some examples of biological therapies used for ankylosing spondylitis
TNF inhibitors ie Infliximab
IL-17 and IL-23 blockers
What are the five typical patterns of joint involvement in psoriatic arthritis?
a) polyarticular symmetrical arthritis - similar pattern to RA
b) large joint oligoarthritis - eg just a knee and an ankle that are swollen
c) arthritis that just affects the DIP
d) mutilating deforming arthritis = arthritis mutilans, ie telescoping of fingers
e) axial disease - like in ankylosing spondylitis but in a pt who has skin psoriasis
What types of arthritis can be responsible for arthritis that is just present in the DIP joints?
osteoarthritis
psoriatic arthritis
What is dactylitis?
inflammation of the tendon sheaths and joints of a digit
What are the hidden sites for psoriasis?
behind the ears in the scalp in the ears genitals belly button multiple pits in nails onchycholysis - creamy white discoloration of the nail and nail detachment
give some examples of conventional DMARDs
ciclosporin cyclophosphamide gold injections hydroxychloroquine methotrexate mycophenolate sulfasalazine
How is psoriatic arthritis managed?
a) early intervention with a conventional DMARD
b) anti-TNF drugs eg infliximab
c) IL-17/ IL-23 blockers
What is reactive arthritis?
STERILE inflammation of the synovial membrane, tendons and fascia triggered by an infection at a distant site, usually GIT infection or STI
give example of GIT infections that can cause reactive arthritis
Salmonella
Shigella
Yersinia
give examples of STIs that cause ReA
Chlamydia
Ureaplasma urealyticum
what are the clinical features of ReA?
classical triad of:
arthritis
conjunctivitis
sterile urethritis
keratoderma blenorrhagica
iritis
circinate balanitis (dermatitis of the glans penis)
What are the differential diagnoses of ReA?
septic arthritis - ie joint infection
gout
How is ReA investigated to exclude other diagnoses?
raised ESR/CRP
aspirate joint to exclude infection/crystals
urethral swab, stool culture
contact tracing if necessary
Explain what enteropathic arthritis is
episodic peripheral synovitis
assymetrical lower limb arthritis
reflects IBD activity
or can have ankylosing spondylitis that is unrelated to IBD activity
the arthritis seen in enteropathic arthritis is erosive, T or F?
false - it is non-erosive
