Rheumatology - Seronegative spondyloarthropathies Flashcards
What are seronegative spondyloarthropathies?
These are a group of rheumatological disorders sharing common features of:
- sacroileitis
- peripheral arthritis (typically large joints, especially of the lower limbs)
- mucocutaneous inflammation
- familial aggregation - HLA-B27
- absence of rheumatoid factor (hence “seronegative”)
They are:
1) AS
2) Psoriatic arthritis
3) Reactive arthritis
4) Enteropathic arthritis
5) Undifferentiated seronegative arthropathy
What groups of patients are normally affected by psoriatic arthritis?
Psoriatic arthritis has an equal sex distribution with a mean age of onset between 30 and 50 years.
It is associated with HLA-DR4 (peripheral joint involvement) and HLA-B27 (spinal disease) haplotypes.
It is more prevalent in HIV positive patients.
The same pathological process occurs in both the joints and skin - increased vascularity with an inflammatory cell infiltrate.
What is the clinical presentation of psoriatic arthritis? What is the most common clinical pattern?
10% of patients with psoriasis develop arthritis. There is no correlation between the presence or severity of psoriatic skin changes and joint involvement.
Several different clinical patterns are recognized:
- asymmetric oligoarthritis (30-50%) typically affecting a few large or small joints. Diffuse swelling of the digits (dactylitis) in which one or two take on a “sausage -like” appearance is a distinctive feature
- symmetrical polyarthritis (20-40%)
- sacroileitis and spondylitis (5-30%) which may be associated with Achiles tendonitis and plantar fasciitis (Enthesitis)
- DIP joint involvement
- arthritis mutilans (up to 15%) causes gross joint destruction of the small joints of the hand and collapse of the fingers resulting in “telescoping” of the digits
What findings on examination suggest psoriatic arthritis?
Nail pitting and onycholysis may be the only evidence of underlying psoriasis. It is important to carefully search for skin changes (including scalp, hairline and behind the ears). Pustular psoriasis of the palms and soles may be confused with the rash of Reiter syndrome (keratoderma blennorrhagica).
Spine and sacro-iliac joint involvement are less predominant than peripheral asymmetric large joints in PsA. Patients may also have conjunctivitis.
How should PsA be investigated?
There is no single diagnostic test for PsA and a high index of clinical suspicion is needed. The following may be useful:
- normochromic, normocytic anaemia and raised inflammatory markers
- negative RF
- HLA-B27 positivity (20% of ALL cases)
- radiological evidence of sacroileitis, DIP joint involvement or digital juxta-articular bone resorption (arthritis mitulans)
How should PsA be managed?
- support measures - activity modification, physiotherapy
- simple analgesics
- NSAIDs
- DMARDs - esp for symmetrical RA-like pattern with methotrexate being the preferred option. Hydroxychloriquine should be avoided as it may cause psoriatic flares
- anti-TNF inhibitors om those patients with >3 tender and swollen joints failing treatment with >2 DMARDs (NICE recommened adalimumab and infliximab)
What is the prognosis of PsA?
This is dependent on the pattern of disease. The symmetrical polyarthritis form follows a similar course to RA, sacroileitis resembles AS and oligoarticular disease tends to run a more benign course. Arthritis mutilans is associated with considerable disability.
Epidemiology of AS
AS is more common in white populations and is strongly associated with HLA-B27. It affects males more commonly than females with a peak age of onset in adolescence/ young adulthood.
There may be a history of inflammatory bowel disease, psoriasis or reactive arthritis.
What is the characteristic finding in AS?
Enthesitis (inflammation of ligament or muscle tendon attachments to bone) is the key feature in AS. Inflammation of the sacroiliac, facet and intervertebral joints is followed by ossification of spinal ligaments and IVDs. Bony outgrowths from the vertebral margins extend vertically and coalesce. Eventually spinal fusion occurs.
What is the clinical presentation of AS?
AS usually presents with insidious onset of inflammatory type pain in the lower back/ buttock and/or thoracic region.
Features of back pain suggestive of inflammation include:
- young (<40 years)
- early morning stiffness (usually > 1hr)
- pain (worse at night and in the morning, improving with exercise)
- stiffness (particularly with disuse)
Any level of the spine can be involved, but classically the lumbar spine is involved early on and the cervical spine relatively late. Advanced disease leads to the classic posture of cervical hyperextension, exaggerated thoracic kyphosis, loss of lumbar lordosis and compensatory knee flexion.
What extra-articular manifestations are common in AS?
- achilles tendinitis
- plantar fasciitis
- large joint involvement
- apical pulmonary fibrosis
- aortitis with aortic incompetence (regurgitation) +/- heart block
- amyloidosis
Examination findings in AS
1) Reduced forward flexion
- demonstrated by Schober’s test: in health an increase from 15 to 22cm is seen on forward flexion measured above and below a line drawn between the dimples of Venus. Decreases spinal flexibility –> distance measured increases to less than 22cm
2) Patrick’s test (Faber)
- pressure on the ipsilateral (or contralateral knee) held in flexion abduction + external rotation –> SIJ stress + pain of ipsilateral SIJ
3) Question mark posture
- extension of cervical spine
- loss of lumbar lordosis with bony ankylosis
How should AS be investigated?
Diagnosis relies on history and examination but the following can be useful
Bloods:
- RF negative
- elevated ESR and CRP
- HLA-B27 positivity (in 95% compared with 5-10% of the general population)
Plain film findings:
- sacroileitis
- squaring of the vertebrae
- vertebral body fusion
- syndesmophytes (bridging spurs of bone at the corners of adjacent vertebral bodies) causing bamboo spine
How should AS be managed?
- physio and hydrotherapy
- NSAIDs
- sulphasalazine may be effective for peripheral joint involvement
- anti-TNF therapy - NICE guidelines recommend etanercept or adalimumab in patients with severe AS with evidence of sustained active spinal disease and where treatment with >2 NSAIDs for 4 weeks has failed to control symptoms
What does reactive arthritis mean?
Reactive arthritis (Reiter’s syndrome) means any joint inflammation arising in relationship to an infectious episode which has usually resolved. The infective organism is not found within the joint itself as the inflammatory process probably results from an immune response to one or more bacterial antigens, following which activated T-lymphocytes and macrophages migrate to the synovium.
