Rheumatology Flashcards
What is a rheumatological condition that needs to be treated immediately?
Septic arthritis
What is septic arthritis?
Joint infection caused by bacteria or a virus that spreads to the fluid surrounding the joint
What is the most common organism that causes septic arthritis?
Staphylococcus aureus
What is the most common organism that causes septic arthritis in young sexually active individuals?
Gonococcus
What other organisms can cause septic arthritis?
1) Streptococcus
2) Gram negative bacilli
What are risk factors for septic arthritis?
1) Pre-existing joint disease e.g. RA
2) CKD
3) Immunosuppression
4) Prosthetic joints
What are the clinical features of septic arthritis?
1) Acutely inflamed, tender, swollen, erythematous, hot joint - most commonly knee
2) Reduced range of movement
3) Systemically unwell
What is the key diagnostic investigation for septic arthritis?
Joint aspiration for MC&S (send synovial fluid for urgent gram stain and culture) - before starting abx
What does the fluid look like after joint aspiration of a septic arthritis joint?
Turbid, yellow, resembling pus
What other investigations would you do for septic arthritis?
1) Blood tests - esp. FBC and CRP
2) Blood cultures
3) Joint x-ray - may be normal or may suggest bone involvement
What will blood tests show in septic arthritis?
High WCC, high ESR/CRP
How do you manage septic arthritis?
1) IV antibiotics according to local guidelines - empirical until sensitivities are known
2) Consider joint washout under GA
3) Splint for < 48h and analgesia
4) Physiotherapy after acute infection resolves
What are potential complications of septic arthritis?
1) Osteomyelitis
2) Arthritis
3) Ankylosis fusion
What imaging would be done if there is concern of osteomyelitis?
MRI
When may surgical washout be necessary after joint aspiration in septic arthritis?
If there is still an effusion in the knee joint despite serial joint aspirations esp. if there is a prosthetic joint
Why is ultrasound of the knee joint not essential as an investigation of septic arthritis?
Bc the swelling and effusion of the knee joint can be determined on examination
What is the role of ultrasound imaging in septic arthritis?
When ultrasound guidance may be needed to aspirate small joints
Bilateral, proximal muscle weakness that develops over weeks-months?
Polymyositis
What is the main feature of polymyositis?
Variable muscle weakness - bilateral, proximal (hip and shoulder girdle) muscle weakness, developing over weeks to months
What are additional symptoms in polymyositis that may be present in approx ⅓ of patients?
1) Muscle pain (myalgia)
2) Muscle tenderness
What two characteristics are preserved until very late in polymyositis?
1) Muscle bulk
2) Reflexes
What are complications that can occur in polymyositis due to other muscles becoming involved as the disease progresses?
1) Dysphonia & dysphagia - pharyngeal or oesophageal muscles
2) Type 2 respiratory failure (low O2, high CO2) due to poor ventilation (SOB) - respiratory muscles (neuromuscular weakness)
What are typical patient characteristics in polymyositis and dermatomyositis?
1) 40-60 year olds
2) Females
What key investigation provides definitive diagnosis for polymyositis and dermatomyositis?
Muscle biopsy
What are differential diagnoses for bilateral proximal muscle weakness?
1) Polymyositis and dermatomyositis
2) Other acquired causes of myopathies e.g. steroid or statin induced
3) Thyroid disease
How does dermatomyositis present?
Muscular features of polymyositis + additional skin rashes
What are the skin rashes that can present in dermatomyositis?
(Rough order of frequency):
1) Heliotrope rash
2) Gottron’s papules
3) Macular erythematous rash - generally on head & neck, trunk or hands
4) Periungual (nailfold) erythema
5) Cutaneous vasculitis (can present as rashes and lead to ulcers)
6) Calcinosis
What is a heliotrope rash?
Lilac discolouration of the eyelid skin + periorbital oedema
What are Gottron’s papules?
Scaly, erythematous papules over knuckles and extensor surfaces of knees and elbows
What are the extra-muscular features of polymyositis and dermatomyositis?
1) Systemic upset (fever/tiredness/malaise/weight loss)
2) Polyarthralgia
3) Interstitial lung disease
4) Raynaud’s phenomenon
5) Myocarditis
What can polymyositis and dermatomyositis be secondary to?
Underlying malignancy esp. dermatomyositis
What % of polymyositis and dermatomyositis cases are secondary to an underlying malignancy?
5-15%
Which cancers are most commonly associated with polymyositis and dermatomyositis?
Breast, colon, lung, oesophagus, ovary
What are the initial investigations to perform on all patients where you suspect polymyositis or dermatomyositis?
1) Muscle derived serum elevation - creatinine kinase (most sensitive, level usually parallels disease activity esp. in PM)
2) EMG - confirms myopathic pattern of disorder and excludes primary neurogenic disorder
3) Muscle biopsy - definitive diagnosis
What does EMG show in polymyositis and dermatomyositis?
Typical neurogenic records include short duration and low amplitude polyphasic motor units on voluntary activation
What does muscle biopsy show in polymyositis?
Endomysial inflammatory infiltrates
What does muscle biopsy show in dermatomyositis?
Perivascular, perimysial inflammatory infiltrate
Which blood tests/serum enzymes are elevated in polymyositis and dermatomyositis?
CLAAA (DM and PM turn muscles into clay)
1) Creatinine kinase
2) Lactate dehydrogenase
3) Aldolase
4) ALT
5) AST
How else can polymyositis and dermatomyositis manifest?
Paraneoplastic syndrome - PM associated with lung cancer, DM associated with visceral carcinomas esp. gastric, colorectal, genitourinary and lung cancers
What is necessary to investigate in polymyositis and dermatomyositis?
Underlying malignancy
What is the main treatment in polymyositis and dermatomyositis?
Corticosteroids
How are polymyositis and dermatomyositis treated with steroids?
Started at high doses initially, CK then monitored to guide the rate of tapering the dose
In addition to steroids, how else is polymyositis and dermatomyositis treated?
Many patients need an additional immunosuppressant e.g. methotrexate or azathioprine as a steroid-sparing agent
What drug can occasionally help with skin disease in dematomyositis?
Hydroxychloroquine
What non-pharmacological therapy is essential in polymyositis and dermatomyositis to rehabilitate patients?
Physiotherapy
What are the characteristic features of rheumatoid hands?
1) ‘Loss of the valleys’ at knuckles - due to swelling of the joints
2) Boutonnière’s (hyperflexed PIP) - due to prolapse of PIPJ through rupture in the central slip of the extensor expansion
3) Swan-neck (hyperextended PIP) - due to rupture of lateral slips
What is the most common cause of Rheumatoid hands?
Rheumatoid arthritis
What are other differentials that can appear like a rheumatoid hand?
1) Psoriatic arthritis
2) Jaccoud’s arthropathy (in association with SLE, arthropathy in SLE can be erosive)
3) Chronic crystal arthritis
How does rheumatoid arthritis present?
Bilateral hand and wrist pain that is worse in the morning, pain relieved by anti-inflammatories
What imaging is done for RA?
X-ray
What does an X-ray show in RA?
Symmetrical polyarthropathy with ulnar deviation of the MCP joints and Z-deformity of the thumb
What is rheumatic fever?
Autoimmune condition caused by antibodies created against the Group A streptococcus bacteria that also targets tissues in the body (when streptococcus is not adequately treated)
How does rheumatic fever present?
1) Multisystem disorder that affects the joints, heart, skin and nervous system
2) Fever occurs 2–4 weeks following a streptococcal infection (tonsillitis) along with:
3) Migratory arthritis
4) Carditis - myocarditis, endocarditis, valvulitis
5) Subcutaneous nodules
6) Erythema marginatum (pink, non-itchy, flat or slightly raised lesions with well-defined borders, usually occurs on the trunk and limbs and can come and go)
7) Sydenham’s chorea (involuntary muscle movements, particularly in the face, hands, and feet, jerky, purposeless movements and difficulty with coordination)
How is rheumatic fever treated?
1) NSAIDs
2) Aspirin
3) Steroids
4) Abx
