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RB Y2 MSK 02 - Rheumatology > Muscle Disease: Polymyositis and Dermatosyitis > Flashcards

Muscle Disease: Polymyositis and Dermatosyitis Flashcards

1
Q

what is polymyositis

A

idiopathic inflammatory syndrome that causes symmetrical proximal muscle weakness

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2
Q

what is dermatomyositis

A

clinically similar to polymyositis but also has cutaneous symptoms

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3
Q

epidemiology

A

both more common in women as they are autoimmune

peak incidence of 40-50

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4
Q

what group of patients have an increased risk of malignancy

A

all patients

particuarly men over the age of 50 with dermatomyositis

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5
Q

what type of cancers is it linked to

A

ovarian, breast, stomach, lung, bladder and colon

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6
Q

pathology

A

T cell mediated cytotoxic proces that is directed against unidentified muscle antigens

CD8 T cells surround non necrotic muscle fibres and eventually invade and destroy them

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7
Q

what do features on a muscle biopsy show

A

necrosis and regeneration of muscle fibres are accompanied by focal chronic inflammation and fibrosis

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8
Q

presentation

A

symmetrical, proximal muscle weakness

some patients have myalgia

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9
Q

what is the onset like

A

insidious

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10
Q

how is it often described by patients

A

difficulty with particular activities eg brushing hair

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11
Q

what are the cuteanous features seen in dermatomyositis

A

gottrons sign

helitrope rash

shawl sign

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12
Q
A

gottrons sign

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13
Q
A

helitrope rash

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14
Q
A

shawl sign

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15
Q

lung involvement

A

ILD

repiratory muscle weakness

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16
Q

what predisposes one to ILD

A

anti Jo 1 antibody

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17
Q

oesophageal

A

dysphagia secondary to oropharyngeal and oesophgeal involvement in 1/3 patients

dysphonia

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18
Q

what type of sign is oesophageal involvement

A

poor progostic

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19
Q

cardiac features

A

myocarditis

20
Q

consitutional symptoms

A

fever, weight loss

21
Q

what feature is often present in the hands

A

Raynaud’s

22
Q

history

A

presenting symptoms

drugs - steroids or statins

FH

social history - alcohol and illicit drugs

23
Q

what features are important in the FH

A
  • FH of neuromuscular disease, exposure to myotoxic drugs and endocrinopathy absent
24
Q

importance of patient having taken steroids or statin

A
  • Statins are associated with inflammatory myopathies (e.g. polymyositis and dermatomyositis). Present as raised CK and proximal muscle weakness following statin use, symptoms persist after discontinuation of the drug
  • Steroids can cause proximal myopathy as they alter protein metabolism, reducing protein synthesis
  • Must rule out these causes
25
Q

examination

A

confrontational testing

isotonic testing

26
Q

what is isotonic testing

A

measuring of muscle stamina over time

27
Q

investigations

A

muscle enzymes

blood tests

inflammatory markers raised

28
Q

what do muscle enzymes show

A

serum CK raised

29
Q

autoantibodies

A

ANA and anti Jo 1

30
Q

EMG

A

findings abnormal in most patients

passing a low electrical current through the muscle to see if it conducts

31
Q

what is the definitive test

A

muscle biopsy

32
Q

MRI

A

can localise the extent of muscle involvement

show muscle inflammation, oedema, fibrosis and calcification

33
Q

management

A

glucocorticoids (prednisolone) combined with IS drugs eg methotrexate/azathioprine

biologic drugs can also be used

34
Q

what may need to be prescribed with the steroid

A
  • Side effect of peptic ulceration – prescribe PPI when necessary, e.g. omeprazole
35
Q

prognosis

A

usually responds slowly to treatment

around 30% patients left with some residual weakness

older patients and those who present later tend to do less well

36
Q

what is inclusion body myositis

A

inflammatory muscle disease characterised by slow weakening and wasting of proximal and distal muscles

37
Q

how does the pathogenesis of inclusion body myositis differ to that of poly and dermato myositis

A

it is autoimmune and destructive, the other two are not destructive

38
Q

what is includsion body myositis often misdiagnosed as

A

polymyositis

39
Q

who does inclusion body myositis occur in

A

OVER 50 (PM: 40-60)

more common in men

40
Q

is the muscle weakness in inclusion body myositis symmetrical?

A

no asymmetrical, symmetrical in PM

41
Q

diagnostic test for inclusion body myositis

A

muscle biopsy - inclusion bodies

42
Q

CK levels in inclusion body myositis

A

raised but not as much as in PM

43
Q

inclusion body myositis prognosis

A

poor response to therapy

44
Q

which muscles are frequently involved in inclusion body myositis, and how does this present

A

quadriceps - frequent falling

45
Q

what is the classical type of facial weakness occurring in inclusion body myositis

A

facial weakness sparing extra ocular muscles

46
Q

are fine motor tasks affected more in PM or inclusion body myositis

A

inclusion body myositis

47
Q

what happens to reflexes in inclusion body myositis

A

lose patellar reflexes

RB Y2 MSK 02 - Rheumatology (33 decks)

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