Idiopathic Inflammatory Myopathies Flashcards

1
Q

What are IMMs?

A

Autoimmune disorder where there is inflammation within the muscles

Polymyositis- chronic inflammation of muscles

Dermatomyositis- inflammation of skin and muscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the symptoms of polymyositis?

A
Proximal muscle weakness
No pain
Muscle wasting 
Acute/insidious onset
Weight loss
Fever

Difficulty squatting and climbing stairs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are symptoms of dermatomyositis?

A

Gottrons lesions
-scaly erythematous patches on knuckles/elbows/knees

Heliotropic rash

Photosensitive rash on back/shoulders/neck

Periorbital oedema

Sc calcinosis

PLUS polymyositis symptoms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What investigations are needed?

A

Bloods
-Serum CK >1000 due to muscle damage

ANA- most +ve
RF- 50% +ve

Myositis specific antibodies

  • Anti- Jo1= polymyositis
  • Anti-Mi 2= dermatomyositis
  • ANA= dermatomyositis

EMG

MRI for abnormal muscle

Muscle biopsy- fibre necrosis with inflammatory infiltrate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How is it diagnosed?

A

The following must be present

  • Clinical presentation
  • Elevated CK
  • Autoantibodies
  • Supportive EMG
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the management?

A
Steroids e.g. prednisolone
Other therapies if steroid response is poor
-DMARDs e.g. azathioprine 
-IV immunoglobulins
-Biological therapy e.g. infliximab

Must screen for appropriate cancers as increased risk

If untreated polymyositis can affect resp muscles causing resp failure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is inclusion body myositis?

A

Affects white males>50

Insidious onset of proximal and distal muscle wasting- can be asymmetrical

Muscle biopsy shows inflammatory infiltrate and vacuoles containing beta amyloid

Rarely responses to steroids etc.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly