Muscle Disease Flashcards
what are the 4 main inflammatory causes of primary muscle disease?
polymyositis
dermatomyositis
inclusion body myositis
polymyalgia rheumatica
How do muscle diseases present?
muscle pain
muscle weakness
muscle stiffness
muscle wasting
which inflammatory cause of primary muscle disease has a noticeable increased incidence of malignancy?
dermatositis
what muscles are usually affected by dermatomyositis or polymyositis?
proximal muscles
eg muscles around pectoral girdle and pevlic girdle
what are the features of cutaneous disease of dermatomyositis?
Gottrons sign
Heliotrope rash
Shawl sign
what is Gottrons sign?
papules over metacarple phalangeal (MCP) joints and proximal interphalangeal joints
what is a heliotrope rash?
a purpley-reddish rash around the eyes
what is a shawl sign?
a purpley-reddish rash around the neck
what drugs used in the treatment of patients with a certain cardiovascular risk factor can cause muscle pain and inflammation?
statins
what illict drug is known for causing muscle pain and inflammation?
cocaine
what 2 types of muscle testing are important features of examining a patient with suspected inflammatory muscle disease?
- confrontational testing- direct test of power
2. isotonic testing- muscle power with repeated exercise
how might you do a confrontational muscle test?
by applying force in the opposite direction to the patient
how might you do a isotonic muscle test?
30s sit to stand test
what enzyme is usually raised in polymyositis?
creatine kinase
what autoantibodies can be present in polymyositis and dermatomyositis?
ANA
anti-Jo-1
what is the gold standard definitive test for polymyositis and dermatomyositis?
muscle biopsy
why are MRI’s useful in the diagnosis of polymyositis and dermatomyositis?
help pinpoint an affected muscle to biopsy
what is the treatment for polymyositis and dermatomyositis?
steroids (only used acutely)
immunosuppressant drugs
IV immunoglobulin
biologic (rituximab)
compare the onset of weakness between polymyositis, dermatomyositis and inclusional body myositis?
polymyositis- months
dermatomyositis- months
inclusional body myositis- years
compare the location of weakness between polymyositis, dermatomyositis and inclusional body myositis?
polymyositis- proximal muscles
dermatoymyositis- proximal muscles
inclusion body myositis- distal muscles
compare the distribution of muscle weakness between polymyositis, dermatomyositis and inclusional body myositis?
polymyositis- symmetrical
dermatomyositis- symmetrical
inclusional body myositis- asymmetrical
compare the creatine kinase levels between polymyositis, dermatomyositis and inclusional body myositis?
polymyositis- elevated
dermatomyositis- normal or elevated
inclusional body myositis- normal or slighly elevated
what is the classic muscle biopsy findings of polymyositis?
endomysial inflammation with CD8+ T cells
what is the classic muscle biopsy findings of dermatomyositis?
perimysial inflammation with CD4+ T cells
+
perifascular atrophy
what is the classic muscle biopsy findings of inclusional body myositis?
rimmed vacules
compare the response of treatment between polymyositis, dermatomyositis and inclusional body myositis?
polymyositis- good response
dermatomyositis- good response
inclusional body myositis- poor response
why is polymyalgia rheumatica an unusual inflammatory muscle disease?
biopsy looks normal
only pain and stiffness- no muscle weakness
what muscles are affected in polymyalgia rheumatica? (distribution and location)
symmetrical proximal muscles around shoulder and hip girdle
what is temporal arteritis?
giant cell arteritis
inflammation of the lining of the temporal artery
what is the major serious consequence of temporal arteritis?
giant cell arteritis
permanent blindness
temporal artery suplies the optic nerve
what happens to the jaw in temporal arteritis?
giant cell arteritis
jaw claudication- aching in muscles when chewing
what kind of headache presents in temporal arteritis?
giant cell arteritis
unilateral, able to localie
what happens to the temporal arteries in temporal arteritis?
(giant cell arteritis?
granulomatous inflammation of the temporal artery
artery becomes tender, enlarged (but with lumen narrowing), and non-pulsatile
why is the temporal artery non-pulsative in temporal arteritis?
vessel wall is so thick due to inflammation:
pulse isn’t conducted through it
why is biopsy not totally effective in suspected temporal arteritis?
skip lesions
there are patches where there is no granulomatous inflammation
what is the treatment of polymyalgia rheumatica? (with no temporal arteritis)
low dose steroids
rapid and dramatic response
what is the treatment of polymyalgia rheumatica with temporal arteritis?
high dose steroids, gradually decreasing dose for 18 -24 months
what is the most common cause of chronic musculoskeletal pain?
fibromyalgia
what may trigger fibromyalgia?
emotional or physical trauma
how do you diagnose fibromyalgia?
absence of abnormal features
inflammatory markers also normal
what is the treatment for fibromyalgia?
education graded exercise complementary medicine (eg acupuncture) anti-depressants anti-convulsants analgesia
who tends to get polymyalgia rheumatica?
elderly individuals
very rare under 50
how do the symptoms of polymyalgia change over the day?
morning stiffness which lasts for more than an hour
symptoms improve as the day goes on (and with movement)
why can dysphagia occur in polymyositis?
secondary to oroparyngeal and esophageal muscle involvement
-poor prognostic sign
what is crucial to diagnose polymyositis and dermatomyositis?
muscle biopsy
what is seen on muscle biopsy of polymyositis?
inflammation, necrosis and regeneration
chronic inflammatory infiltrate with cytotoxic T cell
what should additionally be screened for in dermatomyositis that isn’t screened for on polymyositis?
malignancy
what is fibromyalgia thought to be a disorder of?
the central pain processing
syndrome of central sensitivity
