Myositis Flashcards
myositis is NOT to be confused with
myopathy
categories of myositis/myopathies
1) myositis
2) rhabdo
3) drug-induced myopathy
4) metabolic myopathy
different types of mypotis
polymyositis
dermatomyositis
inclusion body myositis
criteria for myositis
symmetrical weakness of limb-girdle muscles and anterior flexors
what do we typically measure for suspected myositis
CPK
aldolase
AST, ALT
LDH
what increases CPK
acute muscle injury trauma exercise drugs benign hyperCPKemia
EMG findings in myositis
short, small, polyphasia motor units
fibrillations with SHARP waves
bizarre, repetitive discharges
gender and myositises
F>M in DM/P
M>F for IBM
progression of myositis
slow, fixed proximal muscle weakness
by fixed we mean
weak ALL THE TIME, but also have fatigue, post-exertion aches, and pains
why is there an increased risk of malignancy?
secondary to myositis or if myositis is a paraneoplastic syndrome
other things you may see with myositis
raynauds
arthritis
pitting edema of extremities
pulmonary involvement
CDs in polymyositis
CD8>CD4
how to dx polymyositis (4)
prox muslce weakness
increased muscle enzymes
abnormal EMG
abnormal muscle bx
muslce atrorphy in polymyo
sparred until the very late in dz
what muscles are spared in polymyo
ocular and facial
other things yo may see in poly
dysphagia (pharyngeal muslce weakness)
raynauds
SOB (resp muscles) (+ILD –>dyspnea, cough, hypoxemia)
30% of patients exhibit
autoantibody to histidyltransfer RNA synthetase (Jo-1 antigen)
tx polymyo
prednisone
if needed- MTX and azathioprine
dermatomyositis pathophys
humoral ( b cells + CD4>CD8 t cells)–> inflammation in perifasicular and perivascular areas–> muscle fibeer necrosis and degen
*likely to be a paraneoplastic syndrome
skin finds in dermatomyo
-violaceous with scaly desquamation–>occur in sun exposed areas (malar, chest shawl sign), extensor surfaces of elbows and knees, knucles (Gottron’s papules and Gottron’s sign), helicotrorpe
other finding in dermatomyo
dilated nailfold capillaries
juvenile dermatomyositis is adult form +
vasculitis
lipodystrophy
calcinosis
amyopathic dermatomyositis
typical dermatomyo, but NO MUSCLE WEAKNESS
anti-synthetase syndrome
PM or DM associated with anti-Jo-1 antbody
–strong association with ILD–also associated with Raynaud’s, arthritis, mechanic’s hands
characteristics of inclusion body myositis
inflammatory myopathy with neuropathic features, causing paresthesias (tingling) and early involvement of distal muscles
who does IBM usually affect?
middle-aged men–slowly progressive non-painful proximal myopathy w/ no response to treatment and progresses until it kills them
what type of drugs induce drug-induced myopathy?
statin induced myopathy
-steroid-induced myopathy
statin-induced myopathy
rare, but we use statins a lot so we see it–can be used with any dose and can occur at anytime
–>relieved by stopping, but sometimes need steroids
steroid induced myopathy
common, occurs with any dose of steroids
proximal muscle weakness, w/o tenderness and atrophy, normal CPK
bx of steroid induced myopathy shows
no inflammation
polymyalgia rheumatica
does NOT involve musles–inflam of soft tissue
polymyalgia rheumatic clinical presentation
acute onset of morning stiffness and pain esp at shoulder and hip girdle + muscle and joint pain, fatigue
maybe weight loss, depression, fever
**NO MUSCLE WEAKNESS
labs in PR
increase ESR
normochromic normocytic anemia
EMG in PR
normal@
tx of PR
daily lose dose steroids-resolves within 24 hours
metabolic myopathy symptoms
exercise intolerance secondary to cramps or weakness
myoglobin breakdown
primary metabolic myopathy
abnormal glycogen
lipid, purine metabolism
mitochondrial abnormality
secondary metabolic myopathy
endocrine disorder electrolyte disorder uremia liver failure vit d/e def
