Diseases of Muscle Flashcards
T/F
Eye muscles do not contain dystrophin.
True
Normal muscle is endowed with a population of embryonic muscle precursor cells known as _______ cells and as a result, it possesses a remarkable capacity to regenerate.
satellite cells
Muscle connective tissue derives from the
somatopleural mesoderm
At all ages, disuse of muscle decreases fiber size by a smuch as ____ percent and overuse increases the size by about the same amount.
30%
6 Grades of Muscle strength by the Medical Research Council of GB
0 complete paralysis
1 minimal contraction
2 active movement only with gravity eliminated
3 full movement against gravity but cannot offer resistance to manual muscle opposition
4 active movement against gravity and resistance but can be overcome by manual muscle opposition
5 normal strength
stiffness and slowness of contraction in a muscle such as the quadriceps may be seen on change in postures
contraction myoedema
prolonged failure of relaxation, following contraction of a muscle is characteristic of
myotonia
T/F
Pain tends to be prominent in polymyositis and dermatomyositis.
False
pain tends NOT to be prominent but there are exceptions
p1411
T/F
As a general rule, muscle diseases are identified by a predominantly proximal weakness that is symmetric.
true
T/F
When weakness of the orbicularis oculi (muscles of eye closure) is added to weakness of eye opening (levator palpebrae; ptosis), it nearly always signifies myasthenia gravis and occasionally, a rare primary disease of muscle (progressive external ophthalmoplegia [PEO]).
true
T/F
Paradoxical inward movement of the abdomen with inspiration is another sign of diaphragm weakness.
True
p1414
Most common pattern of a number of myopathies.
most often, polymyositis, IBM, dermatomyositis, and the muscular dystrophies present in this fashion
Proximal Limb-Girdle palsies presenting as inability to raise arms or to arise from a squatting, kneeling or sitting position
weakness of IBM has a preference for certain sites
quadriceps or of the forearm muscles particularly the long finger flexors
flexor digitorum profundus
parasitic disease
ocular muscle weakness, causes strabismus and diplopia
tongue weakness -> dysarthria
weakness of masseter and pharyngeal muscles - diff chewing and swallowing
weakness of limb muscles proxima>distal
conjunctival, orbital, facial edema
subconjunctival, subungual splinter hemorrhages
dx: puffy face with tender muscles
eosinophilia >700
ELISA is accurate but positive only after 2 weeks of illness
biopsy is the most reliable confirmatory test
biopsy: segmental necrosis, interstitial inflammatory infiltrates, eosinophils
Trichinosis
caused by nematode Trichinella spiralis
treatment for Trichinosis
no treatment in most cases
severe weakness and pain: thiabendazole 25-50mg/kg daily in divided doses for 5-10 days
prednisone 40-60mg/kg per day
albendazo,e 400mg OD
recovery is complete
except in pts with infarcts
In the AIDS population, myositis from toxoplasma is more common than brain infestation
False
p1416
brain infestation more common
treatment for toxoplasmosis myositis
sulfadiazine in combi with pyrimethamine or trisulfapyrimidine
folic acid is given in addition
an antiretroviral drug used to treat HIV, may induce a myopathy with myalgia and weakness that is indistinguishable from HIV myopathy
zidovudine
T/F
The clinical features of putative ZVD-induced myopathy are much the same as those of HIV myopathy except that moderate pain is said to be characteristic of the druginduced variety
True
T/F
The myopathologic changes in AIDS are also like those of idiopathic polymyositis.
true
idiopathic subacute or chronic symmetrical weakness of proximal limb and trunk muscles without dermatitis
Polymyositis
insidious, course progressive several weeks to months
febrile illness or benign infection may precede the weakness
painless weakness
T/F
Ocular muscles are not affected in PM.
True
but there are rare instances of combined PM and MG
denominative feature is rash
most often, the skin changes precede the muscle syndrome
localized or diffuse erythema, maculopapular eruption, scaling eczematoid dermatitis, exfoliative dermatitis
prominent in childhood DM: Gottron papules
heliotrope
V sign and shawl sign
Dermatomyositis
T/F
Serum CK levels tend to be higher in PM than in DM.
true
because of the widespread single-fiber necrosis in the former. however in DM if there are infarcts in muscle, CK levels will be moderately elevated as well
ESR is normal or mildly elevated
T/F
Absent or low titer ANA and normal ESR do not exclude the diagnosis of PM.
true
T/F
When performing EMG and biopsy, perform the needle examination and biopsy on the same side and site.
False
p1421
EMG on one side and biopsy on the other side