L9 Myopathy Flashcards by Baria Fatmi

what are typical clinical features in myopathy

weakness: usually proximal (biggest muscles)
weakness>wasting
reflexes: normal (except severely wasted muscle)
sensory: normal
EMG: myopathic picture
CK: high

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what does increased amplitude of motor units suggest in EMG

nerve problem

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what does reduced amplitude of whole response suggest

axonal loss

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what amplitude (microvolts) of normal, myopath, neuropathy can they reach

normal: 100
myopathy: 50
neuropathy: 300

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what parts of muscle system are involved in myopathy

cranial, limb, cardiac, respiratory

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what are the 
symptoms
signs
tests
of cranial part

symptoms: swallowing difficulty, can’t whistle
signs: facial weakness, slurred speech
tests: EMG myopathic MRI - to rule out other causes

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what are the 
symptoms
signs
tests
of limb part

symptoms: difficulty getting up from the floor, lifting heavy objects
signs: proximal weakness
tests: EMG - myopathic, muscle biopsy

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what are the 
symptoms
signs
tests
of cardiac part

symptoms: heart failure, syncope (arrthymia), sudden death

signs :cardiomegaly, heart failure
tests: ECG, echo, 24hr tape

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what are the 
symptoms
signs
tests
of respiratory part

symptoms: orthopnoea, morning headaches
signs: reduced vital capacity, paradoxical diaphragm movement
tests: spirometry, overnight oximetry

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what are typical patterns/organ systems involved

limbic girdle muscular dystrophy
duchenne muscular dystrophy
mitochondrial myopathy
statin myopathy
polymyositis

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what are specifc organ involvement /pattern

facioscapulohumeral dystrophy
myotonic dystrophy
chronic progressive external ophthalmoplegia
distal myopathies
inclusion body myositis

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what are multi organ involvement in myopathy

myotonic dystrophy
duchenne muscular dystrophy
mitochondrial disease
HIV myopathy
dermatomyositis

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when is myopathy acquired

acute or sub acute
monophasic or relapsing remitting
exposure history
asymmetrical
adult onset

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when is myopathy inherited

longstanding
progressive
family history
symmetrical
childhood onset

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when is the involvement of cranial, limb, cardiac, respiratory in duchenne muscular dystrophy

cranial: very late
limb: age 3-5, lose ambulation early teens
cardiac: teenager onwards, most common cause of death
respiratory: teenager onwards

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are other systems involved in duchenne muscular dystrophy

scliosis

mild cognitive

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is there an specific pattern of weakness in duchenne muscular dystrophy

no, typical proximal pattern

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what investigations are done for duchenne muscular dystrophy

CK increased several thousand fold
biopsy - absent dystrophin staining
genetic testing dystrophin gene - frameshift mutation

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what treatment is there for duchenne muscular dystrophy

supportive - prolonged lifespan
Prednisolone - proven efficacy, prolonged ambulation
experiemental - restoration of dystrophin, phase 3 trials negative. ataluren licensed. stop mutations

how is cranial, limb, cardiac, respiratory involved in myotonic dystrophy

cranial: myopathic facies
limb: distal upper limb weakness and myotonia
cardiac: arrhythmias, sudden death common, low threshold ICD
respiratory: sometimes

are other organ systems involved in myotonic dystrophy

frontal balding, cataracts, cognitive, hypersomnolence, diabetes, hypogonadism,

is there a specific pattern of weakness in myotonic dystrophy

face and finger flexion

what investigations were done in myotonic dystrophy

EMG shows myotonia, biopsy not needed

genetic testing DMPK gene

what treatment is there in myotonic dystrophy

supportive - prophylactic arrhytmia management
genetic counselling
experimental: early phase block toxic RNA

how are cranial, limb, cardiac, respiratory involved in facioscapulohumeral dystrophy

cranial: facial weakness early limb: peri-scapular, distal lower limb cardiac: 5% mild arrhythmias respiratory: rare - restrictive secondary to kyphoscoliosis

are other organ systems involved in facio. dystrophy

rare-deafnese, retinal vasulopathy

is there a specific pattern of weakness in facio. dystrophy

face, scapular often asymmetric

what investigations were done in facio.dystrophy

CK moderately elevated biopsy generally not needed genetic confirmation - d4z4 repeat 4q

what treatment is there for facio. dystrophy

supportive - surgery to stablise scapula | experimental treatments: lab stage

is cranial, limb, cardiac, respiratory involved in dermatomyositis

c - severe cases limb - yes cardiac - no res - severe cases

are other organ systems involved in dermatomyositis

rashes and associated with malignancies

is there a specific pattern of weakness in dermatomyositis

no, usually classical proximal pattern

is cranial, limb, cardiac, respiratory involved in polymyositis

c - severe cases limb - yes cardiac - no res - severe cases

are other organ systems involved in polymyositis

is there a specific pattern of weakness in polymyositis

no usually classical proximal pattern

what investigations were done in dermamyositis

CK moderately elevated | biopsy needed for diagnosis

what treatment for dermamyositis

immunosuppression | steroids

what investigations were done in polymyositis

CK moderately elevated | biopsy needed for diagnosis

what treatment for dermamyositis

immunosuppression | steroids

is cranial, limb, cardiac, respiratory involved in inclusion body myositis

cranial - swallowing limb - quadriceps, finger flexors cardiac: no respiratory: no

is other organ systems involved in inclusion body myositis

is there specific pattern of weaknessinclusion body myositis

quadriceps, finger flexors, ankle dorsiflexors

investigations for inclusion body myositis

CK slightly elevated | biopsy needed for diagnosis

treatment for inclusion body myositis

immunosuppresion - ineffective | currently no effective therapy

how is image used in - inclusion body myositis - polymyositis + derma - facio - myotonic - duchenne

- ibm- specific pattern noted and may aid in diagnosis - poly + derma: may be useful to guide biopsy to increase yield - facio: STIR hyperintensity associated with inflammation on biopsy - myotonic: specific patterns reported on T1 images, correlation with ankle strength - duchenne: much recent research in quantitative MRI to assess new treatments