L9 Myopathy Flashcards
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
what does increased amplitude of motor units suggest in EMG
nerve problem
what does reduced amplitude of whole response suggest
axonal loss
what amplitude (microvolts) of normal, myopath, neuropathy can they reach
normal: 100
myopathy: 50
neuropathy: 300
what parts of muscle system are involved in myopathy
cranial, limb, cardiac, respiratory
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
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
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
what are the symptoms signs tests of respiratory part
symptoms: orthopnoea, morning headaches
signs: reduced vital capacity, paradoxical diaphragm movement
tests: spirometry, overnight oximetry
what are typical patterns/organ systems involved
limbic girdle muscular dystrophy duchenne muscular dystrophy mitochondrial myopathy statin myopathy polymyositis
what are specifc organ involvement /pattern
facioscapulohumeral dystrophy myotonic dystrophy chronic progressive external ophthalmoplegia distal myopathies inclusion body myositis
what are multi organ involvement in myopathy
myotonic dystrophy duchenne muscular dystrophy mitochondrial disease HIV myopathy dermatomyositis
when is myopathy acquired
acute or sub acute monophasic or relapsing remitting exposure history asymmetrical adult onset
when is myopathy inherited
longstanding progressive family history symmetrical childhood onset
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
are other systems involved in duchenne muscular dystrophy
scliosis
mild cognitive
is there an specific pattern of weakness in duchenne muscular dystrophy
no, typical proximal pattern
what investigations are done for duchenne muscular dystrophy
CK increased several thousand fold
biopsy - absent dystrophin staining
genetic testing dystrophin gene - frameshift mutation
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
no
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
no
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
