CM: Neuromuscular Dz Flashcards
What does a lesion in a UMN cause?
weakness, increased tone (spasticity), hyperreflexia
What does a lesion in a LMN cause?
weakness, hypotonia, hyporeflexia, atrophy, fasciculations
What general characteristics characterize myopathies?
symmetric proximal weakness with normal sensory fxn
reflexes normal or decreased in proportion to weakness
What tests can be used to evaluate the NM system?
electrodiagnostic testing can determine which part of unit is damaged
test blood for Abs or genetic abnormalities
muscle or nerve biopsy
Injuries to the corticospinal tracts have effects where?
if above medullary pyramids - contralateral side
below - ipsilateral side
What diagnostic tests might be necessary with myopathies?
EMG, CK, aldolase, Ab with connective tissue disorders, muscle biopsy
What are general features of inflammatory myopathies?
slowly progressive symmetric proximal weakness
ocular muscles spared, but dysphagia common
may have pain or tenderness
What are distinctive features that can differentiate dermatomyositis from polymyositis?
dermato - skin rash (over eyelids, knuckles)
poly - associated w other connective tissue disorders
What are features common to dermatomyositis and polymyositis?
increased risk of cancer (dermato more)
high CK levels (>1000)
EMG w short small motor units w early recruitment
What is Gowers’ manuever?
children get on hands and knees, elevate posterior,then walk hands up to legs to raise upper body
seen in Duchenne
What is myotonic dystrophy?
AD, CTG repeat on ch 19 - shows anticipation, inherited from mom = imprinting
most common in adults
facial, neck and distal extremity weakness (hatchet face = ptosis, long thin, temporal wasting)
inability to relax muscles after sustained contraction or percussion
What is facioscapulohumeral dystrophy?
can be mild and progress slowly, may develop foot drops and leg weakness, CK normal or slightly elevated, EMG shows myopathic features
What is oculopharyngeal dystrophy?
onset after 50, ptosis and dysphagia
AD, defective PABPN1 gene causes protein to clump together in muscle cell nuclei, interferes w fxn
What does the evaluation of metabolic myopathies include?
ischemic forearm exercise testing - doesn’t show increase in lactate in pts w glycogen disorders
What is an example of a metabolic myopathy?
McArdle’s = disorder of glycogen
What symptoms can accompany mitochondrial myopathies?
retinitis pigmentosa, cardiac conduction defects, short stature, seizures or strokes
serum and CSF lactic acid levels elevated
muscle biopsy shows ragged red fibers
What is Kearns-Sayre syndrome?
mitochondrial dz associated w progressive external opthalmoplegia, retinitis pigmentosa and heart block
unilateral ptosis becomes bilateral
lactate and pyruvate elevated
What are MELAS and MERRF?
mitochondrial ecephalomyopathy, lactic acidosis, stroke
myoclonic epilepsy and ragged red fibers
mitochondrial dizs associated w myopathy
What is myasthenia gravis?
immune mediated - Abs against postsynaptic Ach receptor, usually progressive
What are conditions associated w myasthenia gravis?
thymoma, thymic hyperplasia
other autoimmune conditions
What are signs and symptoms of myasthenia gravis?
fatigue fluctuating throughout day
symptoms progress as day goes on
prolonged use of muscles worsens, rest improves
proximal muscle weakness, ocular symptoms, dysphagia
no sensory involvement
What can help diagnose myasthenia gravis?
CMAP declines in amplitude in MG w/i first 4-5 stimuli, single fiber jitter on EMG, Ab, tensilon test results in temporarily restored muscle fxn
What is Lambert-Eaton myasthenic syndrome?
weakness due to Abs blocking voltage gated Ca channels on presynaptic side of NMJ
DTR diminished or absent, but may be elicited after brief exercise
*postexercise or postactivation facilitation of CMAPs
paraneoplastic and autoimmune forms seen
How is LEMS different than MG?
never starts w ocular involvement, MG can
LEMS more common in men, MG presents earlier in women
