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21 Cards in this Set
- Front
- Back
what two troups are dz of muscle divided into?
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1. neurogenic= distal wekaness, no pain, fasciculations present
2. myopathic= proximal weakness, +/- pain, no fasciculations |
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what characterizes neurogenic m. dz?
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1. distal weakness
2. no pain 3. fasciculations present |
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what characterizes myopathic m. dz?
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1. proximal weakness
2. +/- pain 3. no fasciculations |
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what is duchenne's muscular dystrophy?
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1. x-linked lack of dystrophin
2. progressive proximal weakness and wasting beginning at age 1 yr 3. increased CPK 4. calf hypertrophy 5. Gower's maneuver |
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what are si/sx of duchenne's muscular dystrophy?
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1. progressive proximal weakness and wasting
2. beginning at age 1 yr 3. increased creatine phosphate kinase 4. calf hypertrophy 5. waddling gait 6. Gower's maneuver (pts pick themselves off the floor by using arms to help legs) |
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what is Becker's dystrophy?
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1. dystrophin levels are generally normal in Becker's, but protein qualitity of dystrophin is altered
2. may have nml lifespan, unlike Duchenne type (death occurs in 10-20s) most often d/t pneuomonia |
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what else characterizes duchenne muscular dystrophy?
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1. intellectual retardation
2. skeletal deformities 3. m. contractures 4. cardiac involvment 5. increased CPK |
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what often occurs with polymyositis?
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1. dermatomyositis
2. b/l proximal m. weakness |
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what are si/sx of polymyositis/dermatomyositis?
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1. symmetric weakness/atrophy of proximal limb m.
2. cutaneous manifestation in dermatomyositis (Gottron's sign= scaly patches over the dorsum of proximal IP and MCP jts, periungual erythema, dilations of nailbed capillaries) 3. m. aches 4. dysphonia (laryngeal m. weakness) 5. dysphagia |
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what does dermatomyositis present with?
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1. polymyositis
2. periorbital heliotropic red to purple rash 3. Gottron's sign= scaly patches over the dorsum of proximal IP and MCP jts |
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what is dx for polymyositis and dermatomyositis?
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1. positive ANA
2. increased creatine kinase and aldolase (muscle nzs) 3. m. bx--shows inflamm changes |
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what is myasthenia gravis (MG)?
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1. autoantibodies block the postsynaptic acetylcholine receptor
2. pts present with ptosis, diplopia, difficulty chewing/swallowing, respiratory difficulites, limb weakness |
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what may be a/c thymomas, throid and outher autoimmune dz (e.g. lupus, RA)?
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1. myasthenia gravis (autoAbs blocking the postsynaptic acetylcholine receptor)
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what are sx of myasthenia gravis?
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1. m/c in women in 20-30s or men in 50-60s
2. m. weakness worse with use, diplopia, dysphagia, 3. proximal limb weakness which can progress to cause respiratory failure |
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what is the dx for myasthenia gravis?
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1. trial of edrophonium (short-acting anticholinesterase) causes an immediate increase in strength
2. confirm c/ electromyelography--repetitive stimulation causes a decrease in action potential |
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what is pathopys of myasthenia gravis?
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1. autoAbs binding to Ach receptors--cause m. weakness, ocular palsies, ptosis
2. when given a shrot acting anticholinesterase (edrophonium, neostigmine), m. weakness improves |
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what is lambert-eaton syndrome?
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1. autoAb to PRE-synaptic Ca channels seen c/ small cell lung CA
2. causes defective release of Ach |
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how does MG differ from Lambert-Eaton?
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Lambert-Eaton:
1. sx imporve c/ m. use 2. action potential strength increases with repeated stimulation MG: 1. activity increases weakness of affected m. 2. repetitive stimulation decreases the action potential |
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what CA is Lambert-Eaton a/c?
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1. small cell lung CA
2. defective release of Ach in response to a nerve impluse |
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what happens with aminoglycosides in MG?
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1. aminoglycoside abx prevent the release of Ach from nerve endings
2. are particularly dangerous in pts with prexisting disturbances of neuromuscular transission (e.g. MG) |
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what is tx for MG?
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1. anticholinesterase inhibitors (e.g. pyridostigmine) 1st line
2. steroids, cyclophosphamide, azathioprine for severe dz 3. plasmapheresis temporarily alleviates sx by removing the Ab 4. resection of thymoma can be curative |