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15 Cards in this Set
- Front
- Back
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What is a motor unit?
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an alpha motor neuron and those muscle fibers it innervates
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What is the motor unit potential (MUP)?
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summation of APs of muscle fibers resulting from a motor unit discharge
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What is the CMAP (compound muscle AP)?
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Summation of APs from several motor unit discharges of a peripheral nerve
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What is an MEPP?
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Depolarization of muscle end-plate produced by spontaneous release of a single quanta
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What is an EPP?
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Impulse of motor neuron, synchronous release of many quanta
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What is Gullian Barre?
What are the neurophysiological symptoms of peripheral nerve conduction defect (demyelination)? (4) |
Demyelination of peripheral nerve
1. Absent H-reflex 2. Abnormal late motor response (F-wave) 3. Slowed motor conduction velocity 4. Temporal dispersion |
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What is the safety factor?
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Ratio of threshold/EPP
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What happens to EPP if given Curare?
CMAP? |
Curare blocks nAchR channels
EPP decreases with repetitive stimulation (b/c effectively reduce number of postsynaptic receptors) CMAP decreases because some fibers not firing |
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What is the pathogenesis of Botulism?
What are the neurophysiological defects? (3) |
Botox blocks SNAP complex --> vesicle cannot bind
1. MUP low in amplitude, brief 2. MEPP frequency reduced (amplitude unchanged) 3. EPP reduced |
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What is the pathogenesis of LEMS?
What are the neurophysiological defects? (4) |
Antibody against Ca channel, less Ca in presynaptic terminal
1. Irregular variability in MUP amplitude 2. Facilitation (increase) of CMAP amplitude (w/high freq. stimulation) 3. Normal MEPP amplitude 4. Decreased EPP (decreased quantal content) |
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What is the pathogenesis of Myokymia?
What are the neurophysiological defects? (2) |
Myokymia = increased presynaptic release due to depolarization of presynaptic terminal (K channel mutation)
1. Spontaneous bursts of MUPs 2. Cannot detect CMAP because of asynchronous firing |
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What are the neurophysiological defects of having persistent NT in cleft? (2)
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1. SIngle shock elicits repetitive CMAPs
2. Decremental response to high frequency repetitive stimulation (Na channels deactivate) |
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What are the neurophysiological defects of having a defective Ach receptor (Myasthenia Gravis)?
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1. Variability and reduced amplitude of MUP
2. Jitter (increased variability in the time between APs of muscle fibers from same motor unit) 3. Decremental CMAP amplitude 3 |
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What does a decremental response to stimulation usually signify?
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Problem with the NMJ
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What does an incremental response to stimulation signify?
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Problem with the presynaptic cell
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