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20 Cards in this Set
- Front
- Back
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Sweep |
The period of analysis time that starts with a trigger from the stimulator & ends w/ enough time time to include the response being studied. |
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Latency |
How fast something is. Expressed in milliseconds (msec). |
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Aliasing |
The erroneous representation of an analog wave by digital values. Suggests a lower frequency due to a sampling rate of less than twice its original. |
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Generator Site |
Place in the brain/body that is creating the waveform. |
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Nyquist Principle |
Theory that states as a minimum, the sampling rate of an averager must be twice as fast as the fastest sine wave component. |
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Common Mode Rejection |
For every 10,000 of the same signals, the differential amplifier only amplifies 1 and rejects the others. |
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Display Gain |
The multiplying of the final average wave after it's been processed. |
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Cursor |
Marker on the screen which the computer makes measurements of frequency & amplitude. |
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Temporal Dispersion |
Signals traveling at different rates in different portions of a nerve bundle. |
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Subcortical EP |
Potentials generated by subcortical nuclei. Brainstem and spinal cord. |
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What is Signal-to-Noise Ratio? |
How we average in EP. The higher the signal strength is compared to the noise, the better the response will be. |
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What S/N Ratio do we want? |
2:1 |
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The rule for S/N Ratio? |
As the ratio increases, the # of averages increases by the square root of the # of averages. |
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Near-field Response |
Responses generated close to, or underneath the recording electrodes. |
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Far-Field Response |
Responses generated at a distance from the recording electrode. |
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How are responses assessed? |
Presence/absence of waves. Increased/delayed latencies. Decreased response amplitude. Increased latency most important. |
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What is the difference between Gain & Display Gain? |
Gain is an internal set amount in the amplifier and effects amplitude and voltage. Display gain just changes the appearance of the size of the deflections. |
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What are the 3 EP Stimulus Parameters? |
Determined by modality. SSEP- electrical stimulation. BAER- clicks, tone bursts/pips VEP- reversing check pattern, flashing light or led goggles. |
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SSEP Upper Montage |
Ch 1- Cpc-Cpi Ch 2- Cpi-Ref Ch 3- C5- Ref Ch 4- Epi- Ref
Ref= Epc |
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Specific questions for SSEP |
Symptoms in arms/legs hands/feet. Numbness/tingling. Neck/back pain/injury. Experience lightheadedness, nausea, vomiting, LoC, dizziness. |
