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Somatosensory EPs 1
Somatosensory Evoked Potentials Part I
Question | Answer |
---|---|
For mixed nerves, SEP stimulus intensity is set to generate a) 2 mAmps below a twitch, b) no twitch, c) slight twitch, d) 25 mAmps | slight twitch |
For patients with aneuropathy (who may not twitch), intensity of SEP stimulation for a mixed nerve is usually set between __ and __ mA | 5, 15 |
For purely sensory nerves, stimulus intensity is usually __ - __ times the sensory threshold | 2.5, 3 |
Which of the following is the best wat to set stimulus intensity: (a) current, (b) voltage, (c) threshold, (d) impedence | threshold |
The typical duration of electrical pulses for SEPs in milliseconds | 0.2 |
The typical stimulus rate for SEPs is frm __ - __ per second (higher rates are more painful) | 4, 7 |
Steady state SEPs can be obtained at stimulation rates of __ - __ Hz, but these are painful so they are not used | 12, 200 |
SEP stimulation rates should never be multiples of __ | 60 |
Most SEPs are __ (unilateral / bilateral ) | unilateral |
Impedence of ground electrodes should be less than ___ kiloOhms | 10 |
Impedence of ground electrodes should be less than __ Ohms | 10000 |
The ground electrode is electrically connected to the __ and __ __ to elminated the potential of a voltage gradient between these pieces if equipment | stimulator, recording amplifier |
The low frequency filter for SEPs is usually set from __ - __ Hz | 5, 30 |
The high frequency filter for SEPs is usually set from __ - __ Hz | 2500, 4000 |
Reduction of the HFF leads to a __ (increase / decrease) in the latency of the response | increase |
Surface stimulation of the peripheral nerves in the upper extremities is provided by discs over the __ or __nerves | median, ulnar |
The peripheral electrodes in UE are separated by __ - __ cm for SEPs for disc electrodes | 2, 3 |
When needle electrodes are used for SEPs, the two electrodes are separated by __ cm in the middle of a dermatome | 1 |
For SEPs, the proximal electrode is connected to the __ (positive / negative) pole of the stimulator output and becomes the cathode | negative |
For SEPs, the distal electrode is connected to the __ (positive / negative) pole of the stimulator output and becomes the anode | positive |
Number of trials for median nerve SEPs is between __ and __ | 500, 2000 |
The analysis time for SEPs of the median nerve is __ msec | 40 |
The bandpass for median nerve SEPs is __ - __ Hz | 30, 3000 |
For median nerve SEPs, the __ (cathode / anode) is placed 2 cm proximal to the wrist crease) | cathode |
For median nerve SSEPs, the __ (cathode / anode) is placed 2 cm distal to the wrist crease electrode | anode |
For median nerve SEPs, the stimulus rate is __ - __ Hz | 4, 7 |
For median nerve SEPs, the stimulus duration is __ - ___ microseconds | 200, 300 |
For median nerve SEPs, the stimulus intensity should be set above the level at which __ __ twitch is seen | thumb abduction |
The nomenclature for Erb's point ipsilateral to a stimulus | Epi |
The nomenclature for C5 over the spinous process | C5S |
The nomenclature for contralateral scalp between C3/4 and P3/4 | CPc |
The nomenclature for ipsilateral scalp between C3/4 and P3/4 | CPi |
Channel 1 in an upper extremity SEP | CPc-CPi |
Channel 2 in an upper extremity SEP | CPi-Ref |
Channel 3 in an upper extremity SEP | C5s-Ref |
Channel 4 in an upper extremity SEP | Epi-Ref |
The total number of channels used in an SEP montage | 4 |
The most common site of the cervical recorded in an UE SEP is at the level of __; lesss frequently, recordings are made at __ or __ | C5, C2, C7 |
THe waves seen at C5 are generated by the ____ neurons | dorsal horn |
The peak latency of the __ (negative / positive) peak is measured for Erb's point potential | negative |
Erb's point is __ - __ cm above the clavicle, lateral to the attachment of ___ | 2, 3, sternocleidomastoid |
The Erb's point potential is made of axon potentials conducted __ (orthodromically / antidromically / both / neither) | both |
The 5 major potentials in arm SEPs | EP, N13, P14, N18, N20 |
On other derivations, Erb's point potential is identified as __ | N9 |
EP (aka N9) is best seen in channels including the __ electrode | Epi |
The N13 peak is best seen in channels including the __ electrode | CS5 |
The channel that compares ___ and reference best shows P14 and N18 | CPi |
The channel comparing __ and __ best shows N20 | CPi, CPc |