CNIM apparently on the actual test
An increase in stimulation intensity causes a linear increase of which of the
following SSEP components?
1. N20
2. N45
3. P31
4. P37 - ✔✔ ACTUAL ANSWER- ✔✔ - 3. P31
Epidural electrodes are made of platinum because
1. It is the most durable metal
2. It is the lowest impedance metal
3. The chance of allergic reaction is eliminated
4. Other metals may become toxic when currents are applied - ✔✔ ACTUAL
ANSWER- ✔✔ - 4. Other metals may become toxic when currents are applied
During a median nerve preoperative study, a patient has discomfort at the wrist.
Stimulation electrodes are 10 mm gold disk, stimulus intensity is 20 mA, and
stimulus duration is 100 usec. Which of the following would most likely reduce
the patients discomfort while maintaining adequate stimulation?
1. Increase stimulus duration
2. Use larger stimulating electrode
3. Use smaller stimulating electrode
4. Decrease stimulus intensity below motor threshold - ✔✔ ACTUAL ANSWER-
✔✔ - 2. Use larger stimulating electrode
Which of the following would enhance wave I of the BAEP?
1. Increase the rate
2. Increase the intensity
3. Decrease the analysis time
4. Decrease the number of repetitions - ✔✔ ACTUAL ANSWER- ✔✔ - 2.
Increase the intensity
In BAEPs, wave I can most easily be differentiated from cochlear microphonics
based upon
1. Amplitude
,2. Morphology
3. Click polarity
4. Absence in contralateral recording - ✔✔ ACTUAL ANSWER- ✔✔ - 3. Click
polarity
What is the interstimulus interval of a 50 Hz click stimulus?
1. 0.02 msec
2. 0.20 msec
3. 0.50 msec
4. 20.00 msec - ✔✔ ACTUAL ANSWER- ✔✔ - 4. 20.00 msec
Contralateral masking should be used during BAEPs to
1. Help the patient relax
2. Enhance wave I amplitude
3. Separate the IV/V complex
4. Prevent crossover responses - ✔✔ ACTUAL ANSWER- ✔✔ - 4. Prevent
crossover responses
The complete absence of a BAEP is most likely the result of
1. Sedation
2. Multiple sclerosis
3. Severe hearing loss
4. A normal age variant - ✔✔ ACTUAL ANSWER- ✔✔ - 3. Severe hearing loss
Identification of wave V of the BAEP may require
1. Tympanic electrodes
2. Bilateral stimulation
3. Decreasing stimulus intensity
4. Use of a noncephalic reference - ✔✔ ACTUAL ANSWER- ✔✔ - 3.
Decreasing stimulus intensity
In spinal surgery, the primary purpose of the popliteal fossa recording electrode is
to
1. Verify adequacy of stimulus
2. Limit current spread
3. Confirm amplifier integrity
,4. Provide evidence of a muscle twitch - ✔✔ ACTUAL ANSWER- ✔✔ - 1.
Verify adequacy of stimulus
while performing a posterior tibial SSEP, hypothermia of the lower extremities is
most likely to cause
1. Increased L3-P37 latency
2. Increased T12-P37 latency
3. Slowed peripheral conduction velocity
4. Abnormal prolongation of the P37-N45 complex - ✔✔ ACTUAL ANSWER-
✔✔ - 3. Slowed peripheral conduction velocity
Which of the following peaks in tibial nerve SSEPs is most analogous to P14 of
median nerve SSEP?
1. N20
2. N34
3. P31
4. P37 - ✔✔ ACTUAL ANSWER- ✔✔ - 3. P31
Which of the following devices measures electrode resistance?
1. Ammeter
2. Ohmmeter
3. Voltmeter
4. Photometer - ✔✔ ACTUAL ANSWER- ✔✔ - 2. Ohmmeter
If an evoked potential has a voltage of 10 uV and the associated noise has a
voltage of 50 uV, what is the signal-to-noise ratio after 100 averaged responses?
1. 1:1
2. 1:2
3. 2:1
4. 5:1 - ✔✔ ACTUAL ANSWER- ✔✔ - 3. 2:1
To display median nerve SSEP response as an upward deflection, which of the
following must be known?
1. Waveform polarity and latency of the response
2. Waveform polarity and polarity convention of the amplifier inputs
3. Polarity convention of amplifier inputs and amplitude of the response
, 4. Latency of the response and polarity convention of the amplifier inputs - ✔✔
ACTUAL ANSWER- ✔✔ - 2. Waveform polarity and polarity convention of the
amplifier inputs
If an amplifier is rated as having 120 dB common mode rejection ratio, which of
the following ratios of in-phase to out-of-phase signals would be expected?
1. 10,000:1
2. 100,000:1
3. 500,000:1
4. 1,000,000:1 - ✔✔ ACTUAL ANSWER- ✔✔ - 4. 1,000,000:1
Which of the following cranial nerves innervated the extraocular muscles?
1. Optic
2. Facial
3. Abducens
4. Trigeminal - ✔✔ ACTUAL ANSWER- ✔✔ - 3. Abducens
Which of the following is an example of an SSEP far-field subcortical potential?
1. N20
2. N34
3. Erbs point
4. Popliteal fossa - ✔✔ ACTUAL ANSWER- ✔✔ - 2. N34
Which of the following opposes any change in current?
1. Capacitance
2. Impedance
3. Inductance
4. Resistance - ✔✔ ACTUAL ANSWER- ✔✔ - 3. Inductance
Which of the following electrode materials has little electrode potential drift and a
long time constant?
1. Tin
2. Gold
3. Silver
4. Stainless steel - ✔✔ ACTUAL ANSWER- ✔✔ - 2. Gold
Where should epidural electrodes be placed?
An increase in stimulation intensity causes a linear increase of which of the
following SSEP components?
1. N20
2. N45
3. P31
4. P37 - ✔✔ ACTUAL ANSWER- ✔✔ - 3. P31
Epidural electrodes are made of platinum because
1. It is the most durable metal
2. It is the lowest impedance metal
3. The chance of allergic reaction is eliminated
4. Other metals may become toxic when currents are applied - ✔✔ ACTUAL
ANSWER- ✔✔ - 4. Other metals may become toxic when currents are applied
During a median nerve preoperative study, a patient has discomfort at the wrist.
Stimulation electrodes are 10 mm gold disk, stimulus intensity is 20 mA, and
stimulus duration is 100 usec. Which of the following would most likely reduce
the patients discomfort while maintaining adequate stimulation?
1. Increase stimulus duration
2. Use larger stimulating electrode
3. Use smaller stimulating electrode
4. Decrease stimulus intensity below motor threshold - ✔✔ ACTUAL ANSWER-
✔✔ - 2. Use larger stimulating electrode
Which of the following would enhance wave I of the BAEP?
1. Increase the rate
2. Increase the intensity
3. Decrease the analysis time
4. Decrease the number of repetitions - ✔✔ ACTUAL ANSWER- ✔✔ - 2.
Increase the intensity
In BAEPs, wave I can most easily be differentiated from cochlear microphonics
based upon
1. Amplitude
,2. Morphology
3. Click polarity
4. Absence in contralateral recording - ✔✔ ACTUAL ANSWER- ✔✔ - 3. Click
polarity
What is the interstimulus interval of a 50 Hz click stimulus?
1. 0.02 msec
2. 0.20 msec
3. 0.50 msec
4. 20.00 msec - ✔✔ ACTUAL ANSWER- ✔✔ - 4. 20.00 msec
Contralateral masking should be used during BAEPs to
1. Help the patient relax
2. Enhance wave I amplitude
3. Separate the IV/V complex
4. Prevent crossover responses - ✔✔ ACTUAL ANSWER- ✔✔ - 4. Prevent
crossover responses
The complete absence of a BAEP is most likely the result of
1. Sedation
2. Multiple sclerosis
3. Severe hearing loss
4. A normal age variant - ✔✔ ACTUAL ANSWER- ✔✔ - 3. Severe hearing loss
Identification of wave V of the BAEP may require
1. Tympanic electrodes
2. Bilateral stimulation
3. Decreasing stimulus intensity
4. Use of a noncephalic reference - ✔✔ ACTUAL ANSWER- ✔✔ - 3.
Decreasing stimulus intensity
In spinal surgery, the primary purpose of the popliteal fossa recording electrode is
to
1. Verify adequacy of stimulus
2. Limit current spread
3. Confirm amplifier integrity
,4. Provide evidence of a muscle twitch - ✔✔ ACTUAL ANSWER- ✔✔ - 1.
Verify adequacy of stimulus
while performing a posterior tibial SSEP, hypothermia of the lower extremities is
most likely to cause
1. Increased L3-P37 latency
2. Increased T12-P37 latency
3. Slowed peripheral conduction velocity
4. Abnormal prolongation of the P37-N45 complex - ✔✔ ACTUAL ANSWER-
✔✔ - 3. Slowed peripheral conduction velocity
Which of the following peaks in tibial nerve SSEPs is most analogous to P14 of
median nerve SSEP?
1. N20
2. N34
3. P31
4. P37 - ✔✔ ACTUAL ANSWER- ✔✔ - 3. P31
Which of the following devices measures electrode resistance?
1. Ammeter
2. Ohmmeter
3. Voltmeter
4. Photometer - ✔✔ ACTUAL ANSWER- ✔✔ - 2. Ohmmeter
If an evoked potential has a voltage of 10 uV and the associated noise has a
voltage of 50 uV, what is the signal-to-noise ratio after 100 averaged responses?
1. 1:1
2. 1:2
3. 2:1
4. 5:1 - ✔✔ ACTUAL ANSWER- ✔✔ - 3. 2:1
To display median nerve SSEP response as an upward deflection, which of the
following must be known?
1. Waveform polarity and latency of the response
2. Waveform polarity and polarity convention of the amplifier inputs
3. Polarity convention of amplifier inputs and amplitude of the response
, 4. Latency of the response and polarity convention of the amplifier inputs - ✔✔
ACTUAL ANSWER- ✔✔ - 2. Waveform polarity and polarity convention of the
amplifier inputs
If an amplifier is rated as having 120 dB common mode rejection ratio, which of
the following ratios of in-phase to out-of-phase signals would be expected?
1. 10,000:1
2. 100,000:1
3. 500,000:1
4. 1,000,000:1 - ✔✔ ACTUAL ANSWER- ✔✔ - 4. 1,000,000:1
Which of the following cranial nerves innervated the extraocular muscles?
1. Optic
2. Facial
3. Abducens
4. Trigeminal - ✔✔ ACTUAL ANSWER- ✔✔ - 3. Abducens
Which of the following is an example of an SSEP far-field subcortical potential?
1. N20
2. N34
3. Erbs point
4. Popliteal fossa - ✔✔ ACTUAL ANSWER- ✔✔ - 2. N34
Which of the following opposes any change in current?
1. Capacitance
2. Impedance
3. Inductance
4. Resistance - ✔✔ ACTUAL ANSWER- ✔✔ - 3. Inductance
Which of the following electrode materials has little electrode potential drift and a
long time constant?
1. Tin
2. Gold
3. Silver
4. Stainless steel - ✔✔ ACTUAL ANSWER- ✔✔ - 2. Gold
Where should epidural electrodes be placed?
