CNIM practice exam 3 with complete solutions

If you have high frequency noise in a BAEP: A100/100 pts Change HFF from 3000 to 1500 Hz Change HFF to 200 Hz Change LFF to 150 Hz Change LFF to 30 Hz - Answer- Change HFF from 3000 to 1500 Hz To dissect a vestibular schwannoma, which surgical approach usually sacrifices hearing? suboccipital retrosigmoid middle cranial fossa translabyrinthine - Answer- translabyrinthine According to current OSHA standards, needle electrodes should be reused whenever possible not be soaked in a sodium hypochlorite solution be recapped before discarding not be handled with tongs or forceps while cleaning - Answer- not be soaked in a sodium hypochlorite solution PTN (above) and MN SSEPs (below) are shown. Which of the following is the most likely cause of the changes relative to baseline (blue traces)? Anesthesia is too deep Insufficient blood flow to the left leg Left spinal cord injury Brachial plexus compression - Answer- Left spinal cord injury Movement artifact on the EEG is most likely to produce slow EEG wave activity fast EEG wave activity asymmetrical activity at 60 Hz burst-suppression - Answer- slow EEG wave activity The main advantage of asynchronous bilateral stimulation is? Faster data acquisition Differentiation of local vs. systemic effects Reduction of stimulus artifact Less patient movement - Answer- Differentiation of local vs. systemic effects Increases in latency of both right and left ABR wave V of 0.9 msec. in a 10 minute period would most likely indicate auditory nerve damage ambient noise temperature effects a kink in the sound delivery tubing - Answer- temperature effects Which of the following can increase SEP amplitudes? etomidate fentanyl isoflurane 1/2 MAC of halothane - Answer- etomidate Which of the following neurotransmitters always causes excitation of postsynaptic neurons? gamma amino butyric acid glycine dopamine glutamate - Answer- glutamate The motor cervical spine C5 nerve root produces: Arm abduction Elbow extension wrist extension wrist flexion - Answer- Arm abduction During a spinal instrumentation for scoliosis the surgeon reports that derotation is now being performed. Which of the following is the most appropriate statement? The event should be documented immediately Documentation of this event is not important Documentation of the event should be performed at the end of the surgery after monitoring has been completed This is a good time to take a break from monitoring since there is very little risk to the spinal cord at this time - Answer- The event should be documented immediately During BAEP for posterior fossa craniotomy, if reversible loss of all ipsi BAEP responses occurs: probable neuronal deficit postop complete recovery of neuronal function hypothermia drug effect - Answer- complete recovery of neuronal function For patients showing clamp-related EEG changes during carotid endarterectomy, 80% of the changes appear within the first 10 seconds first 60 seconds frontal leads only alpha frequency range - Answer- first 60 seconds An advantage of referential, as opposed to bipolar recording of spinal cord somatosensory evoked potentials, is the ease of electrode placement less invasion of the surgical field the elimination of electromyographic artifact from the paraspinous muscles avoiding cancellation of the potentials as a result of recording from adjacent levels - Answer- avoiding cancellation of the potentials as a result of recording from adjacent levels An electrode measured 20% lateral to Cz on the right using 10-20 system is C4 A2 T3 C3 - Answer- C4 Waves III to V on the ABR are probably generated at the cortex at the cerebellum at the medulla at the pons-midbrain area - Answer- at the pons-midbrain area An agent that should be avoided immediately before EMG for facial nerve monitoring is N20 vecuronium phenytoin isoflurane - Answer- vecuronium A unit of resistance is symbolized by A μ Ω E - Answer- Ω The effects of halogenated agents on the cortical somatosensory evoked potential are an increase in latencies and an increase in amplitudes minimal compared with the effects on BAEPs negligible an increase in latencies and a decrease in amplitudes - Answer- an increase in latencies and a decrease in amplitudes When recording BAEPs in the OR, some auditory stimulators utilize several inches of tubing to connect the transducer and ear inserts which do not affect the latencies of the waveforms are comparable to acoustically shielded headphones delay the signal to the transducer and can cause 60 Hz artifact delays the arrival of the sound to the ear and separates stimulus artifact - Answer- delays the arrival of the sound to the ear and separates stimulus artifact The biomed safety analyzer is used to: Measure the oxygen content of the patient's blood Calibrate the stimulus output of the evoked potential equipment Test the equipment for signs of biological contamination Measure chassis leakage of equipment - Answer- Measure chassis leakage of equipment All of the following are benefits of EEG monitoring during carotid endarterectomy except detection of occlusion-associated ischemia detection of hypotension detection of heparin dosage detection of hypoxia - Answer- detection of heparin dosage When using monopolar stimulation for direct nerve stimulation the cathode electrode is connected to the negative terminal of the stimulator output the cathode electrode is connected to the positive terminal of the stimulator output the anode electrode is connected to the negative terminal of the stimulator output the cathode electrode is connected to the groun - Answer- the cathode electrode is connected to the negative terminal of the stimulator output The initial waveform recorded of a near-field PTN cortical potential is always obscured by stimulus artifact negative due to depolarization of membrane potentials positive due to electrotonic depolarization of the membrane under the recording electrode of very low amplitude due to the significant distance between the generator and recording electrode - Answer- positive due to electrotonic depolarization of the membrane under the recording electrode When recording a posterior tibial nerve SSEP, the Fpz-C5s channel records subcortical far-field potentials subcortical near-field potentials stationary lumbar potentials the Erb's point potential - Answer- subcortical far-field potentials Stimulation of the motor pathway at the spinal cord can be achieved with little movement in the surgical field by decreasing muscle relaxants slowing the stimulation rate increasing the stimulation rate enough to produce muscle tetany increasing the stimulation duration - Answer- increasing the stimulation rate enough to produce muscle tetany Hearing level (HL) is defined as the average threshold intensity of normally hearing young adults intensity of a long duration sound that has the same amplitude as the peak SPL of a short duration sound lowest intensity that an average ear drum can hear inverse of the sound pressure level - Answer- average threshold intensity of normally hearing young adults A patient is admitted to the operating room diagnosed with a herniated cervical disc at C5-6. The most appropriate nerve(s) to monitor during the resulting surgical procedure would be the peroneal and ulnar nerves median and posterior tibial nerves median and auditory nerves ulnar nerve - Answer- median and posterior tibial nerves Examples of "surgical manipulation" would include blood pressure and heart rate fluctuations core temperature changes oxygenation and ventilation alterations drilling and irrigation - Answer- drilling and irrigation Isola rod system Vascular Neurosurgical Orthopedic Psychiatric - Answer- Orthopedic If not specified, most reports on ABR are displayed vertex positive up vertex positive down negativity up using "N" plus a number to designate a wave - Answer- vertex positive up In monopolar facial nerve stimulation, positive charge flows from cathode to ground from cathode to anode from anode to cathode muscle to ground - Answer- from anode to cathode If over three hours the PTN cortical response attenuates while subcortical is stable: Do a wake-up test Stimulate peroneal nerve Inform the surgeon monitoring is no longer reliable Keep monitoring subcorticals - Answer- Keep monitoring subcorticals Transcranial Magnetic Evoked Potentials are preferred over Transcranial Electric motor evoked potentials for intraoperative monitoring because: They are painless They require less rigorous anesthetic management There is no risk of seizures They are not preferred for intraoperative monitoring - Answer- They are not preferred for intraoperative monitoring General anesthesia during carotid endarterectomy includes all of the following advantages except provides brain protection prevents patient movement provides rapid control of blood pressure provides a measurement of brain activity - Answer- provides a measurement of brain activity Which type of instrumentation is most likely to cause trauma to the spinal cord? Rod cutter sublaminar wires crosslinks subdermal needles - Answer- sublaminar wires Spondylosis is Forward movement of the body of one of the lower lumbar vertebrae on the vertebra below it, or upon the sacrum degeneration of the spine neurofibromatosis deterioration of the spinal cord gray matter which is replaced by a large cyst - Answer- degeneration of the spine EEG burst suppression may result from which of the following N20 50% MAP 70 Isoflurane 1.7% Temperature 35.3 deg. Celsius - Answer- Isoflurane 1.7% Epileptiform discharges in a bipolar linked chain are localized by a phase reversal between two channels a Mu rhythm patient movement a referential montage - Answer- a phase reversal between two channels An electrode suggested as a sensitive stimulator during facial nerve recordings is the single fiber needle bipolar concentric EMG needle gelled surface electrode digital ring electrode - Answer- bipolar concentric EMG needle P14 is a far-field, subcortically generated response which probably reflects activity from the precentral gyrus caudal medial lemniscal activity passage of the afferent volley a stationary cervical potential - Answer- caudal medial lemniscal activity If the surgeon's arm unknowingly brushes an undraped microscope Inform the surgeon Ask the circulating nurse to clean and drape the microscope Place a sticker marked (contaminated) on the microscope There is no need for any action - Answer- Inform the surgeon Which of the following upper extremity somatosensory responses is considered a stationary potential? N20 N13 P14 N18 - Answer- N13 In the 10-20 system of electrode placement, the point 20% (of the nasion-inion distance) anterior to Cz is called Pz Fz Fpz C1 - Answer- Fz When placing stimulating electrodes over a peripheral nerve to elicit a muscle response: the positive electrode should be toward the peripheral portion of the nerve to be stimulated the negative electrode should be toward the peripheral portion of the nerve to be stimulated neuromuscular blockade must be in effect during stimulation The positive electrode must be directly over the nerve whereas the negative electrode needn't be - Answer- the negative electrode should be toward the peripheral portion of the nerve to be stimulated Which of the following should be monitored for an L4-S1 decompression and fusion with pedicle screws Posterior Tibial nerve SSEP and lower extremity EMG Posterior Tibial nerve and Peroneal nerve SSEP Posterior Tibial nerve and Median nerve SSEP Median nerve SSEP and lower extremity EMG - Answer- Posterior Tibial nerve SSEP and lower extremity EMG Blood supply to the spinal cord is by two anterior spinal arteries and a posterior spinal artery is by an anterior spinal artery and two posterior spinal arteries is through a superior spinal artery is through an inferior spinal artery - Answer- is by an anterior spinal artery and two posterior spinal arteries The capacity to resolve amplitudes of 256 discrete steps would require an 8 bit A to D converter. This can be represented by 8/256 28 8 256 - Answer- 28 Normal EEG activity in the wakeful adult Primarily alpha and beta activity Primarily delta and theta activity Beta and delta with spindle formations Burst suppression - Answer- Primarily alpha and beta activity Both SSEP and BAEP waveforms can be affected by structural manipulation using retractors grounding pads suction blood pressure transducers - Answer- retractors SEP stimulating electrodes should be placed about 10 cm apart to prevent a salt bridge have an impedance of 5 K ohms or more placed with the positive electrode proximal placed with the negative electrode proximal - Answer- placed with the negative electrode proximal Monitoring procedures during carotid endarterectomy include monitoring both hemispheres cessation of monitoring following clamp removal monitoring from the compromised hemisphere only recording a full minute of EEG baseline - Answer- monitoring both hemispheres SSEP recordings typically require a bandpass of 5 Hz to 200 Hz 100 Hz to 1,000 Hz 30 Hz to 3,000 Hz 1000 Hz to 5,000 Hz - Answer- 30 Hz to 3,000 Hz Universal Precautions The assumption that every patient has AIDS Use of PPDs with every patient Handwashing after every meal Strategy for preventing disease protection - Answer- Use of PPDs with every patient When the number of trial rejections increases during electrocautery, the best action is: Inform surgeon Increase number of sweeps Pause data collection Increase stimulus intensity - Answer- Pause data collection A stimulus rate that is suitable for ABR monitoring is 4.1 31.1 20 81.1 - Answer- 31.1 Vasospasm of AICA will result in Complete loss of all ABR waves with exception of cochlear microphonic Increased interpeak waves III-V ABR latencies Increased interpeak waves III-V ABR latencies Loss of waves III - V - Answer- Complete loss of all ABR waves with exception of cochlear microphonic What problem may occur when performing intraoperative BAEPs using compressible tubing? The patient's postoperative hearing can become impaired A contamination of the sterile field can occur The compressible tubing can become obstructed and obscure the sound to the ear Their use may cause trauma to the ear canal and should be avoided - Answer- The compressible tubing can become obstructed and obscure the sound to the ear Which describes a semi-critical infectious device? Requires no disinfection after each use use Requires low level disinfection after each Requires high to intermediate disinfection after each use Requires sterilization after each use - Answer- Requires high to intermediate disinfection after each use A train of four following PTN stimulation can be recorded from: Gastrocnemius Tibialis anterior Extensor hallucis brevis Abductor digiti quinti pedi - Answer- Abductor digiti quinti pedi Electromagnetic inductance should never occur in the operating room is produced when a wire carrying current induces a magnetic field that in turn creates current in other wires results only from wires that are not insulated results only from poor ground wires - Answer- is produced when a wire carrying current induces a magnetic field that in turn creates current in other wires Which of the following is associated with loss of proprioception? Romberg's sign Tourette's syndrome Tinel's sign Anterior cord syndrome - Answer- Romberg's sign Transcranial magnetic and electrical motor evoked potentials