CNIM 1 Test with complete solutions

lower motor neurons primarily exit the spinal cord through the... - Answer- ventral nerve roots excitatory neurotransmittor - Answer- glutamate what separates motor and sensory strips? - Answer- central sulcus the layers of protective tissues that surround the central nervous system are called what? - Answer- meninges inhibitory neurotransmitter - Answer- GABA The interconnecting blood vessels at the base of the brain make up... - Answer- circle of willis The tibial nerve cortical SSEP would be affected by a stroke in which artery? - Answer- the anterior cerebral artery what does the artery of adamkiewicz feed? - Answer- its a major feeder vessel to the spinal cord Upper extremity SSEP's transmit through which spinal cord tract? - Answer- fasciculus cuneatus The C8 nerve root exits the spinal cord - Answer- above the T1 vertebrae The nerve roots that extend below the spinal cord make up the... - Answer- cauda equina The nerve root entry levels for the ulnar nerve are: - Answer- C8-T1 The nerve root entry for posterior tibial nerve are - Answer- L4-S3 The tibial and common peroneal nerves form what nerve? - Answer- sciatic stimulation of the median nerve at the wrist will activate which muscle? - Answer- abductor pollicis brevis stimulation of the peroneal nerve is preformed: - Answer- across the head of the fibula, PER is stimulated at the lateral PF, across the fibular head The typical resting membrane potential of a neuron is - Answer- -70mV inside the cell the resting membrane potential of a neuron is primarily maintained by - Answer- the sodium-potassium pump whats the initial even that occurs when the action potential threshold of a neuron is reached? - Answer- the voltage-gated sodium channels open AN EPSP will cause what to happen? - Answer- Depolarization of the post-synaptic membrane, ESPS_ excitatory post synaptic potential, depolarizes the post synaptic membrane where does K and Na move in the sodium potassium pump? - Answer- K pumps into the cell and Na out of the cell activation of an action potential of a neuron will depend on - Answer- its membrane potential based on the spatiotemporal summation of its excitatory and inhibitory inputs TcMEP transmit primarily through which spinal cord tract? - Answer- the lateral corticospinal tract what is the most common result of anterior spinal artery occlusion? - Answer- motor deficits occlusion = blockage/closing which of the following has the greatest effect on SEP monitoring? - Answer- inhalant (sevoflurane) MAC stands for - Answer- minimum alveolar concentration opiods are used primarily for - Answer- analgesia (lack of pain) midazolam is what type of drug? - Answer- Benzodiazepine which of the following drugs has an appreciable effect on peripheral nerve APs? - Answer- peripheral nerve AP are produced by simulating a peripheral nerve and recording the response form the same nerve a short distance aware. anesthesia does not affect these responses which of the following is a barbiturate? - Answer- Methohexital desflurance has a more rapid onset and recovery than isoflurane becasue - Answer- desflurane has a higher blood solubility than isoflurane high solubility means more gas is dissolved, leaving less gas remaining in the system. This brings the body's partial pressures to equilibrium quicker, allowing for faster induction and emergance from anesthesia which of the following is consistent with increasing depth of anesthesia? - Answer- bilateral reduction of cortical SSEP's only which of the following is most affected by halogenated agents? - Answer- posterior tibial cortical potentials neuromuscular blockers work by - Answer- Competitive inhibition of acetylcholine receptors in the motor end plate. in general, most anesthetic drugs have what effect on cortical responses? - Answer- decrease amplitude and increase latency how could one describe the effect of anesthesia on subcortical responses? - Answer- minimal effect T/F all cortical responses are affected equally - Answer- False, not true all of the time T/F later cortical peaks are affected more than earlier peaks - Answer- true all of the time which of the following peaks will be most affected by desflurane? - Answer- P100???? for spontaneous emg monitoring, what drug is used at induction? - Answer- succinylcholine which of the following are known to increase evoked potential amplitudes? - Answer- ketamine Fentanyl infusion will - Answer- increase latency and decrease amplitude which of the following can increase SSEP amplitude? - Answer- etomidate/ketamine what is the most important step to setting up BAEPs? - Answer- placing the foam inserts if you have a lot of high frequency noise in your BAEPs you can... - Answer- change your filter from 2500Hz to 1500Hz if a sound intensity is increased from 20dB to 40dB then the sound pressure has increased by a factor of? - Answer- 10 a 2 fold inc/dec in dB inc/dec pressure by a factor of ten The left ABR data were taken during a microvascular decompression of trigenminal nerve. There is a decrease in wave V with no change in earlier peaks. What could cause this change in wave V? - Answer- retraction of the cerebellum which of the following is the generator for the peak marked A? (peak for wave 5) - Answer- inferior colliculus loss of BAEP during drilling of the internal auditory canal is most likely due to: - Answer- excessive noise In BAEP stimulation, the stimulus type which causes a negative pressure resulting in a slightly earlier latency is: - Answer- rarefraction BAEP condensation clicks from transducer causes - Answer- movement of the tympanic membrane toward the cochlea when testing BAEP you get a wave 1 on your contralateral ear montage. what do you do? - Answer- check earphones for proper side stimulation or insufficient contralateral masking A BAEP has a normal wave 1 and then delayed wave 1-V on one side. what type of surgery is this most consistent with? - Answer- CPA tumor are commonly acoustic neuromas or lower cranial nerve schwannomas and typically present just lateral to the brainstem. This would affect wave 3-5, but not 1. the entire 1-5 complex would have delayed interpeak latencies when to alarm when monitoring BAEP? - Answer- increased I-V interpeak latency or disappearance of wave V where is BAEP wave V generated? - Answer- midbrain what is the very large amplitude potential following the BAEP waves 1-V approx 15mS? - Answer- postauricular myogenic response BAEP cannot be preformed after resection of the? - Answer- acoustic nerve CNS depressants cause - Answer- minimal effect in BAEP because ABR's are subcoritcally generated This audigram indicated that 2kHz frequency, the pt's right ear threshold was 40dB SPL or HL? - Answer- HL BAEP are appropriate for monitoring? - Answer- brainstem functioning BAEP typically involve what stimulus? - Answer- click sound During a posterior fossa resection of an acoustic neuroma, you observe the loss of wave II only in the BAEP. You should... - Answer- continue to monitor without alarm excessive cerumen may cause - Answer- absence of the BAER cerumen: earwar which of the following is the most consistent with discrete lesion of the medial geniculate body? - Answer- no change in 1-V MGB occurs after wave V is generated so its unlikely that we would pick up a lesion with BAEP response Upon seeing the traces of EEG appear flat on left and present on right collected at 19:54 the first thing you should do is... - Answer- inform the surgeon of an abrupt loss of BAEP. alternating clicks can be used to - Answer- eliminate stimulus artifact What montage will help you discern wave IV and V in BAEP? - Answer- Cz-Contralateral ear Regarding wave 1 of the BAEP, the proposed generator is? - Answer- cranial nerve VIII The prominent wave for monitoring BAEP's is? - Answer- Wave V According to the Guidelines, what are the optimal filter settings for recording BAEP's? - Answer- 10-30Hz to Hz The VIII th nerve were transected lateral to the brainstem you might get - Answer- absence of waves III-V The optimal repetition rate for BAEPs is? - Answer- about 11.4Hz Per guidelines whats the acceptable sweep for BAEP? - Answer- 10-15ms To eliminate crossover, guidelines suggest a masking level of: - Answer- 60dB SPL The most appropriate BAEP interstimulus interval is: - Answer- 10-20ms Whats the most common reason for loss of BAEP during retromastoid microvascular decompression? - Answer- compromise vascular supply You would expect a loss of BAEP in which surgery? - Answer- Pontine glioma (CNVIII is more at risk in pontine glioma reversible loss of BAEP indicates: - Answer- complete neurological recovery What is the most appropriate first step in troubleshooting responses from a cortical grid that shows nothing but artifact in the recording? - Answer- make sure the grid is in good contact with the brain and is correct side down after-discharges occur after what? - Answer- direct cortical stimulation lack of after discharges indicates: - Answer- the stimulus is likely below the threshold of seizure activation When no phase reversal is present in an anterior-posterior cortical grid recording - Answer- the maximum amplitude response is closest to the central sulcus the locacton of the central sulcus is between which electrodes: - Answer- C and D the post central gyrus is most likely located at: - Answer- C the motor strip is most likey located at: - Answer- D what drugs would you use for language mapping? - Answer- Fentanyl during a microvascular decompression of the trigeminal nerve. what other monitoring should be done? - Answer- VIIth cranial nerve EMG what cranial nerve is being activated by orbicularis oculi? - Answer- facial Facial nerve CMAP response has a latency of approximately - Answer- 7ms Trigeminal nerve EMG response has a latency of approximately - Answer- 3-5ms Random spike discharges can be heard from a speaker during facial nerve dissection in all of the following except - Answer- electrocautery cranial nerve XII can be monitored using electrodes inserted into the what? - Answer- tongue Neurotonic discharges of facial nerve indicate: - Answer- Possible compromise of facial nerve what might be monitored for a jugular bulb tumor surgery? - Answer- CN VII-XII cancial nerve X can be monitored using electrodes inserted into the - Answer- vocalis visual observation of the facial muscles during facial nerve electrical stimulation may be misleading because - Answer- movement can be from the trigeminal nerve rather than the facial nerve the facial nerve in what surgeries (3)? - Answer- vestibu