Quiz Questions Flashcards
How are ABR peaks labeled?
-Jewett convention (Roman numerals)
Which auditory evoked potential follows the waveform of the acoustic stimulus?
-Cochlear microphonic
What AEP is typically obtained with a frequent and rare stimulus?
-Mismatch negativity
What are the common clinical uses of the ABR?
- Site of lesion testing
- Hearing threshold measurement
- Intraoperative monitoring
A 10-bit number is equal to how many (base ten) values?
-1024
In theory, if you time-domain signal average an AEP by presenting 400 sweeps, the SNR in the average (compared to a single sweep) will improve by what factor?
-20
What is the slope of the click-evoked ABR latency/intensity function in a normal-hearing human adult?
-Approximately 40 microseconds/dB
Which ABR peak is resistant to amplitude changes across rate?
-Wave V
What masking technique is used by the stacked ABR?
-High-pass subtractive masking
From where does the major contribution to cochlear microphonic (CM) arise?
-Hair cells located in the basal region of the cochlea
What procedure is most used to cancel CM in ECochG recordings?
-Averaging condensation and rarefaction polarities
Describe the compound action potential (CAP) in the click ABR.
-Reflects the activation of the auditory nerve fibers located in the basal region of the cochlea
At what frequencies are the best correlations between the CAP and audiometric thresholds found?
-1, 2, and 4 kHz
What is the sensitivity of the SP/AP ratio in diagnosing Meniere’s disease?
-60%
Compared to the ECochG potentials recorded from normal subjects, responses obtained from ears with endolymphatic hydrops show what?
-Increased duration
What ECochG pattern is most frequently observed in patients with auditory neuropathy?
-Prolonges negative potential with reduced amplitude compared to normal hearing subjects
Where can differences in CAP and ABR thresholds be observed?
-Subjects affected by neurological disorders involving the brainstem
Describe hearing thresholds in children discharged from the NICU who show absent ABRs.
-Hearing thresholds cannot be reliably estimated on the basis of ABR recording
What do ECochG responses recorded from children discharged from the NICU show?
-Prolonged duration in more than half of patients
Who was the author(s) of the most recognized early article on the ABR and the detection of acoustic neuromas?
-Selters & Brackmann
What generated wave III of the ABR waveform?
-Cochlear nucleus
Who was the researcher whose intracranial recordings on humans contributed to our understanding of the ABR generator sites?
-Aage Moller
What is one advantage of the ABR over MRI?
-Physiological index
What is the proper term for an acoustic neuroma?
-Vestibular schwannoma
An acoustic neuroma will commonly reveal what ABR finding?
-Extended I-III interval
An absent wave V with a present and normal waves I and III is usually indicative of what?
-Brainstem involvement
Why was the stacked ABR developed?
-Better detect small acoustic neuromas
Vascular loop syndrome may likely manifest in what kind of ABR abnormality?
-An I-III extension
What ABR measures are affected by cochlear hearing loss?
- Increase in absolute latency of wave V
- Decrease in wave I amplitude
- Decrease in wave V amplitude
Among the various stimuli recommended for threshold prediction using ABR, which is most widely recommended and used in clinical evaluation?
-Tone bursts or tone pips
Describe the relationship between ABR thresholds and behavioral thresholds.
- ABR thresholds are at a higher stimulus intensity level than behavioral thresholds
- ABR thresholds are more similar in the high frequencies than the low frequencies
In an individual with normal hearing, how does the wave V latency of a 500 Hz tone burst compare to that of a 2000 Hz tone burst?
-Shorter
In an individual with normal hearing, how does the wave V amplitude for 2 kHz tone burst at 60 dB HL compare to that of a 2 kHz tone burst at 20 dB HL?
-Higher
At what age does wave V latency typically reach adult values?
-12-18 months
Using a 2-0-2 cycle test paradigm, what will the rise and fall times each be for a 500 Hz tone burst with a 0 ms plateau?
-4.0 ms
What region of the cochlear is primarily activated by 100-microsecond click stimuli in an individual with normal hearing?
-2,000-4,000 Hz
A chirp stimulus is designed to deliver frequencies to the ear in what order?
-Low frequencies before high frequencies
In auditory neuropathy, ABRs are expected to be completely absent what percent of the time?
-75%
A protocol for frequency-specific threshold estimation in infants and younger children should include what?
-Air-conduction and bone-conduction stimuli
Are bone-conduction ASSRs the same as air-conduction?
- Yes
- No special concerns are warranted
To avoid interactions, when presenting ASSR frequencies simultaneously, modulation frequencies should be separated by how much?
-3 Hz
What is the consequence of using of modulation stimuli in ASSR?
-Broader stimulus spectrum
Sleep has what effect on the ASSR?
-Amplitudes of low modulation frequency response components decrease with sleep stage
What unit of stimulus level is used more in ASSR testing?
-dB HL
What is employed by detection algorithms for ASSR?
- Phase coherence squared
- Hotlling’s t statistic
- F tests
What is the general relationship between ASSR carrier frequency and behavioral threshold?
-ASSR thresholds are lowest or closest to behavioral thresholds in the mid-frequency range
Why are ASSR for independently amplitude and frequency modulated (IAFM) complex stimuli and word recognition scores correlated?
-Both are dependent on audibility of individual components of a rapidly changing complex stimulus
What component of the stimulus evoked the ASSR?
-Energy at the modulation frequency
What modulation rate will evoke a response dominated by generators in the primary auditory cortex and auditory association areas?
-20 Hz
What practitioner(s) can independently interpret intraoperative neurophysiological monitoring activity?
-Audiologists
In the 70s and 80s, what historically important development that supported the development of intraoperative neurophysiological monitoring?
- Convergence of interest in intraoperative monitoring that followed the use of increasingly sophisticated clinical test measures, AND
- Developments in microsurgical techniques that made neural tissue preservation possible
What factors may affect one’s ability to provide intraoperative neurophysiological monitoring for a patient?
- The patient’s specific diagnosis made in the outpatient clinic
- The preoperative status of the specific function to be monitored
- Whether the audiologist is appropriately trained and skilled in the specific type of monitoring that will be required for the case
What kind of anesthesia effects are typically encountered by audiologists who perform intraoperative neurophysiological monitoring?
-Certain anesthetics may prolong auditory brainstem response latencies and reduce amplitudes
What are some important parts of the motor unit?
- Cell body
- Axon
- Schwann cell
Describe a healthy, unparalyzed motor cranial nerve when not active.
-Ready to response to electrical stimulation
Fill in the blanks: The auditory-evoked measure _________ enables the monitoring audioogist to best observe the response generated by the ____ portion of the auditory nerve.
- Direct either nerve recording
- Proximal
What are some devices used by the monitoring and surgical team?
- Needle electrodes
- Foam inserts for delivery of acoustic stimuli
- Plastic adhesive tape to hold electrodes and leads in place
What is a significant hindrance to effective recording of suprathreshold ABRs in the operating room?
-Masking of stimuli used to elicit the desired auditory-evoked responses caused by prolonged drilling of the temporal bone
What is an example of an exogenous variable that can affect the recording of an MMN?
-Too many deviant stimuli
Which CAEP can be used to estimate hearing thresholds in a way that is clinically relevant to audiologists?
-P1-N1-P2
Which CAEP can be used as a physiological correlate of auditory discrimination?
- MMN
- P300
- P1-N1-P2 change response
True or False: The MMN requires the individual to attend to the oddball stimuli.
-False
Which CAEP best approaches behavioral discrimination thresholds?
-P1-N1-P2 change responses (ACC)
Where can electrode C3 be found?
-Left side of the head
Do CAEPs have endogenous, exogenous, or both kinds of properties?
-Both
The sentence “The box is walking” can be used to elicit what kind of CAEP?
-N400
What CAEPs can be evoked using visual stimuli?
- MMN
- N400
- P1-N1-P2
The oddball paradigm is used to evoke what CAEP?
-P300
True or False: Subtle differences in stimuli can evoked an MMN.
-True
