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244 Cards in this Set
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ECochG
waves and generators |
Cochlear Microphonic
Summating Potential Action Potential 2-3 ms |
CM: outer hair cells
SP: inner hair cells/OHC/organ of corti AP: afferent fibers in distal 8th nerve/spiral ganglion |
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ECochG
Stimulus and acquisition factors |
Stimulus
transducer: ER-3A type: click duration: 1ms polarity: alternating for SP single plolarity (rare or cond) for CM rate: 7.1 intensity: 70-90 dBnHL masking: none presentation: monaural |
Acquisition
Electrodes: TT-Ac, TM-Ai, IEAC-AC, Fpz ground (near field) Filter: 10-15000 Hz amplification: x75,000 analysis time 5 or 15 ms sweeps: <50 (promontory) to > 1500 (EAC electrode) |
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ECochG clinical application
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-enhancement of ABR wave I
-documentation of cochlear status in auditory neuropathy -diagnosis of Meniere's disease: SP/AP <30% (TT) normal; >30% MD |
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ABR
waves and generators |
Wave I: distal 8th nerve
wave III cochlear nucleaus, trapezoid body, superior olivary complex wave V: lateral lemniscus termination in inferior colliculus (contra to stim ear) |
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ABR - click
stimulus and acquisition |
Stimulus
transducer: insert type: click duration: 0.1 ms polarity: rarefaction rate: >20/sec (27.3) intensity: variable masking: rarely needed presenation: monaural |
Acquisition
electrodes: non-inv-Fz High forehead, invert Ai ipsi ear, ground Fpz low forehead filter: 30-3000 Hz, no notch amplification: 100,000 analysis time: 15 ms sweeps: variable prestim baseline: -1 ms |
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ABR click clinical application
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newborn auditory screeing
-estimate auditory sensitivity in newborns and children -neurodiagnosis of 8th n and auditory brainstem dysfunction -monitor 8th n and auditory brainstem during surgery -dx auditory neuropathy -estimate hearing in the 1000-4000 Hz range |
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ABR tone burst
stimulus and acquistion |
stimulus
transducer: insert type: tone burst duration: variable, rise/fall and plateau vary depending on freq polarity: alternating rate:eg 27.1-39.1/sec intensity: variable masking: only if ABR is abnormal and no wave I detected presentation: monaural |
Acquisition:
electrode: non-inv-Fz High forehead, invert Ai ipsi ear, ground Fpz low forehead filter: 30-3000 Hz analysis time: 15-20 ms (20 for 500 Hz) sweeps: variable |
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ABR - tone burst
clinical applications |
frequency specific
information on auditory sensitivity across 500-4000 Hz |
Ramping: Blackman windowing: reduce spectral splatter and increase frequency specificity of tone burst stimulation
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ABR bone conduction
stimulus and acquisition |
Stimulus
tranducer: B-70/71 bone vibrator type: alternating click and tone burst (min stim art) polarity:alternating rate: slower rates to enhance wave 1 (11.1/sec) intensity: 50 dB nHL (55 is limit) masking: rarely needed, solves masking dilemma |
acquisition: same as other ABR
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ASSR generators
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brainstem: fast modulation >60 Hz
cortex: slow modulation <60 Hz |
modulation depth
-amplitude 100% -frequency 20% -modulation rate -82 to 106 hz |
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ASSR
stimulus and acquistion |
Stimulus
transducer: insert type: sinusoid duration: variable polarity: alternating intensity: 0-100 dB SPL masking: available as needed presentation: monaural or binaural |
Acquistion
electrodes: non-inv Cz or Fz inverting nape, inion or ipsi mastoid groudn shoulder, contra mastoid or low forehead filter: HP 1 or 10 Hz, LP 300 or 500 Hz slope 6 dB/octave, no notch amplification: x10,000 analysis time: 1 sec sweeps: variable |
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ASSR
clinical application |
auditory threshold estimation
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capable of estimating electrophysicaolical auditory threshold of up to 120 dB HL
automated response detection |
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AMLR
waves and generators |
Na
Pa (25-35 ms) Nb Pb(P50) 40-60 ms |
Na: thalamus
Pa: primary auditory cortex |
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AMLR
stimulus and acquisition |
Stimulus
transducer: insert type: click or TB (more robust) duration: click -.1ms, TB rise/fall 2 cycles, plateau multi cycles polarity: rarefaction rate: </=7.1/sec intensity </= 70 dB nHL masking: 50 dB presentation: monaural |
Acquisition
electrodes: Channel1 -C3 to Ai/Ac or C3 to NC Channel 2 C4 to Ai/Ac or Nc channel 3 Fz to Ai/Ac or NC channel 4 ourter canthi of eye groudn Fpz filter: band-pass amplification: 75,000 analysis time 100 ms sweeps: 1000 prestimulus baseline: 10 ms |
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AMLR clinical applications
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electrophysiologic documenation of auditory CNS dysfunction including auditory processing disorders above the level of the brainstem
-frequency specific estimation of hearing sensitivity in older children and adults -electrophys eval of cochlear implant performance -Pb (P50) is applied in the measurement of sensory gating in various neuropsychiatric disorders -measure of depth of anesthesia during surgical procedures |
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ALR waves and generators
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P1 (50 ms)
N1 (90-180 ms) P2(180-200 ms) N2 (200-400 ms) |
N1 auditory cortex
P2 probably secondary auditory area |
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ALR
stimulus and acquisition |
Stimulus
tranducer: insert type: tone burst or speech duration: rise/fall 10ms, plateau 50ms polarity rarefaction rate: </= 1.1/sec intensity </= 70 dB nHL masking: 50 dB rarely needed presentation: monaural |
Acquisition
electrodes: non-inv Fz or Cz inverting linked earlobe or NC, other ocular electrodes, ground Fpz filter: bandpass, notch avoided, remove frequency around 60 Hz amplification: 50,000 analysis time: 600 ms sweeps: 1000 |
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ALR
clinical applications |
-electrophys assessment of higher level auditory cns functioning and aud process
-assessment of cognitive functioning in persons with neuropsychiatric disorders -documenting benefits of auditory training -freq specific estimation of hearing sensitivity in cooperative children and adults |
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P300 waves and generators
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P3/300 300 ms
auditory cortex and frontal lobe hippocampus |
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P300
stimulus and acquisition |
Stimulus
transducer: insert type: tone burst or speech duration: rise/fall 10 ms, plateau 50 ms polarity: rarefaction rate: </= 1.1/sec intensity: </= 70 dBnHL masking 50 dB, rarely needed presentation: monaural |
Acquisition
electrodes: noninv Fz, Cz and/or Pz, inverting linked earlobe or NC, other ocular electrode, ground Fpz filter: 0.1 to 100 Hz, no notch amplification 50,000 analysis time: 600 ms sweeps: <500 prestim baseline: 100 ms |
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P300 clinical application
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assessment of higher level auditory processing
-documentation of effectiveness of medical and nonmedical management for different disorders (APD, ADHD) |
-oddball paradigm
-frequent (80%) vs infrequent (20%) |
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MMN waves and generators
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MMN 200-300 ms
auditory cortex |
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MMN
stimulus and acquisition |
Stimulus
transducer: inserts type: tone or speech duration: rise/fall 10 ms, plateau 50 ms polarity: rarefaction rate: </= 1.1/sec intensity: </= 70 dB nHL masking: 50 dB, rarely needed presentation: monaural |
Acquisition
Electrodes: noninv Fz, Cz or Pz, invert linked earlobe, NC or nose, other ocular, ground Fpz filter: 0.1-30 Hz, no notch amplification: 50,000 analysis time: 600 ms sweeps <500 prestim baseline: 100 ms |
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MMN clinical applications
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oddball paradigm
-5-20% deviant stimuli |
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What type of averageing best describes the relationship between the stimulus and the recording equipment in a typical clinical auditory evoked response measurement is
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time-locked averaging
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the french word that refers to placement of electrodes on the scalp in aer measurement is
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montage
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the source of noise in aer measurement reduced by making the patient comfortable or with children sedating the patient is
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myogenic noise
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with auditory evoked response equipment, common mode rejection (cmr) is effective for reducing unwanted electrical activity in AER recordings. CMR is dependent on the
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differential amplifier
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which of the following persons wrote the classic initial description of the ABR in 1971
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Don Jewett
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The most accurate and correct term to describe the electrode located on or near the ear in a typical ABR recording is
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inverting
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The ABR wave ! and the ECochG AP components are generated by
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distal end of the 8th nearve
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For tone burst stimulation in ABR measurement, the 2-1-2 stimulus duration paradigm recommended by Hallowell Davis refers to:
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2 cycles for rise and fall times, and a 1 cycle plateau
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An ABR waveform for a contralateral electrode array can be distinguished from a waveform for an ipsilateral electrode array by:
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no wave I in the contralateral waveform
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For a click stimulus, an intensity of 0 dB nHL generally corresponds to an intensity in peak equivalent (pe) SPL of approximately:
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30 dB
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A generally acceptable upper limit for inter-electrode impedance in AER measurement is
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5K ohms
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What are the advantages of insert earphones in clinical ABR measurement
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increased interaural attenuation
increased ambient noise reduction reduction of ear canal collapse increased patient comfort more precise placement in infants aural hygiene and infection control can be used as tiptrode electrodes insert cusion and tubing can be sterilized for intraoperative use nonsterile portion of the earphone can be placed outside the surgical field flat frequency response reduced transducer ringing with transient signals reduced stim artifact by separating the transducer box and the electrode |
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What is the acceptable upper limit for a normal adult wave I-V latency interval?
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4.5 ms
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ABR latencies are usually adult-like by the youngest age of
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18 months
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Masking in ABR measurement is not required when
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wave I is clearly present in the ipsilateral electrode array
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The largest amplitude for ECochG components is recorded with which electrode?
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trans-tympanic
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The ECochG cochlear microphonic is most likely generated by
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outer hair cells
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What is a characteristic ABR finding in a conductive hearing los
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delay in the wave I latency
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ABR wave I amplitude is increased by what?
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increase in stimulus intensity
slowing stimulus rate use of an earlobe vs astoid electrode use of rarefaction vs alternating polarity |
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Is ABR affected by chloral hydrate
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no
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How does gender affect the ABR inter-wave latency values?
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females are shorter than males
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What is the audiological sign for Meniere's Disease on the ECochG
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an enhanced SP/AP ratio
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Are analog filter settings of 300 to 3000 Hz routinely acceptable for ABR for infants and young children?
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No
30-3000 Hz |
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What is the maximum possible intensity level for bone-conduction click stimulation in ABR measurement?
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55 dB
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Is ABR an accurate and valid test of hearing?
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no
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What is a reasonable amplitude modulation frequency (MF) for a sinusoidal stimulus for ASSR measurement of infants sedated or anesthetized for the assessment?
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88 Hz
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What is an important advantage of ASSR over ABR in the frequency specific assessment of auditory function in infants and young children?
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ASSR can estimate auditory sensitivity even with severe-profound hearing loss
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In applying ASSR clinically with infants, sedation or light anesthesia is
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usually necessary
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What techniques are used in the analysis of ASSRs
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FFT and vector analysis of phase
(fast fourier transformation) |
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Who has published widely on the topic of ASSR?
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Terry Picton
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Who is credited with discovering AMLR?
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Dan Geisler
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Name appropriate electrodes sites for a neuro-diagnostic AMLR recording?
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FZ
C3 C4 Cz |
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What is a strategy for equalizing the effect of the two ear electrodes in AMLR measurement?
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linking the earlobe electrodes with a jumper cable
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The AMLR matures by approximately what age?
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10 years
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The Pa component of the AMLR is generated by the
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Primary auditory cortex
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What manipulation will minimize the likelihood of recording PAM artifact in AMLR measurement?
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lower the stimulus intensity level
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The 40 Hz response never caught on as an electrophysiological technique for estimating auditory thresholds in infants because
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-it is influenced by sedation
-it is influenced by sleep -the optimal stimulus rate varies with age |
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A characteristic feature of the test protocol for recording the P300 response is
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the oddball paradigm
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The P300 response has been studied clinically with patients in what disorders?
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schizophrenia
dementia central auditory processing disorders alzheimer's disease |
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What is a typical normal amplitude for the Pa component in an AMLR waveform?
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1.0 microvolts
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What is a clinical disadvantage of the ALR?
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the pronounced influence on the response of sleep
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Which is more affected by attention, the MMN or the P300?
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P300
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Has the P300 been used in the evaluaiton of dementia of the Alzheimer's type?
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yes
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How does a more difficult discrimination task affect the amplitude of the P300?
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amplitudes are smaller for more difficult discrimination tasks
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What is an optimal high pass filter for the P300?
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0.1-100 Hz
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What component is seen in the waveform for the frequent auditofy stimulus in a typical oddball tast of the P300 recording?
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P2
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What American has extensively researched MMN response?
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Nina Kraus
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Can the ALR, including wave N1 be elicited by speech?
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yes
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what is the amplitude from ALR N1 to P2?
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often as high as 10 microvolts
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Can the ALR be recorded with the same equipment used for ABR measurement?
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yes
you just need to make the appropriate modification of the test protocol |
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What is the association between tinnitus and OAEs?
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people with tinnitus tend to have abnormal or absent OAEs in the frequency region of tinnitus
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Spontaneous emissions my be observed in...
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females more than males
less than 70% of the population |
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What stimuli do TEOAE use?
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brief acoustic signals (clicks)
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What is the frequency of the DPOAE commonly recorded in the ear canal equal to
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twice the lower input frequency minus the higher input frequency
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What OAE response would you expect if the ototoxicity of a drug involved only the inner hair cells?
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present at normal amplitudes
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Does the presence of OAEs always indicate normal hearing sensitivity?
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no
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Does the absence of OAEs always indicate a hearing loss on the audiogram?
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no
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How is the amplitude of OAEs related to the degree of hearing loss (from 0-40 db Hz)?
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amplitude of OAEs is generally inversely related to degree of hearing loss (from 0-40 dB HL)
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Where do the later portions (in time) of the TEOAEs arise from?
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the apical portion of the cochlea
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Is the supression of emissions with contralateral noise is dependent on the efferent auditory system?
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yes
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What are some potential applications of OAEs?
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assessment of malingerers
monitoring for ototoxicity confirming cochlear integrity in the central auditory assessment differentiation of cochlear from retrocochlear auditory dysfunction |
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What is the criterion used for the presence of DPOAEs in clinical recordings?
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amplitude minus noise floor difference of >6 dB
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What is the relationship between OAEs and the efferent auditory system?
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ipsilateral noise suppresses OAEs
contralateral noise suppresses OAEs |
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In DPOAE measurement, what is a typical value for the f2/f1 ratio?
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1.22
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Who discovered outer hair cell motility (and was once on the faculty at UF)?
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William Brownell
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What factors reduce failure rate in newborn hearing screening with OAEs?
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-delay screening until 36 hours
-experienced tester -quiet test environment -manipulate ear canal |
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What factor has the greatest influence on TEOAEs?
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gender
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What is a limitation of TEOAEs in comparison to DPOAEs?
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TEOAEs have an upper frequency limit of 5000 Hz
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Are TEOAEs and DPOAEs produced by the same cochlear mechanisms?
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No
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What is PAM artifact, and how can it be reduced?
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Post auricular muscle. Myogenic response that can seriously interfere with the recording of the AMLR under certain measurement conditions , e.g. high signal intensity, tense subject, and inverting electrode on the mastoid or earlobe (near the PAM). PAM artifact appears as a sharply peaked component in the 13 to 15 ms region. Amplitude of the PAM activity is much greater than for the Pa component. A most effective solution to the PAM artifact problem is reliance on a noncephalic reference electrode (e.g. laryngeal prominence or the nape of the neck).
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General Characteristics of Patients with AN
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-OAEs present
-ECochG cochlear microphonic is clearly recorded with single polarity -ECochG summating potential may be detected or absent depending on site of dysfunction -ECochG action potential usually not present -ABR absent or markedly abnormal -acoustic relfexes are usually not present -hearing thresholds range from normal to profound -word recognition unusually poor -deficits in processing, especially in noise -MLD show no release from masking -electrically elicited compund action potentials (ECAP) and EABR are normal |
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Risk factors for AN
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Perinatal diseases
-hypebilirubinemia -hypoxic insults -ischemic insults -prematurity Neurological disorders -demyelinating diseases -hydrocephalus -immune disorders (guillain-barre syndrome) -inflammatory neuropathies -severe developmental delay Neurometbolic diseases |
Genetic and Hereditary Etiologies
-family history -connexin mutations -otoferlin (OTOF) gene -nysyndromic recessive auditory neuropath -hereditary motor sensory neuropathies (charcot-marie-tooth syndrome) -leber's hereditary optic neuropathy -waardenburg's syndrom -neurogenerative diseases (friedreich's ataxia) -mitochondrial disorders Other -delayed visual maturation |
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Are CM and OAEs complementary or redundant?
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Complementary
-CM refelects receptor potentials at the apical end of the outer hair celss -OAEs reflect OHC motility that results from electromechanical events |
--measurement of OAE is dependent on outward propagation of energy and can be affected by ME dysfunction that doesn't affect CM
-CM generation is not entirely dependent on OHC, some inner hair cell contribution, SP primarily from IHC CM can be recorded in patients with no detectable OAEs |
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What is intraoperative monitoring?
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IOM is continuous direct or indirect electrophysiologic measurement and interpretation of neural and or myogenic responses to intraoperative events.
Involves interpretation and acquisition. The overall purpose of intraoperative monitoring is to facilitate the maintenance of the structural and functional integrity of the neural and sensory elements at risk for high iatrogenic or surgically induced injury. |
Audiologists are the ONLY profession besides surgeons is the only people to carry out AND interpret IOM.
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What’s the purpose of IOM?
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To monitor anatomic and functional integrity of neural, auditory systems.
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Preserve cochlear integrity
Preserve 8th nerve Prevent brainstem injury Evaluate Cochlear implant Any procedure in which hearing preservation is intended and in which the ear is at risk. |
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Posterior Fossa Surgeries
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Tumor resection
Vestibular nerve section Micro vascular decompression Brainstem aneurysm |
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Three surgical approaches to the cerebellar pontine angle
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Translabrinthine
Obliterates the vestibular structures No hearing preservation Retromastoid/Retrosigmoid Gaining smaller window of access Better chance of preserving hearing Suboccipital Acces much larger Moving cerebellum Possible hearing preservation |
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IOM
Recording techniques |
EcochG
ABR Direct 8th nerve recordings- more real time |
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How do you get to be a good peak picker?
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Practice picking peaks!
Always pick peaks when present Don’t pick peaks when there are not peaks to be picked. Be sure to breathe when picking peaks. |
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IOM
Types of electrodes |
Subdermal needle
ABR, facial nerve measurement Corkscrew electrode For placing electrodes where its hard to tape, like hair E.g. for the vertex Insulated trans tympanographic needle EcochG TM electrode EcochG Do not allow for long term measurement Surface electrodes Not preferable for OR Just use needles Round window electrode Direct auditory nerve recording |
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Significant change in IOM ABR
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Look for I-V interwave latency increase of over 1 ms.
If pt. has high level of general anesthesia that can cause increase in interwave interval as well |
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IOM
Mechanisms of Damage |
Cutting
Stretching Compression Avulsion Thermal Ischemia |
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IOM
Non surgical variables |
Anesthesia
Isoflorane Halothane In high concentrations we can see millisecond delay in interwave interval 1-V. Hypothermia Some OR’s are cold, I-V interval delayed Electrical artifact “hostile environment” lots of interference in OR |
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IOM
TT EcochG + ABR |
It’s important to obtain TT ECochG AND ABR.
Good way to see Wave I and V Needed to measure I-V latency. TT-ECochG Not a lot of sweeps are needed given close proximity of electrode Response in about 0.25/sec! TT – EcochG Can measure threshold at beginning and end of procedure |
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IOM EcoghG
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Fast relative to surface recording
Differentiation of neural from end organ damage Reasonable predictor of post op hearing Not sensitive to damage at root entry zone and beyond |
Direct recording
Auditory Nerve Compound Action Potential Electrode ON 8th nerve No averaging, no delay, LARGE potentials. |
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Sources of injury during these surgeries
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Cochlea (site)
Vascular occlusion Rapid change in all AEP from CM to ABR Everything is abolished quickly VIII nerve Stretch, compression, heat, transduction More gradual change in AEP CM n1, wave I unchanged ANCAP, Wave II-V altered |
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Intraoperative CN VII monitoring facial EMG
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Principles of facial EMG
EMG recorded by means of subdermal electrodes EMG monitored both acoustically and visually Responses consisted of desynchronized EMG or a compound biphasic Muscle AP Administration of Neuromuscular blocking agents should be avoided. Nerve integrity monitor (NIM) unit Testing distal, and proximal (relative to tumor) Ideally, both should be the same Proximal measurement needs to get through tumor. |
NIM unit is typically used for CI surgeries and is typically be activated in advertently during ECAP measurement! (High current, facial stimulation)
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Cochlear Implant Measures
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Electric Middle ear muscle response
During surgery after insertion of CI Post op You can see the tendon tense under a microscope! EABR Preop prom stim During surgery after insertion of CI Post operative |
Neural Response Telemetry (ECAP)
During surgery after insertion of CI Post operatively Electric middle, long, auditory steady state responses |
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Names of ECAPs
|
Neural Response Telemetry” (NRT) is a specific brand name for Cochlear Corporation’s ECAP measurements.
If using Advanced Bionics, it’s Neural Response Imaging (NRI). If using Med-El, it’s Auditory Response Testing (ART). Each test is similar, but ultimately these are different tests with different protocols. Name confusion similar to “Baha”, which is specific to Cochlear’s product and not “Oticon Ponto”, or “Med-El BoneBridge”, which are also bone-conduction hearing devices |
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EABR
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Establish integrity of nerve
Select ear Estimate threshold for each electrode (tNRT, not T level) Diagnose problems with CI |
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NRT
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Estimate threshold for each electrode (tNRT, not T level)
Optimize map Dx. Problem with CI Does not need sleep |
Rationale-
Introduce neural synchrony to carry code to brain Problem- retrograde degeneration, less spiral ganglion cell population Less spiral ganglion cells |
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NRT/NRI/ART ECAPS
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Useful for confirmation of device function, but do not give valid information on device placement, T/C/M level settings, or future performance.
It’s a guide, but other information is needed for postop management MEMR are better measurement of comfort levels. Some people just don’t have ECAPs, tends to be seen more in cochlear, nerve malformations. There is very little information that an intraop ECAP will provide that will mandate removal of an implant and try the back up device. Plain film X-rays post op are best to ascertain proper placement of electrode array. Impedance measurements are often more helpful than ECAPS to ascertain success of surgery. |
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Nadol et al 1989
|
Different degrees of spiral ganglion survival (n=66) (Nadol et al 1989)
Viral Labrynthitis – 8K cells Meningitis – 12K cells Sudden SNHL – 22K cells Congenital genetic 11k cells Ototoxicity – 22k Cells Normal 35-40k Cells |
Problems with poorer neural survival
higher stimulus levels required poorer pitch perception gaps in place code potential channel interactions compete lack of response if too few responses (rarity, but happens) |
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IOM
|
Practitioner needs solid training in electrophysiology/anatomy
Truly a team effort, communicate with surgical staff Not a replacement for surgical skills, possibly enhances, early debulking |
IOM limitations
Ineffective with poor communication Poor monitoring is a distraction Can lead to surgical errors, reduction in confidence in technique. |
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Intraoperative Monitoring (IOM)
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Also known as NIM (neurophysiologic intraoperative monitoring)
Has been around for last 25 years Increase in activity in last 10 years Involves continuous direct or indirect electrophys. Measures and interpretation of neural &/or myogenic responses to intraoperative events. |
Involves both acquisition and immediate interpretation of results to be of value to surgeon.
Purpose: To facilitation the maintenance of the structural and functional integrity of the neural/sensory elements at risk for iatrogenic injury. |
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What does iatrogenic refer to?
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Iatrogenic = surgically induced.
Important to identify the anatomy AND functionality of structures. |
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IOM- Assumptions
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Accurately reflect properties of system at risk.
Sufficiently sensitive to detect surgically-induced changes. Exhibit change in time to prevent damage. (i.e. alert surgeon prior to damage occuring) |
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In real estate, it’s all about location, location, location.
According to Dr. Ruth – IOM is all about: |
Vigilance, vigilance, vigilance!
Audiologists, besides physicians, are the only professionals who can carry out and interpret these findings according to our scope of practice. |
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IOM Involves measurement
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Descending (efferent) motor pathways – Facial Nerve
Ascending (afferent) sensory pathways - Auditory |
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What are some mechanisms (or ways) the nerve can be damaged?
|
Cutting
Stretching Compression Avulsion (changes in where never is positioned) Thermal Ischemia (changes in bloodflow) |
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What type of surgery requires IOM?
|
Any procedure in which hearing preservation is intended
AND In which the ear is at significant risk Examples: Tumor resection, brainstem aneurysm, vestibular nerve section, etc. |
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What role can OAEs play in IOM?
|
OAE testing allows for differentiation between sensory and neural forms of hearing loss.
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IOM & CIs
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ESRTs – either visually measured by surgeon watching stapedial muscle or via impedance bridge. Used to estimate comfort (M) levels.
EABRs – used to choose ear, establish integrity of auditory nerve, diagnose problem with CI** Neural Response Telemetry (NRT) – (aka NRI, etc.) quick, less equipment, does not require sedation, used to estimate loudness levels. (Does NOT diagnose prob. With CI) |
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IOM:
|
Practioner needs solid training in electrophysiology and anatomy
Truly a team effort – requires communication with surgeon, anesthesia team, nursing, etc. Not a replacement for surgical skill Poor monitoring is a distraction – can lead to surgical errors. |
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IOM
Two major applications: Peripheral nervous system (Cranial nerves) Central nervous system |
Muscle artifact is rarely a factor with an anesthetized patient
Many sources of electrical interference can occur in the OR: microscopes, cautery devices, ultrasound machines, etc. Time is of the essence! Recording, analyzing and interpreting in seconds. |
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Who coined the term “AN” in 1996?
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Neurologist Arnold Starr and colleagues
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What are the audiological hallmarks of “AN”?
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Present OAEs that do not suppress with contra-lateral noise
Absent or severely abnormal ABR @ high intensity levels Elevated pure tone thresholds Word recognition scores poorer than expected based on pure tone configuration Absent acoustic reflexes both ipsi & contra tones @ 110dBHL Absent masking level difference |
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Cochlear microphonic (CM) activity and/or OAEs implies what?
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Outer hair cell integrity
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How would an ABR look if with nonfunctional inner hair cells and/or a breakdown in the synaptic transmission from the base of the IHCs to the afferent fibers of the 8th nerve.
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Absent ABR, including wave I
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An estimated ____% of children with hearing loss may show patterns consistent with AN.
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11 – 15%
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What gene mutation affects the synapse between the inner hair cells and the auditory nerve?
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Otoferlin (OTOF)
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Possible sites of dysfunction in people with “AN”?
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IHCs
Disruption in neurotransmission across the synapse btw IHCs and the afferent fibers in the distal end of the auditory nerve Abnormalities within the spiral ganglion cells within the distal portion of the auditory nerve Limited myelinated fibers within the auditory nerve Dysfunction within the auditory brainstem |
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Reports show _____ ______ typically identified years before peripheral neuropathy was suspected or diagnosed.
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Auditory dysfunction
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Why are OAEs and CM complimentary?
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Because they are not directly dependent on one another. You can have one & not the other because of how they are generated & how they are recorded.
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OAEs reflect OHC ______from electromechanical events
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Motility
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CM reflect ________ potentials.
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receptor
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Measurement of OAE is dependent on _______.
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Outward movement of energy from the cochlea thru the middle ear to the ear canal.
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ABR is recorded with rarefaction and condensation to differentiate _____ and _____ responses.
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Sensory & Neural
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Who suggested the terms proximal “AN”/type I “AN” (dealing with the ganglion cells, axons & proximal dendrites) or distal “AN”/type II “AN” (terminal dendrites, inner hair cells & synapses?
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Starr et al. 2004
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AN” emcompasses a spectrum of auditory disorders from isolated inner hair cell abnormalities to variations of “nontumor, noncochlear” hearing impairment.
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Children have been reported to achieve a stable audiogram by what mean age?
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18 months
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Deficits in ______ processing of speech is usually cited as the explanation for poor speech perception.
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temporal
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AN patients have more difficulty with dichotic listening tasks & speech perception in background noise.
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Acoustic reflexes are typically ________ with AN.
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Absent or abnormal
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A genetic factor is involved in ____ of children with AN.
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1/3
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Increased or decreased body temperature has shown to make hearing loss worse for individuals with AN.
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Increased
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What audiological result has been known to gradually disappear.
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OAEs
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________ is an indicator of IHC function?
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Summating potential
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Clamping the acoustic tubing with ABR testing should eliminate a true CM thus differentiating cochlear activity from _________ _________.
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Stimulus artifact
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_____ is a 180 degree reversal in polarity of the response waveform associated with a change in the polarity of the stimulus.
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Cochlear microphonic
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__________ abnormalities due to hyposia and genetic etiologies appear to account for a substantial number of at risk infants with hearing loss.
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IHC
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AN is some evidence of ______ integrity with neural _________.
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Cochlear
dysfunction |
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ENnoG Facts
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Introduced by Swiss neurologist, Ugo Fisch,1974
Not a true nerve response, rather a neuromuscular response from facial nerve=CN7 Could also achieve assessment of neural integrity by performing AR ipsi & contra- stapedial muscle reflex- |
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Terminology of Facial nerve injury
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Neuroparaxia=paralysis of nerve, but no degeneration. Bell’s Palsy, gets resolved by itself or by steroid treatment
Axonotmesis= nerve damage, but not severed, peripheral- distal degeneration, with good prognosis Neurotmesis= nerve severed, poor prognosis, seem in cases of Temporal bone fractures, involves degeneration of proximal and distal portion of nerve |
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Methods of FN assessment
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1.House-Brackmann system- clinical exam
2.Hilger- bedside and clinical 3.EMG- Individual nerve fiber 4.Antidromic nerve potentioals 5.Evoked accelerometry 6.AR 7.MRI 8.ENoG |
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House-Brackmann Grading system
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I- WNL. Muscle tone, strength, symmetry & function is observed WNL
II- Mild dysx. Slight weakness, WNL tone& symmetry III-Moderate dysx. Obvious difference between sides, weak mouth and eye closure with max effort. Normal symmetry at rest |
IV- Moderate to severe dysx
Disfiguring asymmetry, obvious weakness, incomplete eye closure V- Severe dysx Asymmetry at rest, barely motion VI- Total paralysis, no movement |
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ENoG Protocol
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Site= STYLOMASTOID FORAMEN- Main trunk
Transducer: prongs of the stimulator Type: continuous, constant current pulse Duration: .2 ms Rate: 1.1/sec Muscle response is slow Intensity: to produce supra-maximal response about 10+mA |
Orientation of the Probe
BLACK, BACK Cathod, - side, black, posterior Anode, + side, red, Anterior |
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ENoG
Acquisition Parameters |
Analysis time 20ms
Filter 3-3000Hz Notch filter, no, takes out 60 Hz that might have some of the response in it Amplification 5000 Sweeps 1-20 Electrodes: Horizental orientation ground=forehead Inverting=nasolabial, Noninverting=corner of mouth |
Artifact= masseter muscle response, 2-3 ms, move prongs back
Response around 5-7 ms, large response of 750-2000 milliVolt Compare sides, no normative data N1, P1, N2 Amplitude measured from peak of P1 to trough of N2 Percent degenaration=100-[affected amp/ unaffected amp *100] |
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VEMP
In 1995 The Name Was Coined By? |
Robertson and Ireland
Assumed an important position in the test battery for patients with balance and vestibular disorders. |
VEMP reflects vestibular system activity that is elicited by high-intensity sounds and detected as a change in muscle potentials within the neck.
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VEMPS are sometimes referred to as “_______-________reflexes.
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Sono-Motor
(reflex stimulated by sound) |
Similar to the acoustic reflex or PAM, however, it is unilateral. It is stimulated ipsilaterally
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The VEMP can be stimulated and recorded in deaf persons?
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TRUE
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VEMP
Biphasic With Latency Region |
Positive peak at a latency of some 13 msec (PI) from the stimulus followed by a negative wave peaking some 10 msec later (N2)
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following the presentation of a high-intensity sound, there is a temporary reduction in muscle activity, recorded as the positive wave
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VEMP Pathways
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The pathway is sound-tympanic membrane-ossicles-saccule-inferior vestibular nerve-vestibulospinal tracts-sternocleidomastoid muscle.
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There are superior and inferior components or divisions within the vestibular ganglion
With respect to VEMP anatomy, the superior division innervates the anterior portion of the macula within the saccule, whereas the inferior division innervates the posterior portion. Although the saccule is served by both the superior and inferior vestibular nerves, clinical findings in patients with various pathologies provide evidence that the VEMP is dependent on the integrity of the inferior vestibular portion of the auditory nerve. In contrast, the superior branch of the vestibular nerve innervates ampulla of anterior and horizontal canals and utricle. |
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VEMP
Stimulus Factors areWhat are the preferred?Clicks or Tone Bursts |
Type of stimulus (click versus tone burst),
Frequency stimulus (low- versus high- frequency tone bursts) and, of course, the Intensity level of the stimulus. For successful measurement of the VEMP, the sternocleidomastoid muscle (SCM) must be maintained in tonic contraction |
Type of stimulus tone burst, In general, tone bursts are more effective than clicks for elicitation of VEMP and, among tone-burst stimuli, low frequency more effective than high frequency. Within published papers, the most commonly used stimulus for clinical measurement of VEMP is a 500 Hz tone burst. |
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VEMP Protocols
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Stimulus
transducer: insert type: click or tone burst (LF) duration: 0.1 ms click or 2-0-2 cylce intensity: >95 dB nHL polarity: rarefaction rate: 3-5 ms |
Acquisition
analysis time: prestim-10-20 ms, post stim- 50-100 ms electrode: large electrode on SCM muscle electrode location: non-inv mid of SCM, invert Sternoclavicular junction or other sites (hand), ground, forehead filter: 1/30 Hz to 250/1500 Hz, no notch amplification: x50-5000 sweeps: 45-250 |
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Three techniques are reported for producing and maintaining contraction of the SCM muscles.
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Rotation of the subject's head to the opposite side, usually against some resistance, while he or she is sitting upright or lying supine
Contraction of SCM muscles bilaterally can be produced by instructing the patient to lift his or her head slightly while lying either supine (on the back) or with the back elevated and head lifted Another technique for activating bilateral SCM muscle activation requires the patient to press the forehead against a soft surface (e.g., padded wall or bar) while in a sitting position |
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VEMP analysis
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Analysis of the vestibular evoked myogenic potential (VEMP). The major component in the latency region of 23 ms may appear positive-going or negative-going depending on which electrode (noninverting or inverting electrode) is located on the sternocleido-mastoid muscle.
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VEMP latency is quite consistent among subjects, but intersubject VEMP amplitude is highly variable,
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NONPATHOLOGIC FACTORS affecting VEMP
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feasible to record the VEMP from infants ranging in age from 1 to 12 months
N23 peak of the VEMP was shorter for the infants in comparison to adult expectations Age plays an important role in VEMP analysis. There are in the vestibular system age-related change few published references on possible gender effects |
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PATHOLOGIC FACTORS affecting VEP
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conducive hearing loss.
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VEMP
Clinical Applications and Populations |
The characteristic VEMP pattern in peripheral pathologies is absence of the response, although delayed latencies for VEMP components are recorded in some diseases (e.g., multiple sclerosis).
Superior canal dehiscence syndrome (SCDS) is a distinct exception to these VEMP patterns. Vestibular sensitivity is enhanced in SCDS, as evidenced by larger than expected VEMP amplitudes and enhanced thresholds (e.g., 60 to 70 dB nHL versus >95 dB nHL) |
The diversity of VEMP findings in Meniere's disease may reflect variable sites of lesions, e.g., hair cells in the horizontal semicircular canal versus the saccule and pathophysiologic mechanisms
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Important names in ECochG
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Wever and Bray discovered CM
Andreev Sohmer Coats Gibson |
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Factors affecting AERs
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subject: age, gender, body temp, state of arousal, muscle artifact
stimulus: intensity, rate, polarity, duration acquistion parameters: type of electrodes, array, analaysis time, # of samples, flitering |
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Objectives of ABR
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-rule out or confirm periph hearin gloss
-differentiate between conductive vs sensory loss -rule out retrocochlear loss -estimate degree of hearing loss |
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ABR normative mneumonic
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Wave V latency 5.5 ms
-amplitude 0.5 microvolts I-V latency 4.5 ms (18 mos+), 5.0 newborns -V/I amp ratio >/= 0.5 microvolts |
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ABR latencies and hearing
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normal hearing : WNL
conductive: delayed wave I, normal I-V latency sensory: little or no wave I, poorly formed waves neural: delayed interwave latencies or absent detectable wave |
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Relationships in ABR latencies
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-increase intensity, decrease latency
-latency increases and amplitude decreases with increased rate -increase in intensity leads to decrease in latency and increase in amplitude -above 70 dB nHL - latency is stable and amplitude goes up |
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Tone burst ABR
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presence or absence of response is more important than latency
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Important names in ABR
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-Davis, 1979 coined ABR
-Jewett and Williston, roman numerals -Moller, Hashimoto - wave I distal 8th nerve |
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ASSR
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-similar to ABR
-insert earphones -surface electrodes -averaging computer -rapid modulation of carier tone amp or freq |
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Important names in ASSR
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Austrailian
-Rickards -Clark -Rance Canadian -Linden -Picton -Stapells |
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ABR vs ASSR
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ADVANTAGES
ABR -estimate normal hearing threshold -ear specific bone info -dx AN ASSR -estimates severe/profound |
DISADVANTAGE
ABR -can't estimate severe/profound -skilled analysis needed -limited BC levels ASSR -no ear specific bone -requires sleep or sedation |
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Auditory dysfunction and ABR and ASSR
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ABR
normal: accurate conductive: ear specific with masking sensory: accurate to moderate loss neural: identified with wave I |
ASSR
normal: overestimate threshold conductive: masking required sensory: accurate from moderate to profound neural: difficult to distinguish profound or CM sensory vs neural HL |
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Sedation and ASSR
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-slower rates, cortical testing more affected
-faster rates are brainstem and not affected |
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important people and AMLR
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-Geisler- founder
-Kilney -Kraus -Lee |
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Components of AMLR
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Na
Pa Nb Pb |
Pa major component
-22-30 ms -1 microvolt near field response electrode needs to be on the temporal lobe |
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nonpathologic factors influencing AMLR
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-filtering, avoid restricted high pass filter settings (10 Hz or lower)
-stim intensity, avoid very high intensity to reduce PAM -stim duration, longer is better -stim rate, slower rates for children and pathology |
subject factors
-matures @ 10 years -sleep, more variable -PAM artifact especially with higher intensity -sedation- reduced amplitude -anesthesia, suppresses AMLR activity (reticular formation generators) |
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ALR waves
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N1
N1b N1c N150 N400 -sustained negativity for duration of stim |
Oddball paradigm
-positive and negative waves -MMN -P300 -P3a |
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ALR subject factors
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age
-matures after 10-12 years -N1 P2 amp decreases and P3 increases with age -latency decreases with age -advancing age: latency increases for 20+ years in all late responses attention -depends on different ALR components sleep -stage of sleep affects ALR -variable in stages 3 and 4 -REM state same as awake |
changes in latency and amplitude can document effective intervention in APD
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Name with P300
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Hallowell Davis
Samuel Sutton |
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Oddball paradigm
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-peak at least 10 microvolts @300 ms
--80% stimulus are frequent -20% are infrequent |
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passive P300
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-smaller amp
-shorter latency -can easily be recorded |
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clinical assessment of APD with P300
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-use speech in noise and temporal processing (gap detection)
-analyze: latency, amp, amp under the curve |
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MMN people
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-Naatanen, finnish
-Kraus, US -Picton, Canada |
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MMN generators
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supratemporal plane of the primary aud cortex
-frontal cortex -possibly thalamus and hippocampus |
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MMN measurement
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deviant wave-stadard wave=MMN
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MMN and brain processes
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-unconscious response
-what ahhpens in the brain before we are aware -standard stimuli creates a memory trace and deviant doesn't match, that creates the MMN -the smaller the difference the more likely to get a response |
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MMN stimuli
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-just noticeable difference
-gap within tonal stim -sound source difference -missing deviant stim -temporal pattern -music -voice onset time -syllables and words |
response is at 200-300 ms
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P300 vs MMN
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P300
-continuous attn -amp related to attn -amp related to task relavance -latency 300 ms -generators in the limbic cortex -larger differences between standard and rare produces larger response |
MMN
-pre perceptual detection of stim -amp is independent of attn -unaffected by task relevance -latency 100-300 ms range -generators in frontal lobe and temporal lobe -smaller differences more effective in eliciting MMN |
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Why is MMN not used clincially
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-needs published norms
-no consensus on stim and acquistion parameters -requires sophisticated stim with evoked responses measurement system -requires statistical verification -insufficient data on reliability of MMN |
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important name in Electroneurography
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Ugo Fisch, swiss,
1974 |
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what is ENoG
|
evoked electromyographic response from distal end of the 7th nerve
-quantifies the aount of degeneration of facial nerve -following injury to proximal end -Bell's Palsey is most common injury involving facial nerve |
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What how is degeneration of the 7th nerve determined in ENoG?
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-compare uninvolved side to involved side
-100-(amp of involv/amp of uninvolv x 100) = % of degeneration |
90% or more is considered significant
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Important names in Auditory Neuropathy
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Star
Picton Sininger Hood Berlin |
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What factors influence ABR
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Subject characteristics:
Age: Young age affects ABR, whereas advancing age primarily affects later latency AERs. ABR undergoes changes over the first 18 months of life. ABR in newborns may have delayed wave 1, but delayed interwave intervals. Individuals above 55 may begin to show delayed absolute and interwave latencies. Gender: Distinct differences in female vs. male ABR results. Females have shorter latency and larger amplitudes than males. Body Temerature: Low body temps can increase latencies. With severe hypothermia, ABR will disappear. Decreased latency and amplitude have been noted with high temps. Drugs: Ototoxic drugs damage outer haircells, affecting the overall latency of ABR. ABR is very useful in monitoring auditory status of individuals using ototoxic drugs. Muscular artifact: Movement affects reading of ABR, creating a higher noise floor or muscular artifact. Hearing Sensitivity: High Frequency Hearing Loss especially affects ABR, specifically wave 1. |
Mechanical or examiner errors:
Electode Error: Incorrect placement of electrode may give results that look abnormal when it should be normal, or slightly normal when it is actually abnormal. Electrical Interference: Electrodes may detect extraneous electrical activity as they are often more prominent than activity inside the head. --Stimulus Artifact: Acoustic Transducers produce an electromagnetic field. If close to the recording electrode it can create some unwanted signals. --Electrical Noise: Electrical power can generate frequencies of 60 Hz and harmonics of this frequency. Electrical interference is unpredictable and elusive. |
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Some non-auditory evoked responses
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Sensory evoked responses (such as visual responses evoked by electrical and photic signals and other somatosensory responses )
Electroneuronography (ENoG) measurement of facial muscle activity secondary to facial nerve activity Vestibular Evoked Myogenic Potential (VEMP) (ENG, rotary vestibular tests, platform posturography). Reflects vestibular system activity elicited by high-intensity sounds and detected as a change in muscle potentials within neck |
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Electrically Evoked Compound Action Potentials (ECAP)
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to document integrity of cochlear implant, estimate detection thresholds and MCL, mapping, info on auditory nerve and spiral ganglion cell viability (Brown et al., 1996) 1988 NIH Consensus Development Conference on CI “measurement of electrical auditory evoked potentials should be basic component in candidate selection”, “before during and after ci” (Kileny, IJA 2003)
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Electrically Evoked Auditory Brainstem Response (EABR)
|
provides info on brainstem auditory function and verify neural function prior to CI used to assess candidacy for CI, verify integrity and performance of CI, estimate communication benefit following CI (measured since 1980s
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Electrically Evoked Cortical Auditory Evoked Responses (EAMLR, EALR, EP300, EMMN)
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provide objective measure of maturation of auditory system secondary to sensory deprivation experienced by children with severe-to-profound peripheral HL, provides info on auditory cortex findings related to speech perception
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Electrically Evoked Auditory Potentials
|
First application in 1970s, within a decade after discovery of ABR
Used to assess candidacy for cochlear implantation, to verify the integrity and performance of CI components, and to estimate communication benefit following CI May be used to determine which ear should be implanted Also used intraoperatively to verify adequate electrode placement Postoperatively it can be evoked by either electrical stimulation directly within the cochlea via the device or by sound stimulation processed by the device |
Artifact
Major problem with electrically evoked responses Artifact is often far larger than the response and duration may extend beyond 5ms and totally obscure early response components Components with latencies beyond 5ms are more likely to be myogenic or generated by the vestibular system or facial nerve Vestibular and myogenic responses may occur within the initial 5ms post-stimulus period Successful measurement of EABRs has been reported by manipulating pulse duration, intensity, and using alternating mode of presentation (bipolar versus monopolar electrodes) Failure to recognize non-auditory evoked responses is problematic in the evaluation of CI candidacy and performance because these artifacts may be recorded from patients with no perception of sound |
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E EAP Anatomy
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Similar anatomic regions underlie responses to auditory and electrical stimulation
Different characteristic patterns of activity Latencies generally shorter because the electrical stimulus directly activates neural pathways (spiral ganglion cells) Unaffected by time delays associated with acoustic travel time from an earphone to the TM, transmission of mechanical energy through the ME and along the cochlear partition, excitation of hair cells, and synaptic transmission from hair cells to auditory nerve afferent fibers Latency shows little change as a function of intensity |
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E EAP protocol
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For both EABR and EAMLR the non-inverting electrode is located at Cz or Fz and inverting electrode is on ipsilateral (ABR, AMLR) or contralateral (AMLR) mastoid or earlobe, ground is located on the forehead
Inverting electrode on contralateral side may minimize stimulus artifact Intraoperatively, subdermal needles may be used |
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ECAP
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Interest in the ECAP began in mid 1980s
Argument for clinical application of ECAP versus EABR for estimating the viability of the auditory nerve Maximum amplitude of P2 is proportional to the number of excitable auditory nerve fibers Generally lower correlations for spiral ganglion cell counts and the amplitude of later EABR waves ECAP can document channel interactions Record with probe electrical pulse presented to one electrode while masker signal is presented to another electrode The amount of channel interaction can be calculated by measurement of the effect of the masker electrode location on the ECAP amplitude for a given stimulus electrode Cochlear Corporation developed a system for measuring ECAPs called Neural Response Telemetry (NRT) |
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Masker-Probe Subtraction Technique
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Most common technique employed to reduce the artifact problem
Waveform generated by the masker-probe combination is subtracted from the waveform produced in the probe alone condition Resulting derived waveform may contain residual electrical artifact associated with the masker signal. These unwanted sources of measurement “noise” are removed by subtracting the waveform recorded in the masker alone condition. |
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ECAP Measurement Types
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Thresholds
Amplitude Growth Functions: plots of ECAP amplitude (uV) as a function of stimulus intensity Recovery Functions: measured with the masker-probe subtraction technique by manipulating the IPI With short IPIs, neurons activated by masker are not recovered before the probe stimulus is presented so no ECAP is generated As IPIs increase, the ECAP emerges |
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ECAP Clinical Applications
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Assessment and documentation of auditory nerve integrity
Confirms neural synchrony postoperatively in patients with ANSD Provides valuable information on the integrity of the cochlear implant device, including electrodes Document postoperatively, with serial measurements, atypical and potentially serious variations in cochlear implant function in the weeks, months, and even years following CI Recorded intraoperatively or soon after cochlear implantation in young children and used to estimate and map objectively behavioral threshold and comfort levels and other stimulation parameters of CIs |
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Electrically Evoked Auditory Brainstem Response (EABR)
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Measurement dates back to 1980s
Preoperatively the EABR is stimulated with electrical signals delivered via a needle placed on the promontory In combination with radiological findings, inter-ear differences in the threshold of EABR were applied in the estimation of nerve survival and nerve stimulability and, therefore, decisions about which ear to implant Subsequent studies suggest that the relation between preoperative EABR findings and postoperative cochlear implant performance is not clear-cut CI performance for children with no detectable EABR preoperatively was comparable to performance for children with a clear preoperative response |
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EABR
|
During the first 24 months, maturation of auditory system affects both acoustically and electrically evoked ABR
age effect is less pronounced for the EABR Electrical stimulation consists of all major waves except wave I and waves appear more rounded Waves are sometimes noted as eIII and eV |
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EABR Artifact
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Short latency component (SLC): another wave occasionally observed within the time period of the EABR but distinct from the conventional EABR wave I
Elicited by high-intensity stimulation and appears as a negative peak with latency of about 3 ms for acoustic stimuli and 2 ms for electrical stimuli May be a response from the vestibular system rather than an auditory response Compound muscle action potential is sometimes observed in 4-6 ms region after a high-intensity electrical stimulation |
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Clinical Applications of EABR
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Preoperative assessment of CN8 integrity
Intraoperative measurement to ensure the integrity of the cochlear implant device Estimation of physiologic threshold for electrical stimulation Not as accurate as the estimation of behavioral thresholds with conventional ABR 4. Estimation of dynamic range |
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Electrically Evoked ASSR
|
Good correspondence between the subjective behavioral threshold estimations and threshold durations of the electrically evoked ASSR
Further and more comprehensive investigation is recommended |
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Advantages of EAMLR
|
Long latency wave components are far removed from electrical artifact
Provide an indication of CI benefit Almost always detected in children about one year after CI, but not typically recorded at time of implant Progressively shorter latencies and larger amplitudes are associated with CI usage Suggests that the thalamo-cortical pathways remain plastic following a period of auditory deprivation Same sujbects showed rapid acquisition of speech skills Changes are more rapid for children implanted before 3.5 years versus those implanted after 7 years Generators within auditory cortex. More closely related to “hearing” |
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Electrically Evoked Auditory Late Response (EALR)
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Protocol for recording the EALR is similar to the protocol for traditional ALR
ALR evoked by tonal and speech stimuli can be reliably recorded from most children and adults following CI Significant EALR threshold differences among electrodes Lowest average EALR threshold for electrode 1 and highest for electrode 7 Latencies for the EALR components (N1 and P2) are not related to electrode site |
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Electrically Evoked P300
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Protocol for recording the EP300 is similar to the protocol for traditional P300
P300 for tonal signals (1500 versus 3000 Hz) recorded from children with CIs were correlated with speech perception performance Responses with the CI approximated normal expectations Latency of P300 is closely related to speech reception ability over a long period after CI |
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Electrically Evoked MMN
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MMN is not applied in clinical assessment of patients with CIs just as the MMN is not incorporated into he clinical test battery for other patient populations.
Normal appearing MMN response elicited by speech signals for CI subjects with good speech perception (assessed with Hearing in Noise Test) Clear MMN could not be detected from CI subjects with poorer speech recognition performance Studies have shown the MMN is recorded less often in patients with CI versus normal subjects |
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ECochG
|
Enhance ABR Wave I
Diagnose auditory neuropathy Diagnose Meniere’s disease Intraoperative monitoring |
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ABR
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Newborn Auditory Screening
Estimate auditory sensitivity in newborns and children. Neurodiagnosis of VIII n and auditory brainstem dysfunction. Monitor VIII n and auditory brainstem during surgery. Diagnose auditory neuropathy. |
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ASSR
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Auditory threshold estimation: adults and children.
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AMLR
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Electrophysiologic documentation of auditory CNS dysf., including auditory processing disorders above the level of the brain.
Freq.-specific estimation of hearing sensitivity in olde children and adults. Elect. evaluation of cochlear implant performance. The Pb comp. (P50) is applied in the measurement of "sensory gating" in various neuropsychiatric disorders. Measure of depth of anesthesia during surgical procedures. |
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ALR
|
Electrophisiologic assessment of higher level auditory CNS functioning and auditory process.
Assessment of cognitive functioning in persons with neuropsychiatric disorders. Documentation of benefits of auditory training. Freq.-specific estimation of hearing sensitivity in cooperative children and adults. |
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P300
|
Assessment of higher level auditory processing.
Documentation of effectiveness of medical and nonmedical management for different disorders (APHD, APD). |
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MMN
|
Assessment of higher level auditory processing, including speech and music perception, and developmental changes in processing.
Documentation of effectiveness of medical and nonmedical management for different disorders (APHD, APD). Elect. documentation of central auditory nervous system plasticity. |
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OAEs Pediatric applications:
• Nerwborn hearing screening • Diagnosis of auditory dysfunction in infants/young children • Monitoring ototoxicity • Preschool/school screenings • Diagnosis of CAPD Adult applications: • Differentiation of cochlear vs. retrocochlear auditory dysfunction • Identification of Pseudohypoacusis • Ototoxicity monitoring • Hearing screening (military, industry) • Diagnose auditory dysfunction in noise/music exposure • Diagnose/manage tinnitus and hyperacusis |
Pediatric applications:
• Nerwborn hearing screening • Diagnosis of auditory dysfunction in infants/young children • Monitoring ototoxicity • Preschool/school screenings • Diagnosis of CAPD |
Adult applications:
• Differentiation of cochlear vs. retrocochlear auditory dysfunction • Identification of Pseudohypoacusis • Ototoxicity monitoring • Hearing screening (military, industry) • Diagnose auditory dysfunction in noise/music exposure • Diagnose/manage tinnitus and hyperacusis |
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ENoG
|
Clinical Assessment of Facial Nerve Function
|
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Important people in ECochG
|
Discovered by
Wever and Bray, 1930 |
Hallowell Davis (father of AER)
Joseph Eggermont, Menieres Jay Hall |
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Important people in ABR
|
Discovered
Jon Jewett and John Williston (1970) |
Starr, confirmation of brain death
Jerger and Hall, effectof age and gender Don, stacked ABR Terry Picton Stapells |
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Important people in ASSR
|
Terry Picton
Stapells |
|
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Important people in AMLR
|
Discovered by
Dan Geisler -1958 |
Goldstein, effect of stim parameters, measures in neonates
Musiek, brain pathologies Kileny, neural generators, electrical elicitation Nina Kraus Lee Scherg |
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Important people in ALR
|
Hallowell Davis
Pauline Davis |
|
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Important people in P300
|
Hallowell Davis -1964
Samuel Sutton -1965 |
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Important people in MMN
|
Discovered by
Dr. Risto Naatanen, 1975 |
Nina Kraus
|
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Important people in OAEs
|
Dr. David Kemp, 1978
|
|
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Important people in ENoG
|
Dr. Ugo Fisch
|
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