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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
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)
ECochG clinical application
-enhancement of ABR wave I
-documentation of cochlear status in auditory neuropathy
-diagnosis of Meniere's disease: SP/AP <30% (TT) normal; >30% MD
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)
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
ABR click clinical application
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
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
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
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
ASSR generators
brainstem: fast modulation >60 Hz
cortex: slow modulation <60 Hz
modulation depth
-amplitude 100%
-frequency 20%
-modulation rate -82 to 106 hz
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
ASSR
clinical application
auditory threshold estimation
capable of estimating electrophysicaolical auditory threshold of up to 120 dB HL

automated response detection
AMLR
waves and generators
Na
Pa (25-35 ms)
Nb
Pb(P50) 40-60 ms
Na: thalamus
Pa: primary auditory cortex
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
AMLR clinical applications
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
ALR waves and generators
P1 (50 ms)
N1 (90-180 ms)
P2(180-200 ms)
N2 (200-400 ms)
N1 auditory cortex
P2 probably secondary auditory area
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
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
P300 waves and generators
P3/300 300 ms

auditory cortex and frontal lobe
hippocampus
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
P300 clinical application
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%)
MMN waves and generators
MMN 200-300 ms

auditory cortex
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
MMN clinical applications
oddball paradigm
-5-20% deviant stimuli
What type of averageing best describes the relationship between the stimulus and the recording equipment in a typical clinical auditory evoked response measurement is
time-locked averaging
the french word that refers to placement of electrodes on the scalp in aer measurement is
montage
the source of noise in aer measurement reduced by making the patient comfortable or with children sedating the patient is
myogenic noise
with auditory evoked response equipment, common mode rejection (cmr) is effective for reducing unwanted electrical activity in AER recordings. CMR is dependent on the
differential amplifier
which of the following persons wrote the classic initial description of the ABR in 1971
Don Jewett
The most accurate and correct term to describe the electrode located on or near the ear in a typical ABR recording is
inverting
The ABR wave ! and the ECochG AP components are generated by
distal end of the 8th nearve
For tone burst stimulation in ABR measurement, the 2-1-2 stimulus duration paradigm recommended by Hallowell Davis refers to:
2 cycles for rise and fall times, and a 1 cycle plateau
An ABR waveform for a contralateral electrode array can be distinguished from a waveform for an ipsilateral electrode array by:
no wave I in the contralateral waveform
For a click stimulus, an intensity of 0 dB nHL generally corresponds to an intensity in peak equivalent (pe) SPL of approximately:
30 dB
A generally acceptable upper limit for inter-electrode impedance in AER measurement is
5K ohms
What are the advantages of insert earphones in clinical ABR measurement
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
What is the acceptable upper limit for a normal adult wave I-V latency interval?
4.5 ms
ABR latencies are usually adult-like by the youngest age of
18 months
Masking in ABR measurement is not required when
wave I is clearly present in the ipsilateral electrode array
The largest amplitude for ECochG components is recorded with which electrode?
trans-tympanic
The ECochG cochlear microphonic is most likely generated by
outer hair cells
What is a characteristic ABR finding in a conductive hearing los
delay in the wave I latency
ABR wave I amplitude is increased by what?
increase in stimulus intensity
slowing stimulus rate
use of an earlobe vs astoid electrode
use of rarefaction vs alternating polarity
Is ABR affected by chloral hydrate
no
How does gender affect the ABR inter-wave latency values?
females are shorter than males
What is the audiological sign for Meniere's Disease on the ECochG
an enhanced SP/AP ratio
Are analog filter settings of 300 to 3000 Hz routinely acceptable for ABR for infants and young children?
No

30-3000 Hz
What is the maximum possible intensity level for bone-conduction click stimulation in ABR measurement?
55 dB
Is ABR an accurate and valid test of hearing?
no
What is a reasonable amplitude modulation frequency (MF) for a sinusoidal stimulus for ASSR measurement of infants sedated or anesthetized for the assessment?
88 Hz
What is an important advantage of ASSR over ABR in the frequency specific assessment of auditory function in infants and young children?
ASSR can estimate auditory sensitivity even with severe-profound hearing loss
In applying ASSR clinically with infants, sedation or light anesthesia is
usually necessary
What techniques are used in the analysis of ASSRs
FFT and vector analysis of phase
(fast fourier transformation)
Who has published widely on the topic of ASSR?
Terry Picton
Who is credited with discovering AMLR?
Dan Geisler
Name appropriate electrodes sites for a neuro-diagnostic AMLR recording?
FZ
C3
C4
Cz
What is a strategy for equalizing the effect of the two ear electrodes in AMLR measurement?
linking the earlobe electrodes with a jumper cable
The AMLR matures by approximately what age?
10 years
The Pa component of the AMLR is generated by the
Primary auditory cortex
What manipulation will minimize the likelihood of recording PAM artifact in AMLR measurement?
lower the stimulus intensity level
The 40 Hz response never caught on as an electrophysiological technique for estimating auditory thresholds in infants because
-it is influenced by sedation
-it is influenced by sleep
-the optimal stimulus rate varies with age
A characteristic feature of the test protocol for recording the P300 response is
the oddball paradigm
The P300 response has been studied clinically with patients in what disorders?
schizophrenia
dementia
central auditory processing disorders
alzheimer's disease
What is a typical normal amplitude for the Pa component in an AMLR waveform?
1.0 microvolts
What is a clinical disadvantage of the ALR?
the pronounced influence on the response of sleep
Which is more affected by attention, the MMN or the P300?
P300
Has the P300 been used in the evaluaiton of dementia of the Alzheimer's type?
yes
How does a more difficult discrimination task affect the amplitude of the P300?
amplitudes are smaller for more difficult discrimination tasks
What is an optimal high pass filter for the P300?
0.1-100 Hz
What component is seen in the waveform for the frequent auditofy stimulus in a typical oddball tast of the P300 recording?
P2
What American has extensively researched MMN response?
Nina Kraus
Can the ALR, including wave N1 be elicited by speech?
yes
what is the amplitude from ALR N1 to P2?
often as high as 10 microvolts
Can the ALR be recorded with the same equipment used for ABR measurement?
yes

you just need to make the appropriate modification of the test protocol
What is the association between tinnitus and OAEs?
people with tinnitus tend to have abnormal or absent OAEs in the frequency region of tinnitus
Spontaneous emissions my be observed in...
females more than males

less than 70% of the population
What stimuli do TEOAE use?
brief acoustic signals (clicks)
What is the frequency of the DPOAE commonly recorded in the ear canal equal to
twice the lower input frequency minus the higher input frequency
What OAE response would you expect if the ototoxicity of a drug involved only the inner hair cells?
present at normal amplitudes
Does the presence of OAEs always indicate normal hearing sensitivity?
no
Does the absence of OAEs always indicate a hearing loss on the audiogram?
no
How is the amplitude of OAEs related to the degree of hearing loss (from 0-40 db Hz)?
amplitude of OAEs is generally inversely related to degree of hearing loss (from 0-40 dB HL)
Where do the later portions (in time) of the TEOAEs arise from?
the apical portion of the cochlea
Is the supression of emissions with contralateral noise is dependent on the efferent auditory system?
yes
What are some potential applications of OAEs?
assessment of malingerers
monitoring for ototoxicity
confirming cochlear integrity in the central auditory assessment
differentiation of cochlear from retrocochlear auditory dysfunction
What is the criterion used for the presence of DPOAEs in clinical recordings?
amplitude minus noise floor difference of >6 dB
What is the relationship between OAEs and the efferent auditory system?
ipsilateral noise suppresses OAEs

contralateral noise suppresses OAEs
In DPOAE measurement, what is a typical value for the f2/f1 ratio?
1.22
Who discovered outer hair cell motility (and was once on the faculty at UF)?
William Brownell
What factors reduce failure rate in newborn hearing screening with OAEs?
-delay screening until 36 hours
-experienced tester
-quiet test environment
-manipulate ear canal
What factor has the greatest influence on TEOAEs?
gender
What is a limitation of TEOAEs in comparison to DPOAEs?
TEOAEs have an upper frequency limit of 5000 Hz
Are TEOAEs and DPOAEs produced by the same cochlear mechanisms?
No
What is PAM artifact, and how can it be reduced?
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).
General Characteristics of Patients with AN
-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
Risk factors for AN
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
Are CM and OAEs complementary or redundant?
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
What is intraoperative monitoring?
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.
What’s the purpose of IOM?
To monitor anatomic and functional integrity of neural, auditory systems.
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.
Posterior Fossa Surgeries
Tumor resection
Vestibular nerve section
Micro vascular decompression
Brainstem aneurysm
Three surgical approaches to the cerebellar pontine angle
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
IOM

Recording techniques
EcochG
ABR
Direct 8th nerve recordings- more real time
How do you get to be a good peak picker?
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.
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
Significant change in IOM ABR
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
IOM
Mechanisms of Damage
Cutting
Stretching
Compression
Avulsion
Thermal
Ischemia
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
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
IOM EcoghG
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.
Sources of injury during these surgeries
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
Intraoperative CN VII monitoring facial EMG
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)
Cochlear Implant Measures
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
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
EABR
Establish integrity of nerve
Select ear
Estimate threshold for each electrode (tNRT, not T level)
Diagnose problems with CI
NRT
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
NRT/NRI/ART ECAPS
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.
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)
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.
Intraoperative Monitoring (IOM)
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.
What does iatrogenic refer to?
Iatrogenic = surgically induced.

Important to identify the anatomy AND functionality of structures.
IOM- Assumptions
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)
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.
IOM Involves measurement
Descending (efferent) motor pathways – Facial Nerve
Ascending (afferent) sensory pathways - Auditory
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)
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.
What role can OAEs play in IOM?
OAE testing allows for differentiation between sensory and neural forms of hearing loss.
IOM & CIs
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)
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.
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.
Who coined the term “AN” in 1996?
Neurologist Arnold Starr and colleagues
What are the audiological hallmarks of “AN”?
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
Cochlear microphonic (CM) activity and/or OAEs implies what?
Outer hair cell integrity
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.
Absent ABR, including wave I
An estimated ____% of children with hearing loss may show patterns consistent with AN.
11 – 15%
What gene mutation affects the synapse between the inner hair cells and the auditory nerve?
Otoferlin (OTOF)
Possible sites of dysfunction in people with “AN”?
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
Reports show _____ ______ typically identified years before peripheral neuropathy was suspected or diagnosed.
Auditory dysfunction
Why are OAEs and CM complimentary?
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.
OAEs reflect OHC ______from electromechanical events
Motility
CM reflect ________ potentials.
receptor
Measurement of OAE is dependent on _______.
Outward movement of energy from the cochlea thru the middle ear to the ear canal.
ABR is recorded with rarefaction and condensation to differentiate _____ and _____ responses.
Sensory & Neural
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?
Starr et al. 2004
AN” emcompasses a spectrum of auditory disorders from isolated inner hair cell abnormalities to variations of “nontumor, noncochlear” hearing impairment.
Children have been reported to achieve a stable audiogram by what mean age?
18 months
Deficits in ______ processing of speech is usually cited as the explanation for poor speech perception.
temporal
AN patients have more difficulty with dichotic listening tasks & speech perception in background noise.
Acoustic reflexes are typically ________ with AN.
Absent or abnormal
A genetic factor is involved in ____ of children with AN.
1/3
Increased or decreased body temperature has shown to make hearing loss worse for individuals with AN.
Increased
What audiological result has been known to gradually disappear.
OAEs
________ is an indicator of IHC function?
Summating potential
Clamping the acoustic tubing with ABR testing should eliminate a true CM thus differentiating cochlear activity from _________ _________.
Stimulus artifact
_____ is a 180 degree reversal in polarity of the response waveform associated with a change in the polarity of the stimulus.
Cochlear microphonic
__________ abnormalities due to hyposia and genetic etiologies appear to account for a substantial number of at risk infants with hearing loss.
IHC
AN is some evidence of ______ integrity with neural _________.
Cochlear
dysfunction
ENnoG Facts
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-
Terminology of Facial nerve injury
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
Methods of FN assessment
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
House-Brackmann Grading system
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
ENoG Protocol
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
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]
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.
VEMPS are sometimes referred to as “_______-________reflexes.
Sono-Motor
(reflex stimulated by sound)
Similar to the acoustic reflex or PAM, however, it is unilateral. It is stimulated ipsilaterally
The VEMP can be stimulated and recorded in deaf persons?
TRUE
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)
following the presentation of a high-intensity sound, there is a temporary reduction in muscle activity, recorded as the positive wave
VEMP Pathways
The pathway is sound-tympanic membrane-ossicles-saccule-inferior vestibular nerve-vestibulospinal tracts-sternocleidomastoid muscle.
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.
VEMP

Stimulus Factors are What 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.
VEMP Protocols
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
Three techniques are reported for producing and maintaining contraction of the SCM muscles.
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
VEMP analysis
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.
VEMP latency is quite consistent among subjects, but intersubject VEMP amplitude is highly variable,
NONPATHOLOGIC FACTORS affecting VEMP
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
PATHOLOGIC FACTORS affecting VEP
conducive hearing loss.
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
Important names in ECochG
Wever and Bray discovered CM
Andreev
Sohmer
Coats
Gibson
Factors affecting AERs
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
Objectives of ABR
-rule out or confirm periph hearin gloss
-differentiate between conductive vs sensory loss
-rule out retrocochlear loss
-estimate degree of hearing loss
ABR normative mneumonic
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
ABR latencies and hearing
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
Relationships in ABR latencies
-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
Tone burst ABR
presence or absence of response is more important than latency
Important names in ABR
-Davis, 1979 coined ABR
-Jewett and Williston, roman numerals
-Moller, Hashimoto - wave I distal 8th nerve
ASSR
-similar to ABR
-insert earphones
-surface electrodes
-averaging computer
-rapid modulation of carier tone amp or freq
Important names in ASSR
Austrailian
-Rickards
-Clark
-Rance
Canadian
-Linden
-Picton
-Stapells
ABR vs ASSR
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
Auditory dysfunction and ABR and ASSR
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
Sedation and ASSR
-slower rates, cortical testing more affected
-faster rates are brainstem and not affected
important people and AMLR
-Geisler- founder
-Kilney
-Kraus
-Lee
Components of AMLR
Na
Pa
Nb
Pb
Pa major component
-22-30 ms
-1 microvolt

near field response electrode needs to be on the temporal lobe
nonpathologic factors influencing AMLR
-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)
ALR waves
N1
N1b
N1c
N150
N400
-sustained negativity for duration of stim
Oddball paradigm
-positive and negative waves
-MMN
-P300
-P3a
ALR subject factors
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
Name with P300
Hallowell Davis
Samuel Sutton
Oddball paradigm
-peak at least 10 microvolts @300 ms
--80% stimulus are frequent
-20% are infrequent
passive P300
-smaller amp
-shorter latency
-can easily be recorded
clinical assessment of APD with P300
-use speech in noise and temporal processing (gap detection)
-analyze: latency, amp, amp under the curve
MMN people
-Naatanen, finnish
-Kraus, US
-Picton, Canada
MMN generators
supratemporal plane of the primary aud cortex
-frontal cortex
-possibly thalamus and hippocampus
MMN measurement
deviant wave-stadard wave=MMN
MMN and brain processes
-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
MMN stimuli
-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
P300 vs MMN
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
Why is MMN not used clincially
-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
important name in Electroneurography
Ugo Fisch, swiss,
1974
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
What how is degeneration of the 7th nerve determined in ENoG?
-compare uninvolved side to involved side
-100-(amp of involv/amp of uninvolv x 100) = % of degeneration
90% or more is considered significant
Important names in Auditory Neuropathy
Star
Picton
Sininger
Hood
Berlin
What factors influence ABR
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.
Some non-auditory evoked responses
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
Electrically Evoked Compound Action Potentials (ECAP)
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)
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
Electrically Evoked Cortical Auditory Evoked Responses (EAMLR, EALR, EP300, EMMN)
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
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
E EAP Anatomy
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
E EAP protocol
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
ECAP
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)
Masker-Probe Subtraction Technique
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.
ECAP Measurement Types
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
ECAP Clinical Applications
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
Electrically Evoked Auditory Brainstem Response (EABR)
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
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
EABR Artifact
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
Clinical Applications of EABR
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
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
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”
Electrically Evoked Auditory Late Response (EALR)
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
Electrically Evoked P300
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
Electrically Evoked MMN
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
ECochG
Enhance ABR Wave I
Diagnose auditory neuropathy
Diagnose Meniere’s disease
Intraoperative monitoring
ABR
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.
ASSR
Auditory threshold estimation: adults and children.
AMLR
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.
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.
P300
Assessment of higher level auditory processing.
Documentation of effectiveness of medical and nonmedical management for different disorders (APHD, APD).
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.
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
ENoG
Clinical Assessment of Facial Nerve Function
Important people in ECochG
Discovered by
Wever and Bray, 1930
Hallowell Davis (father of AER)
Joseph Eggermont, Menieres
Jay Hall
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
Important people in ASSR
Terry Picton
Stapells
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
Important people in ALR
Hallowell Davis
Pauline Davis
Important people in P300
Hallowell Davis -1964
Samuel Sutton -1965
Important people in MMN
Discovered by
Dr. Risto Naatanen, 1975
Nina Kraus
Important people in OAEs
Dr. David Kemp, 1978
Important people in ENoG
Dr. Ugo Fisch