Transcript Hall, Update for Aud Electrophys, Part I

Update on Auditory Electrophysiology
James W. Hall III, PhD
Adjunct Professor
Nova Southeastern University
Salus University
University of Florida
Extraordinary Professor
University of Pretoria South Africa
[email protected] www.audiologyworld.net
James W. Hall III Audiology Consulting, LLC
Update on Auditory Electrophysiology
 Introduction to auditory electrophysiology … 85-years of
research and clinical application
 Electrocochleography (ECochG) … It’s for much more than
just the diagnosis of Meniere’s Disease
 ABR … Over 4000 peer-reviewed publications in the past
decade alone
 ASSR … Filling an important niche in auditory assessment of
children and adults
 Cortical auditory evoked responses … Now we’re really
assessing hearing
 Summary, Questions & Answers
Update on Auditory Electrophysiology:
Objective Assessment from Cochlea to Cortex
 Cortical auditory evoked
responses
 P300 response and other
cognitive evoked responses
 Auditory late response (ALR)
 Auditory middle latency
response (AMLR)
 Auditory steady state response
(ASSR)
 Auditory brainstem response
(ABR)
 Electrocochleography (ECochG)
Update on Auditory Electrophysiology:
Behavioral Audiometry Isn’t Always Enough
 Auditory electrophysiology is feasible in patients who
cannot be assessed validly with behavioral techniques
 Newborn and older infants
 Difficult-to-test children
 Sick patients
 False and exaggerated hearing loss, e.g.,
 Pseudohypacusis
 Functional hearing loss
 Non-organic hearing loss
 “Crocks”
Update on Auditory Electrophysiology:
Behavioral Audiometry Isn’t Always Enough
 Auditory electrophysiology is feasible in sleeping and
unconscious patients
 Naturally sleeping children or adults
 Children who are sedated or anesthetized for auditory
assessment
 Anesthetized patients undergoing surgery who require
intra-operative neurophysiologic monitoring
 Comatose head-injured patients who require intensive
care unit monitoring
 Automated auditory electrophysiology procedures can be
performed by non-audiologic personnel for early newborn
hearing screening (e.g., automated ABR)
Update on Auditory Electrophysiology:
Behavioral Audiometry Isn’t Always Enough (2)
 Auditory electrophysiology has greater sensitivity to
auditory function than behavioral audiometry (e.g., ABR in
early identification of retrocochlear dysfunction)
 Auditory electrophysiology has greater site specificity to
auditory function than behavioral audiometry, e.g.,
 ECochG differentiates sites of dysfunction in auditory
neuropathy spectrum disorder (ANSD)
 ABR differentiates among cochlear, eighth nerve, and
brainstem sites of dysfunction
 Cortical auditory evoked responses specify site of
dysfunction with central auditory nervous system
Update on Auditory Electrophysiology
 Introduction to auditory electrophysiology … 85-years of
research and clinical application
 Electrocochleography (ECochG) … It’s for much more than
just the diagnosis of Meniere’s Disease
 ABR … Over 4000 peer-reviewed publications in the past
decade alone
 ASSR … Filling an important niche in children and adults
 Cortical auditory evoked responses … Now we’re really
assessing hearing
 Summary, Questions & Answers
Original Description of
Electrocochleography (ECochG)
Wever EG and Bray CW.
1930. Action currents in the
auditory nerve in response
to acoustic stimulation.
Proceedings of the National
Acad of Science (USA) 16:
344-350.
Wever EG and Bray CW. 1930.
Auditory nerve impulses.
Science 71: 215.
E. Glen Weaver, Ph.D.
(October 16, 1902 — September 4, 1991)
ELECTROCOCHLEOGRAPHY:
85 Years Old and Still Clinically Important!
Ruben
(CM & AP clinically)
Fromm et al
(CM in human)
Tasaki
(AP in human)
Davis
(SP)
Yoshie,
Portmann
(TT CM & AP)
Wever & Bray
(CM in cat)
1930 1935
Coats
(EAC)
Coats,
Eggermont,
Gibson
(Dx of MD)
Various
Hall
(I/O) (ANSD, CI)
1950 1954 1960 1967 1974 1990 1996
Time in Years
Electrocochleography (ECochG):
Generators
 Cochlear microphonic (CM)
 Outer hair cells
 Receptor potentials
 Summating potential (SP)
 Inner hair cells (> 50%)
 Outer hair cells
 Organ of Corti
 Action potential (AP)
 Afferent fibers in distal 8th cranial nerve
 Spiral ganglion
AP
SP
CM
Electrocochleography (ECochG):
Stimulus Polarity is Important
ECochG Electrode Options:
The Closer to the Cochlea, the Better
TipTrode
Trans-Tympanic
Promontory
Electrode
TM Electrode
TIPtrode:
Part Transducer and Part Electrode
Sub-Dermal Needle Electrode for Trans-Tympanic
Promontory ECochG Recording
ELECTROCOCHLEOGRAPHY (ECochG):
“Traditional” Clinical Applications
 Estimation of auditory sensitivity in young and difficult-totest children
 Enhancement of wave I in ABR measurement
 Enhance inter-wave latency analysis in neuro-diagnosis
 Confirm ear-specific test findings for AC and BC ABR
(wave I is a biological marker for ipsilateral 8th nerve)
 Minimize the need for masking of non-test ear
 Intra-operative neurophysiological monitoring
 Prompt documentation of cochlear status
 Enhance inter-wave latency analysis
 Diagnosis of Meniere’s disease
“Traditional” Clinical Applications of ECochG:
Enhanced Wave I and I/O Monitoring
ECochG in Diagnosis of Meniere’s Disease:
Abnormally Large SP/AP Ratio
Coats AC (1981). The summating potential in Meniere’s and non-Meniere’s ears.
Archives of Otolaryngology, 107, 199-208
ELECTROCOCHLEOGRAPHY: Selected Papers
(PubMed Search on 9/9/14 at www.nlm.nih.gov with key words “Meniere’s
Disease” and “electrocochleography” showed > 400 publications)
 Pou, Hirsch, Durrant et al. (1996). Efficacy of tympanic ECochG in the





diagnosis of endolymphatic hydrops. AJO, 17
Levine, Margolis, Daly. (1998). Use of ECochG in the diagnosis of
Meniere’s Disease. Laryngoscope,108
Orchik, Shea, Ge. (1998). Summating potential and action potential
ratio in Meniere’s Disease before and after treatment. AJO, 19
Zack-Williams et al (2012). A comparison of ECochG and high-pass
noise masking of ABR for diagnosis of Meniere’s disease. Int J Audiol,
51, 783-787
Claes et al (2013). Does “cochlear Meniere’s disease exist? An
ECochG and audiometric study. Audiol Neurotol, 18, 63-70
Oh et al (2014). Can we use ECochG as a clinical tool in the diagnosis
of Meniere’s disease during the early symptomatic period? Acta
Otolaryngol, 134, 771-775
ELECTROCOCHLEOGRAPHY (ECochG):
More Recent Clinical Applications
 Auditory dysfunction in tinnitus
 Cochlear and round window (Soundbridge) implants
 Round window and intra-cochlear recordings
 Intra-operative verification of cochlear implant function
 Intra-operative documentation of low frequency cochlear
function during electrode insertion
 Prediction of speech perception outcomes
 Diagnosis of auditory neuropathy spectrum disorder (ANSD)
 Differentiation of pre- versus post-synaptic auditory
dysfunction
ELECTROCOCHLEOGRAPHY (ECochG):
Cochlear Implant Applications
 Harris et al (2011). Preliminary results and technique for
electrophysiological intra-operative monitoring of residual
hearing during cochlear implantation. Cochlear Implants Int, 12,
209-215
 Mandala et al (2012). Electrocochleography during cochlear
implantation for hearing preservation. Otolaryngol Head Neck
Surg, 146, 774-781
 Calloway et al (2014). Intracochlear electrocochleography during
cochlear implantation. Otol Neurotol, 35, 1451-7
 McClellan et al (2014). Round window electrocochleography and
speech perception outcomes in adult cochlear implant subjects:
Comparison with audiometric and biographical information. Otol
Neurotol, Epub
Role of ECochG in the Diagnosis and Management of
Auditory Neuropathy Spectrum Disorder (ANSD)
Cerebello-pontine angle (CPA)
Internal Auditory Canal
(Auditory Nerve)
Spiral ganglion cells
IHC - 8th CN Synapse
(glutamate)
Inner hair cells
Outer hair cells
Electrococheography (ECochG):
Diagnosis of Auditory Neuropathy Spectrum Disorder
 Guidelines for the Identification and
Management of Infants and Young
Children with Auditory Neuropathy (2010).
 Panel of Experts:
 Yvonne Sininger, Ph.D.
 Arnold Starr, M.D.
 Christine Petit, M.D., Ph.D.
 Gary Rance, Ph.D.
 Barbara Cone, Ph.D.
 Kai Uus, M.D., Ph.D.
 Patricia Roush, Au.D.
 Jon Shallop, Ph.D.
 Charles Berlin, Ph.D.
Identification and Diagnosis of
Auditory Neuropathy Spectrum Disorder (ANSD):
Minimal Test Battery (2010 ANSD Guidelines)
 Tests of cochlear hair cell function
 Otoacoustic emissions (OAEs)
 Cochlear microphonic (ECochG and ABR)
 CM may be present when OAEs are absent (e.g., with middle ear
dysfunction)
 Tests of auditory nerve function
 ABR for high intensity click stimulation (e.g., 80 to 90 dB nHL) with
separate averages for:
 Rarefaction stimulus polarity
 Condensation stimulus polarity
 Additional tests
 Acoustic reflex measurement (generally acoustic reflexes are absent in
ANSD)
 Suppression of otoacoustic emissions (abnormal, e.g, no suppression
in ANSD)
Essential Role of Electrocochleography (ECochG) in the
Diagnosis and Management of Auditory Neuropathy
Spectrum Disorder (ANSD): Medical diagnoses (1)
 Perinatal Diseases
 Hyperbilirubinemia
 Hypoxic insults
 Ischemic insults
 Prematurity
 Neurological Disorders
 Demyelinating diseases
 Hydrocephalus
 Immune disorders, e.g., Guillain-Barre sydrome
 Inflammatory neuropathies
 Severe developmental delay
Essential Role of Electrocochleography (ECochG) in the
Diagnosis and Management of Auditory Neuropathy
Spectrum Disorder (ANSD): Medical diagnoses (2)
 Neuro-metabolic diseases
 Genetic and Hereditary Etiologies
 Family history
 Connexin mutations, e.g., GJB3 (D66del)
 Otoferlin (OTOF) gene
 Non-syndromic recessive auditory neuropathy
 Hereditary motor sensory neuropathies (HMSN), e.g.,
Charcot-Marie-Tooth syndrome
 Leber’s hereditary optic neuropathy
 Waardenburg’s syndrome
 Neurogenerative diseases, e.g., Friedreich’s ataxia
 Mitochondrial disorders, e.g., mitochondrial enzymatic
defect
Other Procedures Important in the Diagnosis and Management
of Auditory Neuropathy Spectrum Disorder (2008 Guidelines)
 Components of assessment
 Pediatric and developmental history
 Otologic evaluation, plus
Imaging of cochlea with CT
Imaging auditory nerve with MRI
 Medical genetics evaluation
 Ophthalmologic evaluation
 Neurological evaluation to assess:
Peripheral nerve function
Cranial nerve function
 Communication assessment
Comprehensive Assessment of
Auditory Neuropathy Spectrum Disorder (ANSD):
MRI of Auditory Nerve
 Brainstem and inner ear abnormalities in children with auditory
neuropathy spectrum disorder and cochlear nerve deficiency. Huang
et al. (UNC). American J Radiol, 31, 2010
• CND was identified in 33.0% of children and 26.9% of ears with
ANSD
• Significantly more patients with bilateral CND had intracranial
abnormalities than those with unilateral CND (60.0% versus
15.8%).
 Unilateral auditory neuropathy caused by cochlear nerve deficiency.
Liu et al (China). Int J Otolaryngol, 2012.
• Cochlear nerve deficiency can be seen by electrophysiological
evidence and may be a significant cause of unilateral AN.
• Inclined sagittal MRI of the internal auditory canal is
recommended for the diagnosis of this disorder.
Auditory Neuropathy Spectrum Disorder ANSD):
Defining Site of Dysfunction is the Key to Accurate Diagnosis
and Effective Management
Action potential (AP)
Summating potential (SP)
Cochlear microphonic (CM)
ECochG in ANSD:
Refining Diagnosis of Site of Dysfunction
 Santarelli, Starr, Michalewski & Arlsan (2008). Neural and receptor
cochlear potentials obtained by transtympanic
electrocochleography in auditory neuropathy. Clinical
Neurophysiology, 119, 1028-1041.
 8 subjects (with AN versus 16 normal subjects (5-48 years)
 Diagnosis: Presence of DPOAEs and absence of ABR
 Enlarged CM in AN patients
 Etiology
 Hereditary (3)
Immunolological (3)
 Degenerative (1)
Congenital (1)
 ECochG measures included
 CM
 SP
 AP
ECochG in ANSD:
Refining Diagnosis of Site of Dysfunction (1)
 McMahon, Patuzzi, Gibson & Sanli. (2008) Frequencyspecific electrocochleography indicates that presynaptic and
postsynaptic mechanisms of auditory neuropathy exist. Ear
& Hearing, 29, 314-325.
 Subjects
14 subjects (7 male and 7 female) with AN versus 2
normal subjects( Dx at 3-24 months)
Diagnosis: large CM potentials and absent ABR
Genetic etiology for 6 subjects
Severe to profound audiometric thresholds
All subjects received cochlear implants
 ECochG recorded with non-inverting “golf club” electrode
near round window electrode via myringotomy
ECochG in ANSD: Examples of ECochG Components
(McMahon et al, 2008)
CM
Condensation
Rarefaction
Alternating
N2
SP
N1
DP (dentritic potential)
Analysis Time
10 ms
ECochG in ANSD:
Refining Diagnosis of Site of Dysfunction (2)
 McMahon, Patuzzi, Gibson & Sanli. (2008) Frequencyspecific electrocochleography indicates that presynaptic
and postsynaptic mechanisms of auditory neuropathy
exist. Ear & Hearing, 29, 314-325.
 Purpose of study was to better define physiology
mechanisms of AN to guide management including
cochlear implantation
 ECochG in AN consistent with:
Pre-synaptic mechanism (abnormal SP) = good EABR
and CI benefit
Post-synaptic mechanism (normal SP + dentritic
potential) but no AP = poor or absent EABR and poor
CI benefit
Update on Auditory Electrophysiology
 Introduction to auditory electrophysiology … 85-years of
research and clinical application
 Electrocochleography (ECochG) … It’s for much more than
just the diagnosis of Meniere’s Disease
 ABR … Over 11,000 peer-reviewed publications with > 4000
within the past decade alone!
 ASSR … Filling an important niche in children and adults
 Cortical auditory evoked responses … Now we’re really
assessing hearing
 Summary, Questions & Answers
The First Comprehensive Description of the
Auditory Brainstem Response (ABR) in Humans
Jewett D and Williston J.
Auditory evoked far fields
averaged from the scalp of
humans.
Brain 4: 681-696, 1971.
Don Jewett
Jewett & Williston, 1971
Normal Subject Waveform Consistency …
the Ideal Clinical Tool
Auditory Brainstem Response (ABR):
An Evidence-Based Test Protocol
0.5 uV
I
Stimulus
Clicks
Tone bursts
Speech
Electrodes
Auditory Evoked
Response System
Filters
Amplifiers
Signal Averager
III
V
8 ms
Generators of ABR Waves:
A Far-Field Response from Sub-Cortical Auditory Pathways
 Generator sites
 I = Distal auditory nerve
 III = Caudal brainstem
 V = Lateral lemniscus
 Relation between anatomy and
response
 Multiple structures contribute to
single waves
 Waves reflect axonal activity
 Laterality
 Wave I = ipsilateral to stimulus
 Waves III and V = contralateral to
stimulus
Robert Galambos, MD, PhD
Director of the Laboratory (Yale University) Where the ABR was
“Discovered” and Pioneer of Early Pediatric Applications of ABR
 1974: Hecox KE & Galambos R. Brain
stem auditory evoked responses in
human infants and adults. Archives
of Otolaryngology 99.
 1975: Schulman-Galambos C. &
Galambos R. Brain stem evoked
responses in premature infants.
JSHR 18.
 1979: Schulman-Galambos C. &
Galambos R. Brain stem evoked
response audiometry in newborn
hearing screening. Archives of
Otolaryngology 105:
James Jerger, Ph.D.
“Father of Diagnostic Audiology”
Baylor College of Medicine and Methodist Hospital, Houston TX
Larry Mauldin Circa 1975
Helped Build
Early AER System
The Cross-Check Principle in Pediatric Audiology
(Jerger J & Hayes D. Arch Otolaryngol 102: 1976)
The Cross-Check Principle Pediatric Audiology
(Jerger J & Hayes D. Arch Otolaryngol 102: 1976)
“We have found than simply observing the auditory behavior of children
does not always yield an accurate description of hearing loss”…
“The basic operation of this principle is that no result be accepted until it
is confirmed by an independent measure.”
Test Battery:
• Behavioral audiometry
• Immittance (impedance) measurements
 Tympanometry
 Acoustic reflexes (contralateral only with SPAR)
• Brainstem-evoked response audiometry (BSER now ABR)
 Click stimulus air conduction
 Click stimulus bone conduction
1948 Vintage Audiologist Using 1980 Model Nicolet CA1000 with Infamous “Aural Dome” TDH Earphones
40 Years of Evidence-Based ABR Applications
(> 11K Pubs) Since Hecox & Galambos (1974)
 Newborn hearing screening
 Diagnosis of hearing loss in infants and young children
 Frequency-specific estimation of auditory sensitivity
 Differentiation of conductive vs. sensorineural hearing loss
 Neuro-diagnosis of retrocochlear and brainstem disorders in
children and adults
 Neurophysiological monitoring
Intra-operative during surgical procedures
Neuro-intensive care unit in head injured patients
 Description of neural representation of auditory processing in
brainstem with speech evoked ABR
Auditory Brainstem Response:
The Research Continues Unabated
(> 350 Publications Each Year)
 Descriptions of ABR applications in new clinical entities and
populations
 Replications of traditional ABR studies in countries with
emerging or rapidly growing audiology communities, e.g.,
India, China, Brazil, Brazil, Iran
 Studies of auditory processing with speech evoked ABR
 Investigations of new technology for ABR measurement
Auditory Brainstem Response:
Applications in New Clinical Entities and Populations
(Plus new technology and studies in emerging audiology countries)
 Elkabariti et al (2014). Speech evoked auditory brainstem
response findings in children with epilepsy. Int J Pedi ORL,
78, 1277-80 (Egypt)
 Talebi & Rezazadeh (2012). The role of ABR in diagnosing
auditory impairments of Dejerine-Sottas. Int J Pedi ORL, 76,
915-917 (Iran)
 Jecmenica & Opancina (2014). Characteristics of brain stem
auditory evoked potentials in children with hearing
impairment due to infectious diseases. J Child Neurol, Epub
(Serbia)
Auditory Brainstem Response:
Applications in New Clinical Entities and Populations
 Allen & Allan (2014). Auditory processing disorders:
Relationship to cognitive processes and underlying neural
integrity. Int J Pedi ORL, 78, 198-208 (click ABR and ARs)
 Hasani & Jafari (2013). Effect of infant prematurity on ABR at
preschool age. Iran J ORL, 25, 107-114 (Iran)
 Kouni et al (2013). Brainstem auditory evoked potentials for
acoustic clicks and complex verbal sounds in young adults
with learning disabilities. Am J Otolaryngol, 34, 646-651
(Greece)
 Quevedo et al (2012). Auditory brainstem response in gas
station attendants. Brazilian J ORL, 78, 63-68
 Weich et al (2012). Brain stem evoked response audiometry in
former drug users. Brazilian J ORL, 78, 90-96
Auditory Brainstem Response:
Revisiting Old Research Topics
 Stevens et al (2013). ABR in newborns: Effects of electrode
configuration, stimulus rate, and EEG rejection levels on test
efficiency. Int J Audiol, 52, 706-712
 Liu & Liu (2013). Hearing screening and diagnosis in a large
sample of infants in central China. J Med Screen, 20, 21-26 (N =
11,894)
 Vinodh et al (2014) Reversibility of brainstem evoked response
audiometry abnormalities at 3 months in term newborns with
hyperbilirubinemia. Indian Pediatr, 51, 134-135 (India)
 Jiang & Wilkinson (2014). Impaired function of the ABR in term
neonates with hyperbilirubinemia. Brain Dev, 36, 212-218
(China)
Auditory Brainstem Response:
Revisiting Old Research Topics
 Mann et al (2012). Brainstem auditory evoked responses in
different phases of menstrual cycle. J Clin Diagn Res, 6, 16401643 [Do you remember? Doty RL, Hall JW III, Flickinger GL, Sondheimer
SJ. Cyclical changes in olfactory and auditory sensitivity during the menstrual
cycle: No attenuation by oral contraception medication. In Olfaction and
Endocrine Regulation. Breipohl H (ed). London: I.R.L. Press, 1982]
 Rosa et al (2014). ABR: Reference-values for age. Codas, 26,
117-121 (Brazil) Naves et al (2012). Assessment of interexaminer agreement and variability in the manual classification
of ABR. Biomed Eng Onine, 22, 11-16
 Koors, Thacker & Coelho (2013). ABR in the diagnosis of
vestibular schwannomas: A meta-analysis. Am J Otolaryngol,
34, 195-204
Auditory Brainstem Response:
Innovative New Applications
Ramkumar, Hall et al (2013). Tele-ABR using a satellite
connection in a mobile van for newborn hearing testing. J
Telemed Telecare, 19, 233-237
Auditory Brainstem Response:
Speech Evoked ABR Assessment of Auditory Processing
 Rance et al (2012). Auditory processing deficits in individuals
with open-angle glaucoma. Int J Audiol, 51, 10-15
 Fujihara & Shiraishi (2014). Correlations between word
intelligibility under reverberation and speech ABRs in elderly
listeners. Clin Neurophysiol, Epub (Japan)
 Malveri et al (2014). Brainstem response to speech and nonspeech stimuli in children with learning problems. Hear Res,
313, Epub (Iran)
 Krisnamurti et al (2013). A case study of the changes in the
speech-evoked ABR associated with auditory training in
children with auditory processing disorders. Int J Pedi ORL,
77, 594-604
Auditory Brainstem Response:
Speech Evoked ABR Assessment of Auditory Processing
(www.brainvolts.northwestern.edu)
 Skoe, Krizman, Spitzer &
Kraus (2013). The auditory
brainstem is a barometer of
rapid auditory learning.
Neuroscience, 243, 104-114
 Hornickel, Lin & Kraus
(2013). Speech-evoked
ABRs reflect familial and
cognitive influences. Dev
Sci, 16, 101-110
Speech-Elicited ABR: Nina Kraus at Northwestern University
Auditory Neuroscience Laboratory
(www.brainvolts.northwestern.edu)
Fidelity to the Stimulus
Amplitude
Experience-Dependence
Frequency (Hz)
Auditory Brainstem Response:
Investigations of New Technology for Measurement
 Neumann & Indermark (2012). Validation of a new TEOAEAABR device for newborn hearing screening. Int J Audiol, 51,
570-575
 Valderrama et al (2012). Recording of ABR at high stimulation
rates using randomized stimulation and averaging. JASA, 132,
3856-3865 (Spain)
 Muhler et al (2013). ABRs to broad-band chirps: Amplitude
growth functions in sedated and anaesthetised infants. Int J
Pedi ORL, 77, 49-53
:
ABR Investigations of New Technology for Measurement:
Chirp Stimuli
 Cebulla & Shehata-Dieler (2012). ABR-based newborn hearing
screening with MB11 BERAphone using an optimized chirp for
acoustical stimulation. Int J Pedi ORL, 76, 536-543 (N = 6866)
 Rodrigues et al (2013). Comparing auditory brainstem
response to tone burst and narrow band CE-chirp in young
infants. Int J Pedi ORL, 77, 1565-60 (Brazil) Stuart & Cobb
(2014). Effect of stimulus and number of sweeps on the
neonate ABR. Ear Hear, 35, 585-588 [chirp]
 Xu et al (2014). Prediction of frequency-specific hearing
threshold using chirp ABR in infants with hearing losses. Int J
Pedi ORL, 78, 812-816
Year 2007 Joint Committee on Infant Hearing (JCIH): Protocol for
Evaluation for Hearing Loss In Infants from Birth to 6 months




Child and family history
Evaluation of risk factors for congenital hearing loss
Parental report of infant’s responses to sound
“Clinical observation of infant’s auditory behavior. Behavioral observation alone is not
adequate for determining whether hearing loss is present in this age group, and is not
adequate for the fitting of amplification devices.”
 Audiological assessment
 Auditory brainstem response (ABR)
 Click-evoked ABR with rarefaction and condensation single-polarity stimulation if
there are risk factors for auditory neuropathy
 Frequency-specific ABR with air-conduction tone bursts
 Bone-conduction stimulation (as indicated)
 Otoacoustic emissions (distortion product or transient OAEs)
 Tympanometry with 1000 Hz probe tone
 Supplemental procedures, e.g.,
 Electrocochleography (ECochG)
 Auditory steady state response (ASSR)
 Acoustic reflex measurement (for 1000 Hz probe tone)