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UPDATING THE
ELECTROPHYSIOLOGY IN
NEONATAL HEARING EVALUATION
José J. Barajas de Prat
IAPA Summer School 2008
Neonatal Hearing Screening and Auditory Neuropathy
Berlin, Germany
April 10th and 11th
WHAT SHOULD THE IDEAL INFANT HEARING
ASSESSMENT?
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Must be applicable to neonates and children
Measure Hearing sensitivity from 250-8 kHz
Assess hearing sensitivity for mild to severeprofound hearing loss
Objectively detect an infant´s response to sound
ELECTROPHYSIOLOGIC TECHNIQUES
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Click and tone- burst evoked ABR
Evoked potentials for tones that are amplitude
and/or frequency modulated
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Auditory-steady state responses (ASSR)
AMLR and 40 Hz
Cortical AEPs
LIMITATIONS OF CONVENTIONAL EVOKED
POTENTIAL TESTS
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Click ABR:
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TB-ABR:
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Cannot be used to estimate the 4 frequency (500-4000 Hz)
audiogram
Lenghtly procedure, relies on subjective analysis of
waveforms
AMLR, 40 Hz and CAEP:
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Unreliable during natural or sedated sleep on infants and
children
CAEP methods with quietly awake infants may hold promise
for estimates of thresholds and speech feature discrimination
abilities
AUDITORY STEADY STATE RESPONSE (ASSR)
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Can be recorded in neonates and children
Are evoked by frequency –specific tonal stimuli
Correlate with elevation in the hearing
thresholds
Can be objectively evaluated
Are used to estimate an audiogram
Jose J. Barajas. (1985). Auditory Brainstem and Middle Latency Response in Early
Detection of Hearing Loss in Infants. New dimensions in otorhinolaryngology – head and
neck surgery (1); pp 289-292.
40 Hz
Jose J. Barajas. (1988). Middle Latency and 40 Hz Auditory Evoked Responses in normal
hearing children: 500 Hz thresholds.Scand Audiol Supp 30:99-104
MEASUREMENTS OF SIGNAL AND NOISE AT DIFFERENT
RATES
Picton TW, John MS, Dimitrijevic A, Purcell D. Human auditory steady-state responses. Int J
Audiol. 2003 Jun;42(4):177-219.
UPDATING THE ELECTROPHYSIOLOGY IN
NEONATAL HEARING
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ASSR in newborns
AEP and early hearing aid fitting and validation
ASSR
 CAEP (Obligatory Cortical Auditory Evoked
Potentials)
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AEP: Cochlear Implants validation
ASSR IN NEWBORNS
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ASSR characteristics in newborns:
The neonatal ASSR
 Amplitude Development in Infants
 Detection of ASSR in the neonatal infant period
 ASSR threshold in babies
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THE NEONATAL ASSR
AVERAGED AMPLITUDE FOR NORMAL- HEARING
INFANTS AND ADULTS
Luts H, Desloovere C, Wouters J.2006. Clinical application of dichotic multiple-stimulus auditory
steady-state responses in high-risk newborns and young children. Audiol Neurootol.;11(1):24-37.
AMPLITUDE DEVELOPMENT
Johns MS, Brown DK, Muir PJ, Picton TW (2004) . Recording Auditory Steady State responses in
young infants. Ear Hear Dec, 25 (6) 539-53.
DETECTION OF ASSR IN THE NEWBORN
Is determine by:
 Amplitude of the response:
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Stimulus type
Modulation rate
Carrier frequency
Electrode configuration
Amplitude of the background noise:
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State of arousal
EEG frequency range
Test duration
OPTIMAL MODULATION RATE FOR EACH CARRIER
500 Hz
1500 Hz
4000 Hz
Rickards FW, Tan LE, Cohen LT, Wilson OJ, Drew JH, Clark GM. (1994). Auditory steady-state
evoked potential in newborns. Br J Audiol.;28(6):327-37.
ASSR THRESHOLDS IN BABIES
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Threshold values
Threshold changes in infancy
Development mechanism affecting ASSR
ASSR vs Tone burst ABR in neonates
ASSR THRESHOLD IN BABIES
Luts, H. “Diagnosis of Hearing Loss in Newborns. Clinical Application of Auditory
Steady- State responses”. Director: Prof. Dr. J. Wouters . Katholieke Universiteit Leuven,
Faculty of Medicine, 2005
ASSR THRESHOLD CHANGES IN INFANCY
Rance, G. & Tomlin, D. (2006). Maturation of ASSR in nomal babies. Ear & Hearing,
27, 20-29.
DEVELOPMENTAL MECHANISMS AFFECTING ASSR
THRESHOLD IN INFANCY
Rance G, Tomlin D. (2006). Maturation of auditory steady-state responses in normal
babies. Ear Hear.;27(1):20-9.
ASSR & TONE-BURST ABRs IN NEONATES
Rance G (2008). Assr in Neonates & Infants. In Auditory Steady-State Response
Generation, Recording, and Clinical Applications. Gary Rance
HEARING LEVEL PREDICTION
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Sensation level
Regresion formula describing ASS behavioral
regression
ASSRs IN HEARING IMPAIRED BABIES
Rance G (2008). ASSR in Neonates & Infants. In The Auditory Steady-State
Response: Generation, Recording, and Clinical Applications. Edited by Gary Rance.
In review.
HEARING LEVEL PREDICTION
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For older children and adult subjects
ASSR/behavioral threshold correlation has been
empirically established
In normally developing babies this relationship
is NOT well defined.
ASSR threshold variance in babies is higher than
for adults (> 30 dB)
Ear canal differences.
 Neural development.
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CONCLUSION
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Maturation factors affect ASSR.
Normally hearing babies present lower
amplitudes than adults and older children.
Neonatal period threshold higher and more
variable.
Need to determine typical response levels for
babies of different ages and developmental
stages.
UPDATING THE ELECTROPHYSIOLOGY IN
NEONATAL HEARING EVALUATION


ASSR in newborns
AEP and early hearing aid fitting and validation
ASSR
 CAEP (Obligatory Cortical Auditory Evoked
Potentials)


AEP: Cochlear Implants Evaluation
LOUDNESS AND ASSR
Zenker Castro F., Barajas de Prat JJ & Larumbe Zabala E. (2008): Loudness and
Auditory Steady State responses in normal hearing subjects. International Journal of
Audiology. In press.
HEARING AID PRESCRIPTION FROM ASSR
Zenker F. & Barajas J.J.(2008) ASSRs: Their role in hearing device fitting. In: The
Auditory Steady State response: generation, recording and clinical application. Edited
by Gary Rance.
UPDATING THE ELECTROPHYSIOLOGY IN
NEONATAL HEARING


ASSR in newborns
AEP and early hearing aid fitting and validation
ASSR
 CAEP (Obligatory Cortical Auditory Evoked
Potentials)


AEP: Cochlear Implants validation
TYPES OF AER THAT HAVE BEEN USED TO
OBJECTIVELY EVALUATE HEARING AIDS FUNCTION
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Auditory Brainstem Responses (ABR)
Auditory Steady state Responses (ASSR)
Obligatory Cortical Auditory Evoked Potential
(CAEP)
Why are we using obligatory cortical responses to
evaluate hearing aid function?
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More likely to correlate well with perception.
Can be elicited by a range of speech phonemes.
Reliable present in awake young infants.
Can be present in children with auditory
neuropathy/dys-synchrony.
CAEP
Suzanne C. Purdy et al. (2004). Aided cortical auditory evoked potentials for hearing
instrument evaluation. 3rd Pediatric Conference “A Sound Foundattion through early
amplification”. Chicago, Illinois
MATURATIONAL EFFECTS ON CORTICAL EVOKED
RESPONSE
Ponton et al. (2000) Maturation human central auditory system activity: evidence from
multi-channel evoked potentials. Clinical Neurophysiology 111 (2): 220-236
CAEP CAN ELICITED BY DIFFERENT SPEECH
PHONEMES IN NEWBORNS
D. KURTZBERG 1989
HEARING AID GAINS AND CAEP AMPLITUDE
Suzanne C. Purdy et al. (2004). Aided cortical auditory evoked potentials for hearing
instrument evaluation. 3rd Pediatric Conference “A Sound Foundattion through early
amplification”. Chicago, Illinois
P1 IN HEARING AIDS
Anu Sharma, Emily Tobey, Michael Dorman, Sneha Bharadwaj, Kathryn Martin, Phillip Gilley, Fereshteh Kunkel. Central
Auditory Maturation and Babbling Development in Infants With Cochlear Implants. ARCH OTOLARYNGOL HEAD
NECK SURG/VOL 130, MAY 2004.
P1 IN COCHLEAR IMPLANTS
Anu Sharma, Michael F. Dorman, Andrej Kral. (2005). The influuence of a sensitive
period on central auditory development in children with unilateral and bilateral cochlear
implants. Hearing Research 203, 134–143.
WELCOME!
EFAS 2009
TENERIFE
SPAIN