Pediatric/Objective Testing Flashcards
Electroacoustic measures
Electroacoustic measures: immittance
•Clinical applications
•Concepts and equipment
•Middle ear analysis
•Static acoustic compliance
•Tympanometry
•Acoustic reflexes
Electrophysiologic measures
•Auditory evoked potentials (ABR)
•Otoacoustic emissions (OAE)
•Otoacoustic emissions (OAE)
•Otoacoustic emissions (OAE)
•Types
•Components
•Clinical applications
•Auditory evoked potentials (ABR
•Auditory evoked potentials (ABR)
•Function and clinical applications
•Basic components
•Clinical montage
Adjustments to Testing
We still need to get pure tone and speech information, even if the person cannot respond traditionally
•Why? Quality of life—but (more importantly) language acquisition!
Behavioral Testing
Pediatrics/Special Needs
• Soundfield Testing
• Altering test procedures as needed
• Behavioral observation audiometry (BOA)
• Visual reinforcement audiometry (VRA)
• Play audiometry
• Case history can be important here
• Activities of daily living (ADL) important too
Hearing tests for the infant
The use of the above EDAE and ABR tests, PLUS
Behavioral audiometry
Auditory signal presented to an infant produces a change in behaviour e.g alerting,
cessation of an activity or widening of eyes. •
Moro’s reflex: sudden movement of limbs and extension of head in response to sound of 80-
90 dB. •
Cochleo-palpebral reflex: Child responds by a
blink to aloud sound. •
Cessation reflex: Infant stops activity or starts crying in response to sound 90db
Issues in Speech Audiometry
• Speech Materials for the Pediatric Population
Speech Materials for the Pediatric Population • Ensure that speech material given is within the child’s receptive
vocabulary
• Age-appropriate response required
• Body parts, colors, picture boards, etc.
Immittance
Immittance: a measure of how readily a system can be set into vibration by a driving force
•A physical characteristic of all mechanical vibratory systems
Most conductive hearing losses tend to stiffen the middle ear
•The effect of stiffness is lessened as stimulus frequency increases. Therefore, most conductive hearing losses are centered around low-frequency decrease of hearing sensitivity
•Frequencies higher than 2000 Hz have negligible contribution to the conductive system.
Admittance
Admittance: total energy flow through a system
Impedance
Impedance: total opposition to energy flow
Immittance Audiometry: Concepts
At high air pressure (+200 daPa), the TM is pushed into the middle ear space
•At low air pressure (-200 daPa), the TM bulges out
•By changing the air pressure against the TM, we make this change of TM compliance happen until the TM reaches a point of resonance (the 0 point)
Equipment for tympanometry
Middle
Ear
Analyzer
Middle Ear Analyzer: Components
3 tubes: pure-tone generator, air pump, microphone
Ear canal volume (ECV)
Ear canal volume (ECV)
•Varies with age and gender
•Children: 0.3 cm3-1.2 cm3
•Adults: 0.6 cm3-2.0 cm3
•Possible causes of large ear canal volume include large ears and TM perforations
•Possible causes of small ear canal volume include atresia and excess cerumen
Tympanometry
Purpose: to determine the point and magnitude of greatest compliance of the tympanic membrane
•Generally conducted with a low-frequency probe tone of either 220 Hz or 226 Hz at about 70 dB SPL
Normal tympanogram
Normal tympanogram
•X-axis: peak pressure between -100 daPa to +100 daPa
•Y-axis: TM compliance between 0.3 cm3-1.7 cm3
Diagnostically useful
•5 types (Jerger, 1970
)
•A (normal)
•AS (shallow; restricted)
•AD (deep or disarticulation; hypermobile)
•B (flat)
•C (neg. pressure; retracted)
Types of Immittance Results
NORMAL: Type A
RESTRICTED: Type AS
HYPERMOBILE: Type AD
FLAT: Type B
RETRACTED Type C
Type A NORMAL
●Normal Tympanic Pressure
●Normal Ear Canal Volume
●Normal Compliance
Type AD Tymp HYPERMOBILE
●Normal Tympanic Pressure
●Normal Ear Canal Volume
●Abnormally high compliance of the TM
(Compliance HIGHER than 1.0cc)
Type AS Tymp RESTRICTED
●Normal Tympanic Pressure
●Normal Ear Canal Volume
●Low Compliance
(Compliance Measures
LOWER than 0.3 cc)
●Often seen in patients with “stiffening pathologies” (i.e. otosclerosis
Type B Tymp FLAT
●No tympanic peak pressure obtained
●Often seen if the middle ear is filled with fluid
●Also seen in patients with cerumen impaction
Type C Tymp RETRACTED
●Negative tympanic pressure
●Normal Ear Canal Volume
●Normal Compliance of the Tympanic Membrane
Acoustic (Stapedial) Reflexes
Bilateral contraction of the stapedius muscles in response to a high-intensity sound
•Measured in units of dB HL at 500, 1000, 2000, and 4000 Hz
•Normal thresholds around 70–100 dB HL with average threshold level ~85 dB HL
•Acoustic reflex arc includes CN VIII, cochlear nucleus, brainstem (at superior olives), and CN VII
•Both ipsilateral and contralateral pathways are involved
Acoustic Reflex: Clinical Interpretation
Acoustic reflex exceedingly sensitive to middle ear disorder
•Crossed (contralateral) reflex threshold testing usually carried out at 500, 1000, 2000 Hz
•Reflex-eliciting stimuli should not exceed 110 dB HL (unless substantial air–bone gap exists)
•If air–bone gap is present, stimulus must be intense enough to overcome the occlusion effect that is present at lower frequencies
Special Considerations:
Pediatric Clients
Tympanometry for those under six months
•Clinically relevant information is obtained at higher frequencies (not at typical 226 Hz measures) because infants have small ear canals
•Not uncommon to use probe frequencies around 1000 Hz when assessing infants to account for size differences
•Difficult to obtain immittance measures from an infant or child who exhibits excessive body movement or who is crying, yawning, or continually talking
•Use of distractive techniques helpful in obtaining measurements in these cases
Auditory Evoked Potentials: Function and Clinical Applications
Auditory evoked potentials (AEPs): measurement of the integrity of electrical voltage evoked in the brain by acoustic stimulation
•Auditory EEG obtained
•Four major applications of AEPs
•Prediction of hearing sensitivity
•Neonatal hearing screening
•Diagnostic assessment of central auditory nervous system function
•Intraoperative monitoring of auditory nervous system function
Sedation with ABR
Non-sedated ABRs < 6 mos
Sedated ABR > 6 mos
Clinical Application: Prediction of Hearing Sensitivity Using ABR
As the intensity of the auditory stimulus decreases, ABR wave morphology degrades and wave V latency increases
•The intensity at which wave V disappears is just below auditory threshold
Otoacoustic Emissions (OAEs)
Frequency-specific, preneural, low-intensity sounds which are generated by the outer hair cells within the cochlea and which emanate into the middle ear and ear canal
•Efferent auditory system
•Probably not essential to hearing
•By-product of active processing by the outer hair cell system
Reveals the integrity of cochlear function
Reveals the integrity of cochlear function
•Present OAEs: healthy outer hair cells
•Normal hearing sensitivity or at most <30 dB HL hearing loss
•Absent OAEs: damaged outer hair cells
•Abnormal hearing sensitivity; hearing loss >30 dB HL
Spontaneous OAEs
Spontaneous: occur without any introduction of an eliciting signal
Evoked AOEs
Evoked: occur during and after presentation of a stimulus
Transient (TE): elicited via click stimulus
•Stimulates a broader range of outer hair cells on the basilar membrane
•Provides timing information
•Distortion–product (DP): elicited via pure tones
•Provides frequency-specific information about outer hair cell function
Transients
Transient (TE): elicited via click stimulus
•Stimulates a broader range of outer hair cells on the basilar membrane
•Provides timing information
Distortion product
Distortion–product (DP): elicited via pure tones
•Provides frequency-specific information about outer hair cell function
Clinical Applications: OAEs
Infant Hearing Screening
•Objective measure, although degree of hearing sensitivity cannot be ascertained
•ABRs can help estimate degree of hearing sensitivity in infants with equivocal results
•Can be carried out easily and quickly
•Not affected by neuromaturation of central auditory nervous system
•Utility limited by outer and middle ear disorders
•If there is fluid in the middle ear space, then OAEs cannot be measured
Pediatric assessment
Pediatric assessment
•Objective measure; can be obtained even with uncooperative child
•Can be obtained quickly and easily
•Utility limited by outer and middle ear disorders
Cochlear function monitoring
Cochlear function monitoring
•Used in patients undergoing ototoxic medical treatments
Diagnostics applications
Diagnostic applications
•Retrocochlear and/or neurological disorders (e.g., tumors)
•Evaluation of patients with functional hearing loss
Newborn Hearing Screening
Montefiore Protocol
•All WBN and NICU babies tested within 24-48 hours of birth, prior to discharge
•PASS? Done
•REFER? Come back for outpatient testing, do tympanometry as well.
•FLAT TYMPS? Return in 2 weeks
•REFER WITH MOBILE TYMPS? Non-sedated ABR
•This appointment will diagnose the hearing loss
•Early Intevention, ENT, genetic testing, hearing aids, speech-language therapy, etc.
Moro’s reflex
Moro’s reflex: sudden movement of limbs and extension of head in response to sound of 80-
90 dB.
Cochlea palpebral réflex
Cochleo-palpebral reflex: Child responds by a
blink to aloud sound.
Cessation reflex
Cessation reflex: Infant stops activity or starts crying in response to sound 90db
