Early Identification and Intervention Gor Children Who Are Hearing Impaired

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Introduction

The prevalence of hearing lossamong newborns and infants in theUnited States is estimated to be 1.5to 6 per 1,000 live births. This esti-mate, however, is based on the num-ber of children who are profoundlydeaf and does not account for infantswho are mildly or moderately toseverely hearing impaired. Thus, thetrue prevalence is no doubt much

higher. More alarming is the factthat the average age at which a childwho has a profound, bilateral, sen-sorineural hearing loss is identifiedis 24 months, while hearing impair-ments of lesser degrees often areidentified at an average age of 48months of age. The impact of thesestatistics is disturbing because thecritical period for language learningis within the first 36 months of life.Thus, undetected or late detectionof significant hearing impairment ininfants and young children resultsin lifelong disability.

Early Detection andIntervention Efforts

Late detection of significant hearingimpairment not only affects a child’s

speech and language learning, butit can result in academic failure,which in turn severely limits careeroptions. Ultimately, the indepen-dence of the hearing impaired indi-vidual is compromised. One nation-wide focus of health professionalsand the federal government is toimprove methods for early identifi-cation of hearing impairment. In1990, as one of the initiatives in the

Healthy People 2000 document, theUnited States Department of Healthand Human Services stated that bythe year 2000, identification of chil-dren who are hearing impaired willbe reduced to 12 months of age oryounger. In accordance with thisinitiative, the National Institutes of Health, in a consensus statement,and the Joint Committee on InfantHearing endorsed universal detec-tion of and intervention for hear-ing impaired infants. In addition,amendments to the Education ofthe Handicapped Act (PL 99-457)

mandate services for children whohave handicaps (including hearingloss) as part of a comprehensive,multidisciplinary early interventioneffort. Despite these initiatives,many caregivers remain unawareof the laws that support them inacquiring early intervention servicesfor their children. In these cases,health professionals have a responsi-bility to inform caregivers of theirrights and to advocate for them andtheir child.

Factors Contributing toDelays in Diagnosis

Physicians and other health profes-sionals need to work with eachother and with caregivers to identifyhearing loss and provide interven-tion. Pediatricians have the opportu-nity to evaluate infants on multipleoccasions in early infancy and sev-eral more visits before the age of24 months. During these visits,the physician can listen to parentalconcerns about a child’s speech,

language, and auditory development.Parental concern is of greater pre-dictive value than the informalbehavioral examination performedin the physician’s office. Accordingto one investigation, parents are usu-ally 12 months ahead of physiciansin identifying their child’s hearingloss. In addition, knowledge of theassociated hearing loss that occursin craniofacial syndromes, amongchildren who have developmental(especially speech) delays, and inother medical conditions that placechildren at risk for hearing loss

will ensure the earliest possiblediagnosis and contribute greatlyto successful management of thehearing disorder. There is no placefor the “wait and see” approach indiagnosing hearing loss.

The purpose of this review is toprovide clinicians with informationabout: the development of the earand the onset of hearing that is nec-

Pediatrics in Review Vol. 19 No. 5 May 1998 155

Early Identification and Intervention forChildren Who Are Hearing ImpairedKatheryn Rupp Bachmann, PhD* and Joan C. Arvedson, PhD†

IMPORTANT POINTS

1. Parental concern about a child’s hearing should precipitate animmediate referral to an audiologist.

2. Audiologists can test the hearing of children at any age.

3. A child who has suspected or diagnosed global delays or speech andlanguage delays should be referred promptly for audiologic testing.

4. Children who have severe emotional or neurological impairment canbe tested accurately by using evoked response testing.

5. Early diagnosis and management of children who have all degreesand types of hearing impairment can be attained through heightenedawareness of physicians and other health professionals to the indica-tors for hearing loss and the need to develop a strong coalition witha licensed audiologist.

*Associate Director of Audiology, Speech- Language-Hearing Department, Children’s Hospital of Buffalo.

† Director, Speech-Language-Hearing Department, Children’s Hospital of Buffalo, Buffalo, NY.

ARTICLE

ABBREVIATIONS

ABR: auditory brainstem response

BOA: behavioral observationaudiometry

COR: conditioned orientationreflex

EAC: external auditory canal

OAE: otoacoustic emissions

SDT: speech detection threshold

SNR: speaker-to-noise ratio

SPL: sound pressure level

SRT: speech recognitionthresholds

VRA: visual reinforcementaudiometry

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essary to identify audiologic healthcare needs of infants and children;indications for referral for audio-logic evaluation; the components of audiologic testing; degrees and typesof hearing loss; and managementof the hearing impaired child.

Development of the Earand the Onset of Hearingin Humans

DEVELOPMENT OF THE EAR

The first signs of ear developmentoccur at about the third week ofgestation, when the neural tube isforming. The five branchial archesnoted at this time encompass fivebranchial grooves or “gill slits” andtheir corresponding pharyngealpouches. As the ear begins to take

its final shape, the outer ear formsfrom ectodermal tissue of the firstand second branchial arches. Themiddle ear ossicles (malleus, incus,and stapes) arise from mesodermaltissue. The malleus and incus arisefrom mesoderm of the first branchialarch, and the stapes arises from thesecond branchial arch. The middleear lining and eustachian tubedevelop from endodermal tissueof the first pharyngeal pouch.The auditory structures and organ

systems of the body associated withthe three germ layers from which allsystems and structures develop areshown in Table 1. (See SuggestedReading for detailed reviews of auditory development by Peckand by Northern and Downs.)

ONSET OF HEARING

Around the 20th week of gestation,the outer ear has developed andtaken on its adult shape. It willcontinue to grow in size, however,until a child reaches age 9 years.The middle ear ossicles are almostcompletely ossified, and the innerear has achieved adult size, althoughdifferentiation of the sensory cells(outer and inner hair cells) in theorgan of Corti is still underway. By24 weeks, the human cochlea and itsend organ have matured structurally.

Myelination of the ganglion nervesat this same time may be taken asevidence that the onset of hearingprobably occurs in the sixth monthof gestation.

Knowledge of normal humanembryology and the associations of each organ system with its respec-tive developmental germ layerenables the health-care professionalto be alert to the presence of physi-cal anomalies and the possibility of related structural defects that include

ear and hearing abnormalities. Forexample, hypertelorism and abnor-mal pigmentation of the skin, hair,or eyes (eg, Waardenburg syndrome)may be associated with cochlearpathology because these anomaliesare related to disturbances of thesurface ectoderm during develop-

ment. Anomalies associated with thefirst and second branchial archesmay include mandibular hypoplasia,an abnormally formed external ear,and the presence of preauricular pitsor tags. In one study, nearly 50%of 46 children who were diagnosedwith permanent hearing loss showedsigns of associated structural defor-mities and related visible physicalanomalies.

Referral for Audiologic

EvaluationChildren who have structural anom-alies or syndromes known to beassociated with hearing impairmentshould be referred promptly foraudiologic evaluation. Other referralcriteria include significant perinatalevents and medical history that maybe associated with sensorineuralhearing impairment. Further, chil-dren who have suspected globaldelays or speech and languagedelays should be referred. The

156 Pediatrics in Review Vol. 19 No. 5 May 1998

EAR DISORDERSHearing Impairment

TABLE 1. Auditory Structures and Associated Organ Systems that Develop from theEmbryologic Germ Layers

GERM LAYER ECTODERM MESODERM ENDODERM

Auditory structures Pinna Ossicles (malleus, incus, Tympanic membrane (TM)stapes) medial layer

Cartilaginous portion Mastoid process Eustachian tubeof external auditorycanal

Membranous portion of Middle layer of TM Lower half of middle earcochlea up to spiralganglion

Outer layer of TM Temporal bone (includingosseous labyrinth ofinner ear)

Associated organ systems Central nervous system Skeletal system Mucous lining of all bodycavities

Visual system Circulatory system Digestive system

Outer layer of skin Excretory system SinusesReproductive system Internal organs

Inner lining of blood vessels




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high-risk indicators identified by theJoint Committee on Infant Hearingcan guide physicians for referral of infants and children for hearingassessment (Table 2). Awareness of

expected speech/language/auditorymilestones is helpful in noting lack of achievement or delayed attain-ment of specific milestones (Table3). A checklist can aid professionalsin obtaining important informationfrom parents and medical records.

Audiologic Evaluation

Recent advances in technology havemade available an extensive batteryof tests for evaluating all parts of the auditory system. A test battery,

rather than a single test, is necessaryfor pediatric assessment to compareand perform a “cross-check” of alltest results.

OUTER EARThe outer ear is evaluated both visu-ally and by otoscopic examination.The size and shape of the pinnaeshould be observed, as should thepresence or absence of skin tags orear pits on or near the pinnae. Theexaminer also should note the pres-ence of abnormal skin growths,debris, or excessive cerumen thatmay block the auditory signal fromreaching the inner ear. Finally, theexaminer should visualize the famil-iar landmarks on the tympanic mem-

brane (TM) (cone of light, umbo,long and short crus of the malleus).

MIDDLE EAR

The middle ear status and function

are evaluated via acoustic immit-tance testing. The complete acousticimmittance test procedure consistsof tympanometry, the physicalvolume test, and stapedial reflexmeasures.

Tympanometry

Tympanometry measures the energytransfer of the ear as a function of air pressure. It involves sealing theexternal auditory canal (EAC) witha tightly fitting probe tip that con-tains three tubes: one connected to



TABLE 2. High-Risk Indicators forHearing Loss*

Checklist of high-risk indicators for hearing loss inchildren birth to 24 months of age. These indicatorsare “red flags” and may assist physicians in makingreferrals of children for audiologic testing.

Birth to 28 days___ Family history of sensorineural hearing loss

(SNHL), congenital___ In utero infection associated with SNHL

(eg, toxoplasmosis, cytomegalovirus, syphilis)___ Craniofacial anomalies

___ Hyperbilirubinemia at levels requiringexchange transfusion

___ Birthweight 10 d

(eg, persistent pulmonary hypertension)___ Ototoxic medications (eg, gentamicin) >5 d

or used in combination with loop diuretics___ Stigmata or features associated with a syndrome

known to include SNHL (eg, Wardenburgsyndrome)

29 days to 24 months___ Parental concern about: hearing, speech/ language, and/or developmental delay

___ Any of the newborn risk factors listed above___ Head trauma with fracture of temporal bone___ Childhood infectious diseases associated with

SNHL (eg, mumps, measles)___ Neurodegenerative disorders, demyelinating

disease___ Recurrent or persistent otitis media

*Adapted from Joint Committee on Infant Hearing. 1994 position statement. Audiol Today. 1994;6:6–9.

TABLE 3. Expected Speech-Language-AuditoryMilestones*

Checklist of selected speech-language-auditory mile-stones achieved by infants and children who have intactcognition and hearing. Failure to achieve these mile-stones by expected age ranges may relate to hearingloss that necessitates audiologic testing.

Birth to 3 months___ Startles to loud noise___ Awakens to sounds___ Blink reflex or eye widening to noises

3 to 4 months___ Quiets to mother’s voice___ Stops playing, listens to new sounds___ Looks for source of new sounds not in sight

6 to 9 months___ Enjoys musical toys___ Coos and gurgles with inflection___ Says “mama”

12 to 15 months___ Responds to his/her name and “no”___ Follows simple requests___ Expressive vocabulary of 3 to 5 words___ Imitates some sounds

18 to 24 months___ Knows body parts___ Expressive vocabulary minimum of 20 to 50 words

(uses two-word phrases)___ 50% of speech intelligible to strangers

By 36 months___ Expressive vocabulary of 500 words (uses 4 to

5 word sentences)___ Speech is 80% intelligible to strangers___ Understands some verbs

*Adapted from Northern J, Downs M. Hearing in Children. 4th ed. Baltimore, Md: Williams and Wilkins, 1991.




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an oscillator-receiver for the presen-tation of a tone, one connected to amicrophone for monitoring soundpressure level (SPL), and one lead-ing to a pump-manometer that both

varies and measures air pressure inthe ear canal. A fixed-frequency toneis presented to the ear while earcanal air pressure is varied from+200 mm to –400 mm H2O. Soundreflection is monitored continuouslyas a function of TM compliance ormobility, which is related directly tothe artificial variation of ear canalair pressure. With extremely positiveor negative ear canal pressures, thecompliance of the TM is reducedand the majority of the sound energypresented to the ear is reflected tothe measuring microphone in the

probe. As the pressure in the earcanal approaches the value of thepressure in the middle ear, the tym-panic membrane becomes morecompliant until it reaches a point of maximum compliance, where thepressure in the canal is equal to thatin the middle ear space. At maxi-mum compliance, sound energy istransmitted through the TM, andlittle acoustic energy is reflected.The measurement of ear canal SPLas a function of pressure changesprovides a direct assessment of TM

compliance, which is plotted as atympanogram.In 1970, Jerger described a classi-

fication system for determining thestatus of the middle ear based onthe tympanogram and maximumcompliance values (peak amplitudemeasures) (Fig. 1). Type A tym-panograms are characterized by amaximum compliance peak at ornear 0 mm H2O (also measured as0 daPa) and are measured consis-tently in normal ears. Type A tym-panograms also are measured inotosclerotic ears, but peak amplitude

measures may be reduced due to theincreased stiffness of the ossicularchain. These reduced compliancetympanograms also are referred toas type AS. In cases of ossicular dis-continuity, the compliance of theTM is increased, often beyond thelimits of the equipment, resulting ina tympanogram classified as typeAD. Type B tympanograms are char-acterized by their “flat line” appear-ance, which indicates immobility of the TM, resulting in no recording of

a maximum compliance peak inthe tracing. Middle ear effusion isthe most consistent diagnosis associ-ated with a type B tympanogram,although TM perforations also gen-erate this type. Type C tympano-grams are similar to type A, butthe maximum compliance peak isshifted to the left, beyond –100 mmH2O. This tympanometric functionindicates significant negative middleear pressure and usually is recorded

just prior to, or during resolutionof, otitis media with effusion.

Type C tympanograms also maybe recorded in circumstances inwhich eustachian tube dysfunction,an inability to aerate the middleear space efficiently, is suspected.

According to recent studies, andas stated in the American Academyof Audiology Position Statement onidentification of hearing loss andmiddle ear dysfunction in preschooland school-age children, measuresof tympanic width in conjunctionwith static compliance and peak

pressure measures “may improve thesensitivity of middle ear screening.”Generally, normal tympanic widthmeasures for children should be lessthan 150 daPa. Children who havea history of middle ear disease,however, often exhibit “wide” tym-panograms (>150 daPa), even in theabsence of middle ear pathology.Thus, peak pressure, tympanicwidth, and static compliance mea-sures should be viewed together,along with acoustic reflex data andphysical volume measures, to deter-

mine any middle ear pathology.

Physical Volume Test

The physical volume test enablescalculation of the physical volumeof the EAC and is extremely usefulin determining TM integrity or ven-tilation tube patency. When the earcanal is sealed, the SPL measuredin the enclosed cavity is relateddirectly to cavity size. Normal phys-ical volume measures in infants andchildren range from 0.3 to 1.0 mL



FIGURE 1. Tympanometric types based on peak amplitude and pressure values, as

described by Jerger.




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and depend on ear canal diameterand probe tip insertion. Volumesless than 0.3 mL may indicate eitherthat the probe tip is malpositionedagainst the ear canal wall or that

excessive cerumen is present. Inboth instances, a tympanogram thatdisplays a type B function (flat line)may be recorded. Physical volumeslarger than 1.0 mL indicate TM per-foration or ventilation tube patency.In these cases, a tympanogram can-not be recorded, yet a type B func-tion still might be drawn. Thus,knowledge of the normal physicalvolumes expected for a child’s earhelp to clarify the etiology of atype B tympanogram recording.

Acoustic Reflex Test

The acoustic reflex test in immit-tance measurement is a powerfuldiagnostic tool used to help deter-mine degree, type, and site of hear-ing loss. It cannot be substituted forconventional audiometry, however,because it is not a test of hearing.The acoustic reflex threshold is ameasure of the lowest signal inten-sity that elicits a measurable con-traction of the stapedius muscle inthe middle ear. In persons who havenormal hearing, tonal signals of 70to 100 dB HL presented to one earelicit this muscle reflex, while whitenoise signals of 65 dB HL inducecontraction of the stapedius muscle.Because it is a bilateral response,

the acoustic reflex threshold canbe measured with the stimulus pre-sented to one ear and the reflexmeasured from either the ipsilateralor the contralateral ear. Helpful

guidelines for interpretation offindings for the acoustic reflexthreshold test, physical volumetest, and tympanometry are foundin Table 4.

INNER EAR

The hearing status of the pediatricpatient can be assessed by subjective(behavioral) or objective testing(which does not require an overtbehavioral response from the child).The type of testing used dependson the child’s developmental ageand abilities (Table 5).

Behavioral Testing

The behavioral hearing test allowsgraphing of a child’s responsethresholds to tonal stimuli of differ-ent frequencies or pitches on anaudiogram (Fig. 2A). Frequency isexpressed on the abscissa from lowto high frequencies. The intensity orloudness level in dB HL (referencedto the hearing levels of normallyhearing individuals) is plotted on theordinate, with the lowest intensitysounds at the top and the highestintensity sounds at the bottom. Akey of symbols is on the form. Sev-eral different techniques can be usedto obtain audiometric information

from children, depending on thechild’s developmental, not chrono-logic age. Behavioral testing tech-niques include sound field testingand conventional audiometry.

Testing in the sound field (asound-treated room) is conductedwith the infant seated independentlyor held on the caregiver’s lap andcentered between two loudspeakers.Primary methods of sound field test-ing include behavioral observationaudiometry (BOA) and visual rein-forcement audiometry (VRA).

BOA is used with neonates andinfants up to 6 months of age. Typi-cally, two audiologists or observersare needed to determine the pres-ence or absence of a response topresentations of warbled pure tones,

speech, or white and narrow-bandnoise at varying intensity levelsthrough the loudspeakers. Toynoisemakers of known frequencyand intensity also may be used,although the primitive nature ofthis test makes it of very littlediagnostic use. Responses, whichdepend heavily on the child’s physi-cal state prior to stimulation, includearousal, startle, eye-widening, cessa-tion of movement, and auropalpebralreflex (closing of the eyes or tight-ening of the lids if eyes alreadyare closed).

VRA is the sound field procedureused most commonly for testing orscreening children from 6 months to



TABLE 4. Guidelines for Interpreting Findings from Immittance Testing*

PHYSICALTYMPANOGRAM VOLUME (mL) ACOUSTIC REFLEX ETIOLOGY

Type A 0.3 to 1.0 60 to 70 dB above audiometric Normal middle ear functionthreshold, but not exceeding100 dB HL

0.3 to 1.0 100 dB HL) Eustachian tube dysfunction

*Adapted from Northern J, Downs M. Hearing in Children. 4th ed. Baltimore, Md: Williams and Wilkins, 1991.




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TABLE 5. Referral Guide for Audiologic Evaluations Based on Developmental Age of Ch

DEVELOPMENTAL AUDITORY TEST/AGE OF CHILD AVERAGE TEST TIME TYPE OF MEASUREMENT TEST PROCEDURE ADVANTAGES

Birth to 9 mo Auditory Brainstem Electrophysiologic measure- Placement of electrodes on Responses not depe

Response (ABR) ment of activity in auditory child’s head; auditory on patient cooper

90 min test nerve and brainstem stimuli presented through ear-specific resulpathways earphones one ear at a time

9 mo to 2.5 y Visual Reinforcement Behavioral test measuring Child is seated between Assesses auditory

Audiometry (VRA) responses of the child to two speakers; child is perception of chi30 min test speech and frequency- conditioned to look toward

specific stimuli presented active speaker; child is

through speakers in a reinforced for correct sound-treated room responses by activation

of a lighted toy

2.5 to 4 y Play Audiometry Behavioral test measuring Child is conditioned to put Ear-specific results30 min test auditory thresholds in a peg in a peg board or assesses auditoryresponse to speech and drop a block in a box perception of chifrequency-specific stimuli when stimulus tone is

presented through ear- heardphones and/or bonevibrator

4 y to adulthood Conventional Behavioral test measuring Patient is instructed to Ear-specific results

Audiometry auditory thresholds in raise his or her hand assesses auditory30 min test response to speech and when stimulus is heard perception of pat

frequency-specific stimuli

presented through ear-phones and/or bonevibrator

All ages Evoked Otoacoustic Physiologic test measuring Small probe containing a Ear-specific results

Emissions (EOAE) specifically cochlear (outer sensitive microphone is dependent on pat10 min test hair cell) function in placed in the ear canal state; quick test t

response to presentation for stimulus delivery

of a stimulus and response detection

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2 years of age. It involves condition-ing the child to respond, usuallywith a head turn toward the activespeaker, when the stimulus is heard.Responses are reinforced visuallyby the examiner activating a lightedtoy animal stationed near or on thespeaker. A variation of VRA testingis called conditioned orientationreflex (COR) and involves correctidentification of the speaker fromwhich the signal is emanating. The

difference between VRA and CORis that any overt response to thestimulus (head turning, pointing, ormimicking the sound) is acceptablein VRA testing, whereas correcthead turning in response to thestimulus is required with COR.One limitation of both techniquesis the inability to assess each earseparately because both ears can lis-ten in the sound field environment.Therefore, results reflect the sensi-tivity of the better hearing ear. Only

when the child can tolerate wearingearphones can ear-specific results beobtained with this method.

The conventional audiometrictest battery includes testing via airconduction and bone conduction,obtaining speech recognition thresh-olds (SRT), and assessing speechdiscrimination ability. Air conduc-tion testing involves the presentationof pure tone stimuli to one ear at atime through earphones. The inten-

sity of the tones is decreased gradu-ally until the lowest intensity thatelicits a response is determined andrecorded as the child’s threshold.The need for sound waves to travelthrough the air of the EAC and mid-dle ear space before reaching theinner ear is the source of the termair conduction testing. It is possibleto bypass the EAC and middle earand stimulate the cochlea directlyvia bone conduction. This methodrequires placement of a bone oscilla-

tor on the child’s forehead or mas-toid. It often is necessary to mask the ear not being tested becausevibration of the skull may elicit aresponse from both cochleas. This

is accomplished by presenting anarrow band noise to the nontest earto “keep it busy” while responsesfrom the test ear are being recorded.

Play audiometry may be usedfor children 2 to 5 years of age toobtain threshold information via airand bone conduction mechanisms.The child is taught to place a peg ina board whenever a tone is heardthrough the earphones or the boneoscillator. Thus, ear-specific infor-mation can be obtained. Speechtesting (Fig. 2B) also may be initi-ated in children in this age range.

SRT is the clinical measure of speech perception obtained mostroutinely. It is recorded as the low-est intensity level at which a listenercan repeat 50% of the speech mate-rial presented. The SRT shouldbe in close agreement with puretone thresholds at 500, 1,000, and2,000 Hz because the speech mater-ial includes phonemes that have mostof their energy in this frequencyrange. Children who cannot repeatwords for SRT testing may pointto pictures on a board to indicate

recognition of the speech stimulus.Younger children who cannot partici-pate in a pointing or repeating task still may respond to speech with ahead turn. The lowest level of speechthat elicits this type of response fromthe child is recorded as the speechdetection threshold (SDT).

Children ages 5 years or olderusually can respond with the con-ventional hand raising technique thatis used with adults to obtain ear-spe-cific threshold information acrossthe frequency range for pure tonesand SRT. Speech discrimination

ability (the ability to understand anddiscriminate speech material) alsomay be assessed. Typically, phoneti-cally balanced words are presentedto the listener at an average conver-sational level (45 dB HL) or athigher levels, and the percentageof words correctly identified andrepeated by the listener is recorded(Fig. 2B). Speech discriminationability often is reduced significantlyin the presence of sensorineuralhearing loss.



FIGURE 2. Recording forms used in audiometric testing. A) Audiogram (dB HL); B) Speech testing, including speech detection threshold (SDT), speech recognition

threshold (SRT), and speech discrimination ability.




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Objective Testing

Auditory brainstem response (ABR)and otoacoustic emissions (OAE)are objective tests of peripheralfunction that can be administered

to individuals of all ages. ABR, alsocommonly referred to as BAER(brainstem auditory evoked poten-tials), and OAE are particularly use-ful with people who are unable orunwilling to respond behaviorally orwhen ear-specific or reliable resultsare not obtained with conventionalaudiometric techniques.

ABR testing employs severalelectrodes on the surface of the per-son’s scalp to record the synchro-nous firing activity of the auditorynerve and brainstem auditory neu-rons in response to brief tonal or

click stimuli. Over the past 25 yearsABR has achieved universal accep-tance as an important screening anddiagnostic tool for assessing periph-eral and brainstem auditory integrity.Because it has high sensitivity andspecificity (98% and 96%, respec-tively), one of its most recognizeduses is in the detection of hearingimpairment in neonates within thefirst few hours of life.

The pediatric patient must sleepduring testing because the ABR isvery sensitive to muscle contractionand movement. ABR testing maybe scheduled around sleeping timesfor infants younger than 6 months.Children older than 6 months oftenrequire conscious sedation withchloral hydrate (50 mg/kg or75 mg/kg administered orally, notto exceed 100 mg/kg or 1,000 mgtotal) or an intramuscular injectionof a mixture of meperidine, prometh-azine/phenylephrine, and chlorprom-azine. Sedation is administeredonly under the specific orders ofa physician and when medicalsupport is available for monitoring

the physical condition of the childbefore, during, and after emergencefrom sedation.

The measurement of OAE is nowrecognized as a powerful method forassessing the status of the cochleaand the outer hair cells of the organof Corti. OAE are acoustic signalsgenerated from within the cochleathat travel in a reverse directionthrough the middle ear space andTM out to the ear canal. These sig-nals are usually inaudible to the

unaided human ear, but they may bedetected with a very sensitive micro-phone/probe system placed in theear canal, much like that used inimmittance testing. Although 50%

of normal hearing ears generateOAE spontaneously, nearly 100%generate OAE in response to anevoking stimulus. Thus, evokedOAE, including transient evokedOAE and distortion product OAE,are used most frequently in clinicalsettings to determine the status of the cochlea. Similarly to ABR, OAEcan be measured in infants withinthe first few days after birth.Because OAE testing is relativelyquick, noninvasive, and does notrequire sleep or sedation, it isan attractive technique for infant

screening. Its limitations involve aninability to quantify hearing loss orhearing threshold levels. However,because the response is eliminatedin the presence of a hearing lossgreater than 35 dB HL, middle earpathology, or debris in the EAC, itis an excellent screening measurefor normal versus abnormal hearing.

ABR and OAE are tests of audi-tory structural integrity, but are nottrue tests of hearing. Even in thepresence of a normal ABR and nor-mal OAE, there is no way to guar-antee that a child “hears” until he or

she is mature enough to indicate sobehaviorally. Thus, follow-up evalu-ations should be scheduled until areliable audiogram can be obtained.

Degrees and Types ofHearing Loss

Normal hearing is defined as thresh-olds of 15 dB HL or better (lowerintensities) for children who are18 months to school age (Fig. 2A).Thresholds greater (worse) than15 dB HL can handicap a child

educationally. Most children whopresent with acute otitis media haveworse thresholds than the 15 dB HLnormal limits for hearing. They fre-quently appear to ignore people andactivities in the classroom or athome, often turn up the volumewhile watching television, and mayask constantly for repetition frompersons who are speaking to them.Children who have greater hearingloss may become withdrawn andisolated from peers because of the

difficulty in communication. Hear-ing loss also causes fatigue becauseadditional effort is needed to listenin the typically noisy classroom.Varied degrees of hearing loss are

associated with characteristic handi-capping effects (Table 6).Three major types of hearing loss

are named for their sites of pathol-ogy: sensorineural (involving thesensory end organ of hearing orcranial nerve VIII), conductive (of or having to do with the air conduc-tion pathways of the EAC and/ormiddle ear space), and mixed(sensorineural hearing loss with anadditional conductive component)(Fig. 3). In cases of normal hearingor sensorineural impairment, boneconduction thresholds closely agree

with air conduction thresholds(within 10 dB) (Figs. 3A and 3C).When pathology of the EAC ormiddle ear space effectivelyobstructs the air conduction path-way, air conduction thresholds arepoorer compared with bone conduc-tion thresholds (>10 dB); the differ-ence between the two scores isdescribed as an air-bone gap, indi-cating the presence of conductivepathology (Fig. 3B). In someinstances, bone conduction thresh-olds may be reduced (


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at the earliest age of identification.Personal FM amplification devices,hearing aids, and cochlear implantsare used to access sounds for chil-dren who have varying degrees andtypes of hearing impairment. A com-plete discussion of each type of amplification is beyond the scope of this article, but amplification alonewill not ensure that the child identi-

fied as having significant hearingloss will develop speech, language,and social/emotional skills normally.

Successful communication isan active process for the hearingimpaired child, fostered by therapeu-tic, parental, and educational accep-tance, patience, and hard work com-pared with the ease with which mostchildren who have normal hearing

learn to communicate. No single“miracle” method can be used toteach a hearing impaired child tocommunicate. Educational methodsrange from the use of sign languagein which the child does not dependon any auditory information to theauditory/verbal method in which thechild is forced to access any and allusable hearing to communicate and



TABLE 6. The Handicapping Effects of Unmanaged Hearing Impairment and the EducationalNeeds Associated with Varying Degrees of Hearing Loss

DEGREE OF HEARING LOSS ASSOCIATED HANDICAP(AVERAGE THRESHOLDS AND BEHAVIORS

AT 500 TO 2,000 Hz) WITHOUT AMPLIFICATION EDUCATIONAL NEEDS

0 to 15 dB HL (normal hearing) • Can detect all aspects of speech • No special needssignal

16 to 25 dB HL (borderline) • May miss up to 10% of speech • Trial of low-gain personal FM systemin noise (eg, classroom) • Medical management of ears

• May respond inappropriately • Make teacher aware of impact on• Peer social interaction affected instruction

26 to 40 dB HL (mild) • May miss up to 50% of speech • Hearing aid or personal FM unit and• Often is labeled as “behavior and preferential seating

problem” and “poor listener” • May need special language, vocabulary,• Self-esteem is affected and reading help

41 to 55 dB HL (moderate) • 50% to 100% of speech may • Amplificationbe missed • Speech therapy and special education

• Voice and speech quality likely (auditory skills, reading, and writing)to be poor; limited vocabulary;defective syntax

• Significantly compromisedcommunication

• Possible low self-esteem

56 to 70 dB HL (moderate • 100% of speech information • Hearing aid essentialto severe) lost unless it is very loud • Resource teacher or special class likely

• Delayed speech and poor needed for all academic areasintelligibility

• Social isolation likely if self-concept not addressed

71 to 90 dB HL (severe) • Loud voices possibly heard • Full-time amplification essentialup to 12 in from ear • Special class, with caregivers’ choice of

• Delayed speech and language method emphasized (auditory/verbal,if loss is prelingual signing, or total communication)

• Declining speech abilitiesand atonal voice if loss ispostlingual

90+ dB HL (profound) • Sound vibrations felt rather • Special program for the deaf likelythan heard for all academic skills

• Visual cues primary for • Some mainstreamingcommunication • Possible candidacy for cochlear implant

• Peer group of hearing impairedchildren preferred (may beissue for family)

*Adapted from Northern J, Downs M. Hearing in Children. 4th ed. Baltimore, Md: Williams and Wilkins, 1991 and Flexer C. Class-

room management of children with minimal hearing loss. Hear J. 1995;48:54–58.




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is not allowed to lip-read or usesigns to a method of total communi-cation in which auditory informa-tion, lip-reading, and signs all areused to communicate. Althoughmany biases for or against eachmethod exist among hearing profes-

sionals, caregivers ultimately mustdecide which method is best fortheir child.

Success with any of the methodsdepends on several important vari-ables that include, but are not lim-ited to: 1) the degree and type of hearing impairment, 2) parent andfamily motivation, 3) presence of ahealthy emotional support network for the family, and 4) developmentof realistic goals and expectationsfor the parents and the child. The

day that a child who has significanthearing loss receives amplificationshould be considered by parents andprofessionals to be the first day of that child’s hearing life. Thus, achild who receives amplificationat 1 year of age or older would be

expected to have speech, language,and auditory skills equivalent tothat of a newborn.

When children who have severehearing impairments reach schoolage, they usually are placed inspecial classrooms with some inte-gration into regular classrooms. Thisis typically part of the individualizededucation plan. Some children, how-ever, can be mainstreamed com-pletely, with classroom amplificationor personal FM amplification sys-

tems used to enhance the teacher’svoice relative to the backgroundnoise. These amplification systemscan be useful for children who haveall degrees of hearing loss.

The child who has a unilateralloss or a mild-to-moderate hearingimpairment often is seated preferen-tially. Seating in close proximity tothe teacher may help the child hearwhat is being said, although thisis ineffective by itself unless theteacher stands in one spot the entireday. Personal FM amplificationsystems require the teacher to weara remote microphone approximately6 inches from the mouth; the signalis transmitted via FM (radio fre-quency) waves to a receiver wornby the child. The receiver may be

connected directly to the child’shearing aids or the child may wearsome form of headphones, similarto portable audiocassette head-phones. The advantage of the FMsystem is that the remote micro-phone can, in essence, place theteacher’s voice 6 inches from thechild’s ear (the distance of themicrophone from the teacher’smouth) no matter where the teacheris located in the room. This enhancesboth the speaker-to-noise ratio (SNR)and the sound quality for the child.

Unfortunately, state and school

officials appear to be reluctant toaccept recommendations for use of an FM unit for children who havemild hearing impairments and uni-lateral losses. Physicians, case work-ers, parents, teachers, and audiolo-gists must advocate proactively forthese children. Section 504 of theRehabilitation Act of 1973 statesthat all children have the right toan appropriate education. With thesupport of this legislation, profes-sionals can advocate confidentlyfor the provision of SNR-enhancing

technology. Flexer recommends“stating that the child’s hearingproblem interferes with his or heraccess to spoken instruction; there-fore, the child is being denied anappropriate education.”

Summary

Early identification of and interven-tion for all children who have hear-ing impairments remain unattainedgoals in the United States. Physi-



FIGURE 3. Examples of a normal audiogram (A) and each of the three major hear-

ing loss types described in the text: (B) conductive, (C) sensorineural, (D) mixed.

Results are shown for right ear only.




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cians typically are the first personsto obtain the medical and family his-tory of infants and children and arethe primary professionals confrontedwith parental concerns about hearing

loss. Heightened awareness of thecommon causes of hearing loss ininfants and children can facilitateprompt and appropriate referrals toaudiologists when hearing loss issuspected. A strong and interactiverelationship between physician andaudiologist is needed to attain thecommon goals of providing the ear-liest and best possible diagnosis of and optimal management for hearingimpaired pediatric patients.

SUGGESTED READING

Bess F, Hall JW III, eds. Screening Children for Auditory Function. Nashville, Tenn:Bill Wilkerson Center Press; 1992

Flexer C. Facilitating Hearing and Listeningin Young Children. San Diego, Calif:Singular Publishing Group, Inc; 1994

Hayes D, Northern J. Infants and Hearing.San Diego, Calif: Singular PublishingGroup, Inc; 1996

Jerger J. Clinical experience with impedanceaudiometry. Arch Otolaryngol. 1970;92:311–314

Northern J, Downs M. Hearing in Children.4th ed. Baltimore, Md: Williams andWilkins; 1991

Peck J. Development of hearing. Part I.Pylogeny. J Am Acad Audiol. 1994;5:291–299

Peck J. Development of hearing. Part III.Postnatal development. J Am Acad Audiol.

1995;6:113–123

ACKNOWLEDGMENTS

The authors thank D. Blackmore, B. Lasky,T. Mancuso, L. Segal-Pallas, S. Seidenberg,and V. Shields-Haseley, members of theSpeech-Language-Hearing Department,who contributed to the research for thismanuscript.



PIR QUIZ

4. You are examining a 3-month-old girlfor the first time. Her family historyis unremarkable. Gestation was 36weeks. Delivery was vaginal, vertex;

Apgar scores were 5 and 9 at 1 and5 minutes, respectively; she receivedbag-mask ventilation briefly; and herbirthweight was 2,300 g. Ampicillinand cefotaxime were administeredfor 2 days. Peak bilirubin was16.4 mg/dL/1.0 mg/dL. There wasno evidence of hemolysis. Photother-apy was administered for 12 hours.She has grown well subsequently.No dysmorphic features are noted onphysical examination. The tympanicmembranes are normal. The most appropriate indication for testingthis infant for hearing loss would be:

A. Absence of cooing.B. Disregard of sudden loud noises.C. Exposure to ototoxic drugs.D. Hyperbilirubinemia.E. Prematurity.

5. You elect to refer the previously notedinfant for evaluation of possible hear-ing loss. The intactness of the audi-tory pathways of this infant could beascertained best by:

A. Acoustic reflex testing.B. Auditory brainstem response

(ABR).C. Play audiometry.D. The conditioned orientation reflex.E. Visual reinforcement audiometry.

6. A mother is concerned about her18-month-old son’s ability to hear aswell as his delayed speech. He has

had recurrent otitis media, and pres-sure equalizing tubes (PET) wereplaced 4 months ago. On examination,the tympanic membranes are dull,but the PETs appear to be in placebilaterally. Acoustic immittance test-ing reveals the following results:Type C tympanograms bilaterally;external auditory canal volumes,0.6 cc and 0.8 cc, AD and AS,respectively; acoustic reflex absentbilaterally. The best interpretationof these data is that:

A. Large effusions are presentbilaterally.

B. Mixed hearing loss is present.C. The eustachian tubes are present.D. The probe was malpositioned.E. The ventilating tubes are

obstructed.

7. One month later, the toddlerdescribed previously returns forre-evaluation. He is alert andattentive. His expressive vocabulary

is limited to four indistinct words.Physical examination reveals nodysmorphic features. His tympanicmembranes generally are translu-cent, with the exception of sclerosisaround the PETs. Acoustic immit-tance testing reveals type A tym-panograms with normal externalauditory canal volumes and acousticreflexes. The most appropriate nextstep would be:

A. Measurement of otoacousticemissions.

B. Reassurance of the parents.C. Referral for PET replacement.D. Referral for play audiometry.E. Referral for visual reinforce-

ment audiometry.

8. An example of best practice in theeducational management of a childwho has a hearing disorder is:

A. Advocating that speaker-to-noise ratio (SNR)-enhancingtechnology be made availableto patients who have persistentmild hearing impairment.

B. Avoiding the combination of signing with other communica-tion methods.

C. Ceding to school officials thedecision about which childrenshould receive a personal FMunit.

D. Keeping the profoundly deaf child out of regular classrooms.

E. Relying on preferential seatingfor the child who has unilateralhearing loss.




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DOI: 10.1542/pir.19-5-1551998;19;155Pediatrics in Review

Katheryn Rupp Bachmann and Joan C. ArvedsonEarly Identification and Intervention for Children Who Are Hearing Impaired

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DOI: 10.1542/pir.19-5-1551998;19;155Pediatrics in Review

Katheryn Rupp Bachmann and Joan C. ArvedsonEarly Identification and Intervention for Children Who Are Hearing Impaired

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Early Identification and Intervention Gor Children Who Are Hearing Impaired

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