HEARING SCREENING IN NEWBORNS Nakul K

Hearing, auditory perception, or audition is the ability to perceive sound by detecting vibrations, changes in the pressure of the surrounding medium through time, through an organ, i.e. the ear.

Hearing loss is one of the most common congenital anomalies, occurring in approximately 2-4 infants per 1000 live births

DEFINITION The extent of hearing loss is defined by measuring the hearing threshold in decibels (dB) at various frequencies. Normal hearing has a threshold of 0 to 20 dB. Hearing loss ranges from mild to profound  and is defined as follows:

Mild — 20 to 40 dB Moderate — 41 to 60 dB Severe — 61 to 90 dB Profound — >90 dB

CLASSIFICATION Conductive loss is generally caused by abnormalities of the outer or middle ear, which limits the amount of external sound that gains access to the inner ear

Sensorineural hearing loss (SNHL) involves the cochlea or auditory neural pathway. Auditory neuropathy (AN), one type of SNHL, is caused by absent or severely distorted auditory brainstem responses with preservation of conductive and cochlear function.

Most neonatal hearing impairment is caused by SNHL. Approximately one-half of these cases are due to genetic causes; the remaining causes are acquired.

Mixed loss is a combination of conductive and SNHL.

INCIDENCE OF CONGENITAL CONDITIONS (PER 10,000)

0

5

10

15

20

25

30

35

Hearing loss Cleft lip orpalate

Downsyndrome

Limb defects Spina bifida Sickle cellanemia

PKU

Congenital Condition Type

Num

ber p

er 1

0,00

0

Source: http://www.infanthearing.org

PREVALENCE OF HEARING LOSS Prevalence estimates vary across studies Estimated that 1 to 3 per 1000 infants will have permanent sensorineural hearing loss3, 4

1/1000 from the well baby nursery 10/1000 from the NICU

Rate increases to 6/1000 by school age4

Need for surveillance

WHY IS EARLY IDENTIFICATION OF

HEARING LOSS IMPORTANT?

Early identification and intervention can make a difference

SCREENING FOR HEARING LOSS IN NEWBORNS IS

BASED ON TWO CONCEPTS1) A critical period exists for optimal language skills to develop,

and earlier intervention produces better outcomes.2) Second, treatment of hearing defects has been shown to

improve communication.Children with hearing loss typically experience significant delays in

language development and academic achievement.

VOCABULARY DEVELOPMENT IN INFANTS

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250

300

350

400

12 mos 14 mos 16 mos 18 mos 24 mos

Age

Num

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f Exp

ress

ive

Wor

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NH BoysNH GirlsToddlers with Hearing Loss

READING COMPREHENSION IN CHILDREN WITH MILD-MOD LOSS

0

20

40

60

80

100

120

140

Grade 1 Grade 4

Academic Grade

Rea

ding

Com

preh

ensi

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tand

ard

Scor

e

Normal HearingHearing Loss

Pediatrics. 2008 Sep;122(3):535-44. doi: 10.1542/peds.2007-2028. Early language outcomes of early-identified infants with permanent hearing loss at 12 to 16 months of age.

Vohr B, Jodoin-Krauzyk J, Tucker R, Johnson MJ, Topol D, Ahlgren M. Prospective, longitudinal study of early-identified infants 30 children with mild-profound hearing loss (HL) compared to 96 normal hearing (NH) controls

Children identified < 3 months had stronger language development at 12-16 months than those identified > 3 months

Pediatrics. 1998 Nov;102(5):1161-71.Language of early- and later-identified children with hearing loss.

Yoshinaga-Itano C, Sedey AL, Coulter DK, Mehl AL.SourceDepartment of Speech, Language, and Hearing Sciences, the University of Colorado-Boulder, Boulder, Colorado, USA.

OBJECTIVE: To compare the language abilities of earlier- and later-identified deaf and hard-of-hearing children.

EFFECTS OF AGE OF IDENTIFICATION ON

LANGUAGE DEVELOPMENTLanguage Quotients at Three Years of Age

by Age of Identification Category

0102030405060708090

100

0-6 mos 7-12 mos 13-18 mos 19-24 mos 25-34 mos

Ages of Identification

Lang

uage

Quo

tient

Sco

re

The participants' receptive and expressive language abilities were measured using the Minnesota Child Development Inventory.

This study compared the receptive and expressive language abilities of

72 deaf or hard-of- hearing children whose hearing losses were identified before 6 months of age with

78 children whose hearing losses were identified after 6 months of age.

Yoshinaga-Itano and her colleagues have shown that when children are identified with hearing loss at birth and receive intervention before 6 months of age, they ‘‘catch up’’ with their normal-hearing peers and demonstrate essentially normal language development by 5 years of age

Pediatrics. 2000 Sep;106(3):E43.

Early intervention and language development in children who are deaf and hard of hearing.

Moeller MP.SourceCenter for Childhood Deafness, Boys Town National Research Hospital, Omaha, Nebraska 68131, USA. moeller@boystown.org

OBJECTIVE: The primary purpose of this study was to examine the relationship between age of enrollment in intervention and language outcomes at 5 years of age in a group of deaf and hard-of-hearing children.

VOCABULARY AT AGE FIVE BY AGE OF INTERVENTION

This study completed at Boys Town National Research Hospital on 112 children supported the Colorado findings.

Children identified earlier had stronger receptive scores on the Peabody Picture Vocabulary Test

CHECKLIST OF HIGH-RISK INDICATORS FOR HEARING LOSS IN CHILDREN FROM BIRTH TO 24 MO OF AGE. Birth to 28 days Family history of sensorineural hearing loss (SNHL), presumably congenital

In utero infection associated with SNHL (eg, toxoplasmosis, rubella, cytomegalovirus, herpes, syphilis)

Ear and other craniofacial anomalies Hyperbilirubinemia at levels requiring exchange transfusion Birth weight less than 1500 g Bacterial meningitis

Low Apgar scores: 0–3 at 5 min; 0–6 at 10 min Respiratory distress (eg, meconium aspiration) Prolonged mechanical ventilation for more than 10 d Ototoxic medication (eg, gentamicin) administered for more than 5 d or used in combination with loop diuretics

Physical features or other stigmata associated with a syndrome known to include SNHL (eg, Down syndrome, Waardenburg syndrome)

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

Any of the newborn risk factors listed above Recurrent or persistent OME for at least 3 mo Head trauma with fracture of temporal bone Childhood infectious diseases associated with SNHL (eg, meningitis, mumps, measles)

Neurodegenerative disorders (eg, Hunter syndrome) or demyelinating diseases (eg, Friedreich ataxia, Charcot-Marie-Tooth syndrome) Joint Committee on Infant Hearing. Year 2000 position

statement: principles and guidelines for early hearing detection and intervention. Pediatrics. 2000

Hearing in Children. 4th ed. Baltimore, MD: Williams & Wilkins; 1991.

AUDITORY PATHWAY

SHOULD THE HEARING SCREENING BE RISK FACTOR BASED OR

UNIVERSAL?

EVIDENCEThe Joint Committee on Infant Hearing (JCIH) first published a set of risk indicators for hearing loss in 1971, which were used primarily for screening infants in the neonatal intensive care unit (NICU), because most infants with risk factors were found in the NICU.

However, subsequent studies reported that

19 to 42 percent of profoundly hearing-impaired children would be missed with targeted, risk factor–based screening .

In 1999, Finitzio and Crumley reported that, according to the identification rates currently reported from various screening programs, approximately 8,000-16,000 newborns are born with hearing loss each year. Of these, 50% are discharged home from the well-baby nursery with no known risk factors for hearing loss, according to the National Institutes of Health.

Although higher risk among NICU graduates should not be ignored, a program in which only neonates meeting the high risk criteria are screened was found to exclude as many as 50% of newborns with significant congenital hearing loss.

This led to the initiation of the universal newborn hearing screening program in USA, and in 1999, the American Academy of Pediatrics estimated that 1 to 3 per 1000 infants born in well-baby nurseries may have permanent hearing loss sufficient to interfere with normal speech and language acquisition

RECOMMENDATIONSAll newborns should be screened, regardless of risk. Highest on the high risk group is parental concern; If universal screening is not feasible, the newborns in the high risk category should definitely undergo hearing screening.

If a newborn passes the newborn hearing screening but has an identified risk for sensorineural and/or conductive hearing loss, these infants should be closely monitored for any changes in hearing status.

The Healthy People 2010 goals include an objective to “increase the proportion of newborns who are screened for hearing loss by one month, have audiological evaluation by three months, and are enrolled in appropriate intervention services by six months.”

These specific recommendations were expanded and articulated as “principles” in the Joint Committee on Infant Hearing (JCIH) Year 2007 Position Statement.

1-3-6 PLAN All infants will access hearing screening using a physiologic measure no later than 1 month of age

All infants not passing initial screening and subsequent rescreening should have confirmatory audiological and medical evaluations no later than 3 months of age

All infants with confirmed permanent hearing loss should receive early intervention as soon as possible no later than 6 months of age

WHAT ARE THE MODALITIES FOR PERFORMING HEARING SCREENING? Auditory brainstem response (ABR), otoacoustic emissions (OAEs), and automated ABR (AABR) testing have been used in newborn hearing-screening programs.

The discovery of OAEs by David Kemp in 1978 allowed the development of an alternative screening technology that has become common place in hospitals.

TIME-LINE IN NEWBORN HEARING SCREENING

1965 - Babbidge Report : Recommended the development and nationwide implementation of "universally applied procedures for early identification and evaluation of hearing impairment."

1967 - Recommendations from the National Conference on Education of the Deaf 2 High-risk register to facilitate identification. Public information campaign. Testing of infants and children 5-12 months of age should be investigated.

1988 - Commission on Education of the Deaf 3 Reported the average age of identification for profoundly deaf children in the US was 2 1/2 years.

1988 - An advisory group of national experts convened 1988 - Former Surgeon General C. Everett Koop issued a challenge 5 That by the year 2000, 90% of children with significant hearing loss be identified by 12 months of age.

1990 - Joint Committee on Infant Hearing (JCIH) - Position Statement 6

Recommended that high-risk infants be screened prior to their discharge from the hospital and no later than 3 months after their birth.

1990 - Healthy People 20007. Goal: To reduce the average age at which children with significant hearing impairment are identified to no more than 12 months by year 2000.

1993 - National Institutes of Health (NIH) Consensus Development Program 8 Recommended all newborns be screened for hearing loss before leaving the hospital.

1994 - The JCIH Position statement 9 Recommended that "all infants with hearing loss should be identified before 3 months of age and receive intervention by 6 months of age."

1999 - The American Academy of Pediatrics endorses:10 Universal newborn hearing screening. Detection of hearing loss before three months of age. Intervention services initiated by six months of age.

2000 - The JCIH Year 2000 Position Statement:11

2001 - Healthy People 2010: 12

Goal 28-11: Increase the proportion of newborns who are screened for hearing loss by age 1 month, have audiologic evaluation by age 3 months, and are enrolled in appropriate intervention services by age 6 months.

HEARING SCREENING TECHNIQUES Otoacoustic emissions (OAE) Auditory brainstem response (ABR) Two stage screening (OAE + ABR)

OTOACOUSTIC EMISSIONS Sounds are presented to the ear

canal and a small microphone measures the response in the ear canal

Average test time is 5 minutes/baby

AUDITORY BRAINSTEM RESPONSE

Sounds are presented and surface electrodes measure brainstem activity

Average test time 30-45 min/baby

2-STAGE SCREENING PROTOCOL All babies are screened using OAEs Those babies who fail the OAE screening receive an ABR

screening prior to leaving the hospital Average test time/baby (25-35 min) Reduces refer rate; useful when follow up is likely to be

difficult or costly Initial cost of equipment is higher than OAE or ABR

screening alone, but follow-up costs are less

OTOACOUSTIC EMISSIONS TEST

BACKGROUNDThe presence of cochlear emissions was hypothesized in the 1940’s on the basis of mathematical models of cochlear nonlinearity. However, OAEs could not be measured until the late 1970s, when technology created the extremely sensitive low-noise microphones needed to record these responses. David Kemp first discovered Otoacoustic emissions in 1978.

Otoacoustic emissions (OAEs) are sounds measured in the external ear canal that reflect movement of the outer hair cells in the cochlea.

Energy produced by outer hair cell motility serves as an amplifier within the cochlea, contributing to better hearing.

Indeed, normal outer hair cells are essential for perfectly normal auditory function.

PURPOSE OF OAE’S The primary purpose of otoacoustic emission (OAE) tests is to determine cochlear status, specifically hair cell function. This information can be used to (1) screen hearing (2) partially estimate hearing sensitivity within a limited range (3) differentiate between the sensory and neural components of sensorineural hearing loss (4) test for functional hearing loss.

TYPES OF OAE’S There are two types of otoacoustic emissions tests which are used clinically. These are: 1. Transient (TEOAEs): These are evoked responses from stimulating the cochlea with a transient signal such as a click or tone burst acoustic signal. TEOAEs are a wide frequency response in the 500 to 4,000 Hz range. They typically do not occur when hearing loss is about 30 Dbhl or greater.

2. Distortion Product (DPOAEs): These are evoked response OAEs from stimulating the cochlea with two simultaneously presented pure tones of different frequency. This type of OAE may be recorded in individuals with a greater degree of hearing loss at higher frequencies. DPOAEs are typically measured in the frequency range of 750 to 6,000 Hz although many OAE devices are capable of measuring at higher frequencies.

ANALYSIS AND INTERPRETATION OF OAES The first step is to verify adequate measurement conditions. Specifically, noise levels must be sufficiently low (usually less than – 10 dB SPL) to permit confident detection of OAE activity and the stimulus intensity levels in the ear canal should be close to the desired (target) levels.

The next step in data analysis is to determine whether reliable (repeatable) OAEs are recorded, that is, whether OAE amplitude exceeds the noise level by 6 dB or more at the test frequency.

Finally, when the difference between OAE amplitude and noise floor ≥ 6 dB SPL, findings are analyzed with respect to an appropriate normal region for OAE amplitude.

Examples of the Pass and Refer outcomes for OAE screening are illustrated in Figure

Amplitudes for distortion product otoacoustic emissions (see DP column) for different stimulus frequencies (5000 to 2000 Hz) are displayed in tabular form, along with the corresponding noise floor (NF) in the ear canal and the signal-to-noise ratio (SNR), i.e., the difference between the distortion product amplitude and the noise floor at that frequency region. As a rule, a SNR of ≥ 6 dB indicates the presence of a DPOAE.

Just to the right of the table, in the figure, the bars depict the SNR for each test frequency and, below, amplitude of the DP (at the frequency 2f1-f2) in dB (SPL) plotted as a function of the f2 stimulus.

DP findings are automatically scored, with screening outcome (PASS or REFER) displayed clearly. DPOAE screening over a limited high frequency range (e.g., 5000 to 2000 Hz) is remarkably quick, often taking as little as 10 to 30 seconds.

Pass” test results represent that OAEs are present, and one can assume the individual's hearing is at least 30 dB or better.

If there is damage to the outer hair cells producing a mild hearing loss, then OAEs may not present.

The test result is "Refer," and the patient may be at risk for possible communication handicaps and can benefit from further diagnostic assessment and possible rehabilitation.

AUDITORY BRAINSTEM RESPONSE

WHAT IS EVOKED POTENTIAL?Electrical potentials that occur in the group of neuron in response to stimulation of a sense organ which can be recorded by surface electrodes is known as Evoked Potential.

eg. SEP, ABR and VEP

INTRODUCTION Auditory brainstem response (ABR) is a neurologic test of auditory brainstem function in response to auditory (click) stimuli.

It’s a set of seven positive waves recorded during the first 10 seconds after a click stimuli. They are labeled as I - VII

PHYSIOLOGY Auditory brainstem response (ABR) typically uses a click stimulus that generates a response from the hair cells of the cochlea, the signal travels along the auditory pathway from the cochlear nuclear complex to the inferior colliculus in mid brain generates wave I to wave V.

ORIGIN OF BAEP

ORIGIN OF EACH WAVE Wave I - Cochlear nerve Wave II - Dorsal & Ventral cochlear nucleus Wave III - Superior olivary complex Wave IV - Nucleus of lateral lemniscus Wave V - Inferior colliculus Wave VI - Medial geniculate body Wave VII - Auditory radiation(cortex

REQUIREMENTS Clinical averager Ear phone Silver cup electrodes Electrode jelly Patient leads

ELECTRODE PLACEMENT (MONTAGE) Cz (at vertex) (recording electrode) Ipsilateral ear lobule or mastoid process (reference electrode). Contra lateral ear lobule (act as a ground)

PROCEDURE Subject lying supine with a pillow under his head. Room should be quite. Clean the scalp & apply electrode. Check the impedance. Apply the ear phone (red for the right ear & blue for the left ear) Select the ear in the stimulator & apply masking to the opposite ear.

CONTD.. Stimulation rate : 11/sec. Repetition : 2000 Find out the threshold of hearing. ABR should be done at around 80dB. Start averaging process & continue until the required repetition accomplished.

Calculate the peak – interpeak latencies for the ABR waves.

NORMAL VALUES Peak latency of a wave = less than the next higher no. wave

Or just add 1 to that wave, latency will be less than that.

eg. Latency of wave 1 is less than 2.

Wave Latency

I <2mSec.

II <3 m.sec

III <4 m.sec

IV <5 m.sec

V <6 m.sec

VI <7 m.sec

IDENTIFICATION OF WAVES Identify wave V which is the most persitent wave. It comes as IV-V complex, and wave V comes to the base line.

Go in reverse order, wave IV, III, II, & I. Also observe their latencies, eg. latency of wave I will be less than 2mSec.

CALCULATION & ANALYSIS Write down the absolute peak latencies for the waves Find out the interpeak latencies of I – III, III – V and I – V.

INTERPRETATION Wave I : small amplitude, delayed or absent may indicate cochlear lesion Wave V : small amplitude, delayed or absent may indicate upper brainstem lesion I – III inter-peak latency: prolongation may indicate lower brainstem lesion. III – V inter-peak latency: prolongation may indicate upper brainstem lesion. I – V inter-peak latency: prolongation may indicate whole brainstem lesion. Shortening of wave the interval with normal latency of wave V indicate cochlear involvement.

APPLICATIONS

NEWBORN SCREENING • Several clinical trials have shown auditory brainstem evoked response

(ABR) testing as an effective screening tool in the evaluation of hearing in newborns, with a sensitivity of 100% and specificity of 96-98%.

HIGHLIGHTS OF JCIH 2007 POSITION

STATEMENT

DEFINITION OF TARGETED HEARING LOSS Expanded from congenital bilateral and unilateral sensory or permanent conductive HL to include neural hearing loss (auditory neuropathy/dyssynchrony) in infants admitted to the NICU > 5 days.

HEARING SCREEN PROTOCOLS Separate protocols are therefore recommended for NICU and well baby nurseries.

NICU babies >5 days are to have ABR included as part of their screen so that neural HL will not be missed

Screening results should be conveyed immediately to families so they understand the outcome and the importance of follow-up when indicated.

For rescreening, a complete evaluation of both ears is recommended, even if only 1 ear failed the initial screen.

RE-ADMISSIONS For readmissions of infants in the first month of life, if there are conditions present which are associated with potential hearing loss (e.g. hyperbilirubinemia req. exchange transfusion or culture + sepsis), a repeat hearing screen is recommended prior to discharge.

2007 JCIH POSITION ON SCREENING

NICU >5 days in NICU ABR should be included to screen for neural loss

Rescreen BOTH ears, even if only one ear fails

Non pass – refer to Audiologist

Readmission – rescreen before discharge

Well baby nursery Screen with OAE or ABR Repeat screen when necessary before discharge

When using 2 step protocol test order should be OAE then ABR

Rescreen BOTH ears, even if only one ear fails

NNF CLINICAL PRACTICE GUIDELINES Recommendation: NICU graduates should undergo first screening prior to discharge while normal newborns, it may be delayed to a post discharge visit (usually at 6weeks when the child presents for immunization).

Infants who do not pass an initial hearing screening at birth should return for follow-up testing within 1 month.

Diagnostic OAE and ABR testing is recommended for any infant who does not pass the second screening session.

Both tests are necessary to differentially diagnose an infant's hearing impairment. In addition, children with risk factors for hearing loss who have a negative hearing screen at birth should undergo audiologic testing every six months until three years of age to look for any progressive hearing loss.

In a recent survey, 4 out of every 1000 children born in India were found to have severe to profound hearing loss

Rehabilitation Council of India. Status of Disability in India-2000: New Delhi; 2000. p. 172-185.

No dedicated national program has been carried out so far in India for early detection of hearing loss in children.

NBHSP using oto acoustic emission was started at Kochi way back in 2000 by Abraham K Paul and now Kochi is the first city in India to have a centralised hearing screening program.

NEWBORN HEARING SCREENING PROGRAM - T U SUKUMARAN, INDIAN PEDIATRICS, VOLUME 48__MAY 17, 2011

REFERENCES1. Year 2007 Position Statement: Principles and Guidelines for Early

Hearing Detection and Intervention Programs- Pediatrics 20072. Joint Committee on Infant Hearing. Year 2000 position statement:

principles and guidelines for early hearing detection and intervention. Pediatrics. 2000

3. Hearing Assessment in Infants and Children: Recommendations Beyond Neonatal Screening- Pediatrics 2003

4. CDC - Historical Moments in Newborn Hearing Screening5. Newborn Hearing Screening - National Center for Hearing Assessment

and Management (NCHAM) at Utah State University6. Auditory Brainstem Evoked Response (ABR)- ksu.edu.sa

7. Pediatricians Guide to Otoacoustic Emissions 8. NNF Clinical Practice Guidelines Hearing Screening9. Update on Newborn Hearing Screening – NIDCD10. Language of early- and later-identified children with hearing loss.

Yoshinaga Itano C, Pediatrics. 1998 11. Early intervention and language development in children who are deaf

and hard of hearing-Moeller MP. ,Pediatrics. 2000 12. Early language outcomes of early-identified infants with permanent

hearing loss at 12 to 16 months of age. Vohr B, Pediatrics 2008 13. Status of newborn hearing screening program in India. Kumar S,

Mohapatra B. Int J Pediatr Otorhinolaryngol. 2011

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