Infant Hearing Screening
Background:
Each year in the United States, approximately 4,000 infants are born who are profoundly deaf, and another 37,000 infants with significant hearing impairment are born.  In fact, the results of many surveys demonstrate that six of every 1,000 newborns have a significant hearing loss.
Hearing impairment in babies is 20 times more prevalent than other disorders for which we already have nationwide screening programs in place.  For example, screening programs are available for PKU (phenylketonuria), sickle cell anemia, and hypothyroidism.  Some data indicates that identifying an infant with hearing loss would be 10 times less expensive than identifying an infant with PKU deficiency or hypothyroidism.  Most would agree that we really should be doing something about the early detection of hearing loss in newborn babies.  However, as Dr. Vanleuwen pointed out, long term data is certainly lacking.  Also, unlike PKU, hearing loss is not fatal and it is always diagnosed sooner or later.
Goals:
The goal of these early detection programs is to identify, as early as possible, all children with significant hearing impairment.  The reasons for this early identification goal are somewhat intuitive.  Speech and communications skills develop at a critical time during a child’s development.  During the first 2 years after birth, the child listens to sounds, begins to imitate those sounds, and then develops speech.  If a child does not hear well or does not hear at all, then the ability to develop speech is at risk.  If a child has a hearing impairment that can be managed effectively with use of hearing aids, then the earlier the child receives the benefit of amplification from a hearing aid, the better.  So, essentially, we want to identify, as early as possible, those children who have hearing impairment so that we can begin providing amplification and possibly speech training as early as we can.
Children born with hearing loss or deafness may look very much like all other children.  So, the challenge for advocates for early identification has always been one of trying to figure out how best to find and identify those children with hearing impairment as early in life as possible.
High-Risk Indicators & the Joint Committee on Infant Hearing:
Until a few years ago, we had no easy way to test the hearing of every neonate or infant.  So, efforts were directed at early identification with the use of the “high-risk registry.”  The idea behind the “high-risk registry” was to provide a method of identifying those children most likely to have hearing impairment (at-risk children) so that their hearing could be tested as soon as possible.
Until about 3 years ago, many of the efforts in the area of early identification of childhood hearing loss were put into developing and refining the high-risk registry.  Since 1970, a multi disciplinary group called the Joint Committee on Infant Hearing regularly met to collectively combine the expertise of the committee members and issue official statements regarding early identification of hearing impairment.  The organizations that comprised the Joint Committee included representatives from the Academy of Otolaryngology-Head and Neck Surgery, the American Speech, Language, and Hearing Association, and the American Academy of Pediatrics, and directors from speech and hearing programs in state health and welfare agencies.  In recent years, the American Academy of Audiology was added as a member organization of the Join Committee.  The first Position Statement issued the Joint Committee on Infant Hearing was in 1974 and subsequent statements were issued in 1982, 1990, and, most recently, in 1994.
The 1994 Joint Committee Position Statement was published as an insert in the December 1994 issue of The Bulletin of the AAO-HNS.  According to the statement, the risk criteria (now called indicators) that are supposed to alert everyone that an infant might have hearing loss include the following:
*family history of childhood hearing loss
*congenital perinatal infection including cytomegalovirus,
rubella, herpes, toxoplasmosis, and syphilis
*birth weight < 1500 grams
*anatomic abnormality of the head and neck
*hyperbilirubinemia at or exceeding a level requiring
exchange transfusion
*bacterial meningitis
*Apgar scores of 0 to 4 at one minute or 0 to 6 at five min.
*parental concern (any time a parent or care giver voices
concern that their child may not be hearing properly, the
physician does need to be suspicious and get the baby’s
hearing tested)
In the September 1995 issue of Otolaryngology-Head and Neck Surgery (113;3:191), the complete text of the 1994 Joint Committee on Infant Hearing Position Statement is published, including a complete list of all of the indicators. the 1994 Joint Committee position statement.  A brief summary follows:
1.  The Joint Committee endorses the goal of universal detection of infants with hearing loss.
2.  The Joint Committee maintains that certain indicators still have a role in alerting gall concerned individuals about which infants would be most likely to have significant hearing loss.
3.  The 1994 statement has added indicators to identify those children who could be born with normal hearing who might be at risk for the development of delayed or late-onset hearing loss.
4.  The statement acknowledges the potential adverse effect of fluctuating conductive hearing loss that often accompanies acute otitis media or persistent middle-ear effusion.
How effective has this decades-long effort of the Joint Committee been at focusing on the specified high-risk criteria or indicators?  Data now demonstrates that the use of the high-risk indicators helps identify only about half of the children who eventually are confirmed to have early childhood hearing impairment.  So the high-risk criteria or list of indicators is not perfect, even though developing and disseminating the risk criteria did heighten the awareness of obstetricians, neonatologist, pediatricians, and otolaryngologists about the need for the early identification of those children with hearing impairment.
Screening Tests:
In the past few years, technology has advanced and screening tests have been developed.  First, we have the development of the commercially available automated auditory brain stem response test (ABR test).  With this automated ABR test, we can assess the hearing of a newborn without having to wait for the child to become old enough for evaluation with conditioned response audiometry.  These ABR units have been technologically refined so that they are essentially little boxes of electronic gadgetry and computer gizmos that can be connected via electrodes to a baby; in about 30 minutes, the box displays either a “pass” or “refer” message.
The ABR test really only evaluates hearing at frequencies >1000 Hz.  Although the automated ABR certainly is a great advancement in objective assessment of hearing in newborns and infants, the test does take approximately 30 minutes to perform.  If we try to advocate that each child born should undergo the ABR test, logistic and dollar expense problems may result.
The second relevant significant technologic advancement has been the advent of the evoked otoacoustic emission test (EAOE test).  This test for otoacoustic emission (OAEs) is a much quicker test to administer than the ABR, but some reports have questioned aspects of the OAE test’s reliability.  The OAE test measures an almost imperceptible sound that actually comes from the outer hair cells in response to test stimuli sounds that are introduced to the ear through a tiny microphone.  If the ear hears, then an OAE is generated and can be measured.  So, this is a quick, relatively inexpensive method of testing the hearing of newborn infants and can be administered by any trained individual.
Universal Hearing Screening for Newborns
To summarize, everyone involved sort of agrees that identifying, as early as possible, those children who have significant hearing loss is a good idea.  For years, our efforts have gone toward using clues to identify those children most at risk for having hearing gloss so that we could then assess the hearing of those children.  With the advent of and then the widespread use of the automated ABR test, we actually had the technologic capability of testing the hearing of any baby, no matter how small or how young.  However, once the quick and easy OAE test became commercially available a few years ago, the inevitable question arose:  Why don’t we test the hearing of each and every child born instead of putting so much effort into figuring out which babies should have their hearing tested?
This idea of universal hearing screening for all newborns seems like a good idea.  After all, if we could identify all babies who have significant hearing impairment, then we could fit them with hearing aids at a very young age.  As a result, these children would have a better chance to develop good speech, and we might be able to avoid some of the misery and hardship that is encountered when significant hearing impairment goes undetected until a child reach 2 or 3 years of age.
In May 1993, the National Institute on Deafness and other Communication Disorders convened a Consensus Conference to deal with this issue of how to best handle the matter of detection of hearing loss during early childhood.  The important outcomes of the NIH Consensus Conference can be summarized as follows:
1.  The conference panelists rejected the concept of attempting to identify hearing-impaired babies with the use of the so-called high-risk indicators.  The NIH panelists agreed that depending upon the use of the high-risk criteria     would miss identifying 50% to 70% of hearing-impaired infants.
2.  The conference panelists recommended that the hearing of all newborns be tested before 3 months of age, preferably before hospital discharge.  The panel recommended a two-stage screening process with an initial assessment using transient OAE and, for those falling the OAE screening test, an ABR test.  Those babies who pass the ABR are to undergo a repeat ABR test 6 months later.  Those who fail the ABR test are to be referred for further diagnostic evaluation.
3.  The conference panelists stated that reasons to pursue audiologic evaluation of an infant or young child include the following:
-parental concern that a child does not seem to be hearing normally
-failure to achieve the normal milestones for speech and language development
-history of bacterial meningitis or cytomegalovirus
-family history of childhood hearing impairment
-previous treatment with ototoxic medications
Controversy Regarding Infant Hearing Screening:
With these weighty position statements from the Joint Committee on Infant Hearing and the NIH Consensus Conference, you would think we should all know exactly what to do in regard to infant hearing screening.  However, a bit of a controversy has developed.
In the February 1994 issue of Pediatrics (93;2:330), an article entitled “Universal screening for infant hearing: Not simple, not risk-free, not necessarily beneficial, and not presently justified” has been published.  The authors of this extraordinarily inflammatory commentary are Fred Bess, an audiologist who is director of the famous Bill Wilkerson Center at Vanderbilt University, and Jack Paradise, perhaps one of the most erudite and esteemed pediatricians in the United States.  Basically, in their commentary which was published in the journal most widely read by pediatricians, these two respected authorities said that the NIH consensus recommendations were wrong.  The points they made are as follows:
1.  Transient OAE tests yield more false-positive results when the testing is done on babies during the first 48 hours after birth compared with the testing of infants at a few weeks of age.
2.  The accuracy and usefulness of the OAE tests as a wide-scale screening method in newborn nurseries has not been sufficiently demonstrated.
3.  Lacking sufficient normative data on the OAE test technique an without carefully developed and field-tested hearing assessment protocols, it is not possible now to come up with pass-fail criteria that are proven to be valid.
4.  As of yet, no good data are available to demonstrate     what happens to babies who pass the OAE screening test early in life.  Could some of these babies actually be “false negatives” on the test who would later be detected as children with significant hearing loss?
This article by Bess and Paradise has created a major upheaval among all the professionals who are dedicated to the early identification of hearing loss in children.  You need to know about two published responses to the Bess and Paradise commentary.  In the July 1995 issue of the International Journal of Pediatric Otorhinolaryngology (32:201-211), an article was published by Karl White and Antonia Maxon, both leading experts in the field of early detection of childhood hearing impairment.  The article is entitled “Universal screening for infant hearing impairment: Simple, beneficial, and presently justified”.  Interestingly, another article with a very similar title was written by two different authors, Jerry Northern (head of the division of audiology at the university hospital in Denver, Colorado) and Deborah Hayes (director of audiology at the Children’s Hospital in Denver).  The Northern and hayes article is entitled “Universal Screening for Infant Hearing Impairment-Necessary, Beneficial, and Justifiable” and was published in the May/June 1994 issue of Audiology Today (the official bulletin of the American Academy of Audiology).  Together, both of these articles with similar titles and different authors clearly refute, point by point, each of the Bess and Paradise objections to the mandates of the NIH consensus statement.
Ten Essential Points (SUMMARY)
1.  The earlier a child’s hearing impairment is discovered, the better.
2.  The Joint Committee on Infant Hearing has, for the past 20 years, periodically issued official statements describing risk criteria or indicators of early childhood hearing impairment.  You should become familiar with thee indicators.
3.  The list of high-risk indicators is helpful in identifying those babies most likely to have hearing impairment.  However, depending upon a set of high-risk indicators, alone, will certainly not identify all children who are either born with or who will undergo the development of significant hearing impairment early in life.
4.  The 1993 NIH consensus conference on infant hearing screening recommended the universal hearing screening for all babies born in the United States.  This recommendation means that some method should be used to assess the hearing of each and every baby soon after birth.
5.  The approach advised by the NIH consensus panel involved the initial hearing assessment using the OAE test and a follow-up ABR test for infants who fail the OAE test.
6.  After the NIH consensus panel’s recommendations were disseminated, Drs Bess and Paradise published in Pediatrics a commentary sharply criticizing the NIH panel’s recommendations.  Two subsequent articles, one by White and Maxon in the International Journal of Pediatric Otorhinolaryngology and the other by Northern and Hayes in Audiology Today refuted, point by point, each criticism set forth by Bess and Paradise.
7.  In the US, 18 states have passed laws mandating infant hearing screening.  An additional five states have statewide infant hearing screening programs without a legislative act requiring these programs.  You need to find out if a law exists in your state that requires hearing testing for all newborn babies, and you should know what types of screening programs already exist in your area.
8.  The universal hearing screening for all babies born in the United States seems inevitable within the near future.  You need to be prepared to have infants and very young children referred to you after they have failed some type of hearing screening evaluation.
9.  Once a baby is referred to you with known or suspected hearing impairment, carefully review the family history looking for evidence of hereditary hearing impairment and for physical examination findings indicating that the baby has a yet-to=be diagnosed syndrome which includes hearing loss as a component.
10. Even the new innovative technologic methods for testing hearing in infants have limitations.  The OAE test is quick and easy, but we do not yet have many years of widespread experience in using this as a screening hearing test in newborns.  The ABR test only evaluates hearing a frequencies >1000 Hz, so a baby with significant low-frequency hearing impairment might pass an ABR screening test.
CAVEAT:
When a parent of grandparent or other care giver expresses concern that their child or grandchild is not hearing normally, assume that the parent, grandparent, or care giver is correct.  More often than not, a parent or grandparent knows when a child has hearing impairment before the tests provide evidence to confirm their suspicions.