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Newborn hearing screening update for midwifery practice
NEWBORN HEARING SCREENING UPDATE FOR MIDWIFERY PRACTICE Deborah Narrigan,
CNM, MSN
ABSTRACT Neonatal identification of congenital hearing impairment allows interventions during the first 3 years, the critical period for language and speech development. Two recently developed biophysical testing methods offer simple, accurate, and relatively inexpensive means to identify the one to three in 1,000 healthy newborns with hearing loss. Universal screening for auditory system integrity is advocated, because almost half of all newborns with hearing impairment have no risk factors associated with this impairment. Critics of universal screening cite the high rate of false positive tests (up to 7%), which increases program costs from follow-up and re-testing large numbers of infants to ensure identifying the few affected infants. As of early 2000, 24 states had introduced some type of auditory screening program, and the U.S. Congress had passed legislation with appropriations mandating state-based auditory screening for all newborns. Midwives practicing in states already mandating biophysical screening need to comply with their local requirements; those in other states may voluntarily incorporate new auditory test methods into practice. J Midwifery Womens Health 2000;45:368 –77 © 2000 by the American College of Nurse-Midwives. One of the main tasks at birth, beyond basic survival, is combining all of the sensory inputs to develop the latent language potential that lies in every human organism. It is this potential for language that must concern us most because it is dependent on adequate functioning of the auditory system. Dr. Marion P. Downs, Pioneering Audiologist (1)
Permanent hearing impairment occurs in one to three of every 1,000 healthy infants born each year in the United States. Until recently, this major health problem escaped detection for most infants until the second year of life (2). Because the most important period of language and speech development is a child’s first 3 years, if a hearing deficit is not identified and treated until the second year, the infant has lost much of the critical period of language development (3). The advent of automated technology that is relatively inexpensive and simple allows biophysical evaluation of newborn auditory function. The combination of these two factors—recognition of the critical nature of early intervention and the availability of practical screening technology— has prompted the call for
Address correspondence to Deborah Narrigan, 4003 Auburn Lane, Nashville, TN 37215.
368 © 2000 by the American College of Nurse-Midwives Issued by Elsevier Science Inc.
auditory screening of all newborns (2,4). This recommendation, however, has garnered some controversy. The core competencies for basic midwifery* practice, as promulgated by the American College of NurseMidwives (ACNM), include the application of knowledge of newborn physical assessment and common screening tests (5). The current standard approach to evaluating newborn hearing is to use behavioral testing whereby the examiner makes a loud noise, such as a clap, and observes the neonate’s reaction, usually a startle response or crying (6). An abnormal response provides only an estimate of a gross, bilateral deficit (7). The advantages of this testing include its simplicity, brevity, noninvasiveness, and low cost. The limitations, however, are numerous. The most important are the lack of standard, parameters of the noise stimulus; rapid extinction of the response; and, most significantly, the subjective judgment of the tester as to whether a normal response has occurred (8). This article outlines the embryology of the auditory system (9), physiology of sound perception, causes of congenital hearing impairment, and the current status of auditory screening for healthy newborns. How the biophysical technology works, issues and controversy in newborn screening program development, and implications of the new testing methods for midwifery care of the newborn are also discussed. EMBRYOLOGY OF THE EAR
The human ear begins formation very early in gestation. By week 6, the pinna begins to form and, by week 20, it reaches adult shape. The external auditory canal is evident by week 8, becoming a complete channel by 28 weeks. In the middle ear, the eustachian tube appears during week 3, with tympanic membrane fully formed by 28 weeks. The three small bones—the malleus, incus, and stapes—are identifiable by week 8, and at birth are adult size and shape. The cochlea, the major structure of the inner ear, is completely formed by week 12. During the final 4 months before birth, the fetus hears and responds to sound (1). * Midwifery as used herein refers to the profession as practiced in accordance with the standards set forth by the American College of Nurse-Midwives (ACNM); midwives refers to ACNM-certified nursemidwives and midwives (CNMs/CMs).
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INFANT AUDITORY SYSTEM DEVELOPMENT
At birth, newborns have sophisticated peripheral auditory function (10) and rudimentary auditory neural pathways. Maturation of the auditory neural pathways occurs as synaptic connections form when sensory input, such as hearing music or voices, travels through the brain. During the first 2 years of life, the auditory system is influenced dramatically by experience with sound, particularly by exposure to speech. Long before infants speak in recognizable words at about the age of 1 year, they have the ability to distinguish speech sounds, interpret voice tone, and recognize names of familiar objects. Lack of auditory experience for hearing-impaired infants in this critical 1st year has been shown to directly inhibit morphologic growth and functional capacity of the auditory neural pathways and severely limits correction with amplification later in life (10). PATHWAY OF SOUND
The pinna “collects” and localizes environmental sound waves; the ear canal, a resonance chamber that also directs sound waves inward toward the tympanic membrane, vibrates when the sound wave contacts it. Once in the middle ear, these sound vibrations set the three bones in motion and sounds are transmitted to the oval window. The tympanic membrane and ossicular chain most efficiently transmit sound at frequencies between 500 and 3,000 Hertz, the frequencies important in understanding speech. In the middle ear, sound waves move from the medium of air through fluid as they continue through the oval window into the cochlea. The cochlea is a spiralshaped canal filled with fluid and lined with cilia or hair cells specialized for receiving sound. Here, mechanical energy (sound wave signals) converts to electrical energy for neural transmission. When a sound wave travels through the cochlear fluid, the cilia sway, initiating afferent electrical nerve impulses to ganglionic nerve cells in the cochlea. This ciliary action—receiving the sound, converting it to electrical energy, and passing the electrical impulse to the neurons—is critical to hearing. In fact, one newborn biophysical test method indirectly evaluates the functional integrity of cochlear cilia by detecting a physiologic “echo” of sound the waving cilia emit out to the external ear (11). Once auditory nerve impulses pass into the cochlea’s neurons, they travel in a complex pattern that leads through a branch of cranial nerve VIII and across to the Deborah Narrigan is a faculty member of Philadelphia University’s Distance Education Masters in Midwifery Program, and former instructor for the newborn courses of the Community-Based NurseMidwifery Education Program, The Frontier School of Midwifery & Family Nursing.
TABLE 1
Terminology Describing Hearing Function (11) Decibel: Named for Alexander Graham Bell, it is the unit to measure loudness abbreviated as dB. It is a scale that compares a sound’s loudness to a reference level such as “hearing level.” Frequency: Number of oscillations of a vibrating body per unit of time; the oscillations are perceived as pitch of a sound, as in music, the different notes such as A or G. Hearing level (HL): A reference for measuring hearing function: for example, 0 dB hearing level is the least loud sound at any frequency needed for a normal ear to perceive that sound 50% of the time. Hertz: The unit to measure frequency; the human ear can detect the range from 20 to 20,000 Hz; human perception of a 250 Hz sound must be transmitted at 26 dB of loudness to be heard. Intensity: The strength of a sound, its loudness Binaural: both ears, bilateral Deaf: profound sensorineural hearing loss greater than 90 dB HL and for whom hearing is impossible even with a hearing aid Hard of hearing: wide range of hearing ability between normal and deaf Hearing impaired: refers to any hearing loss
opposite side of the brain (as a step in perceiving sound as two dimensional). The impulses continue to the brainstem, then on to the midbrain, and finally to the cerebral cortex. Neural fibers number about 25,000 in cranial nerve VIII and in the millions in the midbrain. The interaction of this enormous group of nerves “all exerting mutual influence on one another” (11) attests to the sophistication of the sense of hearing. TYPES OF HEARING LOSS
Standard classification of hearing loss is organized by location of the pathology in the auditory system. See Appendix A for terminology describing sound and hearing deficits. 1. Conductive hearing loss is caused by an external or middle ear disorder. The most common cause of conductive hearing loss in young children is otitis media, effusion in the middle ear (12). For newborns, the presence of vernix or amniotic fluid in the external ear canal can temporarily cause a conductive loss until the debris clears after about 48 hours (2,13). 2. Sensorineural hearing loss results from a disorder of the inner ear, cochlea, or cranial nerve VIII. Most of these disorders affect the cochlear cilia. Several drugs essential to treatment of ill newborns, such as gentamycin, can cause this type of damage (2). 3. Mixed hearing loss is a combination of conductive and sensorineural disorders.
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4. Central hearing loss results from pathology in the brain stem or higher; this problem is rare. Other dimensions of hearing loss include the degree of loss, from minimal to profound, and whether the deficit is unilateral or bilateral, fluctuating or persistent, and static or progressive (12). Although the consequences of profound, bilateral, persistent hearing impairment in children are well known to include communicative, academic, and emotional problems, only recently have less severe impairments been studied. Even minimal sensorineural hearing loss has been associated with elementary school children having more difficulty with handling stress and developing self-esteem than normally hearing peers, although this relationship was not found in a small sample of high school students in the same study (14). CAUSES OF HEARING LOSS IN NEWBORNS
Hereditary hearing loss accounts for 50% of cases of childhood deafness (15). Of these, 80% are inherited as an autosomal recessive trait (a gene for deafness is inherited from each parent, neither of whom is affected). This inheritance results in either anomalous development of cellular structures or progressive degeneration of normally formed inner ear structures. The balance of inherited hearing losses is 18% autosomal dominant and 2% X-linked recessive. The vast majority of hereditary hearing losses are sensorineural, and two-thirds are not associated with other anomalies (15). In other words, most newborns with inherited hearing loss are otherwise healthy, have no family risk factors, and no physical or behavioral findings to suggest a hearing deficit. These facts support adoption of auditory screening for all newborns. Although hearing loss from prenatal insults is rare, congenital infections can cause hearing loss. Cytomegalovirus (CMV) infects 0.2%–2.2% of all newborns making it the most common congenital infection. Up to 10% of infants with CMV demonstrate neurologic symptoms at birth, and 60% of this cohort will develop sensorineural hearing loss (16) that either worsens progressively or appears between ages 2 1/2 and 5 years (17). Far less frequently, congenital syphilis, herpes simplex virus, and toxoplasmosis result in infant hearing loss (18). Additionally, prenatal exposure to alcohol, trimethadione (anticonvulsant drug), methyl mercury, and severe iodine deficiency have been associated with infant hearing loss (18). Infants cared for in a neonatal intensive care unit (NICU) account for the other 50% of cases of neonatal hearing loss. In fact, an alarming 2%– 4% of all NICU graduates acquire a hearing impairment (19). Five factors account for most cases of acquired hearing loss in this population: hypoxia, hyperbilirubinemia requiring ex-
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FIGURE 1. Schematic diagram of auditory brainstem response (ABR) measurement. 1: Acoustic stimulus presented with an earphone to the ear; 2: Electrodes placed on the forehead and nape of the neck detect the response from the auditory system; 3: Computer used to generate the sounds and process the response; 4: The ABR waveform. Reprinted with permission. ©American Society of Contemporary Medicine and Surgery. From Hall J, Baer J. Current concepts in hearing assessment of children and adults. Comp Therapy 1993;19:272– 80.
change transfusion, mechanical ventilation lasting 5 or more days, ototoxic medications, and illness (18). Research on the specific roles of these factors has been limited by retrospective design, varying definitions of hearing loss, and small sample sizes. More detailed discussion of hearing loss in high-risk neonates is beyond the scope of this article.
CURRENT BIOPHYSICAL METHODS FOR SCREENING NEWBORN AUDITORY FUNCTION
Recent technologic advances provide two alternatives to behavioral response auditory testing: auditory brainstem response (ABR) and otoacoustic emissions (OAE) tests. Automated auditory brainstem response (A-ABR) evaluates the integrity of the entire auditory pathway from the external ear to the lower brainstem. It is performed by placing soft earphones over the infant’s ears and sending a series of soft clicks (30 – 40 dB hearing level) into the ears. Electrodes placed on the infant’s forehead and neck detect any brain activity generated by the test clicks. The infant’s brain wave responses travel from the electrodes into a portable computer device, where they are compared to a template of normal newborn brain wave patterns. See Figure 1 for a diagram of the A-ABR test. The automated ABR’s computer provides a pass or fail test report (20). The presence of specific brain wave patterns in response to a soft “click” sound is a strong indicator of normal hearing sensitivity in the range of sounds of human voices. The automated ABR equipment has been marketed for over 10 years; a portable model became available in late 1998 (S. Richards, Natus Med-
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ical Inc, personal communication, November 22, 1999). The test requires a relatively quiet environment, usually takes 5–10 minutes to complete after attaching the equipment, is accurate as early as 33–35 weeks gestational age, and in varying infant behavioral states (21). The A-ABR’s computerized, imbedded template of normal newborn brain waves eliminates the need for test personnel to evaluate the test result (22). Transitory evoked otoacoustic emission test (TEOAE) is a more recently developed device. It evaluates only the integrity of the peripheral auditory system, primarily by examining a function of the cochlea, the most common location for sensorineural hearing loss (21). In the normally functioning cochlea, sound waves generate “echoes” from the cochlear hair cells as they receive and transmit sound waves. When a newborn has this test, a soft rubber probe tip that presents clicks or tones is positioned in the outer portion of the ear canal. A small microphone in the probe detects the otoacoustic emission echoes that occur in response to the test’s click sounds. The probe is attached to a small computer that generates the click, receives the emissions, and evaluates whether the emission pattern is normal (22). The TEOAE devices require calibration to insure accurate comparison of the test patient to a standardized emissions norm. This method has two practical limitations. First, ambient noise can interfere with transmission of the echoes, causing a false-positive test result. Second, debris in the ear canal during the first few postnatal days can block cochlear reception of the test click sounds (22,23). On the other hand, TEOAE compares favorably to A-ABR for specificity and sensitivity, cost, ease, and time needed to perform the test. Neither of these methods has proven definitely superior to the other for screening newborns. In fact, they are both being used in a variety of programs. For example, in Hawaii’s universal newborn screening program, participating hospitals choose either A-ABR or TEOAE (24). In Rhode Island’s two-step program, all newborns receive the TEOAE test; healthy infants who do not pass are re-screened with the TEOAE at 2– 6 weeks, whereas NICU infants who do not pass are screened with the ABR immediately, because they are at high risk for sensorineural deficits (25). This variety of clinical applications makes direct comparison of efficacy and cost of the two modalities very difficult. One of the most valuable features of both automated methods is that non-audiologists can perform the testing. This point is important because the number of audiologists in the United States would be insufficient if only this professional group were qualified to carry out universal newborn screening (22). Instead, audiologists can successfully train non-professionals, audiology students, or other professionals, such as nurses, in 1–2 days. In addition, the equipment manufacturers offer brief on-site
introductory instruction. (E. O’Brien, Natus Medical Inc, personal communication November 9, 1999). A standard training protocol is available (22); whether it is commonly used is not known. As with most skill acquisition, new test personnel have more test failures than those with more experience, and those who frequently perform the test have the most accurate results. Test failure rates have been higher than expected in hospitals with small numbers of births where many staff members perform the screenings (26). Midwives planning to perform the screening would need to participate in a training program with an audiologist experienced with the equipment selected for use. A major issue with both technologies is the rate of false-positive results. As with any screening test, the sensitivity (ability to correctly identify the problem) and the specificity (ability to correctly identify normal function) must be considered together, because improving one of these characteristics will hamper the other (19). Using either test method, most newborn screening programs report up to 7% false-positive results (the test incorrectly finds hearing loss in a normally hearing infant) but very low to no false-negative results (19). A target rate of positive tests (one or both ears do not respond normally) for universal screening is 4%, with 3% found to be false-positives either with re-screening, usually after failing the TEOAE in the first 48 hours of life, or after the more exacting diagnostic evaluation (2). This means that if 1,000 healthy infants are screened, 40 would require a second test. If the prevalence of hearing loss is 3/1,000, 37 of those 40 would pass the second test (2). BACKGROUND FOR NEWBORN SCREENING
As early as the 1960s, audiologists led by Marion Downs advocated assessment of newborn auditory function (27). The rationale put forth then, which remains central to current recommendations, is that early detection allows early intervention, giving young children the optimal opportunity to overcome hearing impairment. Although the idea of testing newborn hearing was reasonable, the only available method at that time was behavioral response testing that had been found too unreliable for widespread screening. More than a decade later, a consortium of organizations called the Joint Committee on Infant Hearing recommended testing infants who had risk factors for hearing loss (27). In 1990, the Joint Committee expanded their list of risk factors to include the following (28): 1. Family history of hereditary childhood sensorineural hearing loss 2. In utero infections, such as cytomegalovirus, rubella, syphilis, and toxoplasmosis
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3. Craniofacial abnormalities, including those with morphologic abnormalities of the pinna and ear canal 4. Birth weight of less than 1,500 grams 5. Hyperbilirubinemia or a serum level requiring exchange transfusion 6. Ototoxic medications including, but not limited to, aminoglycosides, used in multiple courses or in combination with loop diuretics 7. Bacterial meningitis 8. Apgar scores of 0 – 4 at 1 minute or 0 – 6 at 5 minutes 9. Mechanical ventilation lasting 5 days or longer 10. Stigmata or other findings associated with a syndrome known to include a sensorineural and/or conductive hearing loss In the same year, Hawaii began legally mandated universal hearing screening. By 1997, 95% of Hawaii’s newborns were being screened (24), and in 1992, Rhode Island began a similar program (25). In 1993, The National Institutes of Health (NIH) issued a Consensus Statement recommending universal newborn screening citing the advantages of early intervention (3). A year later, the Joint Committee on Infant Hearing also advocated universal detection of infants with hearing loss by 3 months, and intervention started by 6 months of age (29). The two organizations advocated universal rather than risk-based screening, because only 50% of infants with significant hearing loss were being identified if only at-risk infants were tested; in addition, both recognized several practical issues that emanate from recommending universal auditory screening, including complex logistics for states to implement a true universal screening program, needing to insure that treatment services are available, limited data on costs of screening methods and programs, and lack of clinical evidence to advocate one screening method or protocol (3,29). In contrast to NIH’s strong recommendations for universal newborn hearing screening, a 1996 report of the U.S. Preventive Health Services Task Force endorsed the risk-based screening of the 1990 Joint Committee (30). The Task Force opposed universal screening for three reasons. First, a substantial number of infants would be misclassified with a false-positive test because of the low prevalence of hearing impairment in healthy newborns and the limitations of the technology. Second, the costs and feasibility of universal screening programs were largely unknown. Third, evidence of efficacy for early intervention at the time of the report was incomplete (30). Now, 4 years after this Task Force report, however, a consensus is growing among the audiology and pediatric communities on the benefits of universal testing, primarily because all three of the Task Force’s legitimate
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objections have been addressed. First, several states with large-scale screening programs have provided data on rates of false-positive screening as well as costs and logistics of implementing programs. Second, a key study has confirmed the singular advantage of early detection and intervention for hearing-impaired children’s language development (31). The study compared language skills of 76 children whose hearing losses were identified by 6 months of age with 78 children identified after 6 months. The median time for all children to begin use of hearing aides was within 2 months of diagnosis. The group with hearing loss identified before 6 months demonstrated unequivocally better receptive and expressive language skills. No significant differences were found between groups in race, gender, or a wide range of variables associated with language skills, such as degree of hearing loss, cognitive ability, and maternal level of education. Early identification of hearing loss was the single variable that correlated with better language ability confirming earlier research that had reported on very small numbers of children. Noting the lack of randomization in the study, the author pointed out that a study designed with early versus late screening groups could not be done now, because all infants with hearing loss must receive prompt interventions under the federal Individuals with Disabilities Education Act. If a newborn assigned to the later screening and treatment group developed early signs of hearing impairment, the infant could not remain in the study. More importantly, delaying screening beyond 6 months of age might be construed as failing to meet a standard of care. PROPOSED GUIDELINES FOR UNIVERSAL SCREENING OF HEALTHY NEWBORNS
In 1999, the American Academy of Pediatrics (AAP) endorsed universal newborn hearing screening, because it meets criteria that justify health screening programs. These criteria require that the test is easy to use with high degree of specificity and sensitivity, the condition screened for cannot be detected clinically, an effective treatment is available for the condition, early detection and intervention lead to improved health, and the program cost is acceptable (2). The AAP proposed the following guidelines for state-run universal screening programs (2): 1. Screen 95% of all newborns in the state 2. Determine all bilateral hearing impairment 3. Use testing that detects all infants who truly have hearing loss (a false-negative rate of zero) and falsepositive rate of less than 3% 4. Establish a program directed by a physician in all hospitals where births occur 5. Achieve 95% follow-up of all infants referred for diagnostic audiologic assessment
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6. Initiate intervention by 6 months of age for all infants with significant hearing loss 7. Design a centralized, state-wide tracking system to evaluate programs and insure infants receive interventions. In addition to this key organization’s endorsement, legislative momentum is building for mandatory universal auditory screening. After 10 years of legislative lobbying led by the American Speech and Hearing Association (ASHA), the U.S. Congress passed House Bill 1193, The Newborn and Infant Hearing Screening and Intervention Act of 1999, in November 1999. This legislation directs all states to provide hearing screening for all newborns prior to hospital discharge, or if born out of hospital, by age 3 months. The bill also authorizes $7 million to be spent over the next 3 years to support development and technical assistance for state programs. The funds will be split between the Health Resources and Services Administration (HRSA) and the Centers for Disease Control and Prevention. The bill was put into the Department of Labor/Department of Health and Human Services Title 6 of the FY 2000 Budget Act (J. Potter, ASHA Director of Government Relations, personal communication, December 3, 1999). At the state level, 24 states have either passed legislation or enacted laws mandating some type of newborn hearing screening programs as of early 2000, but they differ substantially in their scope and regulations. For example only five state programs currently mandate universal screening: Hawaii, Rhode Island, Mississippi, Utah, and Wyoming. Several state laws specify program initiation during 2000. For a state by state summary of legislative status, see the American Speech and Hearing Association web site information in Appendix B and for model state legislation, see Appendix C. At present, an estimated 20% of infants receive biophysical auditory screening prior to hospital discharge (32); however, with this legislative momentum, that number can be expected to rise rapidly. Several pragmatic issues require attention before any state can offer a quality universal screening program. First, each hospital and community must be prepared to provide appropriate parental notification of positive tests, arrange follow-up for positive tests, and insure availability of intervention services. Effective follow-up of infants with positive screening reports is key, but it has been difficult to achieve. A review of 4 years of Rhode Island’s experience screening 53,000 infants found follow-up for positive tests improved from 74% to 88%, but only after following a “strict” protocol for scheduling appointments, using a statewide tracking data base, visiting nurse resources and community education (25). Preventing “missed cases” (false-negative tests and infants lost to follow-up) is essential. In a review of the legal
ramifications of missed phenylketonuria (PKU) screening cases, nearly 30% resulted in litigation, usually against the infant’s physician and/or the state (33). This experience may be seen as a warning and impetus to establish careful quality assurance mechanisms for follow-up in hearing screening programs. A second program issue is the cost of universal screening associated with a high rate of false-positive screening tests (4%) for the yield of 0.01%– 0.03% true positive tests among healthy newborns. The expenses include not only repeating the screening test, which is commonly done if the infant “fails” the TEOAE due to vernix in the ear canal (13), but the administrative follow-up, reporting, and handling of hundreds of healthy infants to finally identify one with a true hearing loss. In addition, the cost of parental anxiety from a false positive report has been cited (19,34). A recent report based on interviews with parents, however, found those parents whose infants faced retesting did not have significantly more anxiety than a control group of parents whose infants had not had any auditory screening (35). The standard approach to estimating screening test costs is to determine the cost per “case” detected. Two state newborn hearing programs have recently published this cost data. In Hawaii’s experience of screening 10,300 newborns over 5 years, 15 infants or 1.5/1000 were identified with bilateral hearing loss (20). The cost per case identified was $17,750. The cost per child screened was $17. In comparison, Hawaii’s screening program for PKU, (estimated U.S. prevalence of this disorder is 1/12,000 newborns) (30), the cost per infant screened ranged from $17–$50. Colorado’s costs for auditory evaluation were $25 per infant screened, and $9,600 per case detected. Colorado’s cost per case detected for PKU was $40,000 (23). The authors of this report also project that a universal screening program would begin to save a state money by its third year. This estimate assumes that unscreened infants are usually not identified until their second year. True savings would be the avoidable costs of late identification and interventions, the “imperfect recovery of language losses,” and costs of special education (23) that have been shown to be reduced by two thirds for children who have had early and sustained treatment prior to starting school (36). A recent report compares costs for the first time of A-ABR, TEOAE, and a “two-step” program (TEOAE followed by A-ABR re-screen for positive TEOAE results). Sponsored by the manufacturer of a popular A-ABR device, the study used data from five sites and 12,081 newborns to calculate the costs for a hypothetical program screening 1,500 infants a year. Interestingly, costs of the three screening methods were nearly identical. The cost per confirmed case of hearing loss ranged from $14,347 for TEOAE to $16,527 for a two-step program. The cost per infant screened ranged only from
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$29 to $33 (37). Although the actual costs for a screening program appear reasonable, states face a vast array of competing health needs and must choose which ones will be funded and to what extent. In the case of universal newborn hearing, federal appropriation of funds in the FY 2000 budget ear-marked for state program development promises to make this choice attractive and feasible. The third concern about universal auditory screening is that it may have emerged merely because of fascination with new technology, or perhaps from a combination of technology’s allure with advocacy by interest groups. One commentator offering a plea for caution in the face of the relentless march of technology points out that as tests become more readily available, pressures for testing can be expected from people with an interest in those diseases because the “technological and political imperatives are linked” (38). In this case, new technology does offer unequivocal advantages over the old behavioral test method. The “people with an interest” is the audiology community, recently joined by the AAP. These two professional groups form a powerful coalition that at least one critic finds is prematurely propelling the widespread implementation of universal screening (34). The combination of innovative technology, an interested community, and the successful passage of federal legislation makes universal newborn auditory screening highly likely, if not inevitable. IMPLICATIONS FOR MIDWIFERY
One of the hallmarks of midwifery practice is prudently applying technology based on the best available evidence of efficacy and safety (39). In the case of biophysical auditory screening, the substantial evidence of efficacy and safety should encourage midwives to consider including it as part of newborn assessment. Practice issues related to this screening test would include educating parents, obtaining consent, clarifying responsibility for test performance, communicating results, handling falsepositive tests, and establishing insurance reimbursement. Providing prospective parents with educational materials on congenital hearing loss and screening is made easy with the abundance of consumer literature available from such organizations as ASHA. Written consent for testing is only necessary in states with mandated programs. Where testing is not legally mandated, parents have the right to decline the test, even if the hospital where the infant is born has adopted screening as standard care (40). In that case, written documentation of refusal should be obtained. In states with legally mandated programs, clinicians must know the legal grounds, such as religious objections, for refusing this test. For midwifery practices using large or urban hospitals for birth and newborn care, auditory screening may be
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standard nursery care along with screening for inherited metabolic diseases. In that case, auditory testing would be performed by designated staff overseen by an audiologist and the results recorded in the infant’s chart. On the other hand, small or rural hospitals or birth centers where few births occur (less than 100 per year) would probably not have audiology services. In that case, midwives in states with mandated universal screening should turn to the state health department for information on pediatric audiology services in their locale. Establishing a clear mechanism for communicating test results to the midwifery practice is essential, whether or not the state has mandated screening. Equally important is clarifying who is responsible to follow-up positive screening tests—a hospital staff member, the midwifery practice, or a state agency, and which audiology services will handle interventions. Perhaps the most cumbersome feature of any screening program is handling false-positive results. In a midwifery practice with 500 births a year, only one to two infants a year would be expected to have a hearing impairment. If the practice adopted universal biophysical screening, using the AAP’s target false-positive test rate of 4%, 20 out of 500 newborns each year would “fail” the screening and need follow-up and a second test. Although no long term negative consequences appear to result from false positive tests for parents, midwives and other providers of newborn care would need to support parents while they await the definitive diagnostic testing that will, in almost all cases, demonstrate that their new child has normal auditory function. This “cost” will need to be considered and weighed against the benefit of detecting one child in five hundred who stands to gain normal hearing and speech with early detection. In states without mandated screening, midwives would have the latitude to collaborate with their community’s pediatric or audiology colleagues to design a program suited to their practices. The following are several alternative approaches to physiologic hearing screening: 1. Continue with behavioral screening 2. Inform parents about physiologic screening, local audiology services that offer the test and estimated charges 3. Establish a referral system for all newborns in the practice to one or more pediatric audiology providers for screening and diagnostic evaluation as needed. 4. Contract with an audiology practice to come to the birth center, home, or hospital on a case by case basis to screen either all newborns or those whose parents desire the test. CONCLUSION
Although congenital hearing impairment occurs infrequently, if not detected within the first 6 months of life,
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the consequences can be permanent and profound. The advent of technologic methods to easily evaluate the auditory function of newborns offers the reasonable possibility of screening all newborns. Data from a few states that have had such programs for nearly a decade offer evidence of logistic problems and solutions, and demonstrate that the cost per case identified is far lower than for identifying inborn errors of metabolism. Endorsement of universal newborn hearing screening by the AAP as well as federally appropriated funding provided for FY 2000 –2003 to support state programs means this screening will become the standard of care. At present, midwives practicing in states with mandatory newborn hearing screening need to ensure that their newborn care complies with state guidelines. Midwives in other states have a wide array of choices regarding newborn auditory system assessment.
REFERENCES 1. Downs M. Introduction. In: Hayes D, Northern JL. Infants and hearing. San Diego: Singular Publishing Group, 1996:xi–xiii. 2. American Academy of Pediatrics Task Force on Newborn and Infant Hearing. Newborn and infant hearing loss: detection and intervention. Pediatr 1999;103:527–30. 3. National Institutes of Health. Early identification of hearing impairment in infants and young children. NIH Consensus Statement 1993;11: 1–24. 4. U.S. Department of Health and Human Services Public Health Service. Healthy people 2000. Washington (DC): U.S. Government Printing Office, 1990. 5. American College of Nurse-Midwives. The ACNM core competencies for basic midwifery practice. Washington (DC): ACNM, 1997. 6. Kenner C, Brueggemeyer A, Gunderson L. Physical examination of the newborn. In: Comprehensive neonatal nursing: a physiological perspective. Philadelphia: Saunders, editor. 1993:288. 7. Avery G, Fletcher M, MacDonald M. Neonatology pathophysiology and management of the newborn, 4th ed. Philadelphia: Lippincott, 1994: 277. 8. Hayes D, Northern JL. Infants and hearing. San Diego: Singular Publishing Group, 1996:224. 9. Lee KJ. Anatomy of the ear. In: Lee KJ, editor. Essential otolaryngology head and neck surgery. Stamford (CT): Appleton & Lange, 1999: 11–22.
and treatment of hereditary hearing loss. Pediatr Clin North Amer 1999; 46:35– 48. 16. Ramsey MEB, Miller E, Peckham CS. Outcome of confirmed symptomatic congenital cytomegalovirus infection. Arch Dis Child 1991;66: 1068 –9. 17. Fowler KB, McCollister FP, Dahle AJ, Boppana S, Britt WJ, Pass RF. Progressive and fluctuating sensorineural hearing loss in children with asymptomatic congenital cytomegalovirus infection. J Pediatr 1997;130: 624 –30. 18. Rozien NJ. Etiology of hearing loss in children nongenetic causes. Pediatr Clin North Amer 1999;46:49 – 64. 19. Stein L. Factors influencing the efficacy of universal newborn hearing screening. Pediatr Clin North Amer 1999;46:95–105. 20. Mason JA, Herrmann KR. Universal infant hearing screening by automated auditory brainstem response measurement. Pediatr 1998;101: 221– 8. 21. Folsom RC, Diefendorf AO. Physiologic and behavioral approaches to pediatric hearing assessment. Pediatr Clin North Amer 1999;46:107–20. 22. Nemes J. Universal newborn hearing screening: the question is, not if, but when? Hear J 1998;51:21–30, 69. 23. Mehl AL, Thomson V. Newborn hearing screening: the great omission. Pediatr 1998;101. Available at: http://www.pediatrics.org/cgi/content/full/101/1/e4. Accessed November 14, 1999. 24. Johnson JL, Kuntz NL, Sia CC, White KR, Johnson RL. Newborn hearing screening in Hawaii. Hawaii Med J 1997;56:352–5. 25. Vohr BR, Darty LM, Moore PE, Letourneau K. The Rhode Island Hearing Assessment Program: experiences with statewide hearing screening (1993–1996). J Pediatr 1998;133:353–7. 26. Finitzo T, Crumbley WG. The role of the pediatrician in hearing loss: from detection to connection. Pediatr Clin North Amer 1996;46:15– 34. 27. Hayes D, Northern JL. Infants and hearing,8 1–27. 28. Hayes D, Northern JL. Infants and hearing,8 Appendix D, 349. 29. Joint Committee on Infant Hearing. Joint committee on infant hearing 1994 position statement. Pediatr 1995;95:152– 6. 30. U.S. Preventive Services Task Force. Guide to clinical preventive services, 2nd ed. Baltimore: Williams and Wilkins, 1996. 31. Yoshinaga-Itano C, Sedey AL, Coulter DK, Mehl MD. Language of early- and later-identified children with hearing loss. Pediatr 1998;102: 1161–71. 32. National Center for Hearing Assessment and Management. Available at: http://www.infanthearing.org.home page. Accessed January 3, 2000. 33. Tharpe AM, Clayton EW. Newborn hearing screening: issues in legal liability and quality assurance. A J Audiology 1997;6:5–12. 34. Paradise JL. Commentary: universal newborn screening: should we leap before we look? Pediatr 1999;103:670 –2.
10. Sininger YS, Doyle KJ, Moore JK. The case for early identification of hearing loss in children. Pediatr Clin North Amer 1999;46:1–14.
35. Watkin PM, Baldwin M, Dixon R, Beckman A. Maternal anxiety and attitudes to universal neonatal screening. Br J Audiol 1998;32:27–37.
11. Peck JE, Lee KJ. Audiology. In: Lee KJ, editor. Essential otolaryngology head and neck surgery. Stamford (CT): Appleton & Lange, 1999: 25– 6.
36. Executive Board of the Educational Audiology Association. Letter to the editor. Pediatr 1994;94:957.
12. Tharpe AM, Bess FH. Minimal, progressive, and fluctuating hearing losses in children: characteristics, identification, and management. Pediatr Clin North Amer 1999;46:65–78. 13. Maxon AB, White KR, Behrens TR, Vohr BR. Referral rates and cost efficiency in a universal newborn hearing screening program using transient evoked otoacoustic emissions. J Am Acad Audiol 1995;6:271–7. 14. Bess FH, Dodd-Murphy J, Parker RA. Children with minimal sensorineural hearing loss: prevalence, educational performance, and functional status. Ear and Hearing 1998;19:339 –54. 15. Tomaski SM, Grundfast KM. A stepwise approach to the diagnosis
37. Vohr B, Oh W, Stewart EJ, Bentkover JD, Gabbard S, Lemons J, et al. An economic evaluation of infant hearing screening methods. American Academy of Pediatrics National Convention, October 1999. 38. Holtzman NA. What drives neonatal screening programs: a response. New Engl J Med 1992;326:495. 39. Gregor CL, Krebs JM. Fetal assessment. In: Varney H. Varney’s midwifery, 3rd ed. Boston: Jones and Bartlett, 1997:283. 40. Health Resources and Services Administration, Department of Health and Human Services. Early identification of hearing loss implementing universal newborn hearing screening programs. Rockville MD: Health Resources and Services Administration, 1999.
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APPENDIX A TERMINOLOGY DESCRIBING HEARING FUNCTION (11)
Intensity: The strength of a sound, its loudness. Decibel: Named for Alexander Graham Bell, it is the unit to measure loudness abbreviated as dB. It is a scale that compares a sound’s loudness to a reference level such as “hearing level.”
Hearing level (HL): a reference for measuring hearing function; for example, 0 dB hearing level is the least loud sound at any frequency needed for a normal ear to perceive that sound 50% of the time. Binaural: both ears, bilateral.
Frequency: Number of oscillations of a vibrating body per unit of time; the oscillations are perceived as pitch of a sound, as in music, the different notes such as A or G.
Deaf: profound sensorineural hearing loss greater than 90 dB HL and for whom hearing is impossible even with a hearing aid.
Hertz: The unit to measure frequency; the human ear can detect the range from 20 to 20,000 Hz; human perception of a 250 Hz sound must be transmitted at 26 dB of loudness to be heard.
Hard of hearing: wide range of hearing ability between normal and deaf. Hearing impaired: refers to any hearing loss.
APPENDIX B SELECTED RESOURCES ON NEWBORN HEARING SCREENING PUBLICATION
Early Identification of Hearing Loss: Implementing Universal Newborn Hearing Screening Programs National Maternal and Child Health Clearinghouse 2070 Chain Bridge Rd Suite 450 Vienna, VA 22182-2536 Phone: 888-434-4624 E-mail: [email protected] Published in 1999, this free, 34 page booklet provides brief explanations of 13 key activities for program implementation; order by toll-free phone or e-mail; text can be downloaded; see NCHAM information below
WEB SITES/ORGANIZATIONS
American Speech-Language-Hearing (ASHA) 10801 Rockville Pk. Rockville, MD 20852 Phone: 800-498-2071 URL: http://www.ASHA.org
Association
The professional and scientific association for 96,000 members of a variety of professions in the United States and internationally concerned with hearing and speech. See the web site “special section,” Infant Hearing for complete information on status of state legislation for universal screening: www.asha.org/ infant-hearing/bill-status.html#wy.
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Centers for Disease Control and Prevention Early Hearing Detection and Intervention Program (EHDI) 1600 Clifton Rd. Atlanta, GA 30333 Main phone: 404-639-3311 URL: http://:www.cdc.gov/nceh/programs/cddh/ehdi.htm This program collaborates with federal and state initiatives to develop and implement programs, data and surveillance systems, and outcome research; consumer education materials as well as transcriptions of bimonthly teleconferences on scientific topics since 1997 are available at this site
Marion Downs Center for Infant Hearing University of Colorado at Boulder Campus Box 409 Boulder, CO 80309-0409 Phone: 303-492-6283 URL:http://www.Colorado.EDU/slhs/mdnc Operating under a federal grant from the U.S. Public Health Service, the Center coordinates the implementation of universal newborn hearing screening, diagnosis and intervention programs in 17 states. The Center’s primary goal is to establish universal screening (85% of births) in the 17 states by the year 2000. The web site includes detailed state program reports as well as resources and recommendations for program development.
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National Center for Hearing Assessment and Management (NCHAM) Utah State University 2880 Old Main Hill Logan, UT 84322 Phone: 435-797-3589 URL: http://www.infanthearing.org
Begun in 1995, this organization’s goal is to promote the earliest possible identification and management of hearing loss. Activities include conducting research, developing training materials, providing technical assistance that includes software for screening programs and loan of equipment to institutions starting screening programs. Funding is a combination of public and private sources.
APPENDIX C MINIMUM COMPONENTS FOR A STATE UNIVERSAL NEWBORN HEARING SCREENING PROGRAM
1. 85% of children born in the state should be screened 2. Audiologists should be able to participate in the programs and to train and supervise technicians who may perform the screenings. 3. Screening methodology should include auditory brain stem response, otoacoustic emissions, or other objective physiological measures. 4. Screening should be completed no later than 3 months after birth; intervention should be as soon as possible but no later than 6 months after birth. 5. Medicaid and all insurance policies issued in the state should be required to include coverage for screening and follow-up care.
6. Each state should set up an advisory board to advise the state secretary of health and/or education. It should have audiologists, speech-language pathologists, parents, and adult consumers represented. 7. Information collected for tracking purposes should be kept confidential and used only as needed for the intent of the tracking system.
Used with permission from: The American SpeechLanguage-Hearing Association “Leader” April 27, 1999. Available at: http://www.ASHA.org. Accessed November 22, 1999.
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CNM, MSN
ABSTRACT Neonatal identification of congenital hearing impairment allows interventions during the first 3 years, the critical period for language and speech development. Two recently developed biophysical testing methods offer simple, accurate, and relatively inexpensive means to identify the one to three in 1,000 healthy newborns with hearing loss. Universal screening for auditory system integrity is advocated, because almost half of all newborns with hearing impairment have no risk factors associated with this impairment. Critics of universal screening cite the high rate of false positive tests (up to 7%), which increases program costs from follow-up and re-testing large numbers of infants to ensure identifying the few affected infants. As of early 2000, 24 states had introduced some type of auditory screening program, and the U.S. Congress had passed legislation with appropriations mandating state-based auditory screening for all newborns. Midwives practicing in states already mandating biophysical screening need to comply with their local requirements; those in other states may voluntarily incorporate new auditory test methods into practice. J Midwifery Womens Health 2000;45:368 –77 © 2000 by the American College of Nurse-Midwives. One of the main tasks at birth, beyond basic survival, is combining all of the sensory inputs to develop the latent language potential that lies in every human organism. It is this potential for language that must concern us most because it is dependent on adequate functioning of the auditory system. Dr. Marion P. Downs, Pioneering Audiologist (1)
Permanent hearing impairment occurs in one to three of every 1,000 healthy infants born each year in the United States. Until recently, this major health problem escaped detection for most infants until the second year of life (2). Because the most important period of language and speech development is a child’s first 3 years, if a hearing deficit is not identified and treated until the second year, the infant has lost much of the critical period of language development (3). The advent of automated technology that is relatively inexpensive and simple allows biophysical evaluation of newborn auditory function. The combination of these two factors—recognition of the critical nature of early intervention and the availability of practical screening technology— has prompted the call for
Address correspondence to Deborah Narrigan, 4003 Auburn Lane, Nashville, TN 37215.
368 © 2000 by the American College of Nurse-Midwives Issued by Elsevier Science Inc.
auditory screening of all newborns (2,4). This recommendation, however, has garnered some controversy. The core competencies for basic midwifery* practice, as promulgated by the American College of NurseMidwives (ACNM), include the application of knowledge of newborn physical assessment and common screening tests (5). The current standard approach to evaluating newborn hearing is to use behavioral testing whereby the examiner makes a loud noise, such as a clap, and observes the neonate’s reaction, usually a startle response or crying (6). An abnormal response provides only an estimate of a gross, bilateral deficit (7). The advantages of this testing include its simplicity, brevity, noninvasiveness, and low cost. The limitations, however, are numerous. The most important are the lack of standard, parameters of the noise stimulus; rapid extinction of the response; and, most significantly, the subjective judgment of the tester as to whether a normal response has occurred (8). This article outlines the embryology of the auditory system (9), physiology of sound perception, causes of congenital hearing impairment, and the current status of auditory screening for healthy newborns. How the biophysical technology works, issues and controversy in newborn screening program development, and implications of the new testing methods for midwifery care of the newborn are also discussed. EMBRYOLOGY OF THE EAR
The human ear begins formation very early in gestation. By week 6, the pinna begins to form and, by week 20, it reaches adult shape. The external auditory canal is evident by week 8, becoming a complete channel by 28 weeks. In the middle ear, the eustachian tube appears during week 3, with tympanic membrane fully formed by 28 weeks. The three small bones—the malleus, incus, and stapes—are identifiable by week 8, and at birth are adult size and shape. The cochlea, the major structure of the inner ear, is completely formed by week 12. During the final 4 months before birth, the fetus hears and responds to sound (1). * Midwifery as used herein refers to the profession as practiced in accordance with the standards set forth by the American College of Nurse-Midwives (ACNM); midwives refers to ACNM-certified nursemidwives and midwives (CNMs/CMs).
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INFANT AUDITORY SYSTEM DEVELOPMENT
At birth, newborns have sophisticated peripheral auditory function (10) and rudimentary auditory neural pathways. Maturation of the auditory neural pathways occurs as synaptic connections form when sensory input, such as hearing music or voices, travels through the brain. During the first 2 years of life, the auditory system is influenced dramatically by experience with sound, particularly by exposure to speech. Long before infants speak in recognizable words at about the age of 1 year, they have the ability to distinguish speech sounds, interpret voice tone, and recognize names of familiar objects. Lack of auditory experience for hearing-impaired infants in this critical 1st year has been shown to directly inhibit morphologic growth and functional capacity of the auditory neural pathways and severely limits correction with amplification later in life (10). PATHWAY OF SOUND
The pinna “collects” and localizes environmental sound waves; the ear canal, a resonance chamber that also directs sound waves inward toward the tympanic membrane, vibrates when the sound wave contacts it. Once in the middle ear, these sound vibrations set the three bones in motion and sounds are transmitted to the oval window. The tympanic membrane and ossicular chain most efficiently transmit sound at frequencies between 500 and 3,000 Hertz, the frequencies important in understanding speech. In the middle ear, sound waves move from the medium of air through fluid as they continue through the oval window into the cochlea. The cochlea is a spiralshaped canal filled with fluid and lined with cilia or hair cells specialized for receiving sound. Here, mechanical energy (sound wave signals) converts to electrical energy for neural transmission. When a sound wave travels through the cochlear fluid, the cilia sway, initiating afferent electrical nerve impulses to ganglionic nerve cells in the cochlea. This ciliary action—receiving the sound, converting it to electrical energy, and passing the electrical impulse to the neurons—is critical to hearing. In fact, one newborn biophysical test method indirectly evaluates the functional integrity of cochlear cilia by detecting a physiologic “echo” of sound the waving cilia emit out to the external ear (11). Once auditory nerve impulses pass into the cochlea’s neurons, they travel in a complex pattern that leads through a branch of cranial nerve VIII and across to the Deborah Narrigan is a faculty member of Philadelphia University’s Distance Education Masters in Midwifery Program, and former instructor for the newborn courses of the Community-Based NurseMidwifery Education Program, The Frontier School of Midwifery & Family Nursing.
TABLE 1
Terminology Describing Hearing Function (11) Decibel: Named for Alexander Graham Bell, it is the unit to measure loudness abbreviated as dB. It is a scale that compares a sound’s loudness to a reference level such as “hearing level.” Frequency: Number of oscillations of a vibrating body per unit of time; the oscillations are perceived as pitch of a sound, as in music, the different notes such as A or G. Hearing level (HL): A reference for measuring hearing function: for example, 0 dB hearing level is the least loud sound at any frequency needed for a normal ear to perceive that sound 50% of the time. Hertz: The unit to measure frequency; the human ear can detect the range from 20 to 20,000 Hz; human perception of a 250 Hz sound must be transmitted at 26 dB of loudness to be heard. Intensity: The strength of a sound, its loudness Binaural: both ears, bilateral Deaf: profound sensorineural hearing loss greater than 90 dB HL and for whom hearing is impossible even with a hearing aid Hard of hearing: wide range of hearing ability between normal and deaf Hearing impaired: refers to any hearing loss
opposite side of the brain (as a step in perceiving sound as two dimensional). The impulses continue to the brainstem, then on to the midbrain, and finally to the cerebral cortex. Neural fibers number about 25,000 in cranial nerve VIII and in the millions in the midbrain. The interaction of this enormous group of nerves “all exerting mutual influence on one another” (11) attests to the sophistication of the sense of hearing. TYPES OF HEARING LOSS
Standard classification of hearing loss is organized by location of the pathology in the auditory system. See Appendix A for terminology describing sound and hearing deficits. 1. Conductive hearing loss is caused by an external or middle ear disorder. The most common cause of conductive hearing loss in young children is otitis media, effusion in the middle ear (12). For newborns, the presence of vernix or amniotic fluid in the external ear canal can temporarily cause a conductive loss until the debris clears after about 48 hours (2,13). 2. Sensorineural hearing loss results from a disorder of the inner ear, cochlea, or cranial nerve VIII. Most of these disorders affect the cochlear cilia. Several drugs essential to treatment of ill newborns, such as gentamycin, can cause this type of damage (2). 3. Mixed hearing loss is a combination of conductive and sensorineural disorders.
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4. Central hearing loss results from pathology in the brain stem or higher; this problem is rare. Other dimensions of hearing loss include the degree of loss, from minimal to profound, and whether the deficit is unilateral or bilateral, fluctuating or persistent, and static or progressive (12). Although the consequences of profound, bilateral, persistent hearing impairment in children are well known to include communicative, academic, and emotional problems, only recently have less severe impairments been studied. Even minimal sensorineural hearing loss has been associated with elementary school children having more difficulty with handling stress and developing self-esteem than normally hearing peers, although this relationship was not found in a small sample of high school students in the same study (14). CAUSES OF HEARING LOSS IN NEWBORNS
Hereditary hearing loss accounts for 50% of cases of childhood deafness (15). Of these, 80% are inherited as an autosomal recessive trait (a gene for deafness is inherited from each parent, neither of whom is affected). This inheritance results in either anomalous development of cellular structures or progressive degeneration of normally formed inner ear structures. The balance of inherited hearing losses is 18% autosomal dominant and 2% X-linked recessive. The vast majority of hereditary hearing losses are sensorineural, and two-thirds are not associated with other anomalies (15). In other words, most newborns with inherited hearing loss are otherwise healthy, have no family risk factors, and no physical or behavioral findings to suggest a hearing deficit. These facts support adoption of auditory screening for all newborns. Although hearing loss from prenatal insults is rare, congenital infections can cause hearing loss. Cytomegalovirus (CMV) infects 0.2%–2.2% of all newborns making it the most common congenital infection. Up to 10% of infants with CMV demonstrate neurologic symptoms at birth, and 60% of this cohort will develop sensorineural hearing loss (16) that either worsens progressively or appears between ages 2 1/2 and 5 years (17). Far less frequently, congenital syphilis, herpes simplex virus, and toxoplasmosis result in infant hearing loss (18). Additionally, prenatal exposure to alcohol, trimethadione (anticonvulsant drug), methyl mercury, and severe iodine deficiency have been associated with infant hearing loss (18). Infants cared for in a neonatal intensive care unit (NICU) account for the other 50% of cases of neonatal hearing loss. In fact, an alarming 2%– 4% of all NICU graduates acquire a hearing impairment (19). Five factors account for most cases of acquired hearing loss in this population: hypoxia, hyperbilirubinemia requiring ex-
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FIGURE 1. Schematic diagram of auditory brainstem response (ABR) measurement. 1: Acoustic stimulus presented with an earphone to the ear; 2: Electrodes placed on the forehead and nape of the neck detect the response from the auditory system; 3: Computer used to generate the sounds and process the response; 4: The ABR waveform. Reprinted with permission. ©American Society of Contemporary Medicine and Surgery. From Hall J, Baer J. Current concepts in hearing assessment of children and adults. Comp Therapy 1993;19:272– 80.
change transfusion, mechanical ventilation lasting 5 or more days, ototoxic medications, and illness (18). Research on the specific roles of these factors has been limited by retrospective design, varying definitions of hearing loss, and small sample sizes. More detailed discussion of hearing loss in high-risk neonates is beyond the scope of this article.
CURRENT BIOPHYSICAL METHODS FOR SCREENING NEWBORN AUDITORY FUNCTION
Recent technologic advances provide two alternatives to behavioral response auditory testing: auditory brainstem response (ABR) and otoacoustic emissions (OAE) tests. Automated auditory brainstem response (A-ABR) evaluates the integrity of the entire auditory pathway from the external ear to the lower brainstem. It is performed by placing soft earphones over the infant’s ears and sending a series of soft clicks (30 – 40 dB hearing level) into the ears. Electrodes placed on the infant’s forehead and neck detect any brain activity generated by the test clicks. The infant’s brain wave responses travel from the electrodes into a portable computer device, where they are compared to a template of normal newborn brain wave patterns. See Figure 1 for a diagram of the A-ABR test. The automated ABR’s computer provides a pass or fail test report (20). The presence of specific brain wave patterns in response to a soft “click” sound is a strong indicator of normal hearing sensitivity in the range of sounds of human voices. The automated ABR equipment has been marketed for over 10 years; a portable model became available in late 1998 (S. Richards, Natus Med-
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ical Inc, personal communication, November 22, 1999). The test requires a relatively quiet environment, usually takes 5–10 minutes to complete after attaching the equipment, is accurate as early as 33–35 weeks gestational age, and in varying infant behavioral states (21). The A-ABR’s computerized, imbedded template of normal newborn brain waves eliminates the need for test personnel to evaluate the test result (22). Transitory evoked otoacoustic emission test (TEOAE) is a more recently developed device. It evaluates only the integrity of the peripheral auditory system, primarily by examining a function of the cochlea, the most common location for sensorineural hearing loss (21). In the normally functioning cochlea, sound waves generate “echoes” from the cochlear hair cells as they receive and transmit sound waves. When a newborn has this test, a soft rubber probe tip that presents clicks or tones is positioned in the outer portion of the ear canal. A small microphone in the probe detects the otoacoustic emission echoes that occur in response to the test’s click sounds. The probe is attached to a small computer that generates the click, receives the emissions, and evaluates whether the emission pattern is normal (22). The TEOAE devices require calibration to insure accurate comparison of the test patient to a standardized emissions norm. This method has two practical limitations. First, ambient noise can interfere with transmission of the echoes, causing a false-positive test result. Second, debris in the ear canal during the first few postnatal days can block cochlear reception of the test click sounds (22,23). On the other hand, TEOAE compares favorably to A-ABR for specificity and sensitivity, cost, ease, and time needed to perform the test. Neither of these methods has proven definitely superior to the other for screening newborns. In fact, they are both being used in a variety of programs. For example, in Hawaii’s universal newborn screening program, participating hospitals choose either A-ABR or TEOAE (24). In Rhode Island’s two-step program, all newborns receive the TEOAE test; healthy infants who do not pass are re-screened with the TEOAE at 2– 6 weeks, whereas NICU infants who do not pass are screened with the ABR immediately, because they are at high risk for sensorineural deficits (25). This variety of clinical applications makes direct comparison of efficacy and cost of the two modalities very difficult. One of the most valuable features of both automated methods is that non-audiologists can perform the testing. This point is important because the number of audiologists in the United States would be insufficient if only this professional group were qualified to carry out universal newborn screening (22). Instead, audiologists can successfully train non-professionals, audiology students, or other professionals, such as nurses, in 1–2 days. In addition, the equipment manufacturers offer brief on-site
introductory instruction. (E. O’Brien, Natus Medical Inc, personal communication November 9, 1999). A standard training protocol is available (22); whether it is commonly used is not known. As with most skill acquisition, new test personnel have more test failures than those with more experience, and those who frequently perform the test have the most accurate results. Test failure rates have been higher than expected in hospitals with small numbers of births where many staff members perform the screenings (26). Midwives planning to perform the screening would need to participate in a training program with an audiologist experienced with the equipment selected for use. A major issue with both technologies is the rate of false-positive results. As with any screening test, the sensitivity (ability to correctly identify the problem) and the specificity (ability to correctly identify normal function) must be considered together, because improving one of these characteristics will hamper the other (19). Using either test method, most newborn screening programs report up to 7% false-positive results (the test incorrectly finds hearing loss in a normally hearing infant) but very low to no false-negative results (19). A target rate of positive tests (one or both ears do not respond normally) for universal screening is 4%, with 3% found to be false-positives either with re-screening, usually after failing the TEOAE in the first 48 hours of life, or after the more exacting diagnostic evaluation (2). This means that if 1,000 healthy infants are screened, 40 would require a second test. If the prevalence of hearing loss is 3/1,000, 37 of those 40 would pass the second test (2). BACKGROUND FOR NEWBORN SCREENING
As early as the 1960s, audiologists led by Marion Downs advocated assessment of newborn auditory function (27). The rationale put forth then, which remains central to current recommendations, is that early detection allows early intervention, giving young children the optimal opportunity to overcome hearing impairment. Although the idea of testing newborn hearing was reasonable, the only available method at that time was behavioral response testing that had been found too unreliable for widespread screening. More than a decade later, a consortium of organizations called the Joint Committee on Infant Hearing recommended testing infants who had risk factors for hearing loss (27). In 1990, the Joint Committee expanded their list of risk factors to include the following (28): 1. Family history of hereditary childhood sensorineural hearing loss 2. In utero infections, such as cytomegalovirus, rubella, syphilis, and toxoplasmosis
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3. Craniofacial abnormalities, including those with morphologic abnormalities of the pinna and ear canal 4. Birth weight of less than 1,500 grams 5. Hyperbilirubinemia or a serum level requiring exchange transfusion 6. Ototoxic medications including, but not limited to, aminoglycosides, used in multiple courses or in combination with loop diuretics 7. Bacterial meningitis 8. Apgar scores of 0 – 4 at 1 minute or 0 – 6 at 5 minutes 9. Mechanical ventilation lasting 5 days or longer 10. Stigmata or other findings associated with a syndrome known to include a sensorineural and/or conductive hearing loss In the same year, Hawaii began legally mandated universal hearing screening. By 1997, 95% of Hawaii’s newborns were being screened (24), and in 1992, Rhode Island began a similar program (25). In 1993, The National Institutes of Health (NIH) issued a Consensus Statement recommending universal newborn screening citing the advantages of early intervention (3). A year later, the Joint Committee on Infant Hearing also advocated universal detection of infants with hearing loss by 3 months, and intervention started by 6 months of age (29). The two organizations advocated universal rather than risk-based screening, because only 50% of infants with significant hearing loss were being identified if only at-risk infants were tested; in addition, both recognized several practical issues that emanate from recommending universal auditory screening, including complex logistics for states to implement a true universal screening program, needing to insure that treatment services are available, limited data on costs of screening methods and programs, and lack of clinical evidence to advocate one screening method or protocol (3,29). In contrast to NIH’s strong recommendations for universal newborn hearing screening, a 1996 report of the U.S. Preventive Health Services Task Force endorsed the risk-based screening of the 1990 Joint Committee (30). The Task Force opposed universal screening for three reasons. First, a substantial number of infants would be misclassified with a false-positive test because of the low prevalence of hearing impairment in healthy newborns and the limitations of the technology. Second, the costs and feasibility of universal screening programs were largely unknown. Third, evidence of efficacy for early intervention at the time of the report was incomplete (30). Now, 4 years after this Task Force report, however, a consensus is growing among the audiology and pediatric communities on the benefits of universal testing, primarily because all three of the Task Force’s legitimate
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objections have been addressed. First, several states with large-scale screening programs have provided data on rates of false-positive screening as well as costs and logistics of implementing programs. Second, a key study has confirmed the singular advantage of early detection and intervention for hearing-impaired children’s language development (31). The study compared language skills of 76 children whose hearing losses were identified by 6 months of age with 78 children identified after 6 months. The median time for all children to begin use of hearing aides was within 2 months of diagnosis. The group with hearing loss identified before 6 months demonstrated unequivocally better receptive and expressive language skills. No significant differences were found between groups in race, gender, or a wide range of variables associated with language skills, such as degree of hearing loss, cognitive ability, and maternal level of education. Early identification of hearing loss was the single variable that correlated with better language ability confirming earlier research that had reported on very small numbers of children. Noting the lack of randomization in the study, the author pointed out that a study designed with early versus late screening groups could not be done now, because all infants with hearing loss must receive prompt interventions under the federal Individuals with Disabilities Education Act. If a newborn assigned to the later screening and treatment group developed early signs of hearing impairment, the infant could not remain in the study. More importantly, delaying screening beyond 6 months of age might be construed as failing to meet a standard of care. PROPOSED GUIDELINES FOR UNIVERSAL SCREENING OF HEALTHY NEWBORNS
In 1999, the American Academy of Pediatrics (AAP) endorsed universal newborn hearing screening, because it meets criteria that justify health screening programs. These criteria require that the test is easy to use with high degree of specificity and sensitivity, the condition screened for cannot be detected clinically, an effective treatment is available for the condition, early detection and intervention lead to improved health, and the program cost is acceptable (2). The AAP proposed the following guidelines for state-run universal screening programs (2): 1. Screen 95% of all newborns in the state 2. Determine all bilateral hearing impairment 3. Use testing that detects all infants who truly have hearing loss (a false-negative rate of zero) and falsepositive rate of less than 3% 4. Establish a program directed by a physician in all hospitals where births occur 5. Achieve 95% follow-up of all infants referred for diagnostic audiologic assessment
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6. Initiate intervention by 6 months of age for all infants with significant hearing loss 7. Design a centralized, state-wide tracking system to evaluate programs and insure infants receive interventions. In addition to this key organization’s endorsement, legislative momentum is building for mandatory universal auditory screening. After 10 years of legislative lobbying led by the American Speech and Hearing Association (ASHA), the U.S. Congress passed House Bill 1193, The Newborn and Infant Hearing Screening and Intervention Act of 1999, in November 1999. This legislation directs all states to provide hearing screening for all newborns prior to hospital discharge, or if born out of hospital, by age 3 months. The bill also authorizes $7 million to be spent over the next 3 years to support development and technical assistance for state programs. The funds will be split between the Health Resources and Services Administration (HRSA) and the Centers for Disease Control and Prevention. The bill was put into the Department of Labor/Department of Health and Human Services Title 6 of the FY 2000 Budget Act (J. Potter, ASHA Director of Government Relations, personal communication, December 3, 1999). At the state level, 24 states have either passed legislation or enacted laws mandating some type of newborn hearing screening programs as of early 2000, but they differ substantially in their scope and regulations. For example only five state programs currently mandate universal screening: Hawaii, Rhode Island, Mississippi, Utah, and Wyoming. Several state laws specify program initiation during 2000. For a state by state summary of legislative status, see the American Speech and Hearing Association web site information in Appendix B and for model state legislation, see Appendix C. At present, an estimated 20% of infants receive biophysical auditory screening prior to hospital discharge (32); however, with this legislative momentum, that number can be expected to rise rapidly. Several pragmatic issues require attention before any state can offer a quality universal screening program. First, each hospital and community must be prepared to provide appropriate parental notification of positive tests, arrange follow-up for positive tests, and insure availability of intervention services. Effective follow-up of infants with positive screening reports is key, but it has been difficult to achieve. A review of 4 years of Rhode Island’s experience screening 53,000 infants found follow-up for positive tests improved from 74% to 88%, but only after following a “strict” protocol for scheduling appointments, using a statewide tracking data base, visiting nurse resources and community education (25). Preventing “missed cases” (false-negative tests and infants lost to follow-up) is essential. In a review of the legal
ramifications of missed phenylketonuria (PKU) screening cases, nearly 30% resulted in litigation, usually against the infant’s physician and/or the state (33). This experience may be seen as a warning and impetus to establish careful quality assurance mechanisms for follow-up in hearing screening programs. A second program issue is the cost of universal screening associated with a high rate of false-positive screening tests (4%) for the yield of 0.01%– 0.03% true positive tests among healthy newborns. The expenses include not only repeating the screening test, which is commonly done if the infant “fails” the TEOAE due to vernix in the ear canal (13), but the administrative follow-up, reporting, and handling of hundreds of healthy infants to finally identify one with a true hearing loss. In addition, the cost of parental anxiety from a false positive report has been cited (19,34). A recent report based on interviews with parents, however, found those parents whose infants faced retesting did not have significantly more anxiety than a control group of parents whose infants had not had any auditory screening (35). The standard approach to estimating screening test costs is to determine the cost per “case” detected. Two state newborn hearing programs have recently published this cost data. In Hawaii’s experience of screening 10,300 newborns over 5 years, 15 infants or 1.5/1000 were identified with bilateral hearing loss (20). The cost per case identified was $17,750. The cost per child screened was $17. In comparison, Hawaii’s screening program for PKU, (estimated U.S. prevalence of this disorder is 1/12,000 newborns) (30), the cost per infant screened ranged from $17–$50. Colorado’s costs for auditory evaluation were $25 per infant screened, and $9,600 per case detected. Colorado’s cost per case detected for PKU was $40,000 (23). The authors of this report also project that a universal screening program would begin to save a state money by its third year. This estimate assumes that unscreened infants are usually not identified until their second year. True savings would be the avoidable costs of late identification and interventions, the “imperfect recovery of language losses,” and costs of special education (23) that have been shown to be reduced by two thirds for children who have had early and sustained treatment prior to starting school (36). A recent report compares costs for the first time of A-ABR, TEOAE, and a “two-step” program (TEOAE followed by A-ABR re-screen for positive TEOAE results). Sponsored by the manufacturer of a popular A-ABR device, the study used data from five sites and 12,081 newborns to calculate the costs for a hypothetical program screening 1,500 infants a year. Interestingly, costs of the three screening methods were nearly identical. The cost per confirmed case of hearing loss ranged from $14,347 for TEOAE to $16,527 for a two-step program. The cost per infant screened ranged only from
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$29 to $33 (37). Although the actual costs for a screening program appear reasonable, states face a vast array of competing health needs and must choose which ones will be funded and to what extent. In the case of universal newborn hearing, federal appropriation of funds in the FY 2000 budget ear-marked for state program development promises to make this choice attractive and feasible. The third concern about universal auditory screening is that it may have emerged merely because of fascination with new technology, or perhaps from a combination of technology’s allure with advocacy by interest groups. One commentator offering a plea for caution in the face of the relentless march of technology points out that as tests become more readily available, pressures for testing can be expected from people with an interest in those diseases because the “technological and political imperatives are linked” (38). In this case, new technology does offer unequivocal advantages over the old behavioral test method. The “people with an interest” is the audiology community, recently joined by the AAP. These two professional groups form a powerful coalition that at least one critic finds is prematurely propelling the widespread implementation of universal screening (34). The combination of innovative technology, an interested community, and the successful passage of federal legislation makes universal newborn auditory screening highly likely, if not inevitable. IMPLICATIONS FOR MIDWIFERY
One of the hallmarks of midwifery practice is prudently applying technology based on the best available evidence of efficacy and safety (39). In the case of biophysical auditory screening, the substantial evidence of efficacy and safety should encourage midwives to consider including it as part of newborn assessment. Practice issues related to this screening test would include educating parents, obtaining consent, clarifying responsibility for test performance, communicating results, handling falsepositive tests, and establishing insurance reimbursement. Providing prospective parents with educational materials on congenital hearing loss and screening is made easy with the abundance of consumer literature available from such organizations as ASHA. Written consent for testing is only necessary in states with mandated programs. Where testing is not legally mandated, parents have the right to decline the test, even if the hospital where the infant is born has adopted screening as standard care (40). In that case, written documentation of refusal should be obtained. In states with legally mandated programs, clinicians must know the legal grounds, such as religious objections, for refusing this test. For midwifery practices using large or urban hospitals for birth and newborn care, auditory screening may be
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standard nursery care along with screening for inherited metabolic diseases. In that case, auditory testing would be performed by designated staff overseen by an audiologist and the results recorded in the infant’s chart. On the other hand, small or rural hospitals or birth centers where few births occur (less than 100 per year) would probably not have audiology services. In that case, midwives in states with mandated universal screening should turn to the state health department for information on pediatric audiology services in their locale. Establishing a clear mechanism for communicating test results to the midwifery practice is essential, whether or not the state has mandated screening. Equally important is clarifying who is responsible to follow-up positive screening tests—a hospital staff member, the midwifery practice, or a state agency, and which audiology services will handle interventions. Perhaps the most cumbersome feature of any screening program is handling false-positive results. In a midwifery practice with 500 births a year, only one to two infants a year would be expected to have a hearing impairment. If the practice adopted universal biophysical screening, using the AAP’s target false-positive test rate of 4%, 20 out of 500 newborns each year would “fail” the screening and need follow-up and a second test. Although no long term negative consequences appear to result from false positive tests for parents, midwives and other providers of newborn care would need to support parents while they await the definitive diagnostic testing that will, in almost all cases, demonstrate that their new child has normal auditory function. This “cost” will need to be considered and weighed against the benefit of detecting one child in five hundred who stands to gain normal hearing and speech with early detection. In states without mandated screening, midwives would have the latitude to collaborate with their community’s pediatric or audiology colleagues to design a program suited to their practices. The following are several alternative approaches to physiologic hearing screening: 1. Continue with behavioral screening 2. Inform parents about physiologic screening, local audiology services that offer the test and estimated charges 3. Establish a referral system for all newborns in the practice to one or more pediatric audiology providers for screening and diagnostic evaluation as needed. 4. Contract with an audiology practice to come to the birth center, home, or hospital on a case by case basis to screen either all newborns or those whose parents desire the test. CONCLUSION
Although congenital hearing impairment occurs infrequently, if not detected within the first 6 months of life,
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the consequences can be permanent and profound. The advent of technologic methods to easily evaluate the auditory function of newborns offers the reasonable possibility of screening all newborns. Data from a few states that have had such programs for nearly a decade offer evidence of logistic problems and solutions, and demonstrate that the cost per case identified is far lower than for identifying inborn errors of metabolism. Endorsement of universal newborn hearing screening by the AAP as well as federally appropriated funding provided for FY 2000 –2003 to support state programs means this screening will become the standard of care. At present, midwives practicing in states with mandatory newborn hearing screening need to ensure that their newborn care complies with state guidelines. Midwives in other states have a wide array of choices regarding newborn auditory system assessment.
REFERENCES 1. Downs M. Introduction. In: Hayes D, Northern JL. Infants and hearing. San Diego: Singular Publishing Group, 1996:xi–xiii. 2. American Academy of Pediatrics Task Force on Newborn and Infant Hearing. Newborn and infant hearing loss: detection and intervention. Pediatr 1999;103:527–30. 3. National Institutes of Health. Early identification of hearing impairment in infants and young children. NIH Consensus Statement 1993;11: 1–24. 4. U.S. Department of Health and Human Services Public Health Service. Healthy people 2000. Washington (DC): U.S. Government Printing Office, 1990. 5. American College of Nurse-Midwives. The ACNM core competencies for basic midwifery practice. Washington (DC): ACNM, 1997. 6. Kenner C, Brueggemeyer A, Gunderson L. Physical examination of the newborn. In: Comprehensive neonatal nursing: a physiological perspective. Philadelphia: Saunders, editor. 1993:288. 7. Avery G, Fletcher M, MacDonald M. Neonatology pathophysiology and management of the newborn, 4th ed. Philadelphia: Lippincott, 1994: 277. 8. Hayes D, Northern JL. Infants and hearing. San Diego: Singular Publishing Group, 1996:224. 9. Lee KJ. Anatomy of the ear. In: Lee KJ, editor. Essential otolaryngology head and neck surgery. Stamford (CT): Appleton & Lange, 1999: 11–22.
and treatment of hereditary hearing loss. Pediatr Clin North Amer 1999; 46:35– 48. 16. Ramsey MEB, Miller E, Peckham CS. Outcome of confirmed symptomatic congenital cytomegalovirus infection. Arch Dis Child 1991;66: 1068 –9. 17. Fowler KB, McCollister FP, Dahle AJ, Boppana S, Britt WJ, Pass RF. Progressive and fluctuating sensorineural hearing loss in children with asymptomatic congenital cytomegalovirus infection. J Pediatr 1997;130: 624 –30. 18. Rozien NJ. Etiology of hearing loss in children nongenetic causes. Pediatr Clin North Amer 1999;46:49 – 64. 19. Stein L. Factors influencing the efficacy of universal newborn hearing screening. Pediatr Clin North Amer 1999;46:95–105. 20. Mason JA, Herrmann KR. Universal infant hearing screening by automated auditory brainstem response measurement. Pediatr 1998;101: 221– 8. 21. Folsom RC, Diefendorf AO. Physiologic and behavioral approaches to pediatric hearing assessment. Pediatr Clin North Amer 1999;46:107–20. 22. Nemes J. Universal newborn hearing screening: the question is, not if, but when? Hear J 1998;51:21–30, 69. 23. Mehl AL, Thomson V. Newborn hearing screening: the great omission. Pediatr 1998;101. Available at: http://www.pediatrics.org/cgi/content/full/101/1/e4. Accessed November 14, 1999. 24. Johnson JL, Kuntz NL, Sia CC, White KR, Johnson RL. Newborn hearing screening in Hawaii. Hawaii Med J 1997;56:352–5. 25. Vohr BR, Darty LM, Moore PE, Letourneau K. The Rhode Island Hearing Assessment Program: experiences with statewide hearing screening (1993–1996). J Pediatr 1998;133:353–7. 26. Finitzo T, Crumbley WG. The role of the pediatrician in hearing loss: from detection to connection. Pediatr Clin North Amer 1996;46:15– 34. 27. Hayes D, Northern JL. Infants and hearing,8 1–27. 28. Hayes D, Northern JL. Infants and hearing,8 Appendix D, 349. 29. Joint Committee on Infant Hearing. Joint committee on infant hearing 1994 position statement. Pediatr 1995;95:152– 6. 30. U.S. Preventive Services Task Force. Guide to clinical preventive services, 2nd ed. Baltimore: Williams and Wilkins, 1996. 31. Yoshinaga-Itano C, Sedey AL, Coulter DK, Mehl MD. Language of early- and later-identified children with hearing loss. Pediatr 1998;102: 1161–71. 32. National Center for Hearing Assessment and Management. Available at: http://www.infanthearing.org.home page. Accessed January 3, 2000. 33. Tharpe AM, Clayton EW. Newborn hearing screening: issues in legal liability and quality assurance. A J Audiology 1997;6:5–12. 34. Paradise JL. Commentary: universal newborn screening: should we leap before we look? Pediatr 1999;103:670 –2.
10. Sininger YS, Doyle KJ, Moore JK. The case for early identification of hearing loss in children. Pediatr Clin North Amer 1999;46:1–14.
35. Watkin PM, Baldwin M, Dixon R, Beckman A. Maternal anxiety and attitudes to universal neonatal screening. Br J Audiol 1998;32:27–37.
11. Peck JE, Lee KJ. Audiology. In: Lee KJ, editor. Essential otolaryngology head and neck surgery. Stamford (CT): Appleton & Lange, 1999: 25– 6.
36. Executive Board of the Educational Audiology Association. Letter to the editor. Pediatr 1994;94:957.
12. Tharpe AM, Bess FH. Minimal, progressive, and fluctuating hearing losses in children: characteristics, identification, and management. Pediatr Clin North Amer 1999;46:65–78. 13. Maxon AB, White KR, Behrens TR, Vohr BR. Referral rates and cost efficiency in a universal newborn hearing screening program using transient evoked otoacoustic emissions. J Am Acad Audiol 1995;6:271–7. 14. Bess FH, Dodd-Murphy J, Parker RA. Children with minimal sensorineural hearing loss: prevalence, educational performance, and functional status. Ear and Hearing 1998;19:339 –54. 15. Tomaski SM, Grundfast KM. A stepwise approach to the diagnosis
37. Vohr B, Oh W, Stewart EJ, Bentkover JD, Gabbard S, Lemons J, et al. An economic evaluation of infant hearing screening methods. American Academy of Pediatrics National Convention, October 1999. 38. Holtzman NA. What drives neonatal screening programs: a response. New Engl J Med 1992;326:495. 39. Gregor CL, Krebs JM. Fetal assessment. In: Varney H. Varney’s midwifery, 3rd ed. Boston: Jones and Bartlett, 1997:283. 40. Health Resources and Services Administration, Department of Health and Human Services. Early identification of hearing loss implementing universal newborn hearing screening programs. Rockville MD: Health Resources and Services Administration, 1999.
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APPENDIX A TERMINOLOGY DESCRIBING HEARING FUNCTION (11)
Intensity: The strength of a sound, its loudness. Decibel: Named for Alexander Graham Bell, it is the unit to measure loudness abbreviated as dB. It is a scale that compares a sound’s loudness to a reference level such as “hearing level.”
Hearing level (HL): a reference for measuring hearing function; for example, 0 dB hearing level is the least loud sound at any frequency needed for a normal ear to perceive that sound 50% of the time. Binaural: both ears, bilateral.
Frequency: Number of oscillations of a vibrating body per unit of time; the oscillations are perceived as pitch of a sound, as in music, the different notes such as A or G.
Deaf: profound sensorineural hearing loss greater than 90 dB HL and for whom hearing is impossible even with a hearing aid.
Hertz: The unit to measure frequency; the human ear can detect the range from 20 to 20,000 Hz; human perception of a 250 Hz sound must be transmitted at 26 dB of loudness to be heard.
Hard of hearing: wide range of hearing ability between normal and deaf. Hearing impaired: refers to any hearing loss.
APPENDIX B SELECTED RESOURCES ON NEWBORN HEARING SCREENING PUBLICATION
Early Identification of Hearing Loss: Implementing Universal Newborn Hearing Screening Programs National Maternal and Child Health Clearinghouse 2070 Chain Bridge Rd Suite 450 Vienna, VA 22182-2536 Phone: 888-434-4624 E-mail: [email protected] Published in 1999, this free, 34 page booklet provides brief explanations of 13 key activities for program implementation; order by toll-free phone or e-mail; text can be downloaded; see NCHAM information below
WEB SITES/ORGANIZATIONS
American Speech-Language-Hearing (ASHA) 10801 Rockville Pk. Rockville, MD 20852 Phone: 800-498-2071 URL: http://www.ASHA.org
Association
The professional and scientific association for 96,000 members of a variety of professions in the United States and internationally concerned with hearing and speech. See the web site “special section,” Infant Hearing for complete information on status of state legislation for universal screening: www.asha.org/ infant-hearing/bill-status.html#wy.
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Centers for Disease Control and Prevention Early Hearing Detection and Intervention Program (EHDI) 1600 Clifton Rd. Atlanta, GA 30333 Main phone: 404-639-3311 URL: http://:www.cdc.gov/nceh/programs/cddh/ehdi.htm This program collaborates with federal and state initiatives to develop and implement programs, data and surveillance systems, and outcome research; consumer education materials as well as transcriptions of bimonthly teleconferences on scientific topics since 1997 are available at this site
Marion Downs Center for Infant Hearing University of Colorado at Boulder Campus Box 409 Boulder, CO 80309-0409 Phone: 303-492-6283 URL:http://www.Colorado.EDU/slhs/mdnc Operating under a federal grant from the U.S. Public Health Service, the Center coordinates the implementation of universal newborn hearing screening, diagnosis and intervention programs in 17 states. The Center’s primary goal is to establish universal screening (85% of births) in the 17 states by the year 2000. The web site includes detailed state program reports as well as resources and recommendations for program development.
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National Center for Hearing Assessment and Management (NCHAM) Utah State University 2880 Old Main Hill Logan, UT 84322 Phone: 435-797-3589 URL: http://www.infanthearing.org
Begun in 1995, this organization’s goal is to promote the earliest possible identification and management of hearing loss. Activities include conducting research, developing training materials, providing technical assistance that includes software for screening programs and loan of equipment to institutions starting screening programs. Funding is a combination of public and private sources.
APPENDIX C MINIMUM COMPONENTS FOR A STATE UNIVERSAL NEWBORN HEARING SCREENING PROGRAM
1. 85% of children born in the state should be screened 2. Audiologists should be able to participate in the programs and to train and supervise technicians who may perform the screenings. 3. Screening methodology should include auditory brain stem response, otoacoustic emissions, or other objective physiological measures. 4. Screening should be completed no later than 3 months after birth; intervention should be as soon as possible but no later than 6 months after birth. 5. Medicaid and all insurance policies issued in the state should be required to include coverage for screening and follow-up care.
6. Each state should set up an advisory board to advise the state secretary of health and/or education. It should have audiologists, speech-language pathologists, parents, and adult consumers represented. 7. Information collected for tracking purposes should be kept confidential and used only as needed for the intent of the tracking system.
Used with permission from: The American SpeechLanguage-Hearing Association “Leader” April 27, 1999. Available at: http://www.ASHA.org. Accessed November 22, 1999.
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