Incidence and Program Development

Significant hearing loss occurs in approximately 1 to 3 per 1000 newborns with higher rates occurring in neonatal intensive care unit patients. The incidence quadruples by 16 years of age owing to late-onset and progressive conditions. Thus, hearing loss is among the most common birth conditions, but is difficult to recognize without objective testing. Parents and professionals are poor judges of the degree of hearing loss in infants while waiting for signs of speech and language deficits may delay identification for several years. Although some patients have recognizable syndromes or malformations, many children with hearing loss have no distinguishing features. Before the advent of routine hearing screening, a high-risk registry was used to select patients for further testing ( Box 1 ). Unfortunately, the use of the high-risk registry still missed about one half of the patients with congenital hearing loss. With the implementation of universal hearing screening the age of identification of hearing loss improved from 30 to 6 months. In terms of childhood development and plasticity of the developing auditory cortex, the importance of screening and early intervention to improve long-term outcomes is clear.

Objective hearing screening tools have made routine infant screening a realistic possibility. Infant hearing screening is now recommended by the American Academy of Pediatrics, the American Academy of Otolaryngology Head and Neck Surgery, and the American Speech-Hearing-Language Association. Healthy People 2010 and the Joint Commission on Infant Hearing recommend that all babies be screened by 1 month of age. Secondary diagnostic testing for infants who do not pass their hearing screen must be complete by 3 months of age. For infants identified as deaf or hard of hearing, early intervention should be implemented by 6 months of age. This timeline of identification to management is commonly referred to as the “1-3-6” guideline, and is an important initiative in infant hearing screening and intervention programs.

Screening Tools

The 2 commonly used methods for infant hearing screenings are automated otoacoustic emissions (OAE) or automated acoustic brainstem response (AABR) systems ( Table 1 ). Both tools allow for quick, cost-effective screening in the newborn nursery by easily trained technicians. One or both systems may be used to assess a newborn. OAE takes less time to complete than AABR, but may not pass as many babies on the first attempt. OAEs are more sensitive to external ear canal obstruction and middle ear effusions, and may not pass in infants with what could be temporary conductive hearing loss. OAEs do not measure the integrity of the VIIIth nerve or auditory brainstem pathways, and therefore may miss auditory neuropathy. AABR measures the integrity of the cochlea, auditory nerve, and brainstem, and is highly correlated with hearing sensitivity in the 1000 to 8000 Hz range. AABR may take slightly longer and have a higher cost than OAE, but this is matched with a slightly higher pass rate.

Many hospitals employ a 2-tiered hearing screening system, using both OAE and AABR as needed. However, infants in the neonatal intensive care unit should always be tested with AABR because of their increased risk of sensorineural hearing loss and auditory neuropathy. Rescreening is commonly recommended within 1 month, especially if the infant initially underwent OAE and did not pass. In comparison with 1-step OAE to 2-step OAE and AABR programs, the latter has been shown to decrease the audiology referral rate from 5.8% to 1.8%. No significant difference was noted between the 2 methods in terms of the accuracy and identification rates of congenital hearing loss. The total costs (including expenditures and intangible costs) were also lower in the protocol with OAE plus AABR. Infants should be referred for diagnostic testing after no more than 2 to 3 screening tests are not passed. Repeated hearing screens delays definitive diagnostic testing, and can add to cost, inconvenience, and anxiety for families. Benchmarks for hearing screening programs in birthing hospitals include screening a minimum of 95% of infants before 1 month of age, and maintaining a referral rate for diagnostic testing of less than 4%.

Diagnostic Testing

Diagnostic hearing testing is conducted by audiologists with experience in infant hearing loss and should be completed by 3 months of age. A comprehensive test battery includes evaluating the child and taking a complete family history, as well as an electrophysiologic measure of hearing threshold OAEs (such as ABR using frequency-specific stimuli), and a measure of middle ear function, including frequency appropriate tympanograms, bone conduction ABR, and/or pneumatic otoscopy. The cross-check principle applies to older infants and children, using visual reinforcement audiometry, otoacoustic emissions, and tympanometry to most effectively determine the degree, type, and configuration of hearing loss. Diagnostic ABR is often performed under natural sleep in infants under 6 months of age, but sometimes requires sedation. ABR testing allows for testing across many hearing frequencies and levels, and differentiation of conductive from sensorineural hearing loss. This test may take up to an hour or more to complete, but provides the audiologist enough information to fit most infants with appropriate hearing aids. In a recent study, 68% of infants referred for diagnostic testing were confirmed to have permanent hearing loss. Bilateral hearing loss was found in 58.6% of patients and unilateral in 41.4% with severe median thresholds in both unilateral and bilateral cases.

Owing to the duration of infant hearing tests, some infants require sedation. Thus, the ability to offer sedation for infants for hearing testing is an important component of hearing screening systems. If required, sedation should be performed by qualified practitioners who are not conducting the diagnostic test(s). Sedation in infants may require the use of an anesthesiologist with close monitoring and the ability to manage and rescue patients from deep sedation. Audiology practices differ in their ability to perform diagnostic tests for infants, and prolonged waits for an appointment or testing are challenges in some regions. To optimize the referral process for primary care providers, a national database called EHDI Pediatric Audiology Links to Services is being implemented. This database allows practitioners to search for pediatric audiology services, and includes a description of the types of testing and interventions available at each clinic. The referring physician can thereby match each patient with the appropriate audiologic service.

Follow-up Challenges

More than 98% of infants born in the United States are now screened for hearing loss. All states now offer routine screening and many require it by law. A variety of different protocols have been mandated or implemented, but in general families are informed of their infant’s screening results, and provided information necessary for appropriate follow-up. The state health department is typically notified of screening results to track and help manage patients until diagnosis and intervention are complete. However, many challenges exist in the process ( Box 2 ). One of the most common problems is that many patients do not return for diagnostic testing and intervention. Loss to follow-up rates exceed 70% in some regions despite multiple attempts to address the problem. Maternal sociodemographic features (poor, non-white, young) and access issues have been considered primary factors for lack of follow-up. However, 1 recent review found 2 program characteristics to be most important for poor follow-up: The lack of prenatal education about newborn hearing screening and the lack of hospital hearing information functionally integrated with Public Health.

Primary care providers may not have readily available hearing screening results, and may not be aware of the need to refer to specialty services. There remains a need to improve infrastructure for pediatric primary care providers to receive and request infant hearing screening results, facilitate reporting, and coordinate follow-up services for infants identified with hearing loss. Lack of available audiology resources has also been shown to delay testing and early intervention. Lack of early intervention has been documented in up to 30% of patients known to be deaf or hard of hearing. Strategies implemented to decrease the lost to follow-up rate include providing families with good documentation, educating families and caregivers regarding the importance of diagnostic testing and intervention, working with primary care providers to identify and refer appropriate patients, and improving state-based tracking and referral services. Despite these efforts, many patients are still not diagnosed on a timely basis.

Incidence and Program Development

Significant hearing loss occurs in approximately 1 to 3 per 1000 newborns with higher rates occurring in neonatal intensive care unit patients. The incidence quadruples by 16 years of age owing to late-onset and progressive conditions. Thus, hearing loss is among the most common birth conditions, but is difficult to recognize without objective testing. Parents and professionals are poor judges of the degree of hearing loss in infants while waiting for signs of speech and language deficits may delay identification for several years. Although some patients have recognizable syndromes or malformations, many children with hearing loss have no distinguishing features. Before the advent of routine hearing screening, a high-risk registry was used to select patients for further testing ( Box 1 ). Unfortunately, the use of the high-risk registry still missed about one half of the patients with congenital hearing loss. With the implementation of universal hearing screening the age of identification of hearing loss improved from 30 to 6 months. In terms of childhood development and plasticity of the developing auditory cortex, the importance of screening and early intervention to improve long-term outcomes is clear.

Objective hearing screening tools have made routine infant screening a realistic possibility. Infant hearing screening is now recommended by the American Academy of Pediatrics, the American Academy of Otolaryngology Head and Neck Surgery, and the American Speech-Hearing-Language Association. Healthy People 2010 and the Joint Commission on Infant Hearing recommend that all babies be screened by 1 month of age. Secondary diagnostic testing for infants who do not pass their hearing screen must be complete by 3 months of age. For infants identified as deaf or hard of hearing, early intervention should be implemented by 6 months of age. This timeline of identification to management is commonly referred to as the “1-3-6” guideline, and is an important initiative in infant hearing screening and intervention programs.

Screening Tools

The 2 commonly used methods for infant hearing screenings are automated otoacoustic emissions (OAE) or automated acoustic brainstem response (AABR) systems ( Table 1 ). Both tools allow for quick, cost-effective screening in the newborn nursery by easily trained technicians. One or both systems may be used to assess a newborn. OAE takes less time to complete than AABR, but may not pass as many babies on the first attempt. OAEs are more sensitive to external ear canal obstruction and middle ear effusions, and may not pass in infants with what could be temporary conductive hearing loss. OAEs do not measure the integrity of the VIIIth nerve or auditory brainstem pathways, and therefore may miss auditory neuropathy. AABR measures the integrity of the cochlea, auditory nerve, and brainstem, and is highly correlated with hearing sensitivity in the 1000 to 8000 Hz range. AABR may take slightly longer and have a higher cost than OAE, but this is matched with a slightly higher pass rate.

Many hospitals employ a 2-tiered hearing screening system, using both OAE and AABR as needed. However, infants in the neonatal intensive care unit should always be tested with AABR because of their increased risk of sensorineural hearing loss and auditory neuropathy. Rescreening is commonly recommended within 1 month, especially if the infant initially underwent OAE and did not pass. In comparison with 1-step OAE to 2-step OAE and AABR programs, the latter has been shown to decrease the audiology referral rate from 5.8% to 1.8%. No significant difference was noted between the 2 methods in terms of the accuracy and identification rates of congenital hearing loss. The total costs (including expenditures and intangible costs) were also lower in the protocol with OAE plus AABR. Infants should be referred for diagnostic testing after no more than 2 to 3 screening tests are not passed. Repeated hearing screens delays definitive diagnostic testing, and can add to cost, inconvenience, and anxiety for families. Benchmarks for hearing screening programs in birthing hospitals include screening a minimum of 95% of infants before 1 month of age, and maintaining a referral rate for diagnostic testing of less than 4%.

Diagnostic Testing

Diagnostic hearing testing is conducted by audiologists with experience in infant hearing loss and should be completed by 3 months of age. A comprehensive test battery includes evaluating the child and taking a complete family history, as well as an electrophysiologic measure of hearing threshold OAEs (such as ABR using frequency-specific stimuli), and a measure of middle ear function, including frequency appropriate tympanograms, bone conduction ABR, and/or pneumatic otoscopy. The cross-check principle applies to older infants and children, using visual reinforcement audiometry, otoacoustic emissions, and tympanometry to most effectively determine the degree, type, and configuration of hearing loss. Diagnostic ABR is often performed under natural sleep in infants under 6 months of age, but sometimes requires sedation. ABR testing allows for testing across many hearing frequencies and levels, and differentiation of conductive from sensorineural hearing loss. This test may take up to an hour or more to complete, but provides the audiologist enough information to fit most infants with appropriate hearing aids. In a recent study, 68% of infants referred for diagnostic testing were confirmed to have permanent hearing loss. Bilateral hearing loss was found in 58.6% of patients and unilateral in 41.4% with severe median thresholds in both unilateral and bilateral cases.

Owing to the duration of infant hearing tests, some infants require sedation. Thus, the ability to offer sedation for infants for hearing testing is an important component of hearing screening systems. If required, sedation should be performed by qualified practitioners who are not conducting the diagnostic test(s). Sedation in infants may require the use of an anesthesiologist with close monitoring and the ability to manage and rescue patients from deep sedation. Audiology practices differ in their ability to perform diagnostic tests for infants, and prolonged waits for an appointment or testing are challenges in some regions. To optimize the referral process for primary care providers, a national database called EHDI Pediatric Audiology Links to Services is being implemented. This database allows practitioners to search for pediatric audiology services, and includes a description of the types of testing and interventions available at each clinic. The referring physician can thereby match each patient with the appropriate audiologic service.

Follow-up Challenges

More than 98% of infants born in the United States are now screened for hearing loss. All states now offer routine screening and many require it by law. A variety of different protocols have been mandated or implemented, but in general families are informed of their infant’s screening results, and provided information necessary for appropriate follow-up. The state health department is typically notified of screening results to track and help manage patients until diagnosis and intervention are complete. However, many challenges exist in the process ( Box 2 ). One of the most common problems is that many patients do not return for diagnostic testing and intervention. Loss to follow-up rates exceed 70% in some regions despite multiple attempts to address the problem. Maternal sociodemographic features (poor, non-white, young) and access issues have been considered primary factors for lack of follow-up. However, 1 recent review found 2 program characteristics to be most important for poor follow-up: The lack of prenatal education about newborn hearing screening and the lack of hospital hearing information functionally integrated with Public Health.

Box 2

• 
  

  Nonhospitalized births

  
  
• 
  

  Small hospitals without a screening program

  
  
• 
  

  Lack of or unavailable screening resources

  
  
• 
  

  Lack of screening failure follow-up

  
  
• 
  

  Overuse of repeat screens

  
  
• 
  

  Loss to follow-up

  
  
• 
  

  Lack of physician recognition of loss to follow-up

  
  
• 
  

  Lack of referral for definitive testing

  
  
• 
  

  Insufficient clinical resources for diagnostic testing

  
  
• 
  

  Insufficient resources for amplification

  
  
• 
  

  Lack of early intervention

  
  
• 
  

  Lack of long-term follow-up

  
  
• 
  

  Lack of rescreening for high-risk infants

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