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Early Detection and Diagnosis of Infant Hearing Impairment


Key Points

  • Protocols for newborn hearing screening include a hearing screen by 1 month of age, diagnostic hearing testing in those who failed the hearing screen by 3 months of age, and early intervention for infants diagnosed with hearing loss by 6 months of age.

  • The most common causes of congenital hearing loss in infants without apparent risk factors are recessive genetic hearing loss and congenital human cytomegalovirus infection.

  • Hearing screening programs that use only evoked otoacoustic emissions will fail to identify children with auditory neuropathy.

  • Surveillance of hearing and speech and language status is essential for all children, whether the infant passed universal newborn hearing screening or not.

  • Not all conductive hearing losses are temporary or related to middle ear effusion. Some cases of conductive hearing loss will require early intervention.

  • Delayed diagnosis and intervention for hearing loss can lead to poor speech and language outcomes.

Acknowledgments

The author would like to acknowledge the help of Jill Boettger, Roger Faix, Stephanie McVicar, Lonnie Miner, Beth Knackstedt, Elizabeth O’Brien, Betsy Ostrander, Kayla Hirschmugl, and Lindsey Tubaugh.

Epidemiology of Hearing Loss

Neonatal hearing loss is very common. It is estimated to occur in 1 to 3 per 1000 newborns. Certain populations are at increased risk, including those with a family history of hearing loss, infants with perinatal infection, and those requiring a neonatal intensive care unit (NICU) stay. The rate of hearing loss in NICU patients is nearly double, at 2 to 4 per 1000. The World Health Organization estimates that 7.5 million children have a clinically significant hearing loss.

Status of Hearing Loss Diagnosis Before Universal Newborn Hearing Screening

Newborn hearing screening (NHS) is crucial for the early detection of hearing loss. Before universal NHS, only approximately 3% of infants in the United States were screened for hearing loss. Without screening, affected children might not be identified until delayed language development is noted; in milder cases of hearing loss, they may remain unidentified as late as school age. Studies have shown that earlier detection of hearing loss leads to earlier intervention, in turn improving patient outcomes.

Before the implementation of NHS, hearing screening involved a targeted approach based on the presence of risk factors for permanent hearing loss, including a family history of hearing loss, NICU stay greater than 5 days, certain in utero infections, craniofacial anomalies, syndromes known to include permanent hearing loss, neurodegenerative disorders, postnatal infections associated with hearing loss, head trauma, and chemotherapy. Subsequent investigation has shown that this approach identifies at most 50% of hearing loss.

History of Newborn Hearing Screening

The importance of hearing and its implications for speech and language development have been recognized on a national level in the United States since the late 1980s. During this decade, then U.S. Surgeon General Dr. C. Everett Koop recommended that the detection of hearing loss be made a priority for the “Healthy People 2000” national objectives. In that same decade, initiatives were introduced in Utah, Rhode Island, and Hawaii with a goal of statewide screening before neonatal hospital discharge. These pilot projects were designed to test the feasibility of expanding universal NHS to a national level.

Resistance to Newborn Hearing Screening

Perhaps not surprisingly, there was initial resistance to the implementation of universal NHS within the health care community. Some felt that it was not feasible, and others felt that it was not necessary to implement such a large-scale project. False-positive screen results were felt to be potentially harmful, and the upfront cost of this project was large, without a demonstrated benefit. Early results of statewide screening proved these concerns to be unfounded. False-positive rates, although initially as high at 6% to 10%, have decreased to a very acceptable 1% to 2% as screening methods have improved.

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