Hearing loss in neonates and infants

Abstract

Hearing in neonates and infants is crucial for their development of language and communication skills. Unless hearing loss is appropriately managed early, it can cause a significant socioeconomic burden considering its detrimental impact on the child's development and its common nature. It is also the most common congenital sensory deficit, with an approximate incidence of 1.5 per 1,000 newborns. Its etiologies are heterogeneous: genetic causes are reportedly involved in up to 80% of cases, while congenital cytomegalovirus infection is the leading environmental factor contributing to congenital hearing loss. The introduction of newborn hearing screening using automated auditory brainstem response and/or automated otoacoustic emission in many developed countries has helped detect and manage hearing loss early. Current auditory rehabilitation options such as cochlear implantation implementing cutting-edge technologies can treat almost all degrees of hearing loss, emphasizing the importance of early hearing detection and intervention. Rapidly developing genetic diagnostic technologies and future cutting-edge treatment options, including gene therapy, will shed light on the future management of hearing loss in neonates and infants.

Keywords: Child development; Hearing loss; Infant; Newborn; State medicine.

Fig. 1.

Estimates of causes of deafness at birth and 4 years of age in the United States. The incidence of deafness at birth in the United States and its prevalence at 4 years of age were obtained by adjusting estimates from the United Kingdom to include unilateral hearing loss. EVA, enlarged vestibular aqueduct; CMV, cytomegalovirus. Reprinted from Morton and Nance. N Engl J Med 2006;354:2151-64, with permission of Massachusetts Medical Society [7].

Fig. 2.

Approximate causes of congenital hearing loss. Recent genetic studies suggest that up to 80% of congenital hearing loss cases in wealthy nations are genetically based. This figure was traditionally assumed to be around 50%. Environmental factors usually involve prenatal TORCH (toxoplasmosis, syphilis, rubella, cytomegalovirus, and herpes) infection or postnatal bacterial meningitis.

Fig. 3.

Well-baby newborn hearing screening protocol of the newborn nursery unit. This protocol applies to neonates born via an uncomplicated delivery who stayed less than 4 days in the neonatal intensive care unit. *Risk factors are described in Table 2. ABR, auditory brainstem response; NHS, newborn hearing screening. Adapted from Newborn hearing screening guideline update in Korea, 2018 by The Korean Audiological Society [37].

Fig. 4.

Neonatal intensive care unit (NICU) newborn hearing screening protocol. The corrected age is always used. Because a NICU admission longer than 5 days is already a high-risk factor for hearing loss, regular hearing tests are necessary for NICU babies. *Risk factors are described in Table 2. NICU, neonatal intensive care unit; AABR, automated auditory brainstem response; ABR, auditory brainstem response; AOAE, automated otoacoustic emission; NHS, newborn hearing screening. Adapted from Newborn hearing screening guideline update in Korea, 2018 by The Korean Audiological Society [37].

Fig. 5.

Newborn hearing screening protocol used in outpatient clinics. *Risk factors are described in Table 2. NICU, neonatal intensive care unit. Adapted from Newborn hearing screening guideline update in Korea, 2018 by The Korean Audiological Society [37].

Fig. 6.

Country-specific coverage of newborn and infant hearing screening programs. Adapted from Neumann et al. J Clin Med 2022;11:271 [40].