Hearing Loss · HL

Description

Newborn hearing loss is permanent congenital hearing loss identified by universal screening at birth. Roughly 1 to 3 in 1,000 newborns has permanent hearing loss in one or both ears at the population level, and the rate is higher in neonatal intensive care unit graduates. Causes are heterogeneous. Genetic causes account for about half of cases and are mostly nonsyndromic, with biallelic variants in GJB2, encoding the gap-junction protein connexin 26, the single most common cause in many populations. Other genetic causes include GJB6, SLC26A4 (Pendred syndrome), MYO7A and other Usher syndrome genes, OTOF (auditory neuropathy spectrum), and a long tail of additional genes. Acquired causes include congenital cytomegalovirus (CMV) infection, which is the leading nongenetic cause and often missed without targeted screening, prematurity, hyperbilirubinemia requiring exchange transfusion, ototoxic medication exposure, and bacterial meningitis.

Universal newborn hearing screening (UNHS) was added to the federal Recommended Uniform Screening Panel as part of the panel's earliest core conditions and is in place in every US state. Two physiologic methods are used. Otoacoustic emissions (OAE) testing measures cochlear outer hair cell response to sound. Automated auditory brainstem response (AABR) records electrical activity from the auditory nerve and brainstem. NICU babies are typically screened with AABR because OAE alone misses auditory neuropathy. Infants who do not pass the screen are referred for diagnostic audiology, ideally before three months of age, with intervention beginning before six months when indicated. This 1-3-6 benchmark is set by the Joint Committee on Infant Hearing.

Treatments to date

There is no drug therapy that restores hearing in congenital sensorineural loss as of 2026. Management is centered on access to language. Hearing aids are fit in infancy when residual hearing supports amplification. Cochlear implantation is offered to children with severe to profound sensorineural loss, with FDA-approved pediatric indications expanded across decades. Implantation between roughly 9 and 12 months of age, paired with structured auditory and language input, is associated with stronger spoken-language outcomes than later implantation in published cohorts. Bone-anchored hearing systems are an option for conductive or single-sided loss. American Sign Language and Deaf cultural community are a primary path for many families, and several pediatric audiology programs support bimodal language development.

Etiologic workup after a confirmed diagnosis usually includes targeted CMV PCR on newborn dried blood spot or saliva within the first three weeks of life, comprehensive genetic testing including a hearing-loss gene panel or exome, and imaging of the temporal bone when surgical management is being considered. Confirmed congenital CMV is sometimes treated with oral valganciclovir in symptomatic infants based on Kimberlin et al. (New England Journal of Medicine, 2015), which showed a hearing benefit at 24 months in symptomatic congenital CMV.

Gene therapy entered the clinic for OTOF-related auditory neuropathy. AAV-delivered OTOF gene therapy programs from multiple sponsors reported recovery of hearing in young children with biallelic OTOF variants in 2023 and 2024 trial readouts, including a Lancet report by Lv et al. (2024) on a Chinese pediatric cohort. The OTOF programs are the first published evidence that genetic deafness in humans can be reversed with a targeted molecular therapy. Programs targeting other deafness genes are in earlier development.