• Conductive hearing loss results from an obstruction of the air conduction pathway in the outer or middle ear.
• Sensorineural hearing loss results from a defect in the cochlea or auditory nerve.
• Both forms of hearing loss may be congenital or acquired.
• The American Academy of Pediatrics recommends universal newborn hearing screening (UNHS) for all infants for the following reasons:
• Hearing loss in infants is not readily detectable by routine clinical observation.
• Screening programs based on the presence of risk factors or family history will miss up to 50% of children with hearing loss because these children lack identifiable risk factors.
• Infants identified before age 6 months demonstrate better language development than those identified later.
• Screening should be completed during the hospital birth admission; before discharge from the neonatal intensive care unit; or for alternative birth locations, such as home births before 1 month of age.
• When UNHS is not available, infants with the following risk factors should be screened before 1 month of age:
• Stay in neonatal intensive care unit of 48 hours or more.
• Stigmata or other findings associated with syndrome known to include hearing loss.
• Family history of permanent childhood hearing loss.
• Craniofacial anomalies, including abnormalities of the pinna and ear canal.
• In utero infections associated with hearing loss, including cytomegalovirus (CMV), herpes, toxoplasmosis, or rubella.
• Children with the following risk factors for progressive or delayed-onset hearing loss should be tested every 6 months until at least 3 years of age, even if they passed the newborn screening:
• Parental or caregiver concern regarding hearing, speech, language, or developmental delay.
• Family history of permanent childhood hearing loss.
• Stigmata or other findings associated with a syndrome known to include hearing loss or eustachian tube dysfunction.
• Postnatal infections associated with hearing loss, including bacterial meningitis.
• In utero infections, such as CMV, herpes, toxoplasmosis, rubella, and syphilis.
• Neonatal indicators including hyperbilirubinemia requiring exchange transfusion, persistent pulmonary hypertension of the newborn associated with mechanical ventilation, and conditions requiring extracorporeal membrane oxygenation (ECMO).
• Syndromes associated with progressive hearing loss, such as neurofibromatosis, osteopetrosis, and Usher syndrome.
• Neurodegenerative disorders, such as Hunter syndrome, or sensorimotor neuropathies, such as Friedreich ataxia and Charcot-Marie-Tooth disease.
• Head trauma.
• Recurrent or persistent otitis media with effusion for at least 3 months.
• The American Academy of Pediatrics recommends that all children receive hearing screening at their annual well-child visits:
• Age-appropriate objective testing at ages 4, 5, 6, 8, 10, 12, 15, and 18 years of age.
• Subjective evaluation by history at all other annual well-child visits.
• In addition to otoacoustic emissions, auditory brainstem response, and conventional pure tone audiometry, audiologists may use behavioral assessments.
• The external ear includes the external acoustic meatus to the tympanic membrane.
• The middle ear includes the tympanic cavity and ossicles (Figure 52–1).
• The inner ear includes the semicircular canals, vestibule, and cochlea.
• The hair cells are located in the spiral organ within the cochlea and connect to nerve fibers of the cochlear nerve.