In children, conductive hearing loss occurs when there is a decrease in the transmission of sound waves from the external environment to the cochlea or inner ear The most common cause of conductive hearing loss involves an acute or chronic middle ear effusion from an otitis media (OM) Other common causes of acquired conductive hearing loss include impacted cerumen, foreign body of the external ear canal, and infections of the external ear canal (otitis externa) Less commonly, fixation or disruption of the middle ear ossicles may cause conductive hearing loss ( Table 34.1 ) In children with chronic recurrent/OM, a cholesteatoma—an epidermal inclusion cyst of the middle ear—may develop and cause a slowly progressive conductive hearing loss Acute head injury, especially in association with a basilar skull fracture, may produce a conductive hearing loss caused by hemotympanum, rupture of the tympanic membrane, or disruption of the inner ear ossicle Perforation of the tympanic membrane can occur from a self-inflicted injury from a cleaning device such as a cotton swab Rarely, the conductive hearing loss may be related to congenital malformations of the external or middle ear Congenital Sensorineural Hearing Loss Approximately 1.4 in 1,000 infants are born with congenital hearing loss Diagnostic possibilities include genetic disorders, chromosomal abnormalities, metabolic and storage diseases, and abnormal development of the auditory apparatus ( Table 34.1 ) Roughly 50% of cases of congenital sensorineural hearing loss can be linked to a genetic cause, with approximately 30% of these considered syndromic Sensorineural hearing loss has been described in more than 300 syndromes, including Branchio-Oto-Renal (BOR) syndrome (auricular malformations, renal anomalies), CHARGE syndrome (Coloboma, Heart defects, Atresia of the choanae, Retarded growth and development, Genital hypoplasia, and Ear anomalies), Waardenburg syndrome (facial dysmorphism, white forelock), Jervell and Lange-Nielsen syndrome (prolonged Q-T syndrome), Usher syndrome (retinitis pigmentosa and sensorineural hearing loss) as well as the chromosomal disorders caused by trisomies (especially trisomies 13 to 15, 18, and 21) Many of these patients are diagnosed because of anatomic features associated with the specific disorder, although the hearing loss may be present at birth or may develop over time Acquired Sensorineural Hearing Loss Although acquired sensorineural hearing loss occurs less commonly than congenital sensorineural hearing loss, the absence of associated symptoms may make it a more difficult diagnosis Acquired forms of sensorineural hearing loss